NL2029857B1

NL2029857B1 - Low pressure degassing device

Info

Publication number: NL2029857B1
Application number: NL2029857A
Authority: NL
Inventors: Henk Cnossen Jan
Original assignee: Flamco Bv
Priority date: 2021-11-22
Filing date: 2021-11-22
Publication date: 2023-06-13
Also published as: CN116867556A

Abstract

invention relates to a method for testing a degassing device for degassing a gas- containing liquid in a cooling or heating installation, the degassing device comprising: - a main flow channel wherein a main flow of liquid flows through the main flow channeL - at least one flow passage extending between the main flow channel and a degasification zone, - a degasification housing defining an inner volume, wherein the inner volume substantially corresponds to the degasification zone, - at least one valve, - a pressure reduction device connected to the degasification housing, - a pressure sensor configured to measure the pressure in the degasification zone, - a gas outlet in the degasification housing, the gas outlet comprising an outlet tube and an outlet closing body, wherein the outlet tube is closeable by the outlet closing body, - a control unit, comprising a first and/or a second test module, connected to the pressure sensor and configured to receive a pressure difference signal from the pressure sensor, wherein the method comprises the steps: a) closing the at least one valve and measuring a first pressure in the degasification housing with the pressure sensor, b) measuring a second pressure in the degasification housing with the pressure sensor after a period of time, c) comparing the second pressure with the first pressure by the control unit to determine a difference, wherein a difference signal is generated by the control unit when a difference between the first pressure and the second pressure is present.

Description

P34946NL0O1/WHA2/RSM2

Title: Low pressure degassing device

FIELD OF THE INVENTION

The invention relates to the field of degassing a gas-containing liquid in a cooling or heating installation and in particular to a device and a method for degassing the liquid.

BACKGROUND OF THE INVENTION

In the field of degassing liquids, various devices and methods exist.

US2011214571A1 discloses a degassing device that makes use of a vacuum chamber to locally reduce pressure in order to separate gasses from a liquid. The device comprises a channel through which the liquid flows, wherein the liquid also passes through a vacuum chamber. In this vacuum chamber, the main flow channel is delimited by a permeable region through which gasses may pass but the liquid may not.

Outside of this permeable region, an enclosure is located to which a vacuum pump is connected. This vacuum pump has been configured to create a continuous vacuum level in the enclosure in order for the liquid to degas. Further, a vent is connected to the enclosure to permit a venting flow to enter the vacuum chamber to reduce condensation within the enclosure.

In the present invention, it has been recognized that such a device presents several drawbacks. The use of a permeable region allows a certain amount of liquid to migrate into the enclosure causing contamination of the enclosure, and therewith contamination of the vacuum pump, and over time may reduce the amount of liquid in the main flow channel. Further, over time, the permeable region will also degrade due to a build-up of contaminants. This build-up prevents gas passing through, ultimately leading to degassing no longer being possible.

Also, because a continuous vacuum is required to operate the device, the device will likely consume a lot of energy. Further, a vent that feeds gas from the outside to the enclosure will only lead to the vacuum pump needing to work harder to maintain the desired vacuum level and consuming even more energy.

Additionally, a vacuum pump makes a lot of noise and a continuously operating pump even more so. This makes is less suitable for domestic applications.

EP3764001A1 discloses a device wherein a portion of a main flow is branched off through a bypass, flows through a venturi device and enters a degassing chamber. On another side of the degassing chamber, the branched off portion is returned to the main flow.

Additionally, a degassing conduit leads from a suction area to the bypass and joins the bypass in the venturi device. In this degassing conduit the pressure is lower than in the rest of the circuit because of the venturi device. The lower pressure causes the dissolved gasses to separate and the gases can then be evacuated through a ventilator in the degassing chamber.

A drawback of the device is that the liquid in the circuit must always be moving at a certain velocity to make the venturi device work by creating a pressure difference between the return flow and the branch flow. If the velocity is not sufficient an extra pump is needed to create the pressure difference. This results in either a not optimally working device or in an expensive device due to the need of an extra pump. Such a pump would also increase the energy consumption of the device.

Additionally, because the system is dependent on the velocity of the liquid in the circuit it may be difficult to control the pressures in the system and therewith the degassing process.

OBJECT OF THE INVENTION

It is an object of the invention to provide a device and a method for degassing a liquid and, in doing so, overcoming at least one of the abovementioned drawbacks.

SUMMARY OF THE INVENTION

In order to achieve the object, the present invention provides a degassing device for degassing a gas-containing liquid in a cooling or heating installation, the degassing device comprising: - a main flow channel defined by a tube extending between a first side and a second side, wherein in operation a main flow of liquid flows through the main flow channel, - at least one flow passage extending between the main flow channel and the degasification zone, the flow passage being configured to allow communication between the degasification zone and the main flow channel, - a degasification housing defining an inner volume, wherein the inner volume substantially corresponds to the degasification zone,

- at least one valve which is moveable between a closed position and an open position, wherein in the closed position the valve obstructs the flow passage and closes off the degasification zone from the main flow channel and wherein in the open position the valve does not obstruct the flow passage, - a pressure reduction device connected to the degasification housing, wherein during operation, the pressure reduction device is configured to lower the pressure in the degasification zone relative to the pressure in the main flow channel. - a gas outlet in the degasification housing, the gas outlet comprising an outlet tube and an outlet closing body, wherein the outlet tube is closeable by the outlet closing body, wherein the gas outlet and the at least one valve are configured to close the degasification housing and wherein the pressure reduction device is configured to degas the gas-containing liquid.

In an embodiment, the device comprises two flow passages, a first flow passage being a branch flow passage, the branch flow passage being configured to branch off a branch flow being a portion of the main flow, and a second flow passage being a return flow passage extending between the degasification zone and the main flow channel, the return flow channel being configured to return a return flow to the main flow.

By branching of a portion of a main flow of the cooling or heating installation and by obstructing the branch flow passage and/or the return flow passage, the pressure reduction device can reduce the pressure to which the branched off portion, i.e. the branch flow, is subjected. When the pressure is reduced to a level below the pressure inside the main flow channel, gasses that are dissolved in the liquid will become less soluble and will separate from the liquid. The gasses that have been separated from the liquid can then be removed from the degassing device before the liquid joins the main flow. In doing so, the amount of dissolved gasses in the liquid in the cooling or heating installation can be reduced.

In an embodiment, the degassing device may comprise a first valve which is moveable between a closed position and an open position, wherein in the closed position the first valve obstructs the branch flow passage and closes off the degasification zone from the main flow channel. A second valve which is moveable between a closed position and an open position may be used to obstruct the return flow passage to close off the degasification zone from the main flow channel.

By using two separate valves to be able to close off the branch flow passage and the return flow passage, the two valves may be placed at a distance from each other along the main flow. In doing so, the renewal of liquid in the degasification housing may be increased.

In an embodiment, the pressure reduction device is connected to the degasification housing and the pressure reduction device comprises a piston, a cylinder, and a piston actuator. The piston is moveable between an idle pressure position and a low pressure position and is in open communication with the inner volume. In the low pressure position of the piston the degasification zone extends into the cylinder and is larger than in the idle pressure position of the piston. Herein, the degasification zone is delimited by the degasification housing, and at least part of an outer surface of the piston and/or by at least a part of the inner surface of the cylinder. The piston actuator may be one of a mechanical actuator, electrical actuator, magnetic actuator, hydraulic actuator, and pneumatic actuator.

By moving the piston from the idle pressure position to the low pressure position, the degasification zone is pulled into the cylinder and becomes larger than in the idle pressure position of the housing. Because the volume of the degasification zone increases while the content of the degasification zone, i.e. the amount of liquid inside the degasification zone, remains substantially the same, the pressure to which the liquid in the degasification zone is subjected is reduced. The reduced pressure causes the liquid to degas.

In an embodiment, a retracted position of the piston corresponds to the low pressure position and an extended position of the piston corresponds to the idle pressure position.

Alternatively, the extended position of the piston corresponds to the low pressure position and the retracted position of the piston corresponds to the idle pressure position.

In the first case, the piston actuator will pull on the piston to move the piston to the low pressure position and in the second case, the piston actuator will push on the piston to move the piston to the low pressure position.

In an embodiment, the piston actuator is fixed to the degasification housing via one or more resilient members and the piston actuator is resiliently moveable between a first actuator position and a second actuator position.

The piston actuator may be fixed to the degasification housing via the one or more resilient member in order to be able to absorb mechanical vibrations.

In an embodiment, the piston is at least partially moveable within the cylinder.

In an embodiment, the piston is moveable in a direction that is substantially parallel to the main flow channel. By positioning the pressure reduction device in an orientation that allows 5 the piston to move in a direction substantially parallel to the main flow channel, an efficient use of space can be achieved. Because the direction is substantially parallel to the main flow channel, the space occupied by the degassing device in a direction away from the main flow channel can be reduced.

In an embodiment, the piston is moveable in a direction that is substantially orthogonal to the main flow channel. By positioning the pressure reduction device in an orientation that allows the piston to move in a direction substantially orthogonal to the main flow channel, an another efficient use of space can be achieved. Because the direction is substantially orthogonal to the main flow channel, the space occupied by the degassing device in a direction along the main flow channel can be reduced.

In an embodiment, the piston is in direct contact with the liquid and preferably no membrane is present between the piston and the degasification zone. Because no membrane is present, the device becomes more robust and may require less maintenance. The absence of a membrane means that there is one less part that can malfunction and that there is no membrane that may clog, inhibiting the working of the device. Because the piston may directly act on the liquid without first having to deform an elastic member such as a membrane, a pressure reduction can be achieved faster.

In an embodiment, the piston comprises at least one seal, in particular two seals located at a distance from each other, in particular the seals being O-rings, more in particular the seals being double lip seals. Such seals may be used to increase the performance of the pressure reduction device by increasing sealing capabilities and therefore loss of pressure difference.

In an embodiment, the pressure reduction device is located in a lower part of the degasification housing and the pressure reduction device is configured to be operated below a liquid level in the degasification housing.

By being able to place the pressure reduction device in a lower part of the degasification housing and the pressure reduction device being configured to be operated below the liquid level, the pressure reduction device can be positioned close to the main flow channel. This may reduce the amount of space taken up by the degassing device.

In an embodiment, the piston comprises an actuator end and the first valve is a non- return valve. The actuator end is configured to engage the first valve, wherein the movement of the piston from the retracted state to the extended state moves the first valve from an idle closed position to the open position via the actuator end. The movement of the piston from the extended state to the retracted state moves the first valve from the open position to an idle closed position via the actuator end.

In an embodiment, the branch flow passage extends through the cylinder between the main flow channel and the degasification zone and the piston movement is configured to move the first valve to the closed state. In doing so, in a single operation of the piston can be used to close off the branch flow passage and reduce the pressure inside the degasification zone.

Thereby, no additional actuator is needed to move the first valve to the closed state.

In an embodiment, a cavity is located in the cylinder and between the main flow channel and the piston, wherein a branch flow path extends through the cavity.

In an embodiment, the cylinder defines a branch flow hole, wherein the branch flow path extends through the branch flow passage, through the cavity and through the branch flow hole into the inner volume.

In an embodiment, the branch flow passage is defined by the cylinder, the branch flow hole and the piston.

In an embodiment, the first valve is integrated in the pressure reduction device, in particular in the piston, wherein the piston comprises a part which obstructs the branch flow path in the low pressure position. The movement of the piston to the low pressure position herein also closes off the branch flow passage. This does not only result in one less actuator to close of the branch flow passage, but also requires one moving part less, potentially reducing necessary maintenance.

In an embodiment, the second valve is a non-return valve. In such an embodiment, when the pressure is reduced by the pressure reduction device, the relatively higher pressure in the main flow channel forces the second non-return valve to the closed state. In doing so, no actuator may be necessary to close off the valve.

In an embodiment, the gas outlet further comprises a floater chamber and the outlet closing body comprises a floater moveable between a floating position and a lower position at a first predetermined liquid level. When at first a liquid is at a level where the floater is in a floating position and the liquid level starts to drop as a result of the operation of the pressure reduction device, the floater moves downwards to the lower position where it engages an end of the outlet tube and closes off the outlet tube. Not only does the floater replace the need for an actively operated gas outlet valve, by closing off the outlet tube as soon as the liquid has flown out of the outlet tube, the floater reduces the amount of free gas inside the degasification zone. This, in turn, facilitates the reduction of pressure and may increase the amount of gas that can be separated from the gas-containing liquid.

In an embodiment, the gas outlet comprises a gas outlet valve that allows gas and/or liquid to flow between the outside and the degasification zone in an open state, and closes off the degasification zone in a closed position, in particular the gas outlet valve being a ball valve.

In doing so the entire degasification zone can be filled with liquid and the degassing of the liquid can be performed more efficiently than in a situation where more liquid and/or more gas would initially be present, because the pressure reduction can be attained more easily and faster.

In an embodiment, the floater chamber comprises a float valve defining a gas outlet opening and when a liquid level is higher than a second predetermined level, the outlet closing body is moved to an upper position closing the float valve. In doing so, when an amount of liquid flowing into the degasification housing risks overflowing the degasification housing, the gas outlet opening is closed off by the floater inhibiting the liquid to spill out of the degassing device. Thereafter, the liquid will either stop flowing in through the branch flow passage or will enter through the branch flow passage and will flow out through the return flow passage.

In an embodiment, the floater comprises a protrusion located on a lower side of the floater and an outer dimension of the protrusion substantially matches an inner dimension of the outlet tube. Such a protrusion may increase the sealing capabilities of the floater.

In an embodiment, the float valve comprises a backflow preventer configured to allow gas to escape but not to enter the gas outlet, in particular the backflow preventer being a non- return valve. When the pressure reduction device is operated, the backflow preventer prevents more particles to be sucked into the degasification zone. In doing so, a volume increase more effectively and efficiently lowers the pressure because no particles can be added to the volume.

In an embodiment, the floater comprises an O-ring to close off the outlet tube in the lower position and/or an O-ring to close off the gas outlet in the upper position.

In an embodiment, the degassing device further comprises a vacuum pump connected to the gas outlet and a porous chamber located within the inner volume of the degasification housing, wherein the branch flow passage branches off part of the main flow into the porous chamber and the return flow passage extends between the porous chamber and the main flow channel. The porous chamber may comprise a porous element that is permeable to gases and impermeable to the liquid.

By using the combination of the vacuum pump and the porous chamber, the gas outlet does not need to be closed off by a floater, because the vacuum pump functions as a non- return valve for the separated gases. Also, because the porous element is impermeable to the liquid, there is little risk of the liquid reaching the vacuum pump, which would be detrimental to its operation.

In an embodiment, the main flow channel is constricted between the first side and the second side. Such a constriction may increase the pressure near the branch flow passage, forcing a portion of the main flow into the degasification housing. The main flow channel may also comprise a branch flow separator protruding into the main flow channel configured to branch off a portion of the main flow into the degasification zone. The main flow channel may also comprise a main flow valve configured to branch off a portion of the main flow into the degasification zone.

In an embodiment, the constriction comprises a non-return valve.

In an embodiment, the degassing device further comprises a biased switch wherein in the first piston actuator position, the piston actuator engages the biased switch and in the second actuator position, the switch is disengaged.

When the piston actuator is operated to move the piston to the low pressure position, a maximum underpressure risks to be exceeded. When this is about to happen, the low pressure pulls the piston, and therewith the piston actuator, away from the switch towards the second actuator position, disengaging the switch. The disengagement of the switch may deactivate the operation of the piston actuator, inhibiting a further reduction of pressure.

In an embodiment, the degassing device further comprises at least one sensor and a control unit configured to read out the at least one sensor and/or to control the pressure reduction device. In doing so, the pressure inside the degasification housing can be monitored and controlled if necessary.

In an embodiment, a first pressure sensor is located in the main flow channel and a second pressure sensor is located in the degasification zone. The control unit may then be configured to operate the pressure reduction device as a function of an output of the first pressure sensor and/or the second pressure sensor. By measuring the pressure both in the main flow channel and in the degasification zone, the pressure difference between the two can be determined.

In an embodiment, the pressure reduction device comprises the sensor configured to measure a pressure in the degasification zone.

In an embodiment, at least one sensor is a strain gauge or a stress gauge. By connecting the strain gauge or stress gauge to the piston or piston actuator, the force acting on the piston or piston actuator can be determined and can be used to determine the pressure in the degasification housing. The control unit can determine a pressure in the degasification zone.

In an embodiment, at least one sensor is a current measurement device configured to determine the current necessary to move the piston. By determining the current needed to move the piston, the pressure inside the degasification housing may also be determined as a function of the force necessary to move the piston.

In an embodiment, the degassing device further comprises a temperature sensor. The temperature sensor may be located in the main flow channel. The temperature sensor measures a temperature of the liquid in the main flow channel and the control unit reads out the temperature sensor and controls the pressure reduction device.

In an embodiment, the control unit comprises: — a first test module configured for determining the presence of a leak, the first test module being configured to: o close the at least one valve, o subsequently operate the pressure reduction device to reduce or increase the pressure, and o subsequently read out the at least one pressure sensor, o after a period of time read out the at least one pressure sensor a second time and o compare the second measured pressure with the first measured pressure to determine a difference, wherein a difference signal is generated, and/or — a second test module configured for determining the presence of flow in the main flow channel, the second test module being configured to: o read out the at least one pressure sensor, o subsequently close the at least one valve, o after a period of time read out the at least one pressure sensor a second time, and o compare the second measured pressure with the first measured pressure to determine a difference, wherein when the difference is smaller than a threshold value, a difference signal is generated indicative of a lack of flow.

By using such a first and/or second test module, the degassing device can be tested in order to keep it operating well and to be able to perform maintenance in time.

In an embodiment, the first test module is configured to maintain the pressure in the degasification zone constant or substantially constant over a test time period by measuring the pressure in the degasification zone, comparing the measured pressure to a target pressure and operating the pressure reduction device to maintain the pressure in the degasification zone at the target pressure. Herein, the first test module measures an operating parameter of the pressure reduction device in time and it is configured to generate a difference signal indicative of a leak when the measured operating parameter exceeds a predetermined threshold value.

The operating parameter is in particular the position of a piston and/or a power consumption of the pressure reduction device.

Alternatively or additionally, the first test module is configured to maintain a position of the piston constant or substantially constant over a test time period. Herein, said first test module measures the pressure in the degasification zone over a test time period and is configured to generate a difference signal indicative of a leak when a measured pressure difference over time exceeds a predetermined threshold value.

In an embodiment, the first and/or second test module determines the difference and - when the difference is larger than the threshold value, the control unit periodically carries out a degassing cycle, and - when the difference is smaller than the threshold value, the control unit does not carry out any degassing cycle.

By being able to determine whether or not a flow is present in the main flow channel, the degassing device can be operated only when it is useful to do so. This reduces potential wear and reduces the amount of energy consumed.

In an embodiment, the main flow channel is defined by a cup comprising an inlet and an outlet and a lid from which a plate protrudes downwards. The plate divides the cup in an inlet side and an outlet side and allows fluid communication from the inlet side to the outlet side only through the constriction. The lid also separates the main flow channel from the degasification zone and comprises at least one valve located in at least one flow passage. The degasification housing comprises a hood that is placed on top of the lid.

Another aspect of the invention relates to a method for degassing a gas-containing liquid in a cooling or heating installation by using a degassing device, the degassing device comprising: - a main flow channel wherein a main flow of liquid flows through the main flow channel, - at least one flow passage extending between the main flow channel and a degasification zone, - a degasification housing defining an inner volume, wherein the inner volume substantially corresponds to the degasification zone, - a valve which is moveable between a closed position and an open position, - a pressure reduction device connected to the degasification housing, - a gas outlet in the degasification housing, the gas outlet comprising an outlet tube and an outlet closing body, wherein the outlet tube is closeable by the outlet closing body, wherein the method comprises the steps: a) branching off a portion of the main flow through the at least one flow passage, b) moving the at least one valve to the respective closed position, respectively obstructing the at least one flow passage, closing off the degasification zone from the main flow channel, and closing the gas outlet, c) operating the pressure reduction device to lower the pressure in the degasification zone relative to the pressure in the main flow channel, d) opening the at least one valve and the gas outlet, wherein during step c) gas dissolved in the liquid is separated from the liquid and wherein during and/or after step d) liquid in the degasification housing is returned to the main flow channel through at least one flow passage and the separated gas is expelled through the gas outlet.

In an embodiment, the degassing device comprises two flow passages, a first flow passage being a branch flow passage, and a second flow passage being a return flow passage.

In an embodiment, the pressure reduction device is connected to the degasification housing and wherein the pressure reduction device comprises a piston, a cylinder, and a piston actuator. Herein, the cylinder may be in open communication with the inner volume, and during step c) the piston is moved between an extended position and a retracted position. wherein the degasification zone is delimited by the degasification housing and the piston.

In the retracted position of the piston the degasification zone extends into the cylinder and is larger than in the extended position of the piston. Herein, the degasification zone is delimited by the degasification housing, and at least part of an outer surface of the piston and/or by at least a part of the inner surface of the cylinder.

By moving the piston from the extended position to the retracted position, the degasification zone is pulled into the cylinder and becomes larger than in the idle pressure position of the housing. Because the volume of the degasification zone increases while the content of the degasification zone, i.e. the amount of liquid inside the degasification zone, remains substantially the same, the pressure to which the liquid in the degasification zone is subjected is reduced. The reduced pressure causes the liquid to degas.

In an embodiment, the degasification zone is enlarged into the cylinder when the piston is moved from the extended position to the retracted position and the degasification zone is larger in the retracted position than in the extended position. Alternatively, the degasification zone is enlarged into the cylinder when the piston is moved from the retracted position to the extended position and the degasification zone is larger in the extended position than in the retracted position.

In the first case, the piston actuator will pull on the piston to move the piston to the low pressure position and in the second case, the piston actuator will push of the piston to move the piston to the low pressure position.

In an embodiment, the branch flow passage extends through the cylinder between the main flow channel and the degasification zone and wherein step b) and step c) occur substantially simultaneous and wherein the moving of the piston moves at least one of the first valve, the second valve to the closed position, and/or closes the gas outlet.

In an embodiment, the piston comprises an actuator end and the first valve is a non- return valve. When the piston is moved to the extended position, the actuator end moves the first valve to the open position, and when the piston is moved to the retracted position, the valve is allowed to move to the closed position.

In an embodiment, the outlet closing body comprises a floater and when a liquid level is lower than a first predetermined level, the floater is moved to a lower position, closing off the outlet tube.

In an embodiment, the gas outlet further defines a gas outlet opening and wherein when a liquid level is at a second predetermined level, the outlet closing body is moved to an upper position, closing off the gas outlet opening.

In an embodiment, the gas outlet further comprises a float valve and when a liquid level is at the second predetermined level, the float valve closes off the gas outlet opening.

In an embodiment, the floater comprises a protrusion, and an outer dimension of the protrusion substantially matches an inner dimension of the outlet tube and wherein during step b) the protrusion is forced into the outlet tube.

In an embodiment, the floater comprises a backflow preventer. The backflow preventer preventing gas to flow into the degasification zone when an outside pressure is larger than a pressure inside the degasification housing. In particular, the backflow preventer preventing gas to flow into the degasification zone during step c).

In an embodiment, the floater comprises a second protrusion, and an outer dimension of the second protrusion substantially matches an inner dimension of the gas outlet opening and wherein when the liquid level is at the second predetermined level, the protrusion is forced into the outlet tube.

In an embodiment, the main flow channel is constricted between the first side and the second side and the constriction increases pressure near the branch flow passage and forces at least a portion of the main flow into the degasification housing. The main flow channel may also comprise a branch flow separator that branches off at least a portion of the main flow into the degasification zone. The main flow channel may also comprise a main flow valve configured to branch off a portion of the main flow into the degasification zone. In doing so, the renewal of liquid in the degasification zone may be increased.

In an embodiment, prior to step d), the pressure in the degasification zone is increased to substantially the pressure present during step a). This reduces pressure differences between the main flow channel and the degasification housing, and/or pressure differences between the outside and the degasification housing. This facilitates the operation of the gas outlet and the valve configured to close off the branch flow passage and the valve configured to close off the return flow passage.

In an embodiment, the degassing device further comprises a biased switch and the piston actuator is fixed to the degasification housing via one or more resilient members and the piston actuator is resiliently moveable between a first actuator position and a second actuator position. When a force necessary to move the piston to the retracted position exceeds a predetermined value corresponding to a minimum pressure inside the degasification housing, the force moves the actuator from the first actuator position engaging the biased switch to the second actuator position disengaging the switch, wherein the disengagement of the switch interrupts the operation of the pressure difference device. In doing so, for example, a predetermined minimum pressure or maximum underpressure can be ensured to remain above the vapour line of the liquid, preventing the liquid from boiling.

In an embodiment, wherein the degassing device further comprises at least one sensor and a control unit, wherein the control unit reads out the at least one sensor and/or controls the pressure reduction device. In doing so, the pressure inside the degasification housing can be monitored and controlled if necessary.

In an embodiment, the sensor is a force sensor connected to the piston actuator and the degasification housing, wherein the sensor measure a force acting on the piston actuator in a direction substantially parallel to a central axis of the cylinder. By connecting the force sensor to the piston actuator, the force acting on the piston actuator can be determined and can be used to determine the pressure in the degasification housing.

In an embodiment, a first pressure sensor is located in the main flow channel and wherein a second pressure sensor is located in the degasification zone. Herein, the first and second pressure sensor measure respectively a first and a second pressure.

In an embodiment, the control unit further operates at least one of the first valve, the second valve, the main flow valve, and the gas outlet valve.

In a further aspect, the invention relates to a method for testing a degassing device for degassing a gas-containing liquid in a cooling or heating installation, the degassing device comprising: - a main flow channel wherein a main flow of liquid flows through the main flow channel, - at least one flow passage extending between the main flow channel and a degasification zone, - a degasification housing defining an inner volume, wherein the inner volume substantially corresponds to the degasification zone, - at least one valve which is moveable between a closed position and an open position, - a pressure reduction device connected to the degasification housing, - a pressure sensor configured to measure the pressure in the degasification zone, - a gas outlet in the degasification housing, the gas outlet comprising an outlet tube and an outlet closing body, wherein the outlet tube is closeable by the outlet closing body, - a control unit, comprising a first and/or a second test module, connected to the pressure sensor and configured to receive a pressure difference signal from the pressure sensor, wherein the method comprises the steps: a) closing the at least one valve and measuring a first pressure in the degasification housing with the pressure sensor, b) measuring a second pressure in the degasification housing with the pressure sensor after a period of time, c) comparing the second pressure with the first pressure by the control unit to determine a difference, wherein a difference signal is generated by the control unit when a difference between the first pressure and the second pressure is present.

In an embodiment, step a) comprises the sequential steps of: a) 1) closing the at least one valve, a) 2) operating the pressure reduction device to reduce or increase the pressure inside the degasification housing, a) 3) measuring the first pressure.

Herein, the difference signal which is generated by the control unit when the difference between the first pressure and the second pressure is indicative of a leak in the degasification housing which allows liquid and/or gas to escape out of the degasification housing.

A very small difference signal would indicate a very small, perhaps insignificant leak and a larger difference signal would indicate a larger, more significant leak. If such test procedure is performed during maintenance, an operator can judge the difference signal to determine whether or not action should be taken. This may also be done autonomously by the control unit.

In an embodiment, in step a2) the pressure is reduced to below atmospheric pressure and if the second pressure is higher than the first pressure and lower than or equal to the atmospheric, a difference signal is generated which is indicative of a leakage of air from outside into the degasification housing.

In an embodiment, in step a2) the pressure is reduced to above atmospheric pressure but below a pressure in the main flow channel and if the second pressure is lower than the first pressure, a difference signal is generated which is indicative of a leakage from inside the degasification housing to the outside.

In an embodiment, in step a2) the pressure is reduced to above atmospheric pressure but below the pressure in the main flow channel and if the second pressure is higher than the first pressure, a difference signal is generated which is indicative of a leakage from the main flow channel into the degasification housing.

In an embodiment, the control unit controls the pressure reduction device to keep the second pressure substantially equal to the first pressure, and if the pressure reduction device is operated after measuring the first measured pressure, a difference signal is generated which is indicative of a leakage.

By maintaining the pressure in the degasification zone constant or substantially constant over a test time period by measuring the pressure in the degasification zone, comparing the measured pressure to a target pressure and operating the pressure reduction device to maintain the pressure in the degasification zone at the target pressure. Leakage can also be tested. The test module measures an operating parameter of the pressure reduction device in time and is configured to generate a difference signal indicative of a leak when the measured operating parameter exceeds a predetermined threshold value, wherein said operating parameter is in particular the movement of a cylinder and/or a power consumption of the pressure reduction device.

In an embodiment, in step a2) the pressure is reduced to below atmospheric and if the pressure reduction device is operated to reduce the pressure, a difference signal is generated which is indicative of a leakage of air from outside into the degasification housing or from the main flow channel into the degasification zone.

In an embodiment, in step a2) the pressure is reduced to above atmospheric but below a pressure in the main flow channel and if the pressure reduction device is operated to increase the pressure, a difference signal is generated which is indicative of a leakage from inside the degasification housing to the outside.

In an embodiment, in step a2) the pressure is reduced to above atmospheric but below the pressure in the main flow channel and if the pressure reduction device is operated to reduce the pressure, a difference signal is generated which is indicative of a leakage from the main flow channel into the degasification housing.

In an embodiment, the device comprises at least two flow passages, one flow passage being a branch flow passage and one flow passage being a return flow passage and the at least one valve is located in at least one of the at least two flow passages. Herein, during step a), the at least one valve is closed after measuring the first pressure and, when the difference is smaller than a predetermined threshold value, a difference signal is generated indicative of a lack of flow.

By determining whether or not a flow is present in the main flow channel, the control unit is able to determine whether or not degassing the liquid is necessary and/or useful.

In an embodiment, when the difference is larger than the predetermined threshold value, the control unit periodically carries out a degassing cycle, and when the difference is smaller than the predetermined threshold value, the control unit does not carry out any degassing cycle.

In an embodiment, the device further comprises a second valve located in the other of the at least two flow passages and after the method of claim 67 has been performed, any of the methods of claim 59-66 is performed .

In an embodiment, the method is performed prior to or during performing a method according to any of claims 40-57.

In an embodiment, the method is performed periodically.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 depicts an embodiment of the degassing device in an idle state.

Figure 2 depicts an embodiment of the degassing device in a state wherein the pressure reduction device has just started operation.

Figure 3 depicts an embodiment of the degassing device in a low pressure state.

Figure 4 depicts an embodiment of the degassing device after dissolved gas has been separated from the liquid and is being evacuated to outside of the degassing device.

Figure 5 depicts an embodiment comprising a floater chamber, sensors and a control unit in an idle state.

Figure 6 depicts an embodiment comprising a floater chamber, sensors and a control unit in an low pressure state.

Figure 7 depicts an embodiment comprising a floater chamber, sensors and a control unit in an overpressure state.

Figure 8 depicts an embodiment of the degassing device, wherein valves are controlled by the control unit in an idle state.

Figure 9 depicts an embodiment of the degassing device, wherein valves are controlled by the control unit in a low pressure state.

Figure 10 depicts an embodiment of the degassing device, wherein valves are controlled by the control unit in an idle state.

Figure 11 depicts an embodiment of the degassing device, wherein valves are controlled by the control unit in a low pressure state.

Figure 12 depicts an embodiment wherein the piston movement is oriented orthogonally to the main flow channel is an idle state.

Figure 13 depicts an embodiment wherein the piston movement is oriented orthogonally to the main flow channel is a low pressure state.

Figures 14A and 14B depict an embodiment of the piston actuator

Figure 15 depicts an embodiment of the degassing device comprising a porous chamber and a vacuum pump.

Figure 16 depicts an embodiment with one flow passage, wherein the degassing device is in an idle pressure position.

Figure 17 depicts an embodiment with one flow passage, wherein the degassing device isin a low pressure position.

Figure 18 depicts an embodiment comprising a test module and open valves.

Figure 19 depicts an embodiment comprising a test module and with one closed valve.

Figure 20 depicts an embodiment comprising a test module and with two closed valves.

Figure 21 depicts an embodiment where no flow is present.

Figures 22A, 22B, 22C, and 22D depict pressure as a function of pressure reduction device operation and time.

Figures 23A and 23B depict pressure as a function of pressure reduction device operation and time respectively.

Figures 24A and 24B depict pressure as a function of pressure reduction device operation and time respectively.

Figure 25A and 25B depict an embodiment of the degassing device comprising a cup and a hood.

Figure 26A and 26B depict an embodiment of the degassing device comprising a cup and a hood.

DETAILED DESCRIPTION OF THE DRAWINGS

Turning to figures 1-4, a cross section of an embodiment of a degassing device 10 is depicted. The degassing device 10 is connected to a liquid circuit of a cooling or heating installation (not depicted) wherein a liquid of the cooling or heating installation enters the degassing device 10 on a first side 22 and exits the degassing device on a second side 24. In operation, a main portion of the liquid flow passes through a main flow channel 20 and a branch flow is branched off by a branch flow passage 30. After being branched off, the flow passes through the branch flow passage into a degasification zone 42 where the liquid will be degassed. The degasification zone 42 substantially corresponds to an inner volume of a degasification housing 40. In an idle state of the degassing device, the liquid first passes through the branch flow passage 30 and the degasification zone 42, after which the liquid joins the main flow via a return flow passage 50 extending between the degasification zone and the main flow channel.

A pressure reduction device 70 is connected to the degasification housing 40 and is configured to lower the pressure in the degasification zone 42 relative to the pressure in the main flow channel. The pressure can be measured with a sensor 92, in particular with a manometer.

In order to be able to degas the liquid in the degasification zone, the degasification housing must be closed off from the outside, i.e. from the atmosphere outside the degassing device and from the main flow channel. To do so, a valve 60B is present that is moveable between a closed position 62B and an open position 64B. In the closed position the valve obstructs the return flow passage 50 and closes off the degasification zone from the main flow channel. Another valve 60A is present and is configured to be moved between a closed position 62B and an open position 64B and obstructs the branch flow passage in the closed position, closing off the degasification zone 42 from the main flow channel 20.

After the degassing of the liquid has taken place, the separate gas must be evacuated from the device. To this end, a gas outlet 80 is present in the degasification housing and comprises an outlet tube 82 and an outlet closing body 84.

In the depicted embodiment, the pressure reduction device 70 comprises a piston 72, a cylinder 74 and a piston actuator 78. The piston actuator 76 is configured to move the piston 72 between an extended, idle pressure position 722 and a retracted, low pressure position 724.

Because the cylinder is in open communication with the degasification zone 42 and the degasification zone 42 extends into the cylinder and is larger in the retracted position 725 than in the extended position 723 of the piston, the movement of the piston from the extended position 722 to the retracted position 724 reduces the pressure inside the degasification zone 42; the closed off degasification zone grows in size whilst the amount of matter inside it remains substantially the same. The degasification zone 42 is delimited by the degasification housing 40, a part of the outer surface of the piston 72, and a part of the inner surface of the cylinder 74. It will be understood that if the piston actuator would be located on an opposite side of the piston 72 along the direction of movement of the piston, the low pressure position would correspond to an extended position and the idle pressure position would correspond to a retracted position because the piston actuator would push instead of pull. The piston actuator 76 may be one of an electric actuator, a pneumatic actuator, and a hydraulic actuator. The depicted piston movement is a linear movement.

In order to increase the size of degasification zone, the piston 72 comprises two seals 726 in the form of O-rings that enable the piston to move within the cylinder and keep a substantially liquid-tight connection between the piston and the cylinder 74.

In figures 1-4, the pressure reduction device is located in a lower part of the degasification housing and is configured to be operate below a liquid level in the degasification housing. This, together with the substantially parallel direction 1 of the piston movement, enables the degassing device to be compact and to not take in a lot of space far away from the main flow channel.

It can further be seen that the branch flow passage 30 extends through the cylinder 74 between the main flow channel 20 and the degasification zone 42. In figure 1, a branch flow path 32 is depicted extending from the main flow channel through a cavity 742 in the cylinder and entering the inner volume of the degasification housing 40 through a branch flow hole 744 defined by the cylinder. Further, the valve 60A is integrated in the pressure reduction device; the piston 72 is a part that is moveable into the low pressure position and there obstructs the branch flow passage. In doing so, the piston movement is configured to move the valve 60A to the closed state when it moves from the idle pressure position to the low pressure position.

Looking at an upper region of the degassing device 10, the gas outlet 80 is depicted comprising a floater chamber 86 and the outlet closing body 84 comprises a floater that, in figures 1 floats on the liquid at an upper position 846 and in figure 2 floats on the liquid at a floating position 842. The floater is connected to a float valve wherein, when the amount of liquid increases to a certain level, the floater closes off the float valve because of which the increase in liquid level is inhibited (depicted in figure 1). Alternatively, when the liquid level is lower, the floater does not close off the float valve (as depicted in figure 2).

When the pressure reduction device is operated, the liquid level drops due to the increase in volume of the degasification zone. The floater 84 then moves to a lower position 844 (depicted in figure 3) where it engages the outlet tube 82, this occurs when the liquid level is lower than a first predetermined liquid level 88. In order to seal off the gas outlet, a backflow preventer 852 is present. The backflow preventer prevents gas from the outside to flow into the degasification housing when the outside pressure is greater than the pressure inside the degasification housing. In figure 4, when the pressure inside the housing is increased, the backflow preventer 852 is opened and the free gasses released from the liquid may be evacuated via the gas outlet. In particular, the backflow preventer preventing gas to flow into the degasification zone during a pressure reduction step of a degassing method.

In order to create a flow of liquid into the degasification zone 42, the main flow comprises a constriction 26 located between the first side 22 and the second side 24. By being constricted, the pressure in the main flow is increased near the branch flow passage, forcing a portion of the main flow into the degasification housing.

In operation, a method for degassing a gas-containing liquid in a cooling or heating installation by using a degassing device 10 comprises the steps: a) branching off a portion of the main flow through the branch flow passage 30, b) moving the valves GOA, 60B to their respective closed positions 62A, 62B, respectively obstructing the branch flow passage and the return flow passage, closing off the degasification zone from the main flow channel, and closing the gas outlet 80, c) operating the pressure reduction device to lower the pressure in the degasification zane relative to the pressure in the main flow channel, d) opening the first valve, the second valve, and the gas outlet, wherein during step c) gas dissolved in the liquid is separated from the liquid and wherein during and/or after step d) liquid in the degasification housing is returned to the main flow channel through the return flow passage and the separated gas is expelled through the gas outlet.

The abovementioned step b) can be performed by operating the pressure reduction device in the depicted embodiment. In figure 2, the movement 721 of the piston 72 towards the low pressure position leads the non-return valve 60B and the valve SOA for the branch flow passage 30 to close and the decreasing liquid level below a first predetermined level 88 leads the floater to close off the gas outlet tube 82. When the valves 60A, 60B and the gas outlet 80 are closed, the operation of the pressure reduction device lowers the pressure in the degasification zone 42. The end of the movement of the piston 72 in the cylinder 74 by the piston actuator 76 towards the retracted position 724 from the extended position 722 is depicted in figure 3. Here above the liquid in the degasification zone 42, free gas 3 has formed by separating from the liquid. As the valves and the gas outlet are opened, the free gas 3 may evacuate the degassing device through the gas outlet and the liquid in the degasification zone 42 may return to the main flow through the return flow passage.

In the depicted embodiment, prior to step d), the pressure in the degasification zone is increased to substantially the pressure present during step a). this facilitates the opening of the valves.

Turning to figures 5-7, the floater chamber 86 of the gas outlet 80 defines a gas outlet opening 862 through which free gas may be evacuated. The floater 84 itself comprises a protrusion 83 respectively located on a lower side 832 of the floater. The protrusion 83 located on the lower side 832 of the floater has an outer dimension that substantially matches an inner dimension of the outlet tube 82. In doing so the closing of the degasification zone from the outside can be improved because, in operation during step b}, the protrusion 83 is forced in the outlet tube 82. By closing the outlet tube directly when the liquid levels drops sufficiently, the amount of free gasses in the degasification zone is reduced, enabling a faster pressure reduction. Because the protrusion seals the outlet tube , the backflow preventer does not need to be present. However, there is no reason why the protrusion and the backflow preventer shouldn't be combined.

The floater is configured to actuate the float valve 85; when a liquid level is at a second predetermined level 89, the floater 84 is moved to an upper position 846 where it closes the float valve, closing off the gas outlet opening. This is especially useful when too much liquid starts to accumulate inside the degasification zone and the device risks to overflow; the floater 84 together with the floater chamber 86 prevents the overflowing from happening. Herein, the pressure inside the degasification housing is at an overpressure with respect to the outside.

This pressure may be equal to a system pressure, i.e. the pressure in the main flow channel.

To improve the closing, the protrusion comprises an O-ring or a double lip seal to even better seal the gas outlet opening 862 and the gas outlet tube 82.

Further, the cylinder 74 comprises a flared end wherein the branch flow passage extends between the piston 72 and the cylinder 74 when the piston is in the idle pressure position 722.

The degassing device also comprises three sensors 92A, 92B, 92C and a control unit 90 that is configured to read out the sensors and to control the piston actuator 76. By measuring the pressure in the degasification zone with sensor 92A and the pressure in the main flow channel 20 with sensor 92B, a pressure difference can be determined by the control unit 90 and the piston actuator 76 can be operated as a function of these measurements. Also, the temperature of the liquid can be determined using a temperature sensor 92C. By determining the temperature of the liquid a pressure at which the liquid starts boiling can be determined and avoided. The temperature sensor may also measure a temperature of the liquid in the main flow channel and the control unit reads out the temperature sensor and can subsequently control the pressure reduction device.

Besides using separate sensors 92A, 92B, 92C to determine the state of the degassing device and more particularly the pressure in the degasification zone 42, the control unit 80 may also be configured to measure the current necessary to move the piston 72. Based on the current, the force acting on the piston can be determined which gives a measure for the pressure in the degasification zone 42.

In figure 7, an embodiment of the invention is depicted wherein the main flow channel doesn't comprise a constriction, but comprises a branch flow separator 28 protruding into the main flow channel. The branch flow separator is configured to branch off a portion of the main flow into the degasification zone

Moving to figure 8 and figure 9, an embodiment is shown where the pressure reduction device 70 is not integrated with the valve GOA that closes of the branch flow passage 30.

Instead, the branch flow passage can be closed off by an actuated valve GOA that may be moved from the open position 64A to the closed position 62A by the control unit 90. Similarly, the control unit 20 may also control a main flow valve 27 that is configured to temporarily close off the main flow channel 20 to branch off liquid into the degasification housing.

The embodiment depicted in figures 10 and 11 is largely similar to the embodiment depicted in figures 8 and 9. The main difference lies in the presence of a gas outlet valve 87, in particular a ball valve, that may be controlled by the control unit 90. The gas outlet valve allows gas and/or liquid to flow between the outside and the degasification zone in an open position and closes off the degasification zone in a closed position. Soon after the start of the operation of the pressure reduction device 70, the gas outlet valve is closed. In doing so the entire degasification zone 42 is filled with liquid and the degassing of the liquid can be performed more efficiently than if more liquid and/or more gas would initially be present ni the inner volume.

Turning to figures 12 and 13, an embodiment is depicted wherein the piston is moveable in a direction 2 that is substantially orthogonal to the main flow channel. By orienting the pressure reduction device 70 in this manner, the degassing device takes up less lateral space and may be used in narrow spaces. Herein, the cylinder 74 comprises a flared end wherein the branch flow passage extends between the piston 72 and the cylinder 74 when the piston is in the idle pressure position 722.

Further, the piston actuator 76 is fixed to the housing via two resilient member 762.

Besides damping vibrations, the resilient members allow the piston actuator 76 to resiliently move between a first actuator position 764 and a second actuator position 766. In figure 10, the piston actuator is shown in the first actuator position 764 where it engages a biased switch 75 located above the piston actuator. When the pressure reduction device is operated and the pressure inside the degasification zone 42 is reduced, the piston will be pulled away from the switch together with the piston actuator 76. When a predetermined minimum pressure is achieved, e.g. a pressure just above the vapour line of the liquid, the piston actuator moves to the second actuator position 766, disengaging the biased switch 75. Therefore, when in operation, when a force necessary to move the piston to the retracted position 724 exceeds a predetermined value corresponding to a pressure inside the degasification housing, the force moves the piston actuator 76 away from the switch 75, wherein the disengagement of the switch interrupts the operation of the pressure difference device. Besides the mechanical approach using a switch, it will be understood that a stress gauge or a strain gauge in combination with the control unit 90 may achieve the same result; a measured stress or strain value can then be used by the control unit to determine a pressure in the degasification zone.

Turning to figures 14A and 14B, an embodiment of a piston actuator 76 is depicted wherein the piston actuator comprises an electromagnet 71 that is configured to attract and/or repulse the piston 72. By attracting the piston 72 in the idle pressure position 722, the piston 72 is moved into the low pressure position 724. In the depicted embodiment, the piston actuator further comprises a spring 77 that is configured to move the piston back to the idle pressure position 722. This action may also be done by a repulsive force of the magnet 71.

Turning to figure 15, a schematic depiction of an embodiment is shown. Herein the pressure reduction device is a vacuum pump 78 that is connected to the gas outlet 80, wherein the gas outlet comprises a gas outlet valve 87 and a gas outlet tube 82. Further, the degassing device comprises a porous chamber 44 that is located within the volume of the degasification housing 40.

When a first valve 60A is open, a portion of the main flow is branched off by the branch flow passage 30 and flows into the porous chamber 44. When the first valve 860A and a second valve 60B are closed, the vacuum pump is operated and the pressure inside the degasification housing is reduced. This leads to dissolved gas in the liquid to separate from the liquid and the gas may then be sucked through a porous element 442 of the porous chamber and may be evacuated by the vacuum pump. Because the porous chamber 42 is only permeable to gases and not to the liquid, the liquid remains in the circuit. After the separated gas has been evacuated, the valves 60A, 60B are opened and the liquid returns to the main flow channel via the return flow passage.

Turning to figures 16 and 17, a similar embodiment to that of figures 8 and 9 is depicted.

The main difference being the presence of one flow passage 15 that allows communication between the degasification zone and the main flow channel. In the depicted embodiment, the degasification zone 42 is filled with liquid from the main flow channel 20. Subsequently, at least one valve 60 is moved from an open position 64 to a closed position 62 and the pressure reduction device is operated. Thereafter, when the liquid has been degassed, the valve is moved to the open pasition 64 and the liquid returns to the main flow channel 20 through the flow passage 15. By using a single valve 60, the device can be kept smaller and easier to operate in comparison with a device using multiple valves.

In figures 18, 19, 20, and 21 a similar device to that of figures 12 and 13 is depicted.

Here, in the main flow channel 20, the constriction 26 comprises a non-return valve 60C. The first valve 60A and second valve 60B also are non-return valves. To be able to allow the liquid to flow through the first valve 60A, the piston 72 comprises an actuator end 728 that is configured to move the first valve to the open position 64 in the extended state 722 of the piston.

The piston comprises an actuator end 728 and the first valve is a non-return valve.

Herein, the actuator end engages the first valve in the open position, wherein the movement of the piston from the retracted state to the extended state moves the first valve from an idle closed position to the open position via the actuator end. The movement of the piston from the extended state to the retracted state moves the first valve from the open position to an idle closed position via the actuator end.

Here, the control unit 90 comprises a first and/or second test module 91 that may be comprise digital or analogue components. The test module is configured for determining the presence of flow in the main flow channel so that a degassing operation is not performed in vain.

In figure 18, the test module reads out the pressure sensor 92A to determine the pressure inside the degasification zone. This pressure is similar to that in the main flow channel because the first, second and third valve SOA, 60B, and 60C are all open. After the test module closes the first valve GOA via the actuator end 728 in figure 19, the flow in the main channel causes a pressure drop in the degasification zone because of the flow that is still flowing out of the second valve 60B.

Because of the lower pressure in the degasification zone and the second valve is a non- return valve, the second valve 60B moves to the closed state 62B. This is shown in figure 20.

After a period of time, the test module 91 reads out the pressure sensor 90A a second time.

The test module 91 then compares the second measured pressure with the first measured pressure to determine a difference. The difference is compared with a threshold value. Because a flow is present, the difference is larger than the threshold value and no difference signal is generated by the test module.

Turning to figure 21, the same test module has performed the same sequence as in figures 18 and 19. However, because no flow is present in the main flow, no pressure drop has occurred after the closing of the first valve 60A. when the test module compares the second measured pressure with the first measured pressure, the difference is very small. Because the difference is smaller than the threshold value, the test module generates a difference signal indicative of a lack of flow.

Herein, when the difference is larger than the threshold value, the control unit periodically carries out a degassing cycle, and when the difference is smaller than the threshold value, the control unit does not carry out any degassing cycle.

Turning to figures 22A-24B, the consequences of another test module are depicted for different situations. Herein, the test module 91 closes the at least one valve and subsequently operates the pressure reduction device to reduce the pressure. Subsequently, the at least one pressure sensor is read out, and after a period of time, the at least one pressure sensor is read out a second time. The second measured pressure 9 is then compared with the first measured pressure 7 to determine a difference and the test module generates a difference signal. It will be understood that the pressure reduction device can also be used to increase the pressure for the test procedure.

In figures 22A, 23A, and 24A, an additional step is carried out by the test module.

Herein, the test module is configured to maintain the pressure in the degasification zone constant or substantially constant over a test time period by measuring the pressure in the degasification zone, comparing the measured pressure to a target pressure and operating the pressure reduction device to maintain the pressure in the degasification zone at the target pressure.

The testing module then measures an operating parameter of the pressure reduction device in time and is configured to generate a difference signal indicative of a leak when the measured operating parameter exceeds a predetermined threshold value, wherein said operating parameter is in particular the movement of a cylinder and/or a power consumption of the pressure reduction device.

In figures 22A and 22B, both graphs show a leakage of air into the degasification housing. In figure 22A, the pressure is reduced to below atmospheric pressure 8 and the first pressure 7 is measured. Thereafter, the piston is moved to the retracted state over time 2. This means that the pressure reduction device is operated to reduce the pressure but that the pressure remains constant. This is only possible is case of a leak from the outside of the degasification housing in. Based on the presence of a leak, a difference signal is generated.

In figure 22C, no leak is present. Here, the pressure is reduced to below atmospheric pressure 8 and the first pressure 7 is measured. Subsequently, the piston does not need to be moved to maintain the first pressure and is kept at a constant position.

In figure 22B, the pressure reduction device is operated to reduce the pressure to below atmospheric pressure and is subsequently stopped from operating. If no leak is present, the pressure would remain constant over time. However, if a leak is present, the pressure would rise. If the pressure rises to atmospheric pressure and not further, a leak is present from the outside into the degasification zone. Based on the presence of a leak, a difference signal is generated indicative of a leakage of air from outside into the degasification housing. If the pressure rises further to above the atmospheric pressure, a leak is present between the degasification zone and the main flow channel. This is also depicted in figure 23B.

In figure 22D, no leak is present. Here, the pressure is reduced to below atmospheric pressure 8 and the first pressure 7 is measured. Subsequently, time passes and the second pressure 9 is measured. Because the first and second pressures are substantially the same, it can be concluded that no leak is present.

In figure 23A and 23B, both graphs show a leakage from the main flow channel into the degasification zone. In figure 23A, the pressure is reduced to above atmospheric pressure but below the pressure in the main flow channel 4. If the pressure reduction device must be operated to decrease pressure, which is the case, the main flow channel leaks into the degasification zone. Accordingly, a difference signal is generated which is indicative of a leakage from the main flow channel into the degasification housing.

In figure 23B, the same leak is present. First, the pressure is reduced by the operation of the pressure reduction device which is then stopped. If no leak were present, the pressure would remain constant. However, the pressure rises towards the pressure in the main flow channel 4. This indicates a leak from the main flow channel into the degasification zone.

Accordingly, a difference signal is generated which is indicative of a leakage from the main flow channel into the degasification housing

Turning to figures 24A and 24B, both graphs show leakage from the degasification zone to the outside. In figure 24A, the pressure is reduced by the pressure reduction device. If no leak were present, the pressure would remain constant without moving the piston. However, because the liquid is leaking to the outside and because the pressure in the degasification zone 6 is higher than the atmospheric pressure, the pressure reduction device is operated to increase the pressure to keep the pressure constant. This indicates a leak to the outside from the degasification zone. Accordingly. a difference signal is generated which is indicative of a leakage from inside the degasification housing to the outside.

In figure 24B, the pressure is reduced by the pressure reduction device and the pressure reduction device is then stopped. If no leaks were present, the pressure would remain constant.

However, because the liquid leaks to the outside from within the degasification zone, the pressure in the degasification zone 6 decrease over time towards the atmospheric pressure.

It will be understood that each test module can be used after the other and that the testing can also be done prior to performing a degassing method. Also, it will be understood that the methods can be performed periodically for the maintenance of the degassing device.

Turning to figure 25A, 25B, 26A, and 26B, the main flow channel 20 is defined by a cup 100 comprising an inlet 102 and an outlet 104 and a lid 110 from which a plate 112 protrudes downwards, wherein the plate divides the cup in an inlet side 106 and an outlet side 108 and allows fluid communication from the inlet side to the outlet side only through the constriction

26. The lid 110 separates the main flow channel 20 from the degasification zone 42 and comprises two valves 60A and 60B respectively located in a branch flow passage and a return flow passage. The degasification housing comprises a hood 120 that is placed on top of the lid.

To prevent leaks between the lid, hood, and cup, a seal 122 is present. Further, a mounting bracket 124 is present to which the cup 100, the hood 120, and the pressure reduction device 70 are connected. Such a mounting bracket may be used to mount the degassing device to a wall or other structure.

The terms "a" or "an", as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and/or having, as used herein, are defined as comprising i.e., open language, not excluding other elements or steps.

Any reference signs in the claims should not be construed as limiting the scope of the claims or the invention. It will be recognized that a specific embodiment as claimed may not achieve all of the stated objects.

The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

White lines between text paragraphs in the text above indicate that the technical features presented in the paragraph may be considered independent from technical features discussed in a preceding paragraph or in a subsequent paragraph.

Claims

CONCLUSIONS

A degassing device (10) for degassing a gas-containing liquid in a cooling or heating installation, the degassing device comprising: - a main flow channel (20) defined by a tube extending between a first side (22) and a second side (24), wherein in use a main stream of liquid flows through the main flow channel, - at least one flow passage (15) extending between the main flow channel and a degassing zone (42), the flow passage being adapted to allow communication between the degassing zone and the main flow channel, - a degassing housing (40) defining an inner volume, the inner volume substantially corresponding to the degassing zone, - at least one valve (60) movable between a closed position (62) and an open position ( 64), where in the closed position the valve blocks the flow passage and closes the degassing zone from the main flow channel, and where in the open position the valve does not obstruct the flow passage, - a pressure reducing device (70) connected to the degassing housing, where in use the pressure reducing device is adapted to reduce the pressure in the degassing zone relative to the pressure in the main flow channel, - a gas outlet (80) in the degassing housing, the gas outlet comprising an outlet tube {82) and an outlet closing body (84), wherein the outlet tube is closable by the outlet closing body, the gas outlet and the at least one valve being arranged to close the degassing housing, and wherein the pressure reducing device is arranged to degas the gas-containing liquid.

A degassing device according to the preceding claim, wherein the device comprises two flow passages, wherein a first flow passage is a branch passage (30), the branch passage being arranged to branch off a branch flow which is part of the main flow, and wherein a second flow passage a return passageway (50) extending between the degassing zone and the main flow channel, the return passageway being arranged to return a return flow to the main flow channel.

A degassing device according to the preceding claim, wherein the degassing device comprises a first valve (60A) movable between a closed position and an open position, wherein in the closed position the first valve obstructs the branch passage and seals the degassing zone from the main flow channel and wherein in the open position the first valve does not obstruct the branch passage, and wherein the degassing device comprises a second valve (60B) movable between a closed position and an open position, in the closed position the second valve obstructs the return passage and closes off the degassing zone of the main flow channel and wherein in the open position the second valve does not obstruct the return passage.

A degassing device according to any one of the preceding claims, wherein the pressure reducing device is connected to the degassing housing and wherein the pressure reducing device comprises a piston (72), a cylinder (74), and a piston actuator (78) and wherein the piston is movable between an inactive pressure position (722) and a low pressure position (724) and the cylinder is in open communication with the inner volume, in the low pressure position of the piston the degassing zone extends inside the cylinder and is larger than in the inactive pressure position of the piston, wherein the degassing zone is bounded by the degassing housing and by at least a portion of an outer surface of the piston and/or by at least a portion of the inner surface of the cylinder.

A degassing device according to any one of the preceding claims, wherein a retracted position (723) of the piston corresponds to the low pressure position of the piston and an extended position (725) of the piston corresponds to the inactive pressure position, or wherein an extended position of the piston corresponds to the low pressure position of the piston and a retracted position of the piston corresponds to the inactive pressure position.

A degassing device according to any one of claims 4-5, wherein the piston actuator is attached to the degassing housing via one or more spring elements (762) and wherein the piston actuator is resiliently movable between a first actuator position (784) and a second actuator position (766).

A degassing device according to any one of claims 4-8, wherein the piston is movable in a direction (1) substantially parallel to the main flow channel, preferably wherein the main flow channel is oriented substantially horizontally and the direction is oriented substantially horizontally, or in which case preferably the main flow channel is oriented substantially vertically and the direction is oriented substantially vertically.

A degassing device according to any of claims 4-7, wherein the piston is movable in a direction (2) substantially orthogonal to the main flow channel, preferably the main flow channel is oriented substantially horizontally and the direction is oriented substantially vertically.

A degassing device according to any one of claims 4-8, wherein the piston is in direct contact with the liquid and preferably no membrane is present between the piston and the degassing zone.

A degassing device according to any one of claims 4-9, wherein the piston comprises at least one seal (726), in particular two seals spaced apart, the seals being in particular O-rings, more in particularly double lip seals, where the seals are arranged to minimize an amount of fluid that can flow between the piston and the cylinder.

A degassing device according to any one of the preceding claims, wherein the pressure reducing device is located in a lower part of the degassing housing and wherein the pressure reducing device is adapted to be used below a liquid level in the degassing housing.

A degassing device according to any one of the preceding claims, wherein the piston comprises an actuator end (728) and the first valve is a check valve, the actuator end being arranged to engage the first valve, whereby the movement of the piston from the retracted position to the extended position moves the first valve from an inactive closed position to the open position by means of the actuator tip, and the movement of the piston from the extended position to the retracted position moves the first valve from an open position to the inactive pressure position moves through the actuator end.

A degassing device according to any one of the preceding claims, wherein the branch passage extends through the cylinder between the main flow channel and the degassing zone and wherein a piston movement is arranged to move the first valve to the closed position.

A degassing device according to any one of the preceding claims, wherein a cavity (742) is located in the cylinder and between the main flow channel and the piston, a branch flow path (32) extending through the cavity, in particular behind the piston and around a piston rod.

The degassing apparatus of the preceding claim, wherein the cylinder defines a branch flow hole (744), the branch flow path extending through the branch flow passage, through the cavity and through the branch flow hole into the inner volume.

A degassing device according to any one of the preceding claims, wherein the first valve is integrated in the pressure reducing device, in particular in the piston, the piston comprising a part obstructing the branch passage in the low pressure position.

A degassing device according to any one of the preceding claims, wherein the second valve is a non-return valve.

A degassing device according to any one of the preceding claims, wherein the gas outlet further comprises a float chamber (86) and the valve body comprises a float movable between a floating position (842) and a lowered position (844), whereby when a liquid level falls below a predetermined level (88) drops, the float engages an end of the outlet tube in the lower position, closing the outlet tube.

A degassing device according to any one of the preceding claims, wherein the float chamber comprises a float valve (85) defining a gas outlet opening and wherein when a liquid level exceeds a second predetermined level (89), the valve body is moved to a higher position (846). becomes where it closes off the float valve.

A degassing device according to any one of claims 18-19, wherein the bob comprises a protrusion (83) adapted to close the outlet tube and located at a bottom (832) of the float, and wherein an outer dimension of the protrusion corresponds to an inner dimension of the exhaust tube.

A degassing device according to any one of claims 18-20, wherein the float valve comprises a backflow preventer (852) adapted to allow gas to escape and not to allow gas to enter the gas outlet, the backflow preventer being in particular a check valve.

A degassing device according to any one of claims 19-21, wherein the float comprises an O-ring or a double lip seal to close the outlet tube in the lowered position.

A degassing device according to any one of the preceding claims, wherein the gas outlet comprises a gas outlet valve (87), the gas outlet valve permitting gas and/or liquid to flow between the exterior and the degassing zone in an open state and sealing the degassing zone in a closed position, wherein the gas outlet valve is in particular a ball valve.

A degassing apparatus according to any one of the preceding claims, further comprising a vacuum pump (78) connected to the gas outlet, and a porous chamber (44) located in the interior volume of the degassing housing, the branch passage diverting part of the main stream to branches off within the porous chamber and the return passageway extends between the porous chamber and the main flow channel, the porous chamber comprising a porous element (442) permeable to gases and impermeable to liquid.

A degassing apparatus according to any preceding claim wherein the main flow channel is constricted between the first side and the second side, a constriction (26) being adapted to increase pressure adjacent the branch passage causing a portion of the main flow to enter the degassing housing. is forced, and/or wherein the main flow channel includes a branch flow separator (28) extending into the main flow channel and adapted to branch off a portion of the main flow to the degassing zone, and/or wherein the main flow channel includes a main flow valve (27) which is arranged to branch off part of the main stream to the degassing zone.

A degassing device according to the preceding claim, wherein the constriction comprises a non-return valve (60C).

A degassing device according to any one of the preceding claims, further comprising a spring return switch (75) adapted to interrupt use of the pressure reduction device, wherein in the first actuator position the piston actuator depresses the spring return switch, and in the second actuator position the switch springs back .

A degassing device according to any one of the preceding claims, further comprising at least one sensor (92) and a control unit (90) arranged to read the at least one sensor and/or to control the pressure reduction device.

Degassing device according to the preceding claim, wherein a first pressure sensor (92A) is located in the main flow channel and wherein a second pressure sensor (92B) is located in the degassing zone, and wherein the control unit is arranged to control the pressure reduction device as a function of a output of the first pressure sensor and/or the second pressure sensor,

A degassing device according to any one of claims 28-29, wherein at least one sensor is a flow measuring device arranged to determine the flow required to move the piston.

A degassing device according to any one of claims 28-30, wherein the pressure reduction device comprises the sensor adapted to detect a pressure in the degassing zone.

A degassing device according to any one of claims 28-31, wherein at least one sensor is a strain gauge or an extensometer, the at least one sensor being used to measure a strain value or strain value for the control unit to determine a pressure in the degassing zone .

A degassing device according to any one of claims 28-32, further comprising a temperature sensor (92C), the temperature sensor being located in particular in the main flow channel, the temperature sensor measuring a temperature of the liquid in the main flow channel and the control unit reading the temperature sensor and controls the pressure reduction device.

A degassing device according to any one of claims 28-33, wherein the control unit is further configured to control at least one of the first valve, the second valve, and the main flow valve.

A degassing device according to any one of the preceding claims, wherein the pressure reducing device is positioned at least partly on an upstream side of the degassing housing, in particular the piston actuator being located on an upstream side of the degassing housing.

Degassing device according to any one of claims 28-35, comprising at least one pressure sensor (92), the control unit comprising: - a first test module (91) arranged for determining the presence of a leak, the first test module being arranged to : o close at least one valve,

o subsequently control the pressure reduction device to reduce or increase the pressure, and o subsequently read the at least one pressure sensor, o after a period of time read the at least one pressure sensor a second time, and o the second measured pressure compare with the first measured pressure to determine a difference, wherein a difference signal is generated, and/or - a second test module (91) arranged to determine the presence of a flow in the main flow channel, the second test module being arranged to: o read out the at least one pressure sensor, o then close the at least one valve, o after a period of time read out the at least one pressure sensor a second time, and o compare the second measured pressure with the first measured pressure to determine a difference, wherein when the difference is less than a threshold value, a difference signal indicating a lack of flow is generated.

A degassing apparatus according to any one of the preceding claims, wherein the first test module is arranged to maintain the pressure in the degassing zone constant or substantially constant over a test period of time by measuring the pressure in the degassing zone, comparing the measured pressure to a target pressure and pressure reduction device to maintain the pressure in the degassing zone at the target pressure, and wherein the first test module measures an operational parameter of the pressure reduction device over time and is arranged to generate a differential signal indicative of a leak when the measured operational parameter exceeds a predetermined exceeds a certain threshold value, wherein said operational parameter is in particular the position of a piston and/or the power consumption of the pressure-reducing device, and/or wherein the first test module is arranged to keep a position of the piston constant or substantially constant during a test time period and wherein said first test module measures the pressure in the degassing zone during a test time period and is arranged to generate a difference signal indicative of a leak when a measured pressure difference over time exceeds a predetermined threshold value.

A degassing device according to any one of the preceding claims, wherein the first and/or the second test module determines the difference and; - when the difference is greater than the threshold value, the control unit periodically performs a degassing cycle, and - when the difference is less than the threshold value, the control unit does not perform a degassing cycle.

A degassing device according to any one of the preceding claims, wherein the main flow channel is defined by a bowl (100) comprising an inlet (102) and an outlet (104) and a cover (11) from which a plate (112) extends downwards wherein the plate divides the bowl into an inlet side (106) and an outlet side (108) and allows fluid communication through the constriction from the inlet side to the outlet side, and wherein the lid separates the main flow channel from the degassing zone and includes at least one valve located is in at least one flow passage, and wherein the degassing housing includes a hood (120) located on top of the lid.

40. Method for degassing a gas-containing liquid in a cooling or heating installation by means of a degassing device (10), the degassing device comprising: - a main flow channel (20) with a main flow of liquid flowing through the main flow channel, - at least one flow passage (15) extending between the main flow channel and a degassing zone (42), - a degassing housing (40) defining an interior volume, the interior volume substantially corresponding to the degassing zone, - a valve (60) movable between a closed position (62) and an open position (64), - a pressure reducing device (70) connected to the degassing housing, - a gas outlet (80) in the degassing housing, the gas outlet comprising an outlet tube (82) and an outlet closing body (84 ), wherein the outlet tube is closable by the outlet closing body, the method comprising the steps of: a) branching off a portion of the main stream through the at least one flow passage,

b) moving the at least one valve to the closed position, obstructing the at least one flow passage, thereby isolating the degassing zone from the main flow channel, and closing the gas outlet, c) operating the pressure reducing device to reduce the pressure in the degassing zone relative to the pressure in the main flow channel, d) opening the at least one valve and the gas outlet, wherein during step c) gas dissolved in the liquid is separated from the liquid and during and/ or after step d) liquid in the degassing housing is returned to the main flow channel through the at least one flow passage and the separated gas is expelled through the gas outlet.

A method according to the preceding method claim, wherein the degassing device comprises two flow passages, a first flow passage being a branch passage (30) and a second flow passage being a return passage (50).

A method according to any of the preceding method claims, wherein the pressure reducing device is connected to the degassing housing and wherein the pressure reducing device comprises a piston (72), a cylinder (74), and a piston actuator (76), the piston being in open communication with the internal volume, and wherein during step c) the piston is moved between an extended position (722) and a retracted position (724), the degassing zone being defined by the degassing housing and the piston.

A method according to any one of the preceding method claims, wherein the vent zone is enlarged inwardly of the cylinder as the piston is moved from the extended position to the retracted position and the vent zone is larger in the retracted position than in the extended position, or wherein the degassing zone is enlarged inwardly of the cylinder as the piston is moved from the retracted position to the extended position and the degassing zone is larger in the extended position than in the retracted position.

A method according to any one of the preceding method claims, wherein the branch passageway extends through the cylinder between the main flow channel and the degassing zone and wherein step b) and step c) occur substantially simultaneously and wherein moving the piston moves the at least one valve to the closed position moves and/or the gas outlet closes.

The method of the preceding claim, wherein the piston includes an actuator tip (728) and the first valve is a check valve, wherein when the piston is moved to the extended position, the actuator tip moves the first valve to the open position, and wherein when the piston is moved to the retracted position, the valve is allowed to move to the closed position.

A method according to any of the preceding method claims, wherein the outlet valve body comprises a float and wherein when a liquid level is below a predetermined level (88), the float closes an outlet tube (82).

A method according to any of the preceding method claims, wherein the gas outlet further comprises a float valve (85) and wherein when a liquid level reaches a second predetermined level, the float valve closes off the gas outlet opening.

A method according to any one of claims 46-47, wherein the float comprises a protrusion (83) and an outer dimension of the protrusion substantially corresponds to an inner dimension of the exhaust tube and wherein during step b) the protrusion is forced into the exhaust tube.

The method of any of claims 46-48, wherein the float comprises a backflow preventer (852), the backflow preventer preventing gas from flowing into the degassing zone when an outside pressure exceeds a pressure inside the degassing housing, in particular the backflow preventer prevents gas flows into the degassing zone during step c).

A method according to any of the preceding method claims, wherein the main flow channel is constricted between the first side and the second side, a constriction (26) increasing the pressure near the branch passage and forcing a portion of the main flow into the degassing housing, and /or wherein the main flow channel includes a branch flow separator (28) extending into the main flow channel and diverting a portion of the main flow to the degassing zone, and/or wherein the main flow channel includes a main flow valve (27) adapted to divert a portion of the main flow to to branch off the degassing zone.

A method according to the preceding method claim, wherein before step d), the pressure in the degassing zone is increased to substantially the pressure present during step a).

A method according to any of the preceding method claims, wherein the degassing device further comprises a spring return switch (75) and the piston actuator is attached to the degassing housing via one or more spring elements (762) and wherein the piston actuator is resiliently movable between a first actuator position ( 764) and a second actuator position (766), where when a force required to move the piston to the retracted position exceeds a predetermined value corresponding to a minimum pressure inside the degassing housing, the force moves the piston actuator from a first actuator position , where the switch is depressed, to a second actuator position, where the switch is spring-backed, the spring-back of the switch interrupting operation of the pressure reducing device.

A method according to any one of the preceding method claims, wherein the degassing device further comprises at least one sensor (92) and a control unit (90), the control unit reading the at least one sensor and/or controlling the pressure reduction device.

A method according to the preceding claim, wherein the sensor is a force sensor connected to the piston actuator and the degassing housing, the sensor measuring a force acting on the piston actuator in a direction substantially parallel to a central axis of the cylinder.

A method according to the preceding claim, wherein a first pressure sensor (92A) is located in the main flow channel and wherein a second pressure sensor (92B) is located in the degassing zone, and wherein the first and second pressure sensors measure a first and second pressure, respectively.

A method according to any one of claims 53-55, wherein the degassing device further comprises a temperature sensor (92C), the temperature sensor being located in particular in the main flow channel, the temperature sensor measuring a temperature of the liquid in the main flow channel and wherein the control unit reads the temperature sensor and controls the pressure reduction device.

A method according to any one of claims 53-58, wherein the control unit controls at least one of the first valve, the second valve, the main flow valve, and the gas exhaust valve.

58. Method for testing a degassing device (10) for degassing a gas-containing liquid in a cooling or heating installation, the degassing device comprising: - a main flow channel (20), wherein a main flow flows through the main flow channel, - at least at least one flow passage extending between the main flow channel and a degassing zone (42), - a degassing housing (40) defining an interior volume, the interior volume substantially corresponding to the degassing zone, - at least one valve (60) movable between a closed position (62) and an open position (64), - a pressure reducing device (70) connected to the degassing housing, - a gas outlet (80) in the degassing housing, the gas outlet comprising an outlet tube {82) and an outlet closing body (84 ), the outlet tube being closable by the outlet closing body, - a control unit (90) comprising a first and/or a second test module, connected to a pressure sensor and arranged to receive a differential pressure signal from the pressure sensor, the method comprising the steps of: a) closing the at least one valve and measuring a first pressure in the degassing housing with the pressure sensor, b) measuring a second pressure in the degassing housing with a pressure sensor after a period of time, c) comparing the second pressure to the first pressure by the control unit to determine a difference, wherein a difference signal is generated by the control unit when a difference exists between the first and second pressures.

A method of testing a degassing device according to the preceding claim, wherein step a) comprises the sequential steps of: a) 1) closing the at least one valve, a) 2) operating the pressure reducing device to reduce the pressure inside decrease or increase the degassing housing, a) 3) measuring a first pressure, and wherein the differential signal generated by the control unit when the difference between the first pressure and the second pressure is indicative of a leak in the degassing housing containing liquid and/or allows gas to escape the degassing housing.

A method according to the preceding claim, wherein in step a2) the pressure is reduced below atmospheric pressure and wherein if the second pressure is higher than the first pressure and lower than or equal to atmospheric pressure, a difference signal is generated which is indicative for a leak of air from the outside to the inside of the degassing box.

A method according to claim 59, wherein in step a2) the pressure is reduced above atmospheric pressure but below a pressure in the main flow channel and wherein if the second pressure is lower than the first pressure, a difference signal is generated indicative of a leak from inside the degassing housing to the outside.

The method of claim 59, wherein in step a2) the pressure is reduced above atmospheric pressure but below a pressure in the main flow channel and wherein if the second pressure is greater than the first pressure, a differential signal is generated indicative of a leakage from the main flow channel into the degassing housing.

The method of claim 59, wherein the control unit controls the pressure reduction unit to maintain the second pressure substantially equal to the first pressure, and wherein when the pressure reduction device is actuated after measuring the first measured pressure, a difference signal is generated indicative of a leak.

A method according to the preceding claim, wherein in step a2) the pressure is reduced to below atmospheric pressure and wherein when the pressure reducing device is actuated to reduce the pressure, a differential signal is generated indicative of the leakage of air from the outside to the inside the degassing housing or from the main flow channel into the degassing housing.

The method of claim 63, wherein in step a2) the pressure is reduced above atmospheric pressure but below a pressure in the main flow channel and wherein when the pressure reducing device is actuated to increase the pressure, a differential signal is generated indicative of a leak from inside the degassing housing to the outside.

The method of claim 63, wherein in step a2) the pressure is reduced above atmospheric pressure but below the pressure in the main flow channel and wherein when the pressure reduction device is controlled to lower the pressure,

a difference signal is generated indicative of a leak from the main flow channel into the degassing housing.

A method of testing a degassing device according to claim 58, wherein the device comprises at least two flow passages, a flow passage being a branch passage and a flow passage being a return passage, and the at least one valve is located in at least one of the second flow passages , wherein during step a) the at least one valve is closed after measuring the first pressure and wherein, when the difference is less than a predetermined threshold value, a difference signal is generated indicative of a lack of flow.

A method according to the preceding claim, wherein: a) when the difference is greater than the predetermined threshold value, the control unit periodically performs a degassing cycle, and b) when the difference is less than the predetermined threshold value, the control unit does not perform a degassing cycle .

A method of testing a degassing device according to any of claims 67-68, wherein the device further comprises a second valve located in the other of the at least two flow passages and wherein after the method of claim 67 has been performed, each of the methods of claims 59-66 can be performed.

A method of testing a degassing device according to any of claims 67-69, wherein the method is performed prior to or while performing a method according to any of claims 40-57.

A method of testing a degassing device according to any one of claims 58-70, wherein the method is performed periodically.