GB2299413A

GB2299413A - Gas pressure regulator

Info

Publication number: GB2299413A
Application number: GB9506582A
Authority: GB
Inventors: Thomas Potter
Original assignee: CONSULTUS
Current assignee: CONSULTUS
Priority date: 1995-03-30
Filing date: 1995-03-30
Publication date: 1996-10-02
Anticipated expiration: 2015-03-30
Also published as: GB2299413B; GB9506582D0

Abstract

A gas pressure regulator for a pressure vessel such as a beer keg (1) has a pressure reducing valve connected between the pressure vessel (1) and a source of pressurized gas (5). An actuator is provided which can be set between predetermined limits to determine the output pressure of the valve. A temperature sensor, which can detect the ambient temperature, is connected to a control means which is programmed to set the output pressure of the pressure reducing valve at a predetermined value dependent on the temperature detected by the sensor. Thus, temperature variations in the storage environment of the pressure vessel (1) are compensated for by a corresponding increase or decrease of its storage pressure.

Description

A GAS PRESSURE REGULATOR The present invention relates to a gas pressure regulator for use in control of the pressure in a pressure vessel and in particular, but not exclusively, for use in the control of the pressure within a beer keg.

In a keg, beer or lager is stored under pressure so that it is infused with gas, which is usually carbon dioxide. The beer or lager is served under pressure and, in order to make up the pressure within the keg after the removal of a quantity of the liquid therefrom, the keg is connected via one or more pressure reducing valves to a supply of pressurized gas, typically one or more carbon dioxide gas bottles.

It will be appreciated that once the settings on the pressure reducing valves controlling the pressure within the keg have been set, that pressure is maintained regardless of the ambient temperature in the environment in which the keg is stored. However, as keg beer may be stored in an uncooled cellar, there can be large temperature fluctuations in this environment. Such fluctuations cause more or less of the pressurizing gas to dissolve in the liquid. This can have a detrimental effect upon the beer or lager and make it unservable. In the case of certain specially brewed beers or lagers, these effects may also irreversibly spoil them.

The object of the present invention is to overcome or substantially mitigate the aforementioned problem.

According to the present invention there is provided a gas pressure regulator for a pressure vessel comprising a first pressure reducing valve for connection between the pressure vessel and a source of pressurized gas for pressurizing the pressure vessel and with an actuator which can be set to determine the output pressure of the valve; an adjustment means for controlling the setting of the actuator between predetermined limits; a temperature sensor for detecting the ambient temperature; and a control means which is operationally connected to the temperature sensor and the adjustment means and which is programmed to cause operation of the adjustment means to set the output pressure of the pressure reducing valve at a predetermined value dependent on the temperature detected by the sensor.

Preferably, a second pressure reducing valve is provided for connection between the source of pressurized gas and the first pressure reducing the valve whereby said first pressure reducing valve can be fine tuned for controlling a pressure differential thereacross substantially equivalent to the pressure differential between said predetermined limits.

Preferably also, the control means comprises a microprocessor control means.

Preferably also, the adjustment means comprises a motor operationally linked to a feedback potentiometer connected to the control means whereby the position of the actuator and thereby its setting can be determined by the control means.

Preferably also, the potentiometer comprises a resistor with a contact which can travel in incremental steps.

Preferably also, said incremental steps are equivalent to no more than 1.3790 x 104 pascals (2 psi).

Preferably also, the operating range of the potentiometer between said predetermined limits comprises at least three turns of the resistor within a maximum travel of at least ten turns.

Preferably also, the operating range of the potentiometer is equivalent to adjustment of the actuator between said predetermined limits.

Preferably also, said predetermined limits define a pressure range between O.9h5 x 105 pascals and 2.689 x 105 pascals (14 psi and 39 psi).

Preferably also, the temperature sensor comprises a temperature transducer whose output is linearized by the control means.

Preferably also, the output of the temperature transducer is linearized into increments of 1 C.

Preferably also, the control means causes operation of the adjustment means between an ambient temperature range of 4"C to 25"C inclusive.

Preferably also, the pressure reducing valve comprises a safety valve to prevent pressurization of the pressure vessel above a predetermined maximum pressure.

The present invention will now be described by way of example with reference to the accompanying drawings in which: Fig. 1 shows an arrangement of a gas pressure regulator according to the invention when in use in a beer cellar connected to ale and beer kegs, a lager tank and other pressurized vessels containing beverages; Figs. 2 and 3 are side and plan views respectively to an enlarged scale of components forming part of the gas pressure regulator shown in Figure 1; Fig. 4 is a block circuit diagram showing a control means for the regulator.

It will be appreciated that a gas pressure regulator in accordance with the invention can be used in many situations. In this example its use will be described in terms of the control of the pressure within a keg and other pressure vessels for containing carbonated beverages such as vessels 1, 2 and 3 as will now be described.

With reference to the Fig. 1, in a conventional beer cellar lager, ale and beer kegs 1, a lager tank 2, and another pressurized vessel 3 containing a carbonated beverage are connected by gas line hoses 4 to one of a plurality of bottles 5 containing pressurized carbon dioxide for pressurizing the vessels 1, 2, 3. Between the source of pressurized carbon dioxide 5 and each of the beverage pressure vessels 1, 2, 3 is located a gas pressure regulator 6 according to the present invention.

In order to simplify Fig. 1, only one gas line hose 4 is shown in the drawing linking each pressure vessel 1, 2, 3 to the regulator 6 but in reality each vessel 1, 2, 3 will be connected separately to a manifold 7 for connection to the regulator 6. However, the regulator will be connected via a single high pressure hose 8 to the gas bottle 5 in use at the time.

A low pressure sensor 9 may also be connected in the pressure line downstream of the regulator 6, and typically upstream of the manifold.

In use, the beverages in the vessels 1, 2, 3 are stored under a predetermined pressure as controlled by the regulator 6. When any particular beverage is drawn off from its vessel 1, 2, 3 via that vessel's beverage output line 10, then the fall in pressure within the vessel 1,2,3 is immediately compensated for by a flow of pressurized gas from the bottle 5 until the pressure downstream of the regulator 6 is restored to that predetermined by the setting of the regulator 6.

However, a gas pressure regulator 6 according to the present invention and as shown in Fig. 1 is adapted to regulate the pressure under which the beverages are stored depending on the temperature of the cellar. Hence, even though beverages may not be being served and drawn off from the vessels 1, 2, 3 the internal pressure of the vessels 1, 2, 3 will be varied in accordance with the ambient temperature so that the pressure under which the beverages are stored is optimized.

In such a situation, it is necessary to take into account cellar temperatures which in uncontrolled environments may vary between 4"C and 2500 and to determine the desirable storage pressure of the beverage at any temperature in this range. In this example it is desired to vary the pressure linearly between 0.965 x 105 pascals and 2.689 x 105 pascals (14 psi and 39 psi) over this temperature range.

The construction of a gas pressure regulator 6 according to the invention will now be described in more detail with reference, in particular, to Figs. 2, 3 and 4.

The regulator 6 preferably comprises a pair of serially linked pressure reducing valves, which can be of any conventional design but are preferably diaphragm valves. One of the valves (not shown) comprises a conventional pressure reducing valve and is used to reduce the pressure of the pressurized gas source 5 down to just above the pressure level required for the vessels 1, 2, 3.

The second pressure reducing valve 11, however, is adapted to be capable of fine tuning the output pressure of the regulator 6 dependent on the ambient temperature and in accordance with the predetermined criteria stated above.

The output pressure from the regulator 6 at any given time is indicated by a pressure gauge 12.

It will be appreciated that the regulator 6 could simply comprise a single valve 11, but greater control and fine tuning can be achieved if two pressure reducing valves are used.

As previously stated, the pressure reducing valve 11 can be of generally conventional construction and comprises a controllable vent 13 and two safety valves 14, which meet with current codes of practice. However, it also comprises an actuator which is modified so as to be automatically controllable as will now be described.

In this example, the actuator comprises an adjusting screw 15 which can be turned into or out of the valve 11 to control the output pressure. The screw 15 is in turn connected to an output drive shaft 16 from a gearbox 17 which is connected to an electric motor 18. The motor 18 is connected to a electricity supply 19, typically a mains supply via a transformer (not shown). It is anticipated that the gearbox 17 will have reducing gears in the ratio of typically 2560:1.

The drive shaft 16 is also connected to a feedback potentiometer 20 whereby the degree by which the screw 15 is turned, thereby varying its setting with regard to the operation of the valve 11, can be detected. Preferably, the potentiometer 20 comprises a resistor, such as a resistance wire or conductive plastics strip, and a contact which can travel along the resistor in incremental steps equivalent to no more than 1.3790 x 104 pascals (2 psi). The operating range of the potentiometer 20 preferably comprises at least three turns of the resistor within a maximum travel of at least ten turns. To facilitate the initial setting-up of the regulator 6, a reference point is set on the potentiometer 20 which can move the operating range of 3 turns anywhere within the 10 turn range.The operating range of the potentiometer 20 is equivalent to adjustment of the actuator between said predetermined pressure limits of 0.965 x 105 pascals and 2.689 x 105 pascals (14 psi and 39 psi). It will be appreciated, however, that any number of turns can be chosen to represent the predetermined operating range, as can the total number of turns of the potentiometer.

The adjustment of the screw 15 is controlled by a control means comprising a microprocessor 21 which is linked to a temperature sensor 22 for detecting the ambient temperature within the cellar. The temperature sensor 22 comprises a temperature transducer, such as a thermistor, and is powered from the same electricity supply 19 as the motor 18.

The operation of the motor 18 is also controlled by the microprocessor 21 which determines the drive direction of the motor and the duration of its operation, which it turn determines the degree to which the screw 15 is turned.

The microprocessor 21 itself is programmed so the output resistance of the temperature transducer 22, which is non-linear, is applied, for example, to an internal look-up table or other similar means to linearize the results between 4"C and 21iC in increments of 1-C.

Likewise, the position of the adjusting screw 15 is sensed by the potentiometer 20. All positional sensing is calculated by the microprocessor 21 by reference to the reference point and turned into incremental values representing steps equivalent to no more than 1.3790 x 104 pascals (2 psi). Thus for every given temperature within the operating range of 4-C to 21 C inclusive there is a corresponding preferred pressure between the predetermined pressure limits of 0.965 x 105 pascals and 2.689 x 105 pascals (14 psi and 39 psi).

The microprocessor 21 can, however, be programmed so that the setting of DIP switches can he altered to vary the predetermined pressure limits and thereby the operating range of the potentiometer extended or reduced from the 3 turns described in this example. In this way, the carbonation requirements of different beverages can be accommodated in a single regulator.

Should the ambient temperature rise above an upper predetermined limit of say 25"C, the microprocessor 21 is programmed not to respond. In this way the output pressure of the valve 11 should never be increased above the upper predetermined limit. However, to ensure a fail safe condition, the safety valve 14 of the pressure regulating valve 11 is arranged to vent open if the output pressure rises above 3.103 x 105 pascals (45 psi).

In practice, the mechanical parts of the regulator 6 comprising the gearbox 17, motor 18 and potentiometer 20 are preferably housed in a casing 23 which can be wall mounted above the pressure reducing valve 11 or valves, if a pair are used which can also be secured to the wall. The electrical components of the regulator comprising the microprocessor 21 and temperature sensor 22 are housed separately in a suitable housing 24 which is linked via a suitable cable 25 and plug/socket means to the components in the casing 23. By this means, the housing 24 can be located in the best location for detection of the mean ambient temperature in the cellar and away from draughts.

In use, at regular intervals as controlled by the operating clock of the microprocessor 21, the microprocessor 21 determines the ambient temperature within the cellar from the output of the temperature sensor 22. In accordance with its program, the microprocessor 21 then determines the appropriate storage pressure for the beverage and if different from that being sensed by the potentiometer 20 operates the motor 18 for an appropriate time and in the appropriate direction to adjust the screw 15 to increase or decrease the output pressure of the valve 11 to that required. If the output pressure is increased, gas is permitted to flow from the bottle 5 through the regulator 6 to increase the internal pressure of the vessels 1, 2, 3 to the new setting of the valve 11. However, if the output pressure setting is decreased, the vent 13 is temporarily opened to permit gas to escape from the gas lines 4 to reduce the internal pressure of the vessels 1, 2, 3 until the new pressure setting is reached when the vent 13 is closed.

As the gas bottle 5 comprising the source of pressurized carbon dioxide empties, there comes a point at which the output pressure of the regulator 6 can not be maintained at that required. A pressure below the lower predetermined limit, in this example below 0.965 x 105 pascals (14 psi), is detected by the low pressure sensor 9 and an alarm raised, such as the lighting of a warning light. A fresh gas bottle 5 should then be substituted for the empty one.

It will thus be appreciated that temperature variations in the storage environment of the beverage are compensated for by the increase or decrease of its storage pressure to ensure that the beverage is always stored at the desired equilibrium pressure. This ensures carbon dioxide is always kept in solution so that the beverage is always served in a satisfactory condition.

Claims

1. A gas pressure regulator for a pressure vessel comprising a first pressure reducing valve for connection between the pressure vessel and a source of pressurized gas for pressurizing the pressure vessel and with an actuator which can be set to determine the output pressure of the valve; an adjustment means for controlling the setting of the actuator between predetermined limits; a temperature sensor for detecting the ambient temperature; and a control means which is operationally connected to the temperature sensor and the adjustment means and which is programmed to cause operation of the adjustment means to set the output pressure of the pressure reducing valve at a predetermined value dependent on the temperature detected by the sensor.

2. A gas pressure regulator as claimed in Claim 1, wherein a second pressure reducing valve is provided for connection between the source of pressurized gas and the first pressure reducing the valve whereby said first pressure reducing valve can be fine tuned for controlling a pressure differential thereacross substantially equivalent to the pressure differential between said predetermined limits.

3. A gas pressure regulator as claimed in Claim 1 or Claim 2, wherein the control means comprises a microprocessor control means.

4. A gas pressure regulator as claimed in any one of Claims 1 to 3, wherein the adjustment means comprises a motor operationally linked to a feedback potentiometer connected to the control means whereby the position of the actuator and thereby its setting can be determined by the control means.

5. A gas pressure regulator as claimed in Claim 4, wherein the potentiometer comprises a resistor with a contact which can travel in incremental steps.

6. A gas pressure regulator as claimed in Claim 5, wherein said incremental steps are equivalent to no more than 1.3790 x 104 pascals (2 psi).

7. A gas pressure regulator as claimed in any one of Claims 4 to 6, wherein the operating range of the potentiometer between said predetermined limits comprises at least three turns of the resistor within a maximum travel of at least ten turns.

8. A gas pressure regulator as claimed in any one of Claims 4 to 7, wherein the operating range of the potentiometer is equivalent to adjustment of the actuator between said predetermined limits.

9. A gas pressure regulator as claimed in any one of Claims 1 to 8, wherein said predetermined limits define a pressure range between 0.965 x 105 pascals and 2.689 x 105 pascals (14 psi and 39 psi).

10. A gas pressure regulator as claimed in any one of Claims 1 to 9, wherein the temperature sensor comprises a temperature transducer whose output is linearized by the control means.

11. A gas pressure regulator as claimed in Claim 10, wherein the output of the temperature transducer is linearized into increments of 1"C.

12. A gas pressure regulator as claimed in any one of Claims 1 to 11, wherein the control means causes operation of the adjustment means between an ambient temperature range of 4-C to 25-C inclusive.

13. A gas pressure regulator as claimed in any one of Claims 1 to 12, wherein the pressure reducing valve comprises a safety means to prevent pressurization of the pressure vessel above a predetermined maximum pressure.

14. A gas pressure regulator for a pressure vessel substantially as described herein with reference to any one of the accompanying drawings.