WO2020144459A1

WO2020144459A1 - Pipe purge system for air conditioning systems and method of purging pipes using said system

Info

Publication number: WO2020144459A1
Application number: PCT/GB2020/050011
Authority: WO
Inventors: Philip Graeme BUTTLE
Original assignee: Buttle Philip Graeme
Priority date: 2019-01-08
Filing date: 2020-01-06
Publication date: 2020-07-16
Also published as: GB2571006A; GB201900265D0

Abstract

A pipe purge system for purging air conditioning pipes has a valve assembly (1) operable by a remote control (15). An inlet port (2) of the valve assembly (1) can be connected to a nitrogen cylinder (N) and three outlet ports (3, 4, 5) can be connected to ends of pipes (P1, P2, P3) which will carry coolant for the air conditioning. The remote control (15) can then be operated from a remote location adjacent the ends of the pipes to open a passage for nitrogen to purge a first one of the pipes prior to brazing the purged pipe. Subsequent to brazing the remote control can be operated to close the open passage and open a second passage to purge a second pipe for brazing. When required all the passages can be closed by operation of the remote control. The system saves time, labour and nitrogen in brazing the coolant pipes of an air conditioning system.

Description

[Title established by the ISA under Rule 37.2] PIPE PURGE SYSTEM FOR AIR CONDITIONING SYSTEMS AND METHOD OF PURGING PIPES USING SAID SYSTEM

Technical Field

An air conditioning installation comprises at least a fan coil unit deployed at a station within a building, a condenser disposed remote from the fan coil unit, usually outside the building, a supply pipe and a return pipe to supply and return a working fluid to the fan coil unit during operation and miscellaneous power supply, sensor and control systems. As shown in figure 3.1 a three pipe installation system comprises a condenser C, a branch controller B (sometimes known as a changeover box) and a fan coil unit F. At least three pipes run from the condenser C to the branch controller B. A hot working fluid supply pipe PH, to supply heated pressurised fluid, a cold fluid supply pipe PC to supply high pressure cold fluid and a fluid return pipe PR. In figure 3.1 the three pipe system has a single condenser C serving six fan coil units F1-F6 via five branch controllers B1-B5. Each branch controller controls the supply and return of working fluid via one or more pairs of service pipes S. One of the service pipes SD delivers working fluid while the other service pipe SR returns working fluid. Each branch controller is responsive to an air conditioning control unit (not shown) to control the delivery of one of cold fluid or hot fluid to each associated fan coil unit and to return the fluid to the return pipe PR. By this arrangement the air conditioning system can provide air cooling to certain fan coil units such as F1, F5 and F6 because cold fluid is supplied from the condenser C and warm fluid returned to the condenser. Fan coil units F2 and F4 can deliver warm air heating because hot fluid is delivered from the condenser and cooled fluid returned along return pipe PR. Fan coil unit F4 is stopped while the remaining units are operative.

During the installation process the supply pipes PH, PC and return pipe PR must be run from the condenser to each fan coil unit, by way of the branch controllers B. The pipes are most commonly copper pipe and are usually connected by brazing to the branch controller B. This requires a minimum of five brazed joins. In practice this is unusual because in most systems the supply and return pipes must be continued to a next branch controller (eg B2) on the circuit. To achieve this a prefabricated “T” junction (sometimes known as a refnet joint) is required resulting in an additional three brazes, for a total of four for each of P1 to P3 plus two for the service pipes requiring at total of 12 per branch controller. Further braze joints are frequently applied to join lengths of pipe. In a practical air conditioning installation it is not unusual for hundreds of brazed joints to be required. It is important to avoid oxidation of the pipe bore during the brazing process. In order to avoid oxidation air is purged from the pipe bore prior to brazing.

Background Art

The conventional way to purge a pipe bore is to couple a tank of compressed nitrogen to one end of the pipe bore via a supply valve. The valve is opened for a period of time estimated to be sufficient for air to be purged from the bore by the influx of nitrogen. The installer then brazes the joint. The valve is then closed. Because the pipe end is commonly far from the joint this either requires an assistant to operate the valve in response to instructions from the installer or the installer will need to travel between the valve and the joint repeatedly. This is wasteful of nitrogen and, or labour and adds to the cost of installation.

GB2461319 proposes a system in which a purge gas supply valve is actuated remotely by a radio transponder remote control. The system of GB2461319 has one solenoid valve controlling the communication of nitrogen from a supply tank to an inlet port of a manifold. A switch responds to reception of a radio signal at an antenna to deliver current to the solenoid valve. The solenoid valve then opens to allow supply of nitrogen from the tank to the manifold. The manifold then distributes nitrogen from the tank equally to each of several outlet Schrader valves. A flexible gauge line is connected from each Schrader valve one each to each supply or return pipe to be brazed. Once a pipe is connected and the solenoid is opened nitrogen can pass into each connected pipe bore. If two or more pipes are connected and the solenoid is opened nitrogen will pass along all the connected pipes. As explained above all air conditioning systems have at least two pipes and often three. Only one pipe can be brazed at a time so that the nitrogen in any other pipes is wasted.

Disclosure of Invention

According to a first aspect of the present invention there is provided A pipe purge system for use in installing air conditioning systems comprising:
a portable remote control unit (15) capable of transmitting a range of remote control signals, and
a portable valve assembly (1), said valve assembly (1) having an inlet port and at least two outlet ports, said inlet port adapted to be communicated with a purge fluid supply to receive purge fluid, each of said outlet ports being adapted to communicate with one of a supply pipe or a return pipe of an air conditioning system to deliver purge fluid into any of said pipes;
a purge fluid flow control valve sub assembly operable to control the flow of fluid from said inlet port to each outlet port;
a controller capable of receiving a control signal from said remote control, and responsive to a specified one of the range of control signals to control the condition of said flow control valve sub assembly to one of a flow condition or a shut off condition where;
the flow condition is a condition where purge fluid can flow from the inlet port along a selected one of at least two passages to only one of the outlet ports at a time and
the shut off condition is a condition where flow from the inlet port to any outlet port is shut off.

According to a second aspect of the present invention there is provided a method of purging pipes using an apparatus according to claim 1 comprising the steps of:
connecting the inlet port of the portable valve assembly to a supply of purge fluid near a first end of a pipe run comprising at least two pipes whereby purge fluid is supplied to the inlet port;
connecting the outlet ports of the portable valve assembly one each to the first ends of each of the two or more pipes of the pipe run;
at the second ends of the pipes to be brazed, operating the remote control so that the valve assembly (1) opens a passage from the inlet port to not more than one of the outlet ports of the valve assembly whereby purge fluid passes into one of the pipes;
brazing the pipe when purge fluid has purged the pipe;
at the ends of the pipes to be brazed, operating the remote control to close the open passage and to open a second passage from the inlet port to a second outlet port communicating with a second pipe;
when the second pipe has been purged, brazing the second pipe;
at the end of the pipes to be brazed, operating the remote control to signal to the valve assembly to close the passage from the inlet port to the second outlet port.

Preferably the portable remote control unit (15) is powered from an internal power supply such as a chemical cell accumulator. The portable remote control may transmit control signals via the radio part of the electromagnetic spectrum. However, the invention also contemplates transmission of the control signal via acoustic transmission along the pipe or pipes or by any other suitable carrier. Where radio is used it is preferable to choose frequencies to which concrete walls are relatively transparent.

One of the range of control signals may be selected from a control pad of the remote control. The range of control signals may include a shut off control signal to which the controller responds by implementing the shut off condition. There shall be at least two selectable flow control signals, a first flow control signal corresponding to a first flow condition where the controller sets the valve assembly to direct purge fluid to a first of the outlet ports only and, a second flow control signal wherein the controller responds to receipt of the second flow control signal to set the valve assembly to a second flow control condition to direct purge fluid to a second of the outlet ports. In preferred embodiments of the invention the pipe purge system may have a third outlet port to communicate with a third working fluid pipe as is sometimes provided on certain air conditioning systems. In this case the remote control will have at least a third flow control signal. The controller will respond to receipt of the third flow control signal to set the valve assembly to a third flow condition to direct purge fluid from the inlet port to the third outlet port only.

In a preferred embodiment of the invention, the flow control valve assembly may comprise a manifold having an inlet passage communicating with outlet passages to conduct purge fluid from the inlet port to each of the outlet ports. A motorized valve may be installed, one each in each outlet passage of the manifold. Each motorized valve is responsive to the controller to set the flow condition in the associated outlet branch of manifold. In an alternative embodiment a motorized spool valve may replace the solenoid valves and the manifold. The spool valve may have one inlet port and two or three outlet ports to direct purge gas.

The valves may include sensors responsive to the valve condition. Said valve sensors are arranged to report the valve condition to the controller. The controller then reports the valve condition by transmitting a corresponding report signal to the remote control. The remote control may include a receiver to receive said valve condition report signal and an indicator to communicate the reported valve condition to the installer. Thus the installer is reliably informed of the condition of the valve assembly.

When installing an air conditioning system conditions may arise where there is a pressure surge from the purge fluid supply. The purge fluid supply is usually a tank of pressurised nitrogen. Discharge from the tank is by means of a simple screw valve. If the valve on a fresh tank is opened quickly the resulting pressure surge may lead to damage of the components in the valve assembly or to the pipe. To prevent this the valve assembly may include an overpressure protection valve. The overpressure protection valve is preferably set downstream of the inlet port and arranged to open to atmosphere in response to the inlet pressure exceeding a predetermined safe pressure. The overpressure protection will preferably close after opening when the inlet pressure drops below the safe pressure.

The system will preferably include a pressure sensor responsive to the pressure somewhere in the manifold. The pressure sensor will report the manifold pressure to the controller and the controller will transmit the sensed pressure to the remote control. The remote control will report the pressure to the installer. The pressure sensor may detect when the pressure is under or over a predetermined value to indicate simply when the supply of purge fluid is, respectively, insufficient or sufficient to effectively purge the pipe. Purge fluid is commonly nitrogen discharged from a pressurised tank which becomes exhausted with use. The discharge is usually controlled by a simple screw valve fitted to the tank. Commonly an under pressure condition will occur when the tank is become exhausted but may also occur if the tank screw valve is insufficiently opened or there is an obstruction between the tank valve and the valve assembly .

The pressure sensor may sense the analogue pressure in the manifold and report the analogue pressure to the controller to be signalled to the remote control. This may usefully indicate if the pressure is sufficient for a particular length of pipe run and may helpfully warn the installer when the purge reserves are approaching exhaustion.

Brief Description of Drawings

A pipe purge system for use in installing air conditioning systems, in accordance with the present invention, will now be described, by way of example only, with reference to the accompanying figures; wherein,
Figure 1 is a diagrammatic front elevation illustration of a typical air conditioning system being installed in a building;
Figure 2 is a south east isometric view of the building in figure 1;
Figure 3 is an enlarged fragmental view of III in figure 2;
Figure 3.1 is a diagram of a three pipe air conditioning system;
Figure 4 is a south west isometric view of a remote control of the pipe purge system
Figure 5 is an enlarged south east isometric view of a system valve assembly connected to a nitrogen purge gas bottle;
Figure 6 is a high level circuit diagram of the remote control; ; and
Figure 7 is a diagram of the system valve assembly .

Mode(s) for Carrying Out the Invention

Figures 1 and 2 show a multi‑story building in which a fan coil unit “F” is to be installed suspended from the ceiling of the ground floor while the condenser “C” for the unit is to be installed on the roof. The fan coil unit F and condenser C are connected by three copper pipes P1, P2 and P3 which have been run between the condenser, a branch controller B (see figure 3.1) and the fan coil unit F. The branch controller will typically be installed to serve one or more fan coil units on the same floor and in many cases there will be several branch control units on each floor to serve a corresponding number of spaces.

It is now necessary for the installer “I” to join the end of each pipe to a corresponding inlet and outlet coupling of each branch controller by brazing. In order to purge air from the subject pipe prior to brazing the installer couples a valve assembly 1, to a nitrogen gas cylinder “N”. For this purpose the housing of the valve assembly 1 provides access to an inlet port 2 associated with a ¼ inch (10 mm) access valve, which may be a Schrader valve or any other suitable coupling. A preferably flexible inlet hose IH is provided with a complementary Schrader valve coupling leading to a threaded coupling provided on the valve gear of the Nitrogen tank. As shown the valve assembly 1 may be adapted to be suspended from a wheeled trolley carrying the nitrogen tank.

The valve assembly 1 provides three

outlet ports

3, 4, 5 associated with ¼ valves 3.1, 4.1, 5.1 which may be Schrader type valves. The outlet ports are connected, one each to flexible coupling hoses H1, H2, H3 and to the open ends of the three pipes P1, P2, P3 remote from the branch control unit and in this case adjacent the condenser C. It will be appreciated that the purge supply may be delivered from the ends of the pipes adjacent the fan coil unit if it is more convenient to braze the pipe ends adjacent the condenser.

With the valve assembly 1 connected the nitrogen tank valve is opened to deliver nitrogen to the valve assembly 1. In the valve assembly 1 nitrogen is distributed via a manifold 6. In the embodiment the manifold 6 has been assembled from a first ¼ (10mm) T junction connector 7.1 having an inlet communicating with the inlet port, a first outlet communicating with a motorized valve provided by a first solenoid actuated shut off valve 8.1 and a second outlet communicating with a second T junction connector 7.2. The second T‑junction connector provides an outlet communicating with a second solenoid actuated shut off valve 8.2 and a second outlet communicating with a third T‑junction connector 8.3. The third T‑junction connector 8.3 provides a first outlet to a third solenoid actuated shut off valve 8.3 and a second outlet to a fourth T‑junction 7.4. A first outlet from the T‑junction 7.4 communicates with an overpressure relief valve 9, and a second outlet from the fourth T‑junction communicates with a low pressure switch 13. Each solenoid valve 8 communicates downstream with one of the three

outlet ports

3, 4, 5.

Each solenoid valve 8 is responsive to a control signal emitted by a controller 10 which transmits a switching signal along control conductors 11.1, 11.2, 11.3. Each solenoid valve 8 includes a sensor 12.1, 12.2, 12.3 responsive to the open or closed condition of the solenoid valve to communicate a corresponding signal to the controller 10.

Controller 10 also receives a signal from low pressure switch 13.

The valve assembly 1 will also include a power supply (not shown), preferably in the form of a battery and features such as an on/off switch.

Controller 10 communicates with a transceiver 14 able to communicate wirelessly with a remote control 15.

Remote control 15 includes a visual display unit screen 16, on/off switch 17 and a control switch 18. The remote control 15 also includes a controller/processor 19, responsive to the control switch 18 to implement a control program. The remote controller 19 also drives a transceiver 20 to transmit to the valve assembly 1 and responds to signals received from the valve assembly 1 to display various data fields on the visual display unit. The transceivers may use the LPD 433 MHz band. The remote control also includes a power supply 21.

In use once the inlet hose IH and outlet hoses H1-H3 are connected the valve assembly 1 is switched on together with the remote control 15. The

processors

10, 19 will drive the

transceivers

14, 20 through a hand shaking procedure to confirm functionality and each of good or failed communication may be reported on the visual display unit at data field 21. The battery condition of the valve assembly 1 may be reported at field 22 while the condition of the remote control battery may be reported at field 23.

The nitrogen tank supply valve SV is then opened to allow nitrogen to flow into the valve assembly 1 and manifold. If the valve is opened too far or for any other reason the nitrogen pressure exceeds a predetermined safe pressure the overpressure relief valve 9 opens to vent nitrogen to atmosphere. At this stage the installer will be in the vicinity of the tank and valve assembly 1 and will be warned by the nitrogen discharge of the overpressure problem. However, the pressure switch 13 may sense the pressure and report the pressure to controller 10 which in turn will transmit the pressure via transceiver 14 to the remote control 15. Remote control 15 will respond to the pressure signal to display an indication of the overpressure condition in the field 24 on the visual display unit. This may be useful in noisy or windy conditions where hearing or feeling the gas discharge from the overpressure valve may be difficult. The pressure switch 13 may simply respond to the overpressure condition or may sense and report the analogue pressure.

When the supply tank discharge pressure is correctly adjusted the installer will travel to the pipe ends requiring brazing, in this case to the branch controller. At the branch controller the installer can check the communication of the remote control with the valve assembly 1 via the visual display unit. If communication is good and when the installer is ready the installer actuates the control switch 18. The controller 19 responds to actuation of the control switch 18 to transmit a switch signal via transceiver 20 to the valve assembly 1. At the valve assembly 1 the controller 10 responds to receipt of the switch signal to signal to the motor of the first solenoid valve 8.1 to change condition from closed to open. When the sensor 12.1 senses the condition of the 1^st solenoid valve to report when it opens to the controller 10, the controller will also pole the condition of the second and third solenoid valves to determine if they are open or closed. The controller 10 will then transmit signals representing the condition of the solenoid valves to the remote control 15. When the remote control 15 receives the valve condition signals the controller drives the visual display unit to report the solenoid valve conditions in

fields

25, 26, 27, in this case the 1^st solenoid valve is open, the second and third solenoid valves are closed. Nitrogen gas will now flow into the pipe P1. When pipe P1 is judged to be purged the installer may proceed with brazing the joint required on P1.

With the pipe P1 brazed the installer can, without leaving the air conditioning actuate the switch 18 again. The controller 19 will respond again to send the switch control signal to the valve assembly 1. On receipt of the second switch control signal, controller 10 responds by driving signals to close the first solenoid valve 18.1 and to open the second solenoid valve 18.2. The controller 10 will again pole each of the sensors 12.1, 12.2, 12.3 to determine the condition of the solenoid valves, and transmit signals indicative of the solenoid valve conditions to the remote control 15 where they are displayed to the installer on the visual display unit. With the second pipe P2 purged the installer can complete brazing the second pipe joint.

With the second pipe joint brazed the installer actuates the control switch 18 again to cause the controller 10 to control the second solenoid valve 8.2 to close and the third solenoid valve 8.3 to open. The brazing procedure is repeated completing connection to the air conditioning. The installer then actuates the control switch 18 again causing the controller 10 to respond by closing the third solenoid valve.

During operation the pressure switch 13 is persistently responsive to the pressure delivered to the manifold. The controller will periodically pole the pressure switch condition and transmit the pressure value to the remote control unit (15) for display, so allowing the installer to determine the charge state of the nitrogen pressure cylinder. In some variants the pressure switch may switch state at a predetermined threshold pressure. In some variants the predetermined threshold state may be set by an installer according to the length and elevation of the pipe to be brazed. A long pipe and/or great elevation will require more pressure to purge and so a higher predetermined threshold.

In variants of the remote control the visual display unit may be a touch screen and the switches may be virtual switches displayed on the touch screen and actuated by touching the screen. In other variants the battery charge state, solenoid valve conditions, nitrogen pressure and signal strength may be communicated on the remote control by simply illuminating LED lights deployed on a face of the remote control or changing the colour of such lights.

Claims

A pipe purge system for use in installing air conditioning systems comprising:

a portable remote control unit (15) capable of transmitting a range of remote control signals, and

a portable valve assembly (1) , said valve assembly (1) having an inlet port (2) and at least two outlet ports (3,4,5), said inlet port (2) adapted to be communicated with a purge fluid supply to receive purge fluid, each of said outlet ports (3,4,5) being adapted to communicate with one of a supply pipe or a return pipe of an air conditioning system to deliver purge fluid into any of said pipes;

a purge fluid flow control valve sub‑assembly operable to control the flow of fluid from said inlet port (2) to each outlet port (3,4,5);

a controller (10) capable of receiving a control signal from said remote control unit (15), and responsive to a specified one of the range of control signals to control the condition of said flow control valve sub‑assembly to one of a flow condition or a shut off condition characterised in that;

the flow condition is a condition where purge fluid can flow from the inlet port (2) along a selected one of at least two passages to only one of the outlet ports (3,4,5) at a time and

the shut off condition is a condition where flow from the inlet port (2) to any of the outlet ports (3,4,5) is shut off.
A pipe purge system according to claim 1 wherein the flow control valve sub‑assembly comprises motorized valves (8.1, 8.2, 8.3) associated one each with each outlet port in order to control the flow of fluid to the outlet ports (3,4,5).
A pipe purge system according to claim 1 or claim 2 wherein a sensor (12.1, 12.2, 12.3) is associated with each motorized valve (8.1,8.2,8.3) to sense the condition of the valve, whereby the condition of the valve can be reported to the remote control unit (15), said remote control unit being responsive to the motorized valve (8.1,8.2,8.3) condition to display the valve condition.
A pipe purge system according to any one of the preceding claims wherein an overpressure valve is disposed between the inlet port (2) and the flow control valve sub‑assembly to open when the inlet pressure exceeds a predetermined threshold pressure and protect the valve assembly (1).
A pipe purge system according to any one of the preceding claims wherein a pressure sensor (13) is disposed to sense pressure between the inlet port (2) and the flow control valve sub‑assembly.
A pipe purge system according to claim 5 wherein the pressure sensor (13) is arranged to communicate the sensed pressure to the remote control unit (15) for display.
A pipe purge system according to claim 5 or claim 6 wherein the pressure sensor (13) is arranged to communicate when the sensed pressure falls below a predetermined threshold.
A method of purging pipes using an apparatus according to claim 1 comprising the steps of:

connecting the inlet port (2) of the portable valve assembly (1) to a supply of purge fluid near a first end of a pipe run comprising at least two pipes whereby purge fluid is supplied to the inlet port (2);

connecting the outlet ports (3,4,5) of the portable valve assembly (1) one each to the first ends of each of the two or more pipes of the pipe run;

at the second ends of the pipes to be brazed, operating the remote control unit so that the valve assembly (1) opens a passage from the inlet port (2) to not more than one of the outlet ports (3,4,5) of the valve assembly (1) whereby purge fluid passes into one of the pipes;

brazing the pipe when purge fluid has purged the pipe;

at the ends of the pipes to be brazed, operating the remote control unit (15) to close the open passage and to open a second passage from the inlet port (2) to a second outlet port communicating with a second pipe;

when the second pipe has been purged, brazing the second pipe;

at the end of the pipes to be brazed, operating the remote control to signal to the valve assembly (1) to close the passage from the inlet port (2) to the second outlet port.