Patent Publication Number: US-2022228597-A1

Title: Vacuum pump for use during maintenance or commissioning of an hvac-r system, adapter for a vacuum pump, and a method of performing a vacuum test on an hvac-r system

Description:
This invention relates to a vacuum pump for use during maintenance or commissioning of an HVAC-R system, for example an air conditioning system. This invention also relates to an adapter for a vacuum pump for use during maintenance or commissioning of an HVAC-R system. This invention also relates to a method of performing a vacuum test on an HVAC-R system. 
     BACKGROUND 
     Currently, during maintenance/commissioning of a heating, ventilation, air conditioning or refrigeration (HVAC-R) system a technician will perform a vacuum test on the HVAC-R system. This involves connecting a vacuum pump to the HVAC-R system and using the vacuum pump to draw a vacuum on the HVAC-R system. The vacuum pump is used to remove all fluids from the HVAC-R system, including air, remnant refrigeration fluids, and moisture. 
     It is known to provide analogue or digital vacuum gauges to monitor the vacuum level in the HVAC-R system. When performing a vacuum test, the detected vacuum level must reach a threshold level for a pre-determined period of time to demonstrate that the HVAC-R system is sealed, and that sufficient fluid has been removed from the HVAC-R system. Once the vacuum test is complete, the system can be charged (filled) with refrigerant fluid for operation. 
     It is also known to provide digital vacuum gauges with Bluetooth connectivity to allow communication with an Application on a mobile device. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     In accordance with the present disclosure there is provided a vacuum pump for use during maintenance or commissioning of an HVAC-R system, the vacuum pump comprising: 
     a pump having a pump intake for connection to the HVAC-R system, 
     a pressure sensor arranged to detect a pressure in the HVAC-R system, 
     a communications unit configured to connect to a mobile communications network, and 
     a control unit configured to:
         receive pressure data from the pressure sensor;   control operation of the pump, and   communicate with a remote device via the communications unit and the mobile communications network.       

     In some examples, the pressure sensor is arranged to detect a vacuum pressure at the pump intake. In other examples, the pressure sensor is configured for connection to the HVAC-R system at a different location to the connection between the pump and the HVAC-R system. 
     In preferred examples, the vacuum pump further comprises an electrically actuatable valve arranged to control connection of the pressure sensor to one or more of the pump intake and the HVAC-R system at a different location to the connection between the pump and the HVAC-R system, and wherein the control unit is configured to control operation of the electrically actuatable valve. Preferably, the electrically actuatable valve is biased to a closed position. 
     The control unit may be configured to monitor the detected pressure. The control unit may be configured to control operation of the pump to perform a vacuum test. In some examples, the control unit may comprise a memory for storing vacuum test instructions, and the control unit may be configured to retrieve the vacuum test instructions from the memory to perform the vacuum test. In other examples, the communications unit may be configured to receive the vacuum test instructions from the remote device, and the control unit may be configured to control operation of the pump in accordance with the vacuum test instructions received by the communications unit. 
     The vacuum pump may further comprise an electric motor arranged to drive the pump, and a power sensor arranged to detect a power usage of the electric motor. In this example, the control unit may be arranged to receive power data from the power sensor, and the control unit may be configured to monitor power usage of the electric motor. 
     The vacuum pump may further comprise an electrically actuatable valve arranged to control a connection between the pump and the HVAC-R system. The control unit may be configured to control operation of the electrically actuatable valve. The electrically actuatable valve is preferably biased to a closed position. 
     The pump intake is preferably configured for connection to a service port of the HVAC-R system, for example a high pressure service port or a low pressure service port. In some examples, the pump intake may be configured for connection to both the high pressure service port and the low pressure service port of the HVAC-R system. 
     In accordance with another aspect of the present disclosure there is also provided an adapter for a vacuum pump for use during maintenance or commissioning of an HVAC-R system, the adapter comprising: 
     a connector for connecting to the HVAC-R system; 
     a pressure sensor arranged to detect a pressure in the HVAC-R system during use; 
     a communications unit configured to connect to a mobile communications network; 
     and 
     a control unit configured to:
         receive pressure data from the pressure sensor; and   communicate with a remote device via the communications unit and the mobile communications network.       

     The adapter preferably further comprises an electrically actuatable valve disposed to control the connection between the adapter and the HVAC-R system. The control unit is preferably configured to operate the electrically actuatable valve. 
     The communications unit of the vacuum pump and/or the communications unit of the adapter may is preferably configured to connect to the mobile communications network using one or more of GSM, LTE, UMTS, WiMax, LTE-A, 5G mobile communications network, and/or a Low Power Wide Area Network (LPWAN) radio technology, for example a Narrowband IoT network. 
     In accordance with another aspect of the present disclosure there is also provided a method of performing a vacuum test on an HVAC-R system, the method comprising: 
     connecting a pump intake of a vacuum pump to the HVAC-R system, 
     operating the vacuum pump to evacuate fluid from the HVAC-R system, 
     detecting a pressure in the HVAC-R system by a pressure sensor, and 
     communicating with a remote device via a mobile communications network. 
     The method may further comprise monitoring the detected pressure. The method may further comprise detecting a power usage of an electric motor of the vacuum pump. Preferably, the method may comprise controlling the vacuum pump to perform a vacuum test on the HVAC-R system. 
     In examples, the method of performing a vacuum test may comprise: 
     operating the vacuum pump to draw a vacuum on the HVAC-R system, 
     monitoring the detected pressure in the HVAC-R system, and 
     stopping operation of the vacuum pump once the detected vacuum pressure reaches a threshold. 
     The method may further comprise isolating the vacuum pump from the HVAC-R system once the detected vacuum pressure reaches a threshold. 
     The method may further comprise monitoring the detected fluid pressure after stopping operation of the vacuum pump. 
     The method may further comprise communicating data of the vacuum test with the remote device via the mobile communications network, for example a status of the vacuum test or a result of the vacuum test. 
     It will be understood that any data processing, can be performed by a device having one or more processors and a memory including instructions to cause the one or more processors to perform the data processing, such as to process the scan data to generate the control data. The memory is typically a non-transient computer-readable storage medium. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic diagram of an HVAC-R system; 
         FIG. 2  is a schematic diagram of an example vacuum pump for use during maintenance or commissioning of the HVAC-R system of  FIG. 1 ; 
         FIG. 3  is a schematic diagram of a further example vacuum pump for use during maintenance or commissioning of the HVAC-R system of  FIG. 1 ; 
         FIG. 4  is a schematic diagram of a further example vacuum pump for use during maintenance or commissioning of the HVAC-R system of  FIG. 1 ; 
         FIG. 5  is a schematic diagram of a further example vacuum pump for use during maintenance or commissioning of the HVAC-R system of  FIG. 1 ; 
         FIG. 6  is a schematic diagram of a further example vacuum pump for use during maintenance or commissioning of the HVAC-R system of  FIG. 1 ; 
         FIG. 7  is a system diagram of the vacuum pump, including the control unit. 
         FIG. 8  is a schematic diagram of an adapter for a vacuum pump for use during maintenance or commissioning of the HVAC-R system of  FIG. 1 ; 
         FIG. 9  is a system diagram of the adapter for a vacuum pump of  FIG. 8 ; 
         FIG. 10  is a method diagram of a vacuum test performed by the vacuum pump of any of  FIGS. 2 to 7 , or the adapter for a vacuum pump of  FIGS. 8 and 9 . 
     
    
    
     DETAILED DESCRIPTION 
     As shown in  FIG. 1 , an HVAC-R system  1  includes a compressor  2 , a condenser  3 , an expansion valve  4 , and an evaporator  5 . Pipes  6  connect each of these components in a loop such that refrigerant fluid can flow through each in turn, driven by the compressor  2 . 
     The condenser  3  includes a coil of pipes  7  wound to create a large surface area for heat exchange between the refrigerant fluid and air surrounding the condenser  3 . The evaporator  5  is similar, having a coil of pipes  8  that create a large surface area for heat exchange between the refrigerant fluid and the air surrounding the evaporator  5 . In a refrigerant or air conditioning system, the evaporator  5  is disposed within the conditioned area, e.g. within a house or refrigerated room, and the condenser  3  is disposed outside of the conditioned area, e.g. outside of the house or refrigerated room. 
     The compressor  2  may be any compressor of an HVAC-R system, for example one of a reciprocating compressor, a rotary compressor, a scroll compressor, a screw compressor or a centrifugal compressor. The compressor  2  has an intake  9  and an outlet  10 , and drives refrigerant through the HVAC-R system  1  as described hereinafter. 
     During operation, the compressor intake  9  receives refrigerant fluid as a low pressure gas, and compresses the low pressure gas into a high pressure gas. Compressing the gas to increase the pressure will also increase the temperature of the refrigerant. Therefore, at the compressor outlet  10  the refrigerant fluid is a high pressure, high temperature gas. 
     After outlet from the compressor  2 , the high pressure, high temperature gas enters the condenser  3 , which is a heat exchanger located in an area with a lower temperature than the refrigerant entering the condenser  3 . In air conditioning or refrigeration examples, the condenser  3  is located externally of the conditioned area, for example outside of a building or outside of a refrigerated area. As the refrigerant flows through the condenser  3 , heat is lost from the high pressure, high temperature gas within the condenser  3  to a surrounding area, and the refrigerant fluid exits the condenser  3  as a high pressure liquid having a lower temperature than upstream of the condenser  3 . At this stage, the refrigerant fluid is warm, but not as hot as upstream of the condenser  3  because some heat has been lost in the condenser  3 , and the refrigerant fluid has condensed into a liquid. 
     Optionally, a receiver drier  11  is positioned downstream of the condenser  3 . The high pressure liquid passes through the receiver drier  11 . The receiver drier  11  contains extra refrigerant fluid for the HVAC-R system  1 , to account for changes due to small leaks or temperature fluctuations. The receiver drier  11  may also include a drying agent and a filter to remove contaminants from the refrigerant fluid. 
     The high pressure liquid next passes through the expansion valve  4 . The expansion valve  4  typically includes a metered orifice through which the refrigerant fluid must pass. The metered orifice limits the rate at which the refrigerant fluid flows. As a result of this, a large pressure drop is created across the metered orifice. Therefore, as the refrigerant fluid passes through the metered orifice the high pressure liquid quickly loses pressure. The loss of pressure also cools the refrigerant fluid. Therefore, after the expansion valve  4  the refrigerant fluid is at a cold temperature and at a lower pressure, and is starting to evaporate into a gas. 
     Immediately after the expansion valve  4  the cold refrigerant fluid enters the evaporator  5 . In air conditioning or refrigeration examples, the evaporator  5  is typically disposed in an area to be cooled or refrigerated, for example inside a building or a refrigeration unit. Within the evaporator  5  the low temperature refrigerant fluid is heated by absorbing heat from the surroundings of the evaporator  5 . On exit from the evaporator  5  the refrigerant fluid has been evaporated and is a low pressure gas, which is still cool but at a higher temperature than immediately upstream of the evaporator  5  because it has absorbed heat from the surroundings of the evaporator  5 . 
     This low pressure gas is fed back to the compressor intake  9 . In this way, the refrigerant fluid transfers heat from the evaporator  5  to the condenser  3 , and therefore from one area to another, to cool the area where the evaporator  5  is located and/or to heat the area where the condenser  3  is located. 
     It will be appreciated that the boiling point of the refrigerant fluid is not the same as water or air. For example, the boiling point of Ammonia (R717), a typical refrigerant, is −33.3 degrees Celsius. Therefore, it will be appreciated that the high and low temperatures referred to in the description are relative, and the refrigerant fluid can be used in the described manner to efficiently transfer heat from the evaporator  5  to the condenser  3 . 
     As shown in  FIG. 1 , in examples in which the HVAC-R system  1  is used to cool the area surrounding the evaporator  5 , the HVAC-R system  1  may further include a thermal expansion valve  12  for controlling the metered orifice of the expansion valve  4 . The thermal expansion valve  12  is arranged to expand and contract according to the temperature of the refrigerant fluid downstream of the evaporator  5 . In this way, the thermal expansion valve  12  expands or contracts according to the temperature of the surroundings of the evaporator  5 , which directly determines the temperature of the refrigerant downstream of the evaporator  5 . The expanded/contracted state of the thermal expansion valve  12  controls the size of the metered orifice in the expansion valve  4 , so that the flow of refrigerant (and the cooling provided to the surroundings of the evaporator  5 ) is proportionate to the temperature of the surroundings of the evaporator  5 . A smaller metered orifice in the expansion valve  4  will create a lower temperature refrigerant and provide more cooling to the area surrounding the evaporator  5 . In this example, a warmer refrigerant downstream of the evaporator  5 , indicated by relatively high thermal expansion of the thermal expansion valve  12 , indicates that more cooling is required. Therefore, the thermal expansion valve  12  is configured to reduce the size of the metered orifice in response to thermal expansion, and is configured to increase the size of the metered orifice in response to thermal contraction. 
     To improve heat exchange at the evaporator  5  and/or at the condenser  3 , a fan may be provided to create a flow of air over the coiled pipes  7 ,  8  of the evaporator  5  and/or the condenser  3 . 
     As explained above, the pressure of the refrigerant fluid is higher between the compressor outlet  10  and the expansion valve  4 , and lower between the expansion valve  4  and the compressor intake  9 . Therefore, the HVAC-R system has a high pressure side and a low pressure side. 
     Also shown in  FIG. 1 , a low pressure service port  13  is provided between the evaporator  5  and the compressor intake  9 , where the refrigerant fluid is at low pressure. Similarly, a high pressure service port  14  is provided between the condenser  3  (or drier  11 ) and the expansion valve  4 , where the refrigerant fluid is at high pressure. The low pressure and high pressure service ports  13 ,  14  are provided for removing and adding refrigerant to the HVAC-R system  1  during maintenance or commissioning, as explained further hereinafter. 
     It will be appreciated that various HVAC-R systems may include additional or alternative components or arrangements for different applications. The apparatus described hereinafter, for maintenance or commissioning of HVAC-R systems, can be used on any HVAC-R system that includes a high pressure side and a low pressure side, and includes at least one service port (high pressure side and/or low pressure side) for removal or addition of refrigerant fluid to the HVAC-R system. As described above, a typical HVAC-R system  1  will include a high pressure service port  14  and a low pressure service port  13 . 
     During maintenance and commissioning of an HVAC-R system  1  various procedures may be carried out, including a vacuum test. To perform a vacuum test, a vacuum pump is used to extract gas (e.g. air) and residual fluids (e.g. moisture) from the HVAC-R system after maintenance, and/or to test the seals. It is performed after installation or maintenance where parts have been changed or the system opened, and ensures that the system is empty before recharging with refrigerant. 
       FIGS. 2 to 6  illustrate the vacuum pump  15  attached to the HVAC-R system  1  for a vacuum test. The vacuum pump  15  includes a pump  17  for drawing fluid through a pump intake  22  that is attachable to the HVAC-R system  1  via one or both of the high pressure service port  14  and the low pressure service port  13 , as described further hereinafter. The pump intake  22  has a connector. 
     In different examples, the pump  17  may be oil-less or oil lubricated. The pump  17  may comprise a positive displacement vacuum pump, or a reciprocating piston vacuum pump, or a diaphragm pump, or a rotary vane pump, or a rotary screw pump. Preferably, the pump  17  comprises an oil-sealed rotary vane vacuum pump, which are particularly suited to HVAC-R applications. 
     The vacuum pump  15  also has a control unit  18  that controls operation of the pump  17 . The vacuum pump  15  also includes a communications unit  19  configured to communicate with a remote device  20  over a mobile communications network. The control unit  18  is in data communication with the communications unit  19 . In preferred examples, the communications unit  19  includes a receiver for receiving data, for example instructions, from the remote device  20 . The communications unit  19  may comprise a transceiver for receiving data, for example instructions, from the remote device  20 , and for transmitting data to the remote device  20 . In some examples, the communications unit may further comprise an additional transmitter and/or receiver, for example a Bluetooth transmitter and/or receiver. In examples, the remote device  20  may be a mobile phone or a tablet computer, or any device that can connect to a mobile communications network. 
     In preferred examples, the communications unit  19  comprises a transceiver configured to communicate on a mobile communications network, for example a GSM, LTE, UMTS, WiMax, LTE-A, and/or 5G mobile communications network, a Low Power Wide Area Network (LPWAN) radio technology, for example a Narrowband IoT network. The communications unit  19  may be configured to communicate with a remote device  20  via the communications unit  19  using the mobile communications network. The communications unit  19  communicates data to the remote device  20 , for example using SMS format. 
     Advantageously, communicating with the remote device  20  over a mobile communications network removes the need for the remote device  20  to be proximate to the vacuum pump  15 . For example, Bluetooth connectivity is limited in range, whereas using a mobile communications network allows the operator to be further removed from the vacuum pump  15 , which may be advantageous during long vacuum tests or when the operator needs to investigate parts of the HVAC-R system that are removed from the position of the vacuum pump  15 . 
     In preferred examples, the vacuum pump  15  also includes a sensor  21  that is arranged to detect a pressure. In a preferred example, the sensor is a pressure sensor  21  arranged to detect a pressure in the HVAC-R system  21 , as shown in  FIG. 2 . The pressure sensor  21  may be a vacuum pressure sensor. The control unit  18  is configured to receive pressure data from the pressure sensor  21 . The control unit  18  may be configured to operate the pump  17  in accordance with data received from the pressure sensor  21 , as described further hereinafter. 
     In alternative examples, the pressure sensor  21  may be provided separately to the vacuum pump  15 . In this example, the pressure sensor  21  is in data communication with the control unit  18  via a wire or via a wireless connection to provide pressure data to the control unit  18 . For example, the communications unit  19  may further comprise a Bluetooth receiver for receiving pressure data from a separate pressure sensor  21  that includes a Bluetooth transmitter. In this way, the pressure sensor  21  may be located away from the vacuum pump  15 , which may be easier if the high pressure service port  14  and the low pressure service port  13  of the HVAC-R system are not disposed close to one another. 
     In preferred examples, the vacuum pump  15  also includes a shut-off valve  26  between the pump  17  and the HVAC-R system  1 , as shown. The shut-off valve  26  is preferably located to isolate the pump  17  from the HVAC-R system  1 , while permitting the sensor  21  to detect pressure in the HVAC-R system  1 , as shown in  FIGS. 2 to 5 . The shut-off valve  26  is preferably electrically actuatable and can be actuated by the control unit  18  to open and close the fluid connection between the pump  17  and the HVAC-R system  1 . In preferred examples, the shut-off valve  26  is biased to a closed position, so that in the event of power loss the connection to the HVAC-R system  1  is closed. 
     Hoses and pipes are used to fluidly connect the pump intake  22  and pressure sensor  21  to the HVAC-R system  1 . Hoses may include connectors, for example fittings, that include a threaded connector for attachment to the pump intake  22 , the high pressure service port  14 , and the low pressure service port  13 , as appropriate. 
     In further examples, the vacuum pump  15  may include an alarm. The control unit  18  may be configured to operate the alarm if the detected pressure changes suddenly, for example a loss of vacuum seal. The alarm may alternatively me operated in response to peaks in power consumption by the pump  17 . The alarm may be an audible or visual alarm. When operating the alarm, the control unit  18  may additionally send a communication to the remote device  20  via the communications unit  19 . 
     As shown in  FIGS. 2 to 6 , the vacuum pump  15  includes a housing  16  in which the components of the vacuum pump  15  are disposed. 
     In the example illustrated in  FIG. 2 , to perform a vacuum test using the vacuum pump  15 , the pump intake  22  is connected to the HVAC-R system  1  via the low pressure service port  13  to draw a vacuum on the HVAC-R system  1 . The pressure sensor  21  is connected to the HVAC-R system  1  via the high pressure service port  14 . 
     During use, the control unit  18  operates the pump  17  to draw a vacuum on the HVAC-R system, and the pressure sensor  21  is arranged to detect the vacuum pressure in the HVAC-R system  1 . 
     Advantageously, in the arrangement illustrated in  FIG. 2 , the pressure sensor  21  is connected to the HVAC-R system  1  such that it is positioned at a furthest point of the system from the pump  17 . Therefore, the pressure sensor  21  is arranged to detect the vacuum pressure at a location remote from the pump  17 , and therefore detects the lowest vacuum value in the HVAC-R system  1  (the highest vacuum level being at the pump intake  22 ). 
     The control unit  18  receives pressure data from the pressure sensor  21 , the pressure data being indicative of the vacuum pressure in the HVAC-R system  1 . The control unit  18  is configured to communicate with the remote device  20  via the communications unit  19 . For example, the control unit  18  may be configured to send an SMS communication to the remote device  20  via a connection to a mobile communications network provided by the communications unit  19 . 
     In an alternative example similar to that shown in  FIG. 2 , the pump intake  22  is connected to the high pressure service port  14  of the HVAC-R system  1 , and the pressure sensor  21  is connected to the low pressure service port  13  of the HVAC-R system  1 . This operates in the same manner as described with reference to  FIG. 2 , but fluid is drawn from the HVAC-R system  1  via the high pressure service port  14  instead of via the low pressure service port  13 . 
     In the example illustrated in  FIG. 3 , the pump intake  22  is connected to the HVAC-R system  1  via the low pressure service port  13  to draw a vacuum on the HVAC-R system  1 . The pressure sensor  21  is arranged to detect a vacuum pressure at the pump intake  22 , i.e. at the low pressure service port  13  of the HVAC-R system  1 . As shown, the pressure sensor  21  is connected to the pump intake  22  via a branch connection  24 . In this example, the shut-off valve  26  is located between the pump  17  and the branch connection  24  such that when the shut-off valve  26  is closed the pressure sensor  21  can still detect a vacuum pressure via the low pressure service port  13 . 
     During use, the control unit  18  operates the pump  17  to draw a vacuum on the HVAC-R system  1 , and the pressure sensor  21  is arranged to detect the vacuum being pulled on the HVAC-R system  1  by the pump  17 . 
     The control unit  18  receives pressure data from the pressure sensor  21 , the pressure data being indicative of the vacuum pressure in the HVAC-R system  1 . The control unit  18  is configured to communicate with the remote device  20  via the communications unit  19 . For example, the control unit  18  may be configured to send an SMS communication to the remote device  20  via a connection to a mobile communications network provided by the communications unit  19 . 
     In an alternative example similar to that shown in  FIG. 3 , the pump intake  22  is connected to the high pressure service port  14  of the HVAC-R system  1 . This operates in the same manner as described with reference to  FIG. 3 , but fluid is drawn from the HVAC-R system  1  via the high pressure service port  14  instead of the low pressure service port  13 . 
     In the example illustrated in  FIG. 4 , the pump intake  22  is connected to the HVAC-R system  1  via the low pressure service port  13  to draw a vacuum on the HVAC-R system  1 . In this example, a first pressure sensor  21   a  is connected to the HVAC-R system  1  via a connection between a second intake  23  and the high pressure service port  14 . The second intake  23  has a connector. A second pressure sensor  21   b  is arranged to detect the pressure at the pump intake  22 , i.e. at the low pressure service port  13  of the HVAC-R system  1 . As shown, the second vacuum sensor  21   b  is connected via a branch connection  24 . The shut-off valve  26  is located between the pump  17  and the branch connection  24  such that when the shut-off valve  26  is closed the first and second pressure sensors  21   a ,  21   b  can still detect a vacuum pressure via the low pressure service port  13  and the high pressure service port  14 . The vacuum pressures detected by the first and second pressure sensors  21   a ,  21   b  will differ during operation of the pump  17  due to the pressure drop across the HVAC-R system, between the high and low pressure service ports  14 ,  13 . 
     During use, the control unit  18  operates the pump  17  to draw a vacuum on the HVAC-R system  1  via the low pressure service port  13 , the first pressure sensor  21   a  is arranged to detect the pressure at the high pressure service port, and the second pressure sensor  21   b  is arranged to detect the pressure at the pump intake  22  and low pressure service port  13 . 
     The control unit  18  receives pressure data from the first pressure sensor  21   a  and from the second pressure sensor  21   b , the pressure data being indicative of the vacuum pressure in the HVAC-R system  1 . The control unit  18  is configured to communicate with the remote device  20  via the communications unit  19 . For example, the control unit  18  may be configured to send an SMS communication to the remote device  20  via a connection to a mobile communications network provided by the communications unit  19 . 
     In an alternative example similar to that shown in  FIG. 4 , the pump intake  22  is connected to the high pressure service port  14  of the HVAC-R system  1 , the first pressure sensor  21   a  is connected to the low pressure service port  13 , and the second pressure sensor  21   b  is arranged to detect the pressure at the pump intake  22 , i.e. at the high pressure service port  14  of the HVAC-R system  1 . This operates in the same manner as described with reference to  FIG. 4 , but fluid is drawn from the HVAC-R system  1  via the high pressure service port  14  instead of via the low pressure service port  13 . 
     In the example illustrated in  FIG. 5 , the pump  17  is connected to both of the high pressure service port  14  and the low pressure service port  13  of the HVAC-R system  1 . In particular, the pump  17  has a first intake  22  for connection to the low pressure service port  13  and a second intake  23  for connection to the high pressure service port  14 . The pressure sensor  21  is also connected to both the first and second intakes  22 ,  23 , and is therefore arranged to detect the pressure in the HVAC-R system  1  and at the pump  17 . 
     During use, the control unit  18  operates the pump  17  to draw a vacuum on the HVAC-R system  1  via the low pressure service port  13  and via the high pressure service port  14 . The pressure sensor  21  is arranged to detect the pressure applied by the pump  17  to the high pressure service port  14  and the low pressure service port  13  via connection  25 . 
     The control unit  18  receives pressure data from the pressure sensor  21 , the pressure data being indicative of the vacuum pressure in the HVAC-R system  1 . The control unit  18  is configured to communicate with the remote device  20  via the communications unit  19 . For example, the control unit  18  may be configured to send an SMS communication to the remote device  20  via a connection to a mobile communications network provided by the communications unit  19 . 
     In the example illustrated in  FIG. 6 , the pump  17  is connected to the high pressure service port  14  and the low pressure service port  13  of the HVAC-R system  1 . In particular, the pump  17  has a first intake  22  for connection to the low pressure service port  13  and a second intake  23  for connection to the high pressure service port  14 . The pressure sensor  21  is also connected to both the first and second intakes  22 ,  23 , and valves  35   a  and  35   b  are arranged to alter the connections between the pressure sensor  21  and one or the other of the pump intake  22  and second pump intake  23 . Therefore, the valves  35   a ,  35   b  can be configured such that the pressure sensor  21  can detect the pressure in the HVAC-R system  1  via the high pressure service port  14  or via the low pressure service port  13 . 
     During use, the control unit  18  operates the pump  17  to draw a vacuum on the HVAC-R system  1  via the low pressure service port  13 . 
     The valves  35   a ,  35   b  are preferably electrically actuatable valves and the operation of the valves  35   a ,  35   b  is preferably controlled by the control unit  18 . 
     In a first configuration, the second valve  35   b  is open and the first valve  35   a  is closed. In this configuration, the pressure sensor  21  is arranged to detect the pressure applied by the pump  17  to the low pressure service port  13  via the pump intake  22 . In an alternative configuration, the first valve  35   a  is open and the second valve  35   b  is closed. In this configuration, the pressure sensor  21  is arranged to detect the pressure at the high pressure service port  14  via the pump intake  23 . Advantageously, this is the furthest point in the HVAC-R system  1  from the vacuum pump  17 . 
     The control unit  18  receives pressure data from the pressure sensor  21 , the pressure data being indicative of the vacuum pressure in the HVAC-R system  1 . The control unit  18  is configured to communicate with the remote device  20  via the communications unit  19 . For example, the control unit  18  may be configured to send an SMS communication to the remote device  20  via a connection to a mobile communications network provided by the communications unit  19 . 
       FIG. 7  is a system diagram for the vacuum pump  15 . As shown, the control unit  18  includes a controller  27 , an input device  28  and a memory  29 . The controller  27  may be configured to access the memory  29  to retrieve data stored therein. For example, the memory  29  may store instruction data for operating the pump  17 , for example instruction data for a vacuum test. The input device  28  may comprise one or more buttons or switches, or a graphical user interface, such as a touchscreen, for a user to provide information and/or commands to the control unit  18 . In one example, a user can provide an instruction to the control unit  18  via the input device  28 , for example a required vacuum level for a vacuum test, or the user may select a vacuum test from a displayed list of vacuum tests. In response, the control unit  18  may operate the pump  17  to perform the vacuum test, as described further hereinafter. 
     The control unit  18 , in particular the controller  27 , is in communication with the communications unit  19  for communicating with the remote device  20 . The control unit  18  is also connected to the pressure sensor  21  for receiving pressure data, and to the shut-off valve  26  and pump  17  for controlling operation of each. As illustrated, the control unit  18  may also be in communication with one or more electrically actuatable valves  35   a ,  35   b , such as those in the example of  FIG. 6 , to control operation of the electrically actuatable valves  35   a ,  35   b.    
     In some examples, the vacuum pump  25  further comprises a power sensor  30  arranged to detect the power being drawn by the pump  17 . In particular, the pump  17  comprises an electric motor for driving the pump  17 , and the vacuum pump  15  may include a power sensor  30 , for example a current sensor, arranged to detect the power being drawn by the electric motor of the pump  17 . The control unit  18  may be configured to receive power data detected by the power sensor  30 . When performing a vacuum test, the power drawn by the electric motor of the pump  17  will initially be higher, as the pump  17  performs work to draw fluid from the HVAC-R system  1 , and the power drawn by the electric motor of the pump  17  will decrease as the vacuum level increases as there is less work being performed by the pump  17 . Therefore, by measuring and monitoring the power being drawn by the electric motor of the pump  17  the control unit  18  can determine relative vacuum levels. 
     The control unit  18  is configured to operate the pump  17 . In particular, the control unit  18  receives pressure data from the pressure sensor  21 , and operates the pump  17  to perform a vacuum test. 
     The control unit  18  may be configured to operate the pump  17  until the vacuum pressure detected by the pressure sensor  21  reaches a threshold value. The control unit  18  may be configured to operate the pump  17  until the vacuum pressure detected by the pressure sensor  21  passes a threshold value for a pre-determined period of time. In some examples, as described further hereinafter, the control unit  18  may be configured to operate the pump  17  until the vacuum pressure detected by the pressure sensor  21  reaches a threshold value, the control unit  18  may then be configured to close the shut-off valve  26 , stop operation of the pump  17 , and monitor the vacuum pressure detected by the pressure sensor  21  for a pre-determined period of time. 
       FIG. 8  illustrates an adapter  36  for use with a vacuum pump  37 . In this example, the vacuum pump  37  has a pump  17 , a first intake  22 , and a second intake  23 . The adapter  36  has a connector  38 . As illustrated in  FIG. 8 , the vacuum pump  37  is connected to the low pressure service port  13  of the HVAC-R system  1  via the first intake  22 , and the adapter  36 , in particular the connector  38 , is connected to the high pressure service port  14  of the HVAC-R system  1 . 
     In alternative examples of use of the adapter  36 , the connector  38  of the adapter  36  can be connected to the second intake  23  of the vacuum pump  37 . In yet another example, the adapter  36  may be connectable to the first intake  22  of the vacuum pump  37  along with the connection to the HVAC-R system  1 , for example via a T junction connector. In examples, the adapter  36  can be connected to the HVAC-R system  1  or to vacuum pump  37  via a hose, or in other examples the connector  38  may screw directly onto the high pressure service port  14  of the HVAC-R system  1  or to the second intake  23  of the vacuum pump. 
     In each example, the adapter  36  is connected to detect the vacuum pressure generated by the vacuum pump  37 , either at the pump itself  17 , or via the HVAC-R system  1 . 
     As illustrated, the adapter  36  includes a pressure sensor  21  connected to the connector  38 . The adapter  36  also includes a valve  39  disposed between the connector  38  and the pressure sensor  21 . The adapter  36  further includes a control unit  18  and a communications unit  19  analogous to the control unit  18  and communications unit  19  of the examples of  FIGS. 2 to 7 . The valve  39  is preferably an electrically actuatable valve and is operated by the control unit  18 . The valve  39  is preferably biased to a closed position. 
     The communications unit  19  is configured to communicate with a remote device  20  over a mobile communications network. The control unit  18  is in data communication with the communications unit  19 . In preferred examples, the communications unit  19  includes a receiver for receiving data, for example instructions, from the remote device  20 . The communications unit  19  may comprise a transceiver for receiving data, for example instructions, from the remote device  20 , and for transmitting data to the remote device  20 . In some examples, the communications unit may further comprise an additional transmitter and/or receiver, for example a Bluetooth transmitter and/or receiver. In examples, the remote device  20  may be a mobile phone or a tablet computer, or any device that can connect to a mobile communications network. 
     In preferred examples, the communications unit  19  comprises a transceiver configured to communicate on a mobile communications network, for example a GSM, LTE, UMTS, WiMax, LTE-A, and/or 5G mobile communications network, a Low Power Wide Area Network (LPWAN) radio technology, for example a Narrowband IoT network. The communications unit  19  may be configured to communicate with a remote device  20  via the communications unit  19  using the mobile communications network. The communications unit  19  communicates data to the remote device  20 , for example using SMS format. 
     The pressure sensor  21  may be a vacuum pressure sensor. The control unit  18  is configured to receive pressure data from the pressure sensor  21 . 
     The adapter  36  preferably comprises a housing  40  in which the pressure sensor  21 , valve  39 , control unit  18  and communications unit  19  are located, and the connector  38  is preferably arranged on the housing  40 . 
     In this example, the adapter  36  is arranged such that the pressure sensor  21  can detect the vacuum pressure in the HVAC-R system  1  generated by the vacuum pump  37 . The control unit  18  can communicate, via the communications unit  19 , with the remote device  20  to provide pressure information to the remote device  20 . 
     In further examples, the control unit  18  may be connected, for example via a Bluetooth connection provided by the communications unit  19 , to the vacuum pump  37  to control operation of the vacuum pump  37 . In particular the pump  17  and/or any electrically actuatable valves of the vacuum pump  37 . 
       FIG. 9  illustrates a system diagram of the adapter  36  of  FIG. 8 . As shown, and similarly to the system diagram of  FIG. 7 , the control unit  18  includes a controller  27 , an input device  28  and a memory  29 . The controller  27  may be configured to access the memory  29  to retrieve data stored therein. For example, the memory  29  may store instruction data for a vacuum test. The input device  28  may comprise one or more buttons or switches, or a graphical user interface, such as a touchscreen, for a user to provide information and/or commands to the control unit  18 . In one example, a user can provide an instruction to the control unit  18  via the input device  28 , for example a required vacuum level for a vacuum test, or the user may select a vacuum test from a displayed list of vacuum tests. 
     The control unit  18 , in particular the controller  27 , is in communication with the communications unit  19  for communicating with the remote device  20 . The control unit  18  is also connected to the pressure sensor  21  for receiving pressure data, and to the valve  39  for controlling operation of the valve  39 . 
     As illustrated, in some examples the communications unit  19  provides a connection to the vacuum pump  37  for controlling operation of the pump  17 . In these examples, the control unit  18  may be configured to operate the pump  17 . In particular, the control unit  18  receives pressure data from the pressure sensor  21 , and operates the pump  17  to perform a vacuum test. 
     The control unit  18  may be configured to operate the pump  17  until the vacuum pressure detected by the pressure sensor  21  reaches a threshold value. The control unit  18  may be configured to operate the pump  17  until the vacuum pressure detected by the pressure sensor  21  passes a threshold value for a pre-determined period of time. In some examples, as described further hereinafter, the control unit  18  may be configured to operate the pump  17  until the vacuum pressure detected by the pressure sensor  21  reaches a threshold value, the control unit  18  may then be configured to close the shut-off valve  26 , stop operation of the pump  17 , and monitor the vacuum pressure detected by the pressure sensor  21  for a pre-determined period of time. 
     In examples in which the control unit  18  of the adapter  36  does not operate the pump  17 , the control unit  18  can monitor the vacuum pressure in the HVAC-R system  1  using the pressure sensor  21 , and can communicate this to the remote device  20 . 
     The adapter  36  described with reference to  FIGS. 8 and 9  can be used together with a vacuum pump  37 , for example a standard vacuum pump  37 , to provide further control and remote data communication for performing a vacuum test, as described below. In particular, the adapter  36  allows an operator to receive information remotely through the communications unit  19 , and optionally also allows the operator to send remote instructions to the adapter and/or vacuum pump  37 . 
     In various examples, the vacuum pump  15  of  FIGS. 2 to 7 , in particular the control unit  18 , may be configured to operate the vacuum pump  17  in various ways to perform a vacuum test. Similarly, the adapter  36 , in particular the control unit  18 , together with the vacuum pump  37 , as illustrated in  FIGS. 8 and 9 , may be configured to perform a vacuum test. A preferred example vacuum test  31  is described with reference to  FIG. 10 . 
     A first stage of the example vacuum test  31  comprises a connection test  32 . During the connection test  32 , the connection to the service port  13 ,  14  of the HVAC-R system  1  (i.e. the hose) is closed, and the pump  17  is operated to generate a negative pressure against the connections within the vacuum pump  15 ,  37 , and between the vacuum pump  15 ,  37  and the HVAC-R system. The connection test  32  thereby ensures that the vacuum pump  15 ,  37  and associated hoses are properly connected and leak free. If the test fails the control unit  18  signals to the technician, for example using the alarm and/or the communications unit  19 . The technician then checks the hoses and valves and tightens connections if required. The connection test  32  will be quite fast, as it is only testing the equipment and not the HVAC-R system  1 . Therefore, usually the technician is present for the connection test  32 . 
     After the connection test  32 , an intermediate vacuum test  33  is conducted. The connection(s) between the vacuum pump  15  and the high pressure and/or low pressure service port  13 ,  14  of the HVAC-R system  1  is opened. The control unit  18  is configured to open the shut-off valve  26  and operate the pump  17  to generate a vacuum in the HVAC-R system  1 . The pressure sensor  21  or pressure sensors  21   a ,  21   b  detects the vacuum pressure in the HVAC-R system. 
     The control unit  18  operates the pump  17  until the detected pressure reaches a predetermined threshold value. Once the threshold is passed, the pump  17  is deactivated and the shut-off valve  26  is closed, sealing the HVAC-R system  1  from the pump  17 . The control unit  18  then monitors the pressure data from the pressure sensor  21  to determine if the HVAC-R system  1  is holding the vacuum that has been applied. The control unit  18  may monitor the pressure in the HVAC-R system  1  for a pre-determined period of time. The intermediate vacuum test  33  is passed if the HVAC-R system  1  holds the applied vacuum for the pre-determined period of time. During the intermediate vacuum test  33 , the predetermined vacuum threshold and the predetermined period of time are large enough to identify if there large leaks in the HVAC-R system  1 , for example a disconnected or burst pipe. If the intermediate vacuum test  33  fails, the control unit  18  sends a communication to the technician via the communication unit  19  and/or the alarm. The engineer should investigate the HVAC-R system  1  to identify the leak. If the intermediate vacuum test  33  is passed, a full vacuum test  34  is performed. 
     During the full vacuum test  34  the connection(s) between the vacuum pump  15  and the high pressure and/or low pressure service port  13 ,  14  of the HVAC-R system  1  is opened. The control unit  18  operates the pump  17  until the detected pressure reaches a predetermined threshold. The predetermined threshold is higher than during the intermediate vacuum test  33 . Once the threshold is passed, the pump  17  is deactivated and the shut-off valve  26  is closed, sealing the HVAC-R system  1  from the pump  17 . The control unit  18  then monitors the pressure data received from the pressure sensor  21  to determine if the HVAC-R system  1  is holding the vacuum that has been applied. The control unit  18  may monitor the pressure in the HVAC-R system  1  for a pre-determined period of time. The intermediate vacuum test  33  is passed if the HVAC-R system  1  holds the applied vacuum for the pre-determined period of time. 
     The full vacuum test  33  is passed if the HVAC-R system  1  holds the applied vacuum for the pre-determined period of time. The predetermined pressure threshold and period of time are typically larger and longer, respectively, during the full vacuum test  34  than during the intermediate vacuum test  33 . 
     The intermediate and full vacuum tests  33 ,  34  described above may take a long time, dependent on the size of the HVAC-R system  1 , the equipment and configuration of the HVAC-R system  1 , and the gauge (diameter) of pipes and hoses in the HVAC-R system  1 . These factors influence the pressure drop across the HVAC-R system, and in some large commercial applications the intermediate and full vacuum tests  33 ,  34  may take up to 12 hours or longer. Advantageously, providing the vacuum pump  15  with a communications unit  19  that is configured to communicate with a remote device  20  over a mobile communications network means that the technician does not need to be present for the duration of the vacuum test  31  as they can receive updates and alarms from anywhere with mobile communications network. 
     It will be appreciated that different vacuum tests may comprise different sub-tests to those described with reference to the example of  FIG. 10 . For example, a vacuum test may only comprise the full vacuum test  34  described above. 
     During any stage of a vacuum test the control unit  18  may be configured to send updates to the technician via a connection to the mobile communications network provided by the communications unit  19 . For example, the control unit  18  may be configured to send regular updates, for example hourly updates. Alternatively or additionally, the control unit  18  may be configured to send updates to the technician via the communications unit  19  when certain milestones have been passed (e.g. intermediate vacuum test  33  passed). The control unit  18  may be configured to send the update as an SMS communication to the remote device  20 . 
     The control unit  18  may be configured to respond to a communication received by the communications unit  19  over the mobile communications network. For example, the communications unit  19  may receive a request for an update, and the control unit  18  can be configured to respond with status information of the vacuum test, for example a current detected pressure and time. In other examples, the communications unit  19  may receive an instruction, for example an instruction to perform a vacuum test or to increase the vacuum, and the control unit  18  can be configured to operate the pump  17  in response to such an instruction. 
     In preferred examples, the connectors of the vacuum pump  15  and/or the adapter  36 , as described herein, are threaded connectors for connection with an HVAC-R hose. In particular, the connector of the pump intake  22 , the connector of the second intake  23 , and the connector  38  of the adapter  36  preferably comprise a threaded connector for connecting to an HVAC-R hose. Preferably, the threaded connectors are configured for attachment to standard refrigerant hoses as used in HVAC-R maintenance. For example, the threaded connectors may have a threaded connection with size: ⅛ inch (3.175 mm), or ⅜ inch (9.525 mm), or ½ inch (12.7 mm), or ⅞ inch (22.225 mm). In preferred examples, the threaded connectors are ¼ inch (6.35 mm) SAE connectors. Preferably, the connectors comprise a male threaded connector. 
     In summary, there is provided a vacuum pump  15  for use during maintenance or commissioning of an HVAC-R system  1 . The vacuum pump  15  has a pump  17  having a pump intake  22  for connection to the HVAC-R system  1 , in particular one or more of a high pressure service port  14  and a low pressure service port  13  of the HVAC-R system  1 . The vacuum pump  15  also includes a communications unit  19  that is configured to connect to a mobile communications network. The vacuum pump  15  also includes a pressure sensor arranged to detect a pressure in the HVAC-R system  1 . The vacuum pump  15  also includes a control unit  18  configured to communicate with the pressure sensor  21 , control operation of the pump  17 , and communicate with a remote device via the mobile communications network. In examples, the remote device  20  may be a mobile phone or a tablet computer, or any device that can connect to a mobile communications network. Therefore, the vacuum pump  15  can remotely communicate updates to the remote device  20  over a mobile communications network, and can optionally also receive instructions or requests from the remote device  20  over a mobile communications network. 
     There is also provided an adapter  36  for a vacuum pump  37  for use during maintenance or commissioning of an HVAC-R system  1 . The adapter  36  includes a connector  38  for connecting to the HVAC-R system  1 . Optionally, the connector  38  is for connecting to the HVAC-R system  1  via the vacuum pump  37 . The adapter  36  further includes a pressure sensor  21  arranged to detect a pressure in the HVAC-R system  1  during use. The adapter  37  further includes a communications unit  19  configured to connect to a mobile communications network, and a control unit  18  configured to communicate with the pressure sensor  21  and with a remote device  20  via the mobile communications unit  19 . 
     There is also provided a method of performing a vacuum test that includes using a vacuum pump to draw a vacuum on the HVAC-R system  1  and communicating with a remote device  20  via a mobile communications network, for example to send updates to the remote device  20 , or to receive instructions from the remote device  20 . 
     Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. 
     Features, integers, characteristics or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.