CN106525358B

CN106525358B - Valve pressure testing system and method

Info

Publication number: CN106525358B
Application number: CN201611186877.XA
Authority: CN
Inventors: 邱东; 张晓祥
Original assignee: Beijing Siemens Cerberus Electronics Ltd
Current assignee: Beijing Siemens Cerberus Electronics Ltd
Priority date: 2016-12-20
Filing date: 2016-12-20
Publication date: 2020-02-18
Anticipated expiration: 2036-12-20
Also published as: CN106525358A

Abstract

The invention discloses a valve pressure testing system and a valve pressure testing method. This valve pressure test system includes: the device comprises a valve mounting table (1), a pressure pump group (2), a pressure transmitter (3), a differential pressure transmitter (4), a flow measuring device (5), an air control valve group (6) and a control device (7) electrically connected with the devices. The technical scheme in the embodiment of the invention can improve the effective rate of the valve pressure test and reduce the labor cost.

Description

Valve pressure testing system and method

Technical Field

The invention relates to a heating, ventilating and air conditioning system in the field of building control, in particular to a system and a method for carrying out pressure test on a valve used in the heating, ventilating and air conditioning system.

Background

The heating, ventilating and air conditioning system in the building control system is a general term for heating, ventilating and air conditioning systems in a building or a building, and is an important component of the whole building in terms of function. With the development of urbanization, large commercial buildings or office buildings all adopt advanced heating, ventilating and air conditioning systems. One field device used to control the flow of a cooling or heating medium in a hvac system is a valve. The field-mounted valves may be connected to a controller. The controller can open/close the control valve or control the opening of the valve according to the data collected by the field sensor so as to control the flow.

The valves used in the heating and ventilating system are various in kind, and may be classified into, for example, a shut-off valve (e.g., ball valve, butterfly valve), a regulating valve (e.g., pressure reducing valve), a check valve, a flow dividing valve, etc., according to the application and use. The regulating valve can be further divided into an electric differential pressure regulating valve, a pressure independent regulating valve and the like. In order to enable continuous, smooth, long-term operation of these field-mounted valves, it is generally required that the valves employed should have high reliability and good safety performance. For this reason, each valve requires a series of tests before it is shipped. In these tests, the pressure test phase is the last test cycle of the valve test. The pressure test includes, for example: inner and outer leak tests. The internal leakage test value is used for representing and measuring the flow characteristic of the valve, and the external leakage test value is used for representing and measuring the strength characteristic of the valve. Taking a two-way valve and a three-way valve as an example, the internal leakage test typically comprises a straight-through test, i.e. measuring whether a fluid leakage occurs in a straight-through situation, for example, for a two-way or a three-way valve. For three-way valves, the internal leakage test also includes a bypass test, wherein the path switching of the straight-through and bypass of the three-way valve is achieved by a change in the position of the valve stem assembly. The leakage test is generally called a high pressure test, in which high pressure water is injected while the valve stem of the valve is placed in a neutral position to test whether the valve leaks water.

Conventional pressure testing systems typically monitor, control, and convert manually various testing steps during the testing process. This requires, on the one hand, that the operator is an experienced professional and, on the other hand, that there is also a risk of possible non-professional operations.

To this end, those skilled in the art are also working to find other solutions to automate valve testing.

Disclosure of Invention

In view of this, the embodiment of the present invention provides a valve pressure testing system on one hand and a valve pressure testing method on the other hand, so as to improve the efficiency of the valve pressure testing and reduce the labor cost.

The valve pressure testing system provided in the embodiment of the invention comprises: the valve mounting table is used for fixing a valve to be tested at a set testing position; the pressure pump group comprises a high-pressure pump and at least one low-pressure pump; the high-pressure pump is used for injecting water flow into the inlet end of the valve according to set high pressure when the leakage test of the valve is carried out; each low-pressure pump in the at least one low-pressure pump is used for injecting water flow to the inlet end of a valve according to set low pressure when the low-pressure pump is gated to carry out internal leakage test of the valve; the pressure transmitter is used for measuring the water pressure at the inlet end of the valve when the leakage test of the valve is carried out; the differential pressure transmitter is used for measuring the water pressure difference between the inlet end and the outlet end of the valve when the internal leakage test of the valve is carried out; the flow measuring device is used for measuring the internal leakage flow when the internal leakage test of the valve is carried out; the pneumatic control valve group comprises a plurality of pneumatic control valves, each pneumatic control valve is a two-way valve, and the pneumatic control valves are respectively arranged between the pressure pump group and the inlet end of the valve and between the outlet end of the valve and the flow measuring device; each pneumatic control valve is used for communicating the passages on the two sides of the pneumatic control valve when the pneumatic control valve is opened, and disconnecting the passages on the two sides of the pneumatic control valve when the pneumatic control valve is closed; and the control equipment is electrically connected with the valve mounting platform, the pressure pump group, the pressure transmitter, the differential pressure transmitter, the flow measuring device and the pneumatic control valve group, the control equipment is configured to be used for controlling the opening and closing or water flow regulation of the corresponding pressure pump in the pressure pump group according to the current pressure test type and the valve body size and specification of the valve, and controlling the opening/closing of each pneumatic control valve in the pneumatic control valve group and reading the measurement values of the pressure transmitter (3), the differential pressure transmitter (4) and the flow measuring device (5).

In one embodiment, the at least one low pressure pump comprises: a first low pressure pump and a second low pressure pump; the frequency modulation pressure of the second low-pressure pump is greater than that of the first low-pressure pump; the control equipment is used for selecting the first low-pressure pump when the current pressure test type is an internal leakage test and the water flow pressure difference is smaller than a set pressure difference value, and otherwise, selecting the second low-pressure pump.

In one embodiment, the valve testing system further comprises: the valve control lifting appliance is connected with a valve rod of the valve through an air cylinder; the control device can control the air cylinder in the valve control lifting appliance to disturb the valve rod of the valve to remove air in the valve cavity of the valve when water flows through the valve.

In one embodiment, when a set pressure is applied to a sealing pressure plate of the valve port and the valve is placed in a through state, the control device starts a low-pressure pump of the at least one low-pressure pump at a fixed frequency to fill the valve with water, and controls an air control valve in the air control valve group to open/close so that a through output port of the valve is respectively in fluid communication with the differential pressure transmission and the flow measurer; (ii) a After a first set time period, adjusting the driving frequency of the low-pressure pump according to the water pressure difference value read from the differential pressure transmitter to enable the water pressure difference value of the differential pressure transmitter to meet set requirements; and after a second set time period, reading the metering value of the flow measuring device, and comparing the read metering value with the straight-through flow standard metering value to obtain a straight-through flow test result.

In one embodiment, the control device is further configured to, under the condition that a set pressure is applied to a sealing pressure plate of the valve port and the valve is placed in a bypass state, regularly open a low-pressure pump of the at least one low-pressure pump to fill the valve with water, and control opening/closing of a pneumatic control valve in the pneumatic control valve group to make a bypass output port of the valve in fluid communication with the differential pressure transmission and the flow measurer respectively; after a first set time period, adjusting the driving frequency of the low-pressure pump according to the water pressure difference value read from the differential pressure transmitter to enable the water pressure difference value of the differential pressure transmitter to meet set requirements; and after a fourth set time period, reading the metering value of the flow measuring device, and comparing the read metering value with the bypass flow standard metering value to obtain a bypass flow test result.

In one embodiment, when the valve rod stays at the stroke middle position, the control device opens a low-pressure pump in the at least one low-pressure pump and controls the opening/closing of a pneumatic control valve in the pneumatic control valve group, so that the low-pressure pump fills water to the inlet end of the valve; after a fifth set time period, controlling the opening/closing of a pneumatic control valve in the pneumatic control valve group so as to close the passage at the outlet end of the valve and other passages except the passage between the inlet end of the valve and the pressure pump group, controlling the high-pressure pump to be opened and controlling the low-pressure pump to be closed; reading a water pressure value of the pressure transmitter, adjusting the driving pressure of the high-pressure pump according to the read water pressure value, and adjusting the pressure applied to the sealing pressure plate by the telescopic pressure plate and the telescopic holding claw until the water pressure value meets the set requirement; and after a sixth set time period, informing and observing whether water leakage exists or not to obtain an external leakage test result.

In one embodiment, the control device is further configured to control the pneumatic control valve at the inlet end of the valve to open and then control the pneumatic control valve at the outlet end of the valve to open after the external leakage test is completed; and when the pressure in the valve cavity is lower than a second set threshold value, controlling the sealing pressure plate to be opened.

In one embodiment, the pneumatic valve block comprises: a first pneumatic valve disposed between the pressure pump cluster and the inlet end of the valve; and a fifth pneumatic control valve disposed between the straight through outlet end of the valve and the flow measuring device.

In one embodiment, the pneumatic valve block further comprises: a seventh pneumatic control valve disposed between the bypass outlet end of the valve and the flow measurement device.

In one embodiment, the pneumatic valve block further comprises: the second pneumatic control valve is arranged between the inlet end of the valve and the first interface of the differential pressure transmitter; the third pneumatic control valve is arranged between the straight outlet end of the valve and the second interface of the differential pressure transmitter; and a fourth pneumatic valve arranged between the bypass outlet end of the valve (8) and the second interface of the differential pressure transmitter.

In one embodiment, the pressure testing system further comprises: an electromagnetic actuator for enabling a portion of the test water flow from the low pressure pump to flow back into a tank with the valve sealed well when performing an internal leakage test of the valve; the gas accuse valves includes: an eighth pneumatic control valve disposed between the electromagnetic actuator and the inlet end of the valve; the control equipment further controls the eighth pneumatic control valve to be opened when the pressure testing type of the valve is the internal leakage testing, and controls the eighth pneumatic control valve to be closed when the pressure testing type is the external leakage testing.

In one embodiment, the flow measurement device comprises: and the electromagnetic flowmeter is used for measuring the internal leakage flow rate when the internal leakage test of the valve is carried out.

In one embodiment, the flow rate measurement device further comprises: the electronic scale and the metering barrel positioned on the electronic scale are used for metering the internal leakage flow when the flow is less than a set low-flow threshold value during the internal leakage test of the valve; the gas accuse valves further includes: the sixth pneumatic control valve is arranged between the straight-through outlet end of the valve and the metering barrel of the electronic scale; the control equipment further controls the sixth pneumatic control valve to be opened when the pressure test type of the valve is an internal leakage test and the flow is smaller than the set low-flow threshold; otherwise, controlling the sixth pneumatic control valve to close.

In one embodiment, a drain opening is formed below the metering bucket; the gas accuse valves further includes: a ninth pneumatic control valve arranged at the water outlet end of the metering tank; the control equipment further controls the ninth pneumatic control valve to be closed when the pressure test type of the valve is an internal leakage test and the flow is less than the set low-flow threshold value; otherwise, controlling the ninth pneumatic control valve to be opened.

In one embodiment, the pressure testing system further comprises: the pressure stabilizing tank is used for supplementing water to the valve when a set large flow occurs during the internal leakage test of the valve, and maintaining a stable pressure difference test condition; the gas accuse valves further includes: a tenth pneumatic control valve disposed between the surge tank and the inlet end of the valve; and the control equipment is further used for controlling the opening and closing of the tenth pneumatic control valve according to the flow value measured by the flow measuring device when the internal leakage test of the valve is carried out.

The valve pressure testing method provided by the embodiment of the invention is applied to the valve pressure testing system; the method comprises the following steps: fixing a valve to be tested at a set testing position by using the valve mounting table; controlling the corresponding pressure pumps in the pressure pump group to be opened and closed according to the current pressure test type, the size and the specification of the valve body of the valve, and controlling the opening and closing of each pneumatic control valve in the pneumatic control valve group so as to realize the pipeline communication between the valve and the corresponding pressure pumps in the pressure pump group, the differential pressure transmitter and the flow measuring device; adjusting the injection water flow of the high-pressure pump according to the pressure value measured by the pressure transmitter; and adjusting the injected water flow of the low-pressure pump according to the differential pressure value measured by the differential pressure transmitter.

According to the scheme, as the control equipment and the series of pneumatic control valves are arranged in the valve pressure testing system in the embodiment of the invention, the pipeline communication between the valve to be tested and the corresponding pressure pump, the differential pressure transmitter and the flow measuring device can be realized by controlling the opening and closing of the corresponding pressure pump and the opening and closing of each pneumatic control valve; adjusting the injection water flow of the high-pressure pump according to the pressure value measured by the pressure transmitter; according to the differential pressure value measured by the differential pressure transmitter, the injected water flow of the low-pressure pump is adjusted, so that the automatic control of the pressure testing process can be realized, the operation time is stable, the efficiency of the valve pressure testing is improved, and the labor cost is reduced.

In addition, through setting up first low-pressure pump and second low-pressure pump, can increase the interior hourglass test pressure scope of pressure test system, improve the interior hourglass test ability of pressure test system.

Further, by using an electromagnetic flowmeter and an electronic scale to replace a glass float flowmeter in the prior art, the metering accuracy level of the flow can be improved. And when the small flow, through adopting electronic scale and measuring bucket to carry out the measuring mode of valve back water receiving, can be so that the test result is more directly perceived to also can eliminate pipeline ponding error.

In addition, through setting up the valve mount table including lift platform and flexible pressure disk, compare the valve mount table of formula that sinks among the prior art, can make things convenient for the test position of adjusting valve, and the valve test scope is bigger. And through further setting up a plurality of sealed pressure disks to can select corresponding sealed pressure disk according to the bore of the valve that awaits measuring, conveniently realize the measurement of straight-through and bypass.

In addition, through setting up electromagnetic actuator and can be used to leak the test in and appear sealing up under the good condition, prevent to hold out the pump, protect the pump.

In the process of internal leakage testing, the internal leakage testing pressure difference can be quickly and stably established by adopting a mode of firstly setting frequency and then converting frequency. Through setting up fixed pressure disk pressure seal valve for the "deformation" of valve is controllable stable, can obtain accurate stable piston leakproofness and test accuracy.

In the outer leakage test process, the low-pressure pump is firstly used for injecting water into the valve to perform high-pressure exhaust, after the exhaust of gas is confirmed, the low-pressure pump is closed to start the high-pressure pump to pressurize, and the sealing performance of the outer leakage test can be improved. Also, by increasing the pressure plate force applied to the seal pressure plate while the water pressure is increased, the valve can be protected from damage by overpressure.

Finally, through setting up the surge tank, can conveniently carry out the rapid moisturizing to the valve under the condition that appears leaking when interior hourglass test to the water pressure difference is stabilized.

Drawings

The foregoing and other features and advantages of the invention will become more apparent to those skilled in the art to which the invention relates upon consideration of the following detailed description of a preferred embodiment of the invention with reference to the accompanying drawings, in which:

fig. 1 is a schematic diagram of a connection relationship of a valve pressure testing system according to an embodiment of the present invention.

Fig. 2 is a schematic diagram of a pipeline when the valve pressure testing system performs internal leakage straight-through testing on a large flow rate in the embodiment of the invention.

Fig. 3 is a schematic diagram of a pipeline when the valve pressure testing system performs an internal leakage straight-through test on a small flow in the embodiment of the invention.

Fig. 4 is a schematic diagram of a pipeline during an internal leakage bypass test performed by the valve pressure testing system in the embodiment of the invention.

Fig. 5 is a schematic diagram of a pipeline in the first half section when the valve pressure testing system performs the leak test according to the embodiment of the invention.

Fig. 6 is a schematic diagram of the pipeline in the second half section when the valve pressure testing system performs the leak test according to the embodiment of the present invention.

Wherein the reference numbers are as follows:

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail by referring to the following examples.

Fig. 1 is a schematic structural diagram of a valve pressure testing system according to an embodiment of the present invention. As shown in fig. 1, the valve pressure test system includes: the device comprises a valve mounting table 1, a pressure pump group 2, a pressure transmitter 3, a differential pressure transmitter 4, a flow measuring device 5, a pneumatic control valve group 6 and a control device 7.

In this embodiment, a case that the valve 8 to be tested is a three-way valve is taken as an example, wherein the port a of the valve 8 is an inlet port, the port AB is a through outlet port, and the port B is a bypass outlet port.

The valve mounting table 1 is used for fixing a valve 8 to be tested at a set test position. Wherein different sized valves typically have different test positions.

The valve mounting table 1 in this embodiment may be an existing valve mounting table, or a newly designed valve mounting table in the present invention. Considering that some conventional valve installation tables adopt a sinking type installation table which is limited by a limited space and has a narrow measurable valve caliber range, the embodiment provides a novel valve installation table which comprises a lifting platform 11, a vertical telescopic holding claw (not shown in the figure) and a telescopic pressure plate 12. The lifting platform 11 is used for conveying the valve 8 to a set vertical test position, and the central line of the lateral flange of the valve 8 to be tested is ensured to be concentric with the central line of the telescopic pressure plate 12. Specifically, the lifting platform 11 may be controlled by the first cylinder 13, or may be controlled by a motor. The vertical telescopic holding claw is positioned on the lifting platform 11 and used for pressing a bottom flange of the valve 8. Specifically, the vertical telescopic holding claw can be controlled by an oil cylinder (not shown in the figure) or can be controlled by a motor. The telescopic pressure plate 12 is used for pressing the side flange of the valve 8. Specifically, the retractable platen 12 may be controlled by the second cylinder 14, or may be controlled by a motor. For another example, considering that some conventional valve mounting tables need to mount a blind flange during a three-way test and to dismount the blind flange after the three-way test, the valve mounting table 1 in this embodiment may further include a plurality of sealing pressure plates (not shown in the figure), each of which is used to seal a port of the valve 8 with a corresponding caliber. For example, the seal platen may include: a sealing pressure plate for sealing the side flange of the valve 8, a sealing pressure plate (equivalent to the above-mentioned bottom flange) for communicating with the bypass line of the three-way valve and realizing the sealing and positioning of the bypass line, a sealing pressure plate for positioning the bottom flange of the two-way valve, and the like.

The group of pressure pumps 2 comprises a high-pressure pump 21 and at least one low-

pressure pump

22, 23. The high-pressure pump 21 is used for pumping water in the water tank 10 to the inlet end a of the valve 8 and forming injection water flow at a set high pressure when performing an external leakage test of the valve 8. High-pressure pump 21 may be a gas-driven booster pump, or may be another pressure-adjustable pump. Each

low pressure pump

22, 23 is used to inject a flow of water at a set low pressure into the inlet end a of the valve when the low pressure pump 22/23 is gated for a valve leak test. For example, two low-pressure pumps, i.e., a first low-pressure pump 22 and a second low-pressure pump 23; the frequency-modulated pressure of the second low-pressure pump 23 is greater than the frequency-modulated pressure of the first low-pressure pump 22. Thus, in some embodiments, the first low-pressure pump 22 and the second low-pressure pump 23 may also be referred to simply as a low-pressure pump and a medium-pressure pump, respectively. The first low-pressure pump 22 and the second low-pressure pump 23 may be variable-frequency pumps, or may be other types of pumps. When a corresponding pump is selected from the first low-pressure pump 22 and the second low-pressure pump (intermediate-pressure pump) 23, the first low-pressure pump 22 is selected according to a small pressure difference, and the second low-pressure pump (intermediate-pressure pump) 23 is selected according to a large pressure difference. Of course, in some embodiments, only one low pressure pump may be required to meet the leak test requirements. This embodiment is not limited thereto.

In the present embodiment, a case where the high-pressure pump 21 is a gas-driven booster pump is taken as an example, and a case where the first low-pressure pump 22 and the second low-pressure pump 23 are variable-frequency pumps is taken as an example. Each pressure pump in the group of pressure pumps 2 is also provided with a check valve 24 and a manual valve 25. The check valve 24 serves to restrict the direction of water flow of the pressure pump. The manual valve 25 is used to close the manual valve manually to shut off the water in the pipeline when the pump is replaced or repaired.

The pressure transmitter 3 is used for measuring the water pressure at the inlet end a of the valve 8 when performing the leakage test of the valve 8.

The differential pressure transmitter 4 is used for measuring the water pressure difference between the inlet end a and an outlet end AB or B of the valve 8 when performing the internal leakage test of the valve 8. At present, in some traditional valve pressure testing systems, a differential pointer meter is connected to the back of a front valve of a valve and is used for pressure guiding through a hard pipe, so that the on-way loss of pipeline pressure exists, and a pressure taking point is far away from a valve port, so that the pressure difference measurement is not accurate enough. When adopting differential pressure transmitter 4 to measure the water pressure difference in this embodiment, can adopt the flexible to draw the pressure pipe from the front and back of valve 8 and draw the pressure, its pipeline pressure loss is little, and it can be nearer apart from the valve port to get the pressure point.

The flow rate measuring device 5 is used for measuring an internal leakage flow rate when an internal leakage test of the valve 8 is performed. The flow rate measuring device 5 may be implemented by various flow rate measuring devices. For example, flow measuring device 5 may be a glass float flow meter as used in some conventional valve pressure testing systems today. Alternatively, in consideration of the current situation that the glass float flowmeter is easily pressurized when the position thereof is higher than the valve port of the valve 8 and the accuracy level of the glass float flowmeter is relatively low, the flow rate measuring device 5 in the present embodiment may be realized by using the electromagnetic flowmeter 51, and the accuracy of the electromagnetic flowmeter 51 is relatively high. Further, if considering that the range of the electromagnetic flowmeter 51 is more biased to measure a large flow, an electronic scale 52 and a measuring tank 53 disposed on the electronic scale 52 may be provided to measure a small flow in this embodiment for the sake of safety.

The pneumatic control valve group 6 includes a plurality of

pneumatic control valves

61, 62, 63, 64, 65, 66, 67, which are respectively disposed between the pressure pump group 2 and the inlet end a of the valve 8, between the inlet end a, the outlet end AB, B of the valve 8 and the differential pressure transmitter 4, and between the outlet ends AB, B of the valve 8 and the flow rate measurement device 5. Each pneumatic control valve is used for communicating the passages on the two sides of the pneumatic control valve when the pneumatic control valve is opened, and disconnecting the passages on the two sides of the pneumatic control valve when the pneumatic control valve is closed (closed). In the embodiment shown in fig. 1, it is exemplified that the pneumatic valve group 6 includes 7 pneumatic valves, and the 7 pneumatic valves include, for example, at least a first pneumatic valve 61, a second pneumatic valve 62, a third pneumatic valve 63, a fourth pneumatic valve 64, a fifth pneumatic valve 65, a sixth pneumatic valve 66, and a seventh pneumatic valve 67. The first pneumatic valve 61 is disposed between the pressure pump group 2 and the inlet end a of the valve 8 for conducting the high pressure or low pressure water injection path. A second pneumatic control valve 62 is provided between the inlet end a of the valve 8 and the first interface of the differential pressure transmitter 4 for introducing the pressure at the inlet end of the valve 8. A third pneumatic control valve 63 is arranged between the through outlet port AB of the valve 8 and the second connection of the differential pressure transmitter 4 for introducing the pressure at the through outlet port of the valve 8. A fourth pneumatic valve 64 is arranged between the bypass outlet B of valve 8 and the second connection of differential pressure transmitter 4 for introducing the pressure at the bypass outlet of valve 8. The third pneumatic valve 63 and the fourth pneumatic valve 64 are not simultaneously open. A fifth pneumatic control valve 65 is provided between the through outlet end AB of the valve 8 and the electromagnetic flow meter 51 to measure the AB-end flow. A sixth pneumatic valve 66 is arranged between the straight-through outlet end AB of the valve 8 and the electronic scale 52 in order to measure the small flow at the AB end. A seventh pneumatic control valve 67 is provided between the bypass outlet end B of the valve 8 and the electromagnetic flow meter 51 to measure the B-end flow.

Of course, in some embodiments, if the pressure resistance of the selected differential pressure transmitter 4 satisfies the pressure during the leak test, the second pneumatic control valve 62 may be omitted; additionally, the third pneumatic valve 63 and the fourth pneumatic valve 64 may be omitted in some applications.

In addition, in view of preventing the pressure of the water flowing from the low-pressure pumps 22 and 23 to the inlet end a of the valve 8 from generating strong reaction force to the pump body and causing pump stall in the case of good sealing of the valve 8 when the internal leakage test is performed, the pressure test system in this embodiment may further include an electromagnetic actuator 9 for allowing a part of the test water flowing from the low-pressure pumps 22 and 23 to flow back to a water tank 10 in the case of good sealing of the valve 8. Accordingly, an eighth pneumatic control valve 68 may be further included between the electromagnetic actuator 9 and the inlet end a of the valve 8.

Further, in order to conveniently empty the measuring water in the measuring tank 53, in this embodiment, a drain opening (not shown) is further provided below the measuring tank 53, and a ninth pneumatic control valve 69 is provided for the drain opening. When the ninth pneumatic control valve 69 is opened, the measuring water in the measuring tank 53 can be discharged into a water leakage collecting tank 101 through the drain opening and the corresponding pipeline. In addition, in order to prevent the water in the measuring bucket 53 from overflowing to contaminate the testing area, an overflow pipe 531 is provided above the measuring bucket 53, and when the water in the measuring bucket 53 exceeds the water level at the position where the overflow pipe 531 communicates with the measuring bucket 53, the excess water flows into the leakage water collecting tank 101 along the overflow pipe 531.

In this embodiment, when the water in the leaking water collecting tank 101 reaches a certain amount, such as a set liquid level, the water is pumped to the water tank 10 by a liquid level returning pump 102.

The pneumatic control valve in the embodiment can be a pneumatic control ball valve, or can be other types of pneumatic control valves.

Control device 7 is electrically connected to valve mount table 1 pressure pump crowd 2 pressure transmitter 3 differential pressure transmitter 4 flow measuring device 5 and gas accuse valves 6, control device 7 configure into according to current pressure test type and the valve body size, the specification of valve, corresponding pressure pump 21 in the control

pressure pump crowd

2, 22, 23 open and close to the opening/closing of each gas accuse

valve

61, 62, 63, 64, 65, 66, 67, 68, 69 in the control gas accuse valves 6, with the pipeline intercommunication between corresponding pressure pump, differential pressure transmitter 4, flow measuring device 5 and the electromagnetic actuator 9 in realizing valve 8 and the pressure pump crowd 2. At the same time, the control device 7 can also read the measured values of the pressure transmitter (3), the differential pressure transmitter (4) and the flow measuring device (5) and adjust the injection water flow of the corresponding pressure pump (21, 22, 23) in the pressure pump group (2). For example, the control device 7 can regulate the injection water flow of the high-pressure pump 21 according to the pressure value measured by the pressure transmitter 3; or the injection water flow of the low pressure pumps 22, 23 is adjusted on the basis of the differential pressure value measured by the differential pressure transmitter 4. Specifically, in the case that the high-pressure pump 21 selects the gas-driven booster pump, the gas flow for driving the gas-driven booster pump can be adjusted by controlling the proportional regulating valve 211 matched with the gas-driven booster pump, so as to adjust the driving pressure of the gas-driven booster pump; in the case of a variable frequency pump selected for the low pressure pumps 22, 23, the flow of water from the variable frequency pump can be regulated by controlling the drive frequency of the variable frequency pump. In this embodiment, the control device 7 may comprise a central control module, a man-machine interaction module, and a proportional regulating valve 211 for controlling the high-pressure pump 21 and a frequency converter for controlling the low-pressure pump, etc. The central control module is realized by a Programmable Logic Controller (PLC), a singlechip or a CPU and the like. The human-computer interaction module can comprise a touch screen, an indicator light and the like.

In addition, in order to realize the conversion of the external leakage test, the direct internal leakage test and the bypass internal leakage test in the present application, the pressure testing system in the present application may further include a valve control hanger (not shown in the figure), which is connected to a valve rod (not shown in the figure) of the valve 8 through an air cylinder (not shown in the figure) so as to switch the valve 8 to be tested between the direct, bypass and off states.

The valve test process for performing the valve test control by the control device 7 in this embodiment will be described in detail below. The control device 7 is electrically connected to the other respective devices described above to effect control or data reading of these devices. As will be understood by those skilled in the art, the control device 7 may be a control device formed by a Microcontroller (MCU) and its peripheral circuits, wherein the MCU can obtain measurement data of the field devices by reading its data ports, and the MCU can set or change the operating state of the external devices connected to the MCU (e.g., on/off of pneumatic valves, etc.) by writing to its output ports. The control device 7 described above may also be implemented in software. This software may run on a dedicated industrial computer, computer or even mobile device with processing capabilities. The following exemplarily shows a pressure test procedure implemented under the control of the control device 7.

1. The process of directly testing the large flow is as follows:

fig. 2 is a schematic diagram of a pipeline when the valve pressure testing system performs internal leakage straight-through testing on a large flow rate in the embodiment of the invention. In fig. 2, the thickest and arrowed lines indicate that water is in the pipes and can flow; the thicker line without arrows indicates that there is water in the pipeline, but the water cannot flow after the corresponding pneumatic control valve is closed; the other thin lines indicate no water in the line.

And step 11), the control device 7 controls the telescopic pressure plate 12 and the telescopic holding claws to apply a set pressure to the sealing pressure plate at the port of the current sealing valve 8 so as to seal the port flanges at two sides of the valve 8 and prevent the valve 8 from deforming. For example, when the bore of the valve 8 is smaller than DN80, an oil pressure of 0.8MPa may be used; when the caliber of the valve 8 is larger than DN80, the oil pressure of 1.2MPa can be adopted.

Step 12) the control device 7 controls the first pneumatic control valve 61, the second pneumatic control valve 62, the third pneumatic control valve 63, the fourth pneumatic control valve 64, the fifth pneumatic control valve 65, the seventh pneumatic control valve 67, the eighth pneumatic control valve 68 and the ninth pneumatic control valve 69 to be opened, and controls the sixth pneumatic control valve 66 to be closed.

And step 13) the control device 7 starts the first low-pressure pump 22 or the second low-pressure pump (medium-pressure pump) 23 at a fixed frequency to fill water into the valve 8 according to the size and specification of the valve body of the valve 8, controls the cylinder in the valve control hanger to disturb the valve rod of the valve 8 so as to remove gas in the valve cavity of the valve 8, controls the fourth pneumatic control valve 64 and the seventh pneumatic control valve 67 to be closed after a first set time period, and controls the cylinder in the valve control hanger to pull up the piston of the valve rod so as to enable the valve 8 to be in a direct connection state. The first set time period may be, for example, 6 seconds, but may be, of course, 5 seconds, 5.5 seconds, 6.5 seconds, 7 seconds, or the like. In this step 13), for different valves 8, the control device 7 controls the cylinders in the valve control spreader to generate different air pressures, so as to apply different valve closing tensions to the pistons.

Step 14) the control device 7 controls and reads the water pressure difference value of the differential pressure transmitter 4, and adjusts the frequency of the frequency converter of the first low-pressure pump 22 or the second low-pressure pump (medium-pressure pump) 23 according to the read water pressure difference value, so that the water pressure difference value of the differential pressure transmitter 4 meets the set requirement; after a second set period of time, it is determined that residual water in the post-valve line has been drained and a steady state is entered. If there is no water inlet before the valve is plugged, the valve test system will always build a differential pressure without testing. The second set time period may be, for example, 40 seconds, or may be, for example, 39 seconds, 39.5 seconds, 40.5 seconds, or 41 seconds. Compare among the prior art, wait for the stable condition of rivers through artifical timing, the testing process in this embodiment has practiced thrift manpower and materials, has improved efficiency of software testing.

And step 15), the control device 7 controls the reading of the metering value of the electromagnetic flowmeter 51, and compares the read metering value with the first standard metering value to obtain a direct connection large flow test result. If the read metering value is consistent with the first standard metering value, the valve 8 is qualified; if the difference between the two is larger than the first set difference threshold value, the valve 8 is unqualified, and an alarm can be further used for prompting an operator.

2. The process of direct flow test of small flow is as follows:

fig. 3 is a schematic diagram of a pipeline when the valve pressure testing system performs an internal leakage straight-through test on a small flow in the embodiment of the invention. In fig. 3, the thickest and arrowed lines indicate that water is in the pipes and can flow; the thicker line without arrows indicates that there is water in the pipeline, but the water cannot flow after the corresponding pneumatic control valve is closed; the other thin lines indicate no water in the line.

Step 21) -step 24) as in step 11) -step 14) above;

step 25) the control device 7 controls reading of the metering value of the electromagnetic flowmeter 51, comparing said metering value with a set low flow threshold. When the metering value is lower than a set threshold value, controlling the sixth pneumatic control valve 66 to be opened, and controlling the fifth pneumatic control valve 65 and the ninth pneumatic control valve 69 to be closed; and after a third set time period, reading the metering value of the electronic scale 52, and comparing the read metering value with the second standard metering value to obtain a direct small flow test result. If the read metering value is consistent with the second standard metering value, the valve 8 is qualified; if the difference between the two is larger than the second set difference threshold value, the valve 8 is unqualified, and an alarm can be further used for prompting an operator. The set low flow threshold may be, for example, 2L/min, but of course, the set low flow threshold may be other values determined according to actual conditions. The third set time period may be, for example, 1 minute, that is, 1 minute of water is taken by the measuring bucket 53 above the electronic scale 52, and then the weight of the water in the measuring bucket 53 measured by the electronic scale 52 is read. Of course, the third set time period may also be other values determined according to actual conditions.

It can be seen that, when the inner leakage straight-through test is performed, the control device 7 may apply a set pressure on the sealing pressure plate at the port of the valve 8 and set the valve 8 in the straight-through state, and turn on a low-pressure pump of at least one low-

pressure pump

22, 23 at a fixed frequency to fill the valve 8 with water, and open/close the air control valve in the air control valve group 6 to make the straight-through output port AB of the valve 8 respectively communicate with the differential pressure transmission 4 and the flow measurer 5; after a first set time period, adjusting the driving frequency of the low-pressure pumps 22 and 23 according to the water pressure difference value read from the differential pressure transmitter 4 to enable the water pressure difference value of the differential pressure transmitter 4 to meet the set requirement; and after a second set time period, reading the metering value of the flow measuring device 5, and comparing the read metering value with the straight-through flow standard metering value to obtain a straight-through flow test result.

3. The bypass test process:

fig. 4 is a schematic diagram of a pipeline during an internal leakage bypass test performed by the valve pressure testing system in the embodiment of the invention. In fig. 4, the thickest and arrowed lines indicate that water is in the pipes and can flow; the thicker line without arrows indicates that there is water in the pipeline, but the water cannot flow after the corresponding pneumatic control valve is closed; the other thin lines indicate no water in the line.

Step 31) after the direct flow test is completed, the control device 7 controls the air cylinder in the valve control lifting appliance to press down the piston rod of the valve 8, so that the valve 8 is in a bypass state.

Step 32) reading the water pressure difference value of the differential pressure transmitter 4, and adjusting the frequency of the frequency converter of the first low-pressure pump 22 or the second low-pressure pump (medium-pressure pump) 23 according to the read water pressure difference value to enable the water pressure difference value of the differential pressure transmitter 4 to meet the set requirement. After a fourth set period of time, it is determined that residual water in the post-valve line has been drained and a steady state is entered.

And step 33) reading the metering value of the electromagnetic flowmeter 51, and comparing the read metering value with a third standard metering value to obtain a bypass flow test result. If the read metering value is consistent with the third standard metering value, the valve 8 is qualified; if the difference between the two is larger than the third set difference threshold value, the valve 8 is unqualified, and an alarm can be further used for prompting an operator.

The leakage of the three-way bypass is typically higher than 1.4L/min and is therefore not typically measured by the electronic scale 52.

If the bypass flow test is not performed after the through flow test is performed, but the bypass flow test is performed directly, the control device 7 will control the third pneumatic valve 63, the fifth pneumatic valve 65, and the ninth pneumatic valve 69 to be turned off, and control the fourth pneumatic valve 64 and the seventh pneumatic valve 67 to be turned on, and then perform the above-mentioned test process.

It can be seen that, under the condition that a set pressure is applied to the sealing pressure plate at the port of the valve 8 and the valve 8 is in a bypass state, the control device 7 starts a low-pressure pump of at least one low-

pressure pump

22, 23 at a fixed frequency to fill the valve 8 with water, and controls the opening/closing of the pneumatic control valve in the pneumatic control valve group 6 to make the bypass output port B of the valve 8 in fluid communication with the differential pressure transmission 4 and the flow measurer 5 respectively; after a first set time period, adjusting the driving frequency of the low-pressure pumps 22 and 23 according to the water pressure difference value read from the differential pressure transmitter 4 to enable the water pressure difference value of the differential pressure transmitter 4 to meet the set requirement; and after a fourth set time period, reading the metering value of the flow measuring device 5, and comparing the read metering value with the bypass flow standard metering value to obtain a bypass flow test result.

4. The external leakage test process:

fig. 5 is a schematic diagram of a pipeline in the first half section when the valve pressure testing system performs the leak test according to the embodiment of the invention. Fig. 6 is a schematic diagram of the pipeline in the second half section when the valve pressure testing system performs the leak test according to the embodiment of the present invention. In fig. 5 and 6, the thick line indicates that water is in the pipeline and can flow; the other thin lines indicate no water in the line.

And 41) placing a limiting block on the piston of the valve rod of the valve body 8, so that the valve rod of the valve 8 stays at a stroke middle position, and starting a high-pressure test. For example, it may be activated by a human-machine interaction module activation key of the control device 7. In this embodiment, make valve 8's valve rod stop at the stroke meso position through utilizing a stopper, solved some traditional valve test system at present, the piston of valve rod is heavier or carry out the sealed back, and manual work and water pressure can not lift the valve rod to the condition of meso position stroke, and the mode that uses the stopper in this embodiment realizes simply convenient operation.

Step 42) when the valve rod of the valve 8 stays at the stroke middle position, the control device 7 controls the first air control valve 61, the fifth air control valve 65, the seventh air control valve 67, the eighth air control valve 68 and the ninth air control valve 69 to be opened, and controls the second air control valve 62, the third air control valve 63, the fourth air control valve 64 and the sixth air control valve 66 to be closed. The second low pressure pump (medium pressure pump) 23 is turned on to fill the valve 8 with water. The ninth pneumatic control valve 69 is opened to continuously empty the measuring water in the measuring tank 53 of the electronic scale 52.

Step 43) after a fifth set time period, determining that air in the valve cavity is discharged, controlling the fifth pneumatic control valve 65, the seventh pneumatic control valve 67 and the eighth pneumatic control valve 68 to be closed, controlling the high-pressure pump 21 to be opened, and controlling the second low-pressure pump (medium-pressure pump) 23 to be closed; the air pressure continuously increases, the water pressure output by the high-pressure pump 21 increases, and the water pressure value of the pressure transmitter 3 is read until the read water pressure value meets the set pressure requirement. Further, for safety, a safety upper limit value, such as a safety upper limit of 3Mpa, may be set. The fifth set time period may be, for example, 9 seconds. By setting automatic exhaust time, the problem that in the prior art, because the valve 8 is not tightly sealed, air and water are mixed when water is filled, and the pressure can only reach 2.1Mpa when the DN125 and DN150 valves are tested is solved.

And step 44), in order to avoid damaging the valve body, a Proportional Integral Derivative (PID) pressure regulating mode can be adopted, and in the process of water pressure rising, the pressure applied to the sealing pressure plate by the telescopic pressure plate 12 and the telescopic holding claw can be simultaneously regulated.

Step 45) after a sixth set time period, the control device 7 sends a notification to notify that manual observation is required for water leakage, so as to obtain an external leakage test result. The sixth set time period may be, for example, 1 minute or 2 minutes, or may be any other reasonable time period. The process may be a manual process.

Step 46) controlling the equipment 7 to control pressure relief, namely, firstly controlling the eighth pneumatic control valve 68 to open, and then controlling the fifth pneumatic control valve 65 and the seventh pneumatic control valve 67 to open, namely, adopting a pressure relief mode of firstly opening the valves and then opening the valves to protect the observation window from being damaged by impact.

Step 47) controls the opening of the sealing pressure plate when the pressure in the valve chamber is below a second set threshold, for example 0.9 Mpa. Compared with the situation that splashing is generated due to large internal pressure when the valve seal is opened manually in the prior art, the process can improve the safety of the system.

Step 48) controlling the valve 8 to be lifted and blowing dry water.

It can be seen that, when the valve rod stays at the stroke middle position, the control device 7 opens one of the at least one low-

pressure pump

22, 23 and controls the opening/closing of the pneumatic control valve in the pneumatic control valve group 6, so that the low-pressure pump fills water to the inlet end a of the valve 8; after a fifth set time period, controlling the opening/closing of the pneumatic control valves in the pneumatic control valve group 6 to close the passages at the outlet end of the valve 8 and other passages at the inlet end except the passage between the inlet end and the pressure pump group 2, controlling the high-pressure pump 21 to be opened and controlling the low-pressure pumps 22 and 23 to be closed; reading the water pressure value of the pressure transmitter 3, adjusting the driving pressure of the high-pressure pump 21 according to the read water pressure value, and adjusting the pressure applied to the sealing pressure plate by the telescopic pressure plate 12 and the telescopic holding claw until the water pressure value meets the set requirement; and after a sixth set time period, informing and observing whether water leakage exists or not to obtain an external leakage test result.

In addition, the pressure testing system in this embodiment may further include a surge tank 103, which is configured to replenish water to the valve 8 when a set large flow rate occurs during the internal leakage test of the valve 8, so as to maintain a stable differential pressure test condition. Accordingly, a tenth pneumatic control valve 60 may be further provided between the surge tank 103 and the inlet end a of the valve 8. The control device 7 may be further configured to control the opening and closing of the tenth pneumatic control valve 60 according to the flow value measured by the flow measuring device 5 when performing the internal leakage test of the valve 8.

In addition, the pointer pressure gauge 104 in the pressure testing system is used to indicate whether the device is operating or not.

The manual valve 105 next to the seventh pneumatic valve 67 is used to facilitate verification of the blocking of the fifth pneumatic valve 65 and the seventh pneumatic valve 67.

An air bubble observation window 106 and an exhaust valve 107 corresponding to the air bubble observation window 106 are arranged beside the electromagnetic flowmeter 51, whether air bubbles exist in the water flow passing through the electromagnetic flowmeter 51 can be observed through the air bubble observation window 106, so that the air bubble observation window 106 can be used for determining the duration of each set time period, such as the duration of the first set time period and the duration of the fifth set time period, specifically, before automatic control is carried out, a test process is manually operated firstly, whether air bubbles exist in the water flow is observed through the air bubble observation window 106, if the air bubbles do not exist, the water flow is determined to be stable, and then the durations of the first set time period and the fifth set time period can be determined.

In the embodiment of the invention, the use description of the pressure gauge is as follows:

if the withstand voltage of the selected differential pressure transmitter 4 is smaller than the pressure bearing of the pressure transmitter 3, the second pneumatic control valve 62 needs to be closed to isolate the differential pressure transmitter 4 when the leakage test is performed. If the pressure resistance of the selected differential pressure transmitter 4 meets the pressure during the leak test, the second pneumatic control valve 62 is not required to perform valve closing isolation.

The valve pressure testing method provided in the embodiment of the invention is applied to the valve pressure testing system shown in fig. 1, and the testing process of the valve pressure testing method is consistent with the control process of the control module 7. For example, a valve 8 to be tested is fixed at a set test position by using the valve mounting table 1; according to the current pressure test type and the size and specification of the valve body of the valve 8, controlling the corresponding pressure pumps 21, 22 and 23 in the pressure pump group 2 to be opened and closed, and controlling the

pneumatic valves

61, 62, 63, 64, 65, 66, 67, 68, 69 and 60 in the pneumatic valve group 6 to be opened and closed, so as to realize pipeline communication between the valve 8 and the corresponding pressure pumps 21, 22 and 23, the differential pressure transmitter 4 and the flow measuring device 5 in the pressure pump group 2; adjusting the water flow pressure of the high-pressure pump 21, such as the driving pressure, according to the pressure value measured by the pressure transmitter 3; the water flow pressure, e.g. the drive frequency, of the low pressure pumps 22, 23 is adjusted on the basis of the differential pressure value measured by the differential pressure transmitter 4. The detailed test method can be referred to the above detailed control process of the control module 7 in the pressure test system, and is not described herein again.

In the outer leakage test process, the low-pressure pump is firstly used for injecting water into the valve for exhausting, after the gas is confirmed to be exhausted, the low-pressure pump is closed, the high-pressure pump is started for pressurizing, and the sealing performance of the outer leakage test can be improved. Also, by increasing the pressure plate force applied to the seal pressure plate while the water pressure is increased, the valve can be protected from damage by overpressure.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims

1. A valve pressure testing system, comprising:

the valve mounting table (1) is used for fixing a valve (8) to be tested at a set testing position;

a group of pressure pumps (2) comprising a high-pressure pump (21) and at least one low-pressure pump (22, 23); the high-pressure pump (21) is used for injecting water flow to the inlet end of the valve (8) according to a set high pressure when the leakage test of the valve (8) is carried out; each low-pressure pump (22, 23) of said at least one low-pressure pump (22, 23) for injecting a flow of water at a set low pressure into the inlet end of said valve (8) when said low-pressure pump (22, 23) is gated for an internal leakage test;

the pressure transmitter (3) is used for measuring the water pressure at the inlet end of the valve (8) when the leakage test of the valve (8) is carried out;

the differential pressure transmitter (4) is used for measuring the water pressure difference between the inlet end and the outlet end of the valve (8) when the internal leakage test of the valve (8) is carried out;

the flow measuring device (5) is used for measuring the internal leakage flow when the internal leakage test of the valve (8) is carried out;

the pneumatic control valve group (6) comprises a plurality of pneumatic control valves (61, 62, 63, 64, 65, 66, 67, 68, 69 and 60), each pneumatic control valve is a two-way valve, and the pneumatic control valves are respectively arranged between the pressure pump group (2) and the inlet end of the valve (8) and between the outlet end of the valve (8) and the flow measuring device (5); each pneumatic control valve is used for communicating the passages on the two sides of the pneumatic control valve when the pneumatic control valve is opened, and disconnecting the passages on the two sides of the pneumatic control valve when the pneumatic control valve is closed; and

a control device (7) electrically connected to the valve mounting table (1), the pressure pump group (2), the pressure transmitter (3), the differential pressure transmitter (4), the flow measuring device (5) and the pneumatic control valve group (6), wherein the control device (7) is configured to control the opening and closing or the water flow regulation of the corresponding pressure pump in the pressure pump group (2) and the opening/closing of each pneumatic control valve (61, 62, 63, 64, 65, 66, 67, 68, 69, 60) in the pneumatic control valve group (6) according to the current pressure test type, and read the measured values of the pressure transmitter (3), the differential pressure transmitter (4) and the flow measuring device (5);

the control device (7) is used for opening a low-pressure pump in the at least one low-pressure pump (22, 23) at a fixed frequency to fill the valve (8) with water under the condition that a set pressure is applied to a sealing pressure plate of the valve port and the valve (8) is placed in a through state, and controlling the opening/closing of a pneumatic valve in the pneumatic valve group (6) to enable a through output port (AB) of the valve (8) to be respectively communicated with the differential pressure transmission (4) and the flow measurer (5) in a fluid mode; after a first set time period, according to the water pressure difference value read from the differential pressure transmitter (4), the control device (7) adjusts the driving frequency of the low-pressure pumps (22, 23) to enable the water pressure difference value of the differential pressure transmitter (4) to meet the set requirement; and after a second set time period, the control equipment (7) reads the metering value of the flow measuring device (5), and compares the read metering value with the through flow standard metering value to obtain a through flow test result.

2. Pressure testing system according to claim 1, characterized in that the at least one low-pressure pump (22, 23) comprises: a first low-pressure pump (22) and a second low-pressure pump (23); the frequency modulation pressure of the second low-pressure pump (23) is greater than the frequency modulation pressure of the first low-pressure pump (22);

the control device (7) is used for selecting the first low-pressure pump (22) when the current pressure test type is an internal leakage test and the water flow pressure difference is smaller than a set pressure difference value, and otherwise, selecting the second low-pressure pump (23).

3. Pressure testing system according to claim 1, characterized in that the valve mounting table (1) comprises: a lifting platform (11), a telescopic pressure plate (12), a vertical telescopic holding claw and a plurality of sealing pressure plates; wherein,

the lifting platform (11) is used for conveying the valve to a set vertical testing position;

the telescopic pressure plate (12) is used for pressing a side flange of the valve;

the vertical telescopic holding claw is used for pressing a bottom flange of the valve;

each sealing pressure plate in the plurality of sealing pressure plates is used for carrying out port sealing on the valve (8) with the corresponding caliber.

4. The pressure testing system of claim 3, further comprising: a valve control sling connected to the valve stem of the valve (8) by a cylinder;

the control device (7) is capable of controlling the air cylinder in the valve control sling to disturb the valve stem of the valve (8) to expel air from the valve cavity of the valve (8) when water flows through the valve (8).

5. A pressure testing system according to claim 1, wherein the control device (7) is further configured to, in case a set pressure is applied to the sealing pressure plate of the valve port and the valve (8) is placed in a bypass state, regularly open a low-pressure pump of the at least one low-pressure pump (22, 23) to fill the valve (8) with water, and control the opening/closing of a pneumatic valve in the pneumatic valve group (6) such that a bypass output port (B) of the valve (8) is in fluid communication with the differential pressure transmission (4) and the flow measurer (5), respectively; after a first set time period, the control equipment (7) adjusts the driving frequency of the low-pressure pumps (22, 23) according to the water pressure difference value read from the differential pressure transmitter (4) so that the water pressure difference value of the differential pressure transmitter (4) meets the set requirement; and after a fourth set time period, the control equipment (7) reads the metering value of the flow measuring device (5), and compares the read metering value with the bypass flow standard metering value to obtain a bypass flow test result.

6. A pressure testing system according to claim 4, characterized in that the control device (7) opens a low-pressure pump of the at least one low-pressure pump (22, 23) and controls the opening/closing of a pneumatic valve of the pneumatic valve group (6) when the valve stem is in the stroke neutral position, so that the low-pressure pump fills the inlet end (A) of the valve (8) with water; after a fifth set time period, controlling the opening/closing of a pneumatic control valve in the pneumatic control valve group (6) so as to close the passage at the outlet end of the valve and other passages except the passage between the inlet end of the valve and the pressure pump group (2), controlling the high-pressure pump (21) to be opened and controlling the low-pressure pumps (22 and 23) to be closed; the control equipment (7) reads the water pressure value of the pressure transmitter (3), adjusts the driving pressure of the high-pressure pump (21) according to the read water pressure value, and adjusts the pressure applied by the telescopic pressure plate (12) and the telescopic holding claw until the water pressure value meets the set requirement; after a sixth set time period, the control device (7) issues a notification that it is necessary to observe whether there is a water leak.

7. The pressure testing system of claim 6, wherein the control device (7) is further configured to control the pneumatic control valve at the valve inlet end to open and then control the pneumatic control valve at the valve outlet end to open after the leak test is completed; and when the pressure in the valve cavity is lower than a second set threshold value, controlling the sealing pressure plate to be opened.

8. Pressure testing system according to any of claims 1 to 7, characterized in that the pneumatically controlled valve pack (6) comprises:

a first pneumatic valve (61) arranged between the group of pressure pumps (2) and the inlet end (A) of the valve (8); and

a fifth pneumatic control valve (65) arranged between the through outlet end (AB) of the valve (8) and the flow measuring device (5).

9. Pressure testing system according to claim 8, characterized in that the pneumatically controlled valve pack (6) further comprises:

a seventh pneumatic control valve (67) arranged between the bypass outlet end (B) of the valve (8) and the flow measuring device (5).

10. Pressure testing system according to any of claims 1 to 7, characterized in that the pneumatically controlled valve pack (6) further comprises:

a second pneumatic control valve (62) arranged between the inlet end (A) of the valve (8) and the first interface of the differential pressure transmitter (4);

a third pneumatic control valve (63) arranged between a through outlet end (AB) of the valve (8) and a second interface of the differential pressure transmitter (4); and

a fourth pneumatic valve (64) arranged between the bypass outlet end (B) of the valve (8) and the second interface of the differential pressure transmitter (4).

11. The pressure testing system of any of claims 1-7, further comprising: an electromagnetic actuator (9) for enabling a portion of the test water flow from the low-pressure pump (22, 23) to flow back into a water tank (10) when the valve (8) is sealed well during a leak test of the valve (8);

the pneumatic control valve group (6) comprises: -an eighth pneumatic control valve (68) arranged between said electromagnetic actuator (9) and the inlet end (a) of said valve (8);

the control equipment (7) further controls the eighth pneumatic control valve (68) to be opened when the pressure test type of the valve (8) is an inner leakage test, and controls the eighth pneumatic control valve to be closed when the pressure test type is an outer leakage test.

12. Pressure testing system according to any of the claims 1 to 7, characterized in that the flow measuring device (5) comprises:

and the electromagnetic flow meter (51) is used for measuring the internal leakage flow when the internal leakage test of the valve (8) is carried out.

13. A pressure testing system according to claim 12, characterized in that the flow measuring device (5) further comprises: the electronic scale (52) and the metering barrel (53) positioned on the electronic scale (52) are used for metering the internal leakage flow when the flow is less than a set low flow threshold value when the internal leakage test of the valve (8) is carried out;

the pneumatic control valve group (6) further comprises: a sixth pneumatic valve (66) arranged between the through outlet end (AB) of the valve (8) and the metering bucket (53) of the electronic scale (52);

the control equipment (7) further controls the sixth pneumatic control valve (66) to be opened when the pressure test type of the valve (8) is an internal leakage test and the flow rate is smaller than the set low flow rate threshold value; otherwise, controlling the sixth pneumatic control valve (66) to close.

14. A pressure testing system according to claim 13, wherein a drain opening is provided below the metering tank (53);

the pneumatic control valve group (6) further comprises: a ninth air control valve (69) provided at a drain port end of the measuring tank (53);

the control equipment (7) further controls the ninth pneumatic control valve (69) to be closed when the pressure test type of the valve (8) is an internal leakage test and the flow is less than the set low flow threshold value; otherwise, controlling the ninth pneumatic control valve (69) to be opened.

15. The pressure testing system of claim 1, further comprising: the pressure stabilizing tank (103) is used for supplementing water to the valve (8) when a set large flow rate occurs during the internal leakage test of the valve, so as to keep a stable pressure difference test condition;

the gas accuse valves further includes: a tenth pneumatic control valve (60) disposed between the surge tank (103) and the inlet end (A) of the valve (8);

the control equipment (7) is further used for controlling the opening/closing of the tenth pneumatic control valve (60) according to the flow value measured by the flow measuring device (5) when the internal leakage test of the valve is carried out.

16. A valve pressure testing method, which is applied to the valve pressure testing system according to any one of claims 1 to 12; the method comprises the following steps:

fixing a valve to be tested at a set testing position by using the valve mounting table;

controlling the corresponding pressure pumps in the pressure pump group to be opened and closed according to the current pressure test type, and controlling the opening and closing of each pneumatic control valve in the pneumatic control valve group so as to realize pipeline communication among the valves, the corresponding pressure pumps in the pressure pump group, the differential pressure transmitter and the flow measuring device; adjusting the injection water flow of the high-pressure pump according to the pressure value measured by the pressure transmitter; and adjusting the injected water flow of the low-pressure pump according to the differential pressure value measured by the differential pressure transmitter.