Remedial measures for leakage of ASCO solenoid valve

The pre installation incoming inspection of ASCO solenoid valves is a very important step to confirm whether the arrival of the regulating valve meets the design requirements. Each technical requirement of the regulating valve should meet the design requirements, but the following items should be emphasized during the incoming inspection.

2.1 Valve Body/Interior Specification This item mainly includes: valve model, valve type, nominal diameter, valve seat size, valve core form, flow characteristics, leakage level, valve body material, valve core material, valve seat material, CV value, flange standard grade size, and sealing surface form. If any content is found to be inconsistent with the design, it should be confirmed and approved by the design.

2.2 The main content of the actuator section should include checking the actuator model, type, mode of action, spring range, gas supply pressure, etc.

2.3 The locator section mainly checks the input signal, air source pressure, electrical and air source interface size, and explosion-proof level of the locator, among which the explosion-proof level shall not be lower than the design level requirements.

2.4 Accessories: Carefully clean all accessories according to the design technical requirements of the regulating valve, such as filter pressure reducing valve, valve position switch, solenoid valve, handwheel mechanism, and special tools. The inspection of the above contents can be achieved through methods such as cleaning, measuring instruments, viewing nameplates, and specialized testing methods (such as identifying flange and bolt materials through spectral analysis).

The water pressure test of the regulating valve body includes the pressure test of the valve body and the leakage test when the valve core is fully closed. Normally, when designing a regulating valve with a pressure exceeding 10MPa, the valve body must undergo a pressure resistance test to verify the pressure resistance of the valve body itself and the upper valve cover.

3.1 Issues to be noted during the pressure test of regulating valves: (1) The pressure test of the regulating valve body shall be conducted using a manual pressure test pump, and the use of an electric pressure test pump is strictly prohibited. (2) The test medium is clean water. (3) The test pressure is 1.25 times the design pressure. (4) The pressure gauge used for pressure testing should be calibrated and qualified, with a degree not lower than level 1.5, and the upper limit of the scale should be 1.5 to 2 times the test pressure. (5) During the pressure test of the pneumatic valve, the valve core should be opened at least 20% to prevent damage to the valve core due to excessive pressure on one side. Under normal circumstances, the valve core of the regulating valve allows for a certain amount of leakage. Depending on the difference in the leakage level of the regulating valve, only differential pressure regulating valves (V and VI leakage levels) are generally required to undergo leakage tests.

3.2 Issues to be noted during leakage testing: (1) The pressure test of the regulating valve body should be carried out using a manual pressure test pump for water pressure testing, and it is strictly prohibited to use an electric pressure test pump (valves with VI level leakage should be tested using air pressure). (2) The test medium is clean water (clean air is used for VI level leakage valves). (3) The leakage level test pressure is the large differential pressure designed for valve operation (see design parameters). (4) The pressure gauge used for pressure testing should be calibrated and qualified, with a degree not lower than level 1.5, and the upper limit of the scale should be 1.5 to 2 times the test pressure.

The individual calibration of 4ASCO solenoid valve should be carried out before the installation of newly installed pneumatic control valves. The performance indicators that should be achieved for calibration are: basic error: ± 1.5% return error: 1.5% insensitive zone: 0.6%. Nowadays, there are many productions of throttle valves and electrical valve positioners with different functions. Electrical valve positioners tend to be intelligent, and the specific calibration methods are different, which will not be repeated here.

The installation of 5ASCO solenoid valve and regulating valve is a key issue that should be paid attention to. The poor installation quality directly affects the operation and performance of the regulating valve. During the installation process, the following issues should be noted: (1) Before installing the regulating valve, the dust accumulated during storage must be carefully checked, and the valve must also be kept clean during installation.

In practical applications, incidents of leakage are also quite common. Don't panic when this problem occurs, take some effective remedial measures, and generally the problem can be solved.

The method of changing the flow direction is to alter the state of the valve stem at different positions, which is very effective for regulating valves with high pressure and pressure difference. After the pressure conversion, the flow direction also changes, and the leakage problem is solved.

There are many reasons for leakage, and many flat seals have poor sealing performance under temperature and pressure, which can easily cause leakage. In this case, lens gaskets can be used for sealing to achieve satisfactory results.

Sometimes leakage is caused by gasket problems, because so far, most sealing gaskets still use asbestos board, which has a relatively short lifespan. So when there is a problem with the gasket, changing it decisively will have an effect.

The packing of pneumatic control valves is mostly made of PTFE packing, and its properties will also change when the temperature changes greatly. At this time, the occurrence of leakage is also reasonable. Flexible graphite fillers can overcome these drawbacks and have a long service life, so some have already started using graphite fillers, but the cost is slightly higher.

In short, any unexpected situation actually has a reason behind it, and industry insiders can roughly identify where the problem lies with a little judgment. It is easy to find the crux of the problem and solve it.

(1) The fluid resistance is small because the internal medium channel of the gate valve body is straight through, and the flow direction of the medium through the gate valve does not change, so the fluid resistance is small.

(2) The opening and closing torque is small, and it is easier to open and close because the direction of the gate movement is perpendicular to the direction of the medium flow when opening and closing the gate valve. Compared with the globe valve, the opening and closing of the gate valve is easier.

(3) The flow direction of the medium is not restricted, and the medium can flow in any direction from both sides of the gate valve without disturbance or pressure reduction, achieving the purpose of use. It is more suitable for pipelines where the flow direction of the medium may change.

(4) The structural length is shorter because the gate of the gate valve is vertically placed inside the valve body, while the valve disc of the globe valve is horizontally placed inside the valve body, so the structural length is shorter than that of the globe valve.

(5) When the seal is fully opened, the sealing surface is less susceptible to erosion.

(6) When fully open, the sealing surface is less susceptible to erosion by the working medium than the globe valve.

(7) The body shape is relatively simple, the casting process is relatively easy, and it has a wide range of applications.

What are the drawbacks of ASCO solenoid valves

(1) The sealing surface is prone to damage, and there is relative friction between the two seals that come into contact with the gate and valve seat during opening and closing, which can easily damage the sealing components and affect their service life, making maintenance difficult.

(2) The opening and closing time is long and the degree is large. Due to the need to fully open or close the gate valve when opening and closing, the stroke of the gate plate is large, and a certain amount of space is required for opening. The external dimensions and installation space are also large.

(3) Generally, gate valves with complex structures have two sealing surfaces, which add some processing, grinding, and maintenance. There are many difficult parts, making manufacturing and maintenance more challenging, and the cost is higher than that of globe valves.

Under certain working conditions in certain departments (such as oil pipelines in the petroleum sector), it is not allowed to use valves with reduced diameter. On the one hand, this is to reduce the resistance loss of the pipeline, and on the other hand, it is to avoid obstacles to mechanical cleaning of the pipeline caused by diameter shrinkage.