Discussion on Problems Caused by Suspected Minimum Pressure Valve of Compressor

Discussion on Problems Caused by Suspected Minimum Pressure Valve of Compressor

In the process of using the compressor, in order to achieve the purpose of normal and high-efficiency production, most of the time, we will give more choices and maintenance to the host and spare parts, but often ignore some details such as safety. Understanding and grasping the situation. It should be noted that "the destruction of a thousand-mile embankment in an ant nest" seems to be a small problem. If carelessness is not paid attention to, it will not only cause unnecessary waste, but even lead to a major accident one day. Therefore, during the long journey of the compressor, no matter how big or small the problem is, it is necessary to pay attention and thoroughly understand and solve it. This is the prerequisite to ensure that the compressor can keep working safely and effectively.

So, we will start with the suspected minimum pressure check valve in the compressor application process as a starting point, and initiate a solicitation and discussion of opinions from industry insiders, in order to discuss the purpose of mutual benefit. Let's listen to the heated discussion among netizens.

　　 　　ID: A reed crossing the river

Recently I encountered two machines in a row, one is 20m3 and the other is 3m3, and they all have the same problem: when the machine is turned on, the pressure is not increased (about 0.2MPa), close the exhaust valve and hold it down for a while, then open it again. To run normally! What is the reason? Ask the experts for guidance!

　　ID: miaojiulai

　　 1. Check the piston inside the bleed solenoid valve;

　　 2. Whether the minimum pressure check valve is closed when it is just turned on. Generally these two problems.

　　ID: A reed crossing the river

　　Whether the minimum pressure check valve is closed when it is just turned on? How can I check that it is all inside, and I can't see it?

　　ID: miaojiulai

　　 You said that it is not pressurized, then does the machine display loading? Your question is too vague, make it clear, let's discuss it in detail together!

　　ID: Gequsuo

When the machine starts to run, you can start to compress, but there is no upward pressure, you need to pay attention to it. It should be known that the process of realizing the upward pressure is to compress the gas drawn in through the small hole in the suction valve, that is, the suction valve opens the device. Where did the qi go if it was not mad? Is it leaking from the back, or the suction valve cannot be transmitted? If you want to study it, you can always open the pipe that feeds the suction valve to see if you can get gas, and confirm whether the relevant solenoid valve is working!

　　ID: Xiaotianshui

　　 If there is a minimum pressure valve repair kit, replace it directly, if not, replace it with a new minimum pressure valve.

　　ID: miaojiulai

　　 The pressure of the pressure gauge of the machine just turned on is high and the pressure of the gas tank is low. The pressure of the general machine is about 5 kg. The pressure of the gas storage tank starts from 0, and both of them start from 0. There is a problem with the valve.

　　ID: oakrain

　　 The following is a quote from "Yiwei Crossing the River": Is the minimum pressure check valve closed when it is first turned on? How can I check it? It's all inside, and I can't see it?

　　 The machine will shut down for three minutes after the test, and it will not stop, usually because the minimum pressure valve is leaking.

　　ID: jk-0530

　　 agree with the opinions upstairs, study!

　　ID: liuqinglin168

　　 Judging from my experience, the most likely cause is that the minimum pressure valve is broken. It is recommended to replace one.

　　ID: adsl65362408

　　 is actually very simple. When this happens, just one sentence: the control system leaks.

　　ID: A reed crossing the river

　　 Thank you everyone! When the machine is turned on, it shows loading, but it does not press up. As for whether it is the minimum pressure valve (not fully opened), who can give a good detection method? Because the shutdown check is definitely not available. The control system should be fine. Two machines, one has been used for more than a year, and the other has just started to be used. It is still making do with it.

　　ID: miaojiulai

　　 Hehe, you are so stupid, is there a gas tank behind the machine? Is there a pressure indicator on the machine? The pressure on the machine just turned on should be about 5 kg, (the load is) lower than this pressure, the minimum pressure valve has a problem. Do you have any opinions on this answer?

　　ID: Bodhi tree

The dumbest way to judge the minimum pressure valve damage: turn on, fill the air, close the shut-off valve when shutting down, after unloading completely, open the shut-off valve, observe the pressure display, or open the oil drain hole. This is the outlet is not one-way Valve.

　　ID: turbo.yan

　　 There are many reasons for not loading at the beginning, but according to your description, it is an old machine. It should be that the piston in the bleed solenoid valve or the minimum pressure check valve has problems.

　　The reason for not loading, if the air cylinder pushes the butterfly valve to open, it needs a certain pressure, generally at least 2.5bar to push. As for the leakage of the minimum pressure valve, many analyses above are correct, but now many minimum pressure valves have the problem of low pressure leakage, which is relatively concealed, and it is still very difficult to determine. In particular, many minimum pressure valves leak in one direction, that is, they leak from the inside and outside of the machine (in the direction of the gas tank), and they will not leak in the reverse direction.

　　Upstairs, he said that looking at the pressure display on the panel and the pressure gauge of the gas tank, it is impossible to compare whether there is a leak. One is that the leakage is not large and not obvious, and the other is that there are valves between the two measuring points, which have a pressure difference. The most important reason is that these pressure gauges and pressure transmitters have not been adjusted, whether they are on the machine or the gas tank, and the data that comes out are unreliable. You can still look at the high pressure, and be sure to be precise. Error.

　　 The minimum pressure valve (or pressure holding valve) cannot keep the pressure. The reason for the leakage is that many manufacturers now use F4 as a seal. The material of F4 is relatively hard and it is prone to low pressure leakage.

　　ID: zyouqiang12

　　 1. The main machine has internal leakage in the control pipeline. When the machine is turned on, the internal air pressure leaks through the control pipeline to the rear of the pressure holding valve, which is the detection point of the pressure sensor. Second, the small machine should be checked from the reason that it does not load when it is turned on. There should be a method. Personally, I think: No matter whether the problem of large or small machine, it should appear in the control pipeline.

　　ID: yjj511

　　After the equipment is operating normally, when it becomes no-load and then load, will it still be like this? The solenoid valve is clogged, and the intake valve may malfunction.

　　ID: Reminder

　　 The intake valve is more likely. Which intake valve do you use? Check if the O-ring is worn out?

　　ID: lanboxs

　　 The following is a speech quoted by "One Reed Crossing the River": Thank you! When the machine is turned on, it shows loading, but it does not press up. As for whether it is the minimum pressure valve (not fully opened), who can give a good detection method? Because the shutdown check is definitely not available. The control system should be fine. Of the two machines, one has been used for more than a year, and the other has just started. Still making do with it now.

　　 directly remove the air outlet and turn it on. If air comes out as soon as it is turned on, it is a leak.

　　ID: zynzyn65

　　 Don't make it complicated, I personally feel that the most likely reason is that the suction valve is not opened.

　　ID: Old Red Army

　　 When the screw air compressor is just started, the air source to open the intake valve is established by the minimum pressure valve. (The minimum pressure valve opening pressure is generally about 4.5kg, while the opening pressure of the intake valve with a reaction force spring applied to the air compressor is only 2-3kg). In addition, the air is sucked into the compressor body by the vacuum breaking valve in the intake valve. After compression, part of the air is released and the other part is used to build up the pressure in the system and control the air. So I think there may be three reasons: 1. The minimum pressure valve is not closed tightly or the opening pressure setting is too low. 2. The discharge valve discharge side flow is too large. The discharge flow rate should be adjusted on the premise of maintaining the system internal pressure and current value normal. 3. The vacuum-breaking valve in the intake valve may be jammed, resulting in a decrease in air intake.

　　ID: j8886

　　 What I said upstairs makes sense, let’s study.

　　ID: kekedejihao

　　 I think it should be the problem of the minimum pressure valve, and the air intake end of the machine is blocked.