I have seen people complaining a lot about how their air compressor safety valve keeps opening. As an air compressor user, you should also have this question in your head.
Today I am going to explain why this happens and how you can fix it. But first, I would like to give a short introduction about a safety valve and how it works, if you are not familiar with it.
What Is a Safety Valve?
A pressure relief valve for an air compressor helps to keep you protected if the pressure of the compressor gets too high.
It is also called a pressure relief valve as it reliefs pressure whenever the compressor pressure reaches a critical point. Usually, the pressure level of a safety valve is kept below to the maximum pressure that a compressor can take.
Whenever the pressure of your compressor is about to reach this maximum level, the safety valve will relief air from the compressor so that the pressure drops.
How do Safety Valves Work in an Air Compressor
A safety valve follows a very simple mechanism to work. Here is how it actually works –
- There is a Nozzle inside the valve. From the inlet part of the valve, this nozzle first gets an amount of pressure on it. In other words, the nozzle is there to inlet the air at a certain pressure.
- You have to set a pressure level initially for a safety valve. As I have already said, this pressure needs to be lower than the compressor’s maximum pressure level. When the nozzle reaches this pressure, the Disc inside the valve starts to lift and relief the air from the tank.
- There is a Spring inside the valve, which is attached to the disc. The spring is made in such a way that it will only bend when the pressure reaches the level you have set. So, the disc is lifted up and drawn down by the spring.
- Finally, when the pressure decreases to the point you have set, the disc automatically closes and keeps the air from getting out.
Reasons Why Air Compressor Safety Valve Keeps Opening
Now let’s come to the main point of this article. There are basically two reasons for a safety valve to pop open suddenly. These are –
When There Is an Internal Problem
There are a number of components inside a safety valve but it is typically three main components, the nozzle, the disc, and the spring. You have already known how these three components work.
However, if any of these three components get damaged, then the problem begins. For example –
- If the nozzle is not functioning properly, there will be a problem with the air inlet. In this case, it will accidentally push a lot of air inside the valve and the valve will open.
- When the disc of the valve is old, it will have holes and crack in it. So it will, without any high pressure, start to discharge air out.
- Finally, if the spring is old or damaged, then it will lift up the disc way before it reaches the set pressure. In this case, air will also discharge from the valve.
When There Is a Problem with the Pressure Switch
Another reason for a safety valve to pop open is when the pressure switch is damaged. A pressure switch has a very serious function in an air compressor. It is set with two pressure level, a cut-out, and a cut-in pressure.
When the pressure switch reads the cut in pressure from the pump, it starts to run the compressor. And, when the pressure reaches the cut-out level, it shuts the compressor down.
However, if there is any problem occurred in the pressure switch (i.e. when the diaphragm of the switch is broken or damaged) then the switch won’t shut down even when it reaches the cut-out pressure.
In this case, the compressor will go to critical pressure level. When it happens, the safety valve will automatically pop open. This is how the pressure switch is responsible for the safety valve to open suddenly.
How to Stop the Safety Valve from Opening
There are a number of ways that you can follow to stop a safety valve from opening suddenly. Here are the best ways to keep your compressors safety valve from opening unnecessarily.
- At first, check if the internal part of the safety valve is damaged or not. If you find a damaged part (i.e. the nozzle or the disc) replace this part and it should be fine.
- If you cannot replace the damaged part of the safety valve, you can simply change this safety valve and place a new one. A newer safety valve is always better than a repaired one.
- The pressure switch is also responsible for this. So if you don’t find any problems with the safety valve, then check the pressure switch. If the pressure switch is broken, change it.
- Sometimes, there are troubles with adjusting the pressure switch. If you are also having trouble, check out this article on air compressor pressure switch adjustment to adjust your pressure switch.
Frequently Asked Questions on Air Compressor Safety Valve
How do I adjust the safety valve on my air compressor?
First of all, you need to find out how much pressure your air compressor can take. You will see there is an option to set a pressure level on the safety valve.
When you find out your compressors limit, you can set the pressure level on the safety valve according to that limit. Always use a lower pressure level than the maximum level of pressure that a compressor can take.
What is the purpose of a safety valve?
The purpose of a safety valve is to discharge air from the compressor when the pressure level reaches too high. High pressure can explode the tank and cause critical accidents. To stop this from happening, a safety valve is used on a compressor.
How often should safety valves be replaced?
Most of the safety valves are built to last for years. An average safety valve can easily last for 18 to 24 months. However, you should frequently test your safety valve and change it if there is the slightest chance of malfunctioning. Never take the risk of keeping a faulty safety valve attached to your compressor.
How often should safety valves be tested?
In most cases, you should check your safety valve at least once a month to see if it is in good condition or not. But I recommend you to check at least once every time it discharges.
You already know how to fix it if the air compressor safety valve keeps opening, but it is also important to test the safety valve when it discharges.
Because after discharge it will leave debris around the nozzle and the disc. You have to clean this to keep the safety valve away from malfunctioning.