A compressor bleed valve is a small component on some compressors that allows for the reduced flow of air into the compressor and will then open a circuit if the main compressor is to be interrupted. These valves are important because they allow for the main compressor to be in operation while at the same time a backup system is trying to take over. In the event that the compressor should lose the connection, a spark will ignite the alternate drive system that would then cause the entire system to shut down.
One of the problems with using a backup air source is that this will only work if there is a connection between the two. If the two compressors are both disconnected, the compressor bleed valve cannot properly open. A backup system also cannot take the place of the compressor bleed valve if the compressor bleed valve is ever lost. If the compressor bleed valve should fail, the blow off valve will open, releasing the compressed air from the system, which would cause the compressor to shut down.
The blow off valve is often located near the top of the door of the compressor and is located in a location that allows for a valve to easily be adjusted and opened in the event of a backup system being needed. This is very important when checking that all system connections on the system are secure, because if the compressor fails to open it will allow a build up of pressure and this could cause a fire if it is not handled. Not only does the compressor bleed valve allows for the backup system to operate, but also it can help prevent the system from becoming disconnected completely.