We are using safety valves of gas and steam for detergent slurries. Why they do not function?
I suggest that you rethink that application. Even if the valve does function it might not pass enough slurry quickly enough to relieve the pressure overload.
Not sure but I would check for corrosion inside the valves. I assume the valves are positioned so that they are not exposed directly to the slurry. If possible, empty the system and test with compressed air to see if the release at the correct pressure. It is very important that this type of safety device work correctly. Also suggest contacting the mnfr. You get what you pay for so I recommend that you do NOT skimp on investment in safety equipment, consider the cost if the safety equipment fails to do what it is intended to do. Killing employees is not very popular with surviving employees and it costs a LOT of money.
A gas valve is designed for gas, not thick slurry! When the valve opens, the aperture is nowhere near large enough to allow a significant flow of slurry. The simplest thing would be to use a burst diaphragm, designed to burst at a particular pressure and sized for the appropriate flow rate. You need to replace it after every use, but they are cheap. Otherwise you are stuck designing a custom valve, which would be pretty expensive.
