Preventing Creep in Pressure Regulators
by Katie Dennis, on Thu, Sep 26, 2013 @ 13:09 PM
The right preventive measures and inspections will help your regulators do their job
Creep: An increase in outlet pressure typically caused by regulator seat leakage. Get the Swagelok Regulator Reference Guide »
Every regulator is susceptible to creep. That's an increase in outlet pressure that occurs when pressure escapes, even though the poppet is closed.
Causes of creep
The seat of the problem is in the seat itself. Regulator seats can be compromised by particulates in the process stream, which can cause minor imperfections in the sealing surface. The high flow and small orifice that is created in a pressure regulator combine to turn a very small particle into a fast projectile. This projectile can nick the sealing surface of the seat and cause leakage. Any other damage to the poppet or the seat can also cause creep. Using a regulator with a soft seat can reduce the opportunity for creep.
How to prevent creep
One good way to prevent creep is with upstream filtration. Make sure you are removing all particulates from the process stream before it reaches the regulator. Some regulators include an integral filter upstream of the seat to help protect the seat. This small filter can reduce the potential for creep and increase the life expectancy and accuracy of your regulator.
It's also important to use your regulator as it was intended, and not as a shut-off device. When selecting a regulator, the total system design must be considered to ensure safe, trouble-free performance. Using the appropriate block valve, upstream or downstream, depending on your system design, can help prevent creep. Use of an appropriate shut off valve will help to maintain accuracy and prevent creep.
Also consider a self-venting option to eliminate damage to the diaphragm caused by captive pressure. Will your system fluid and design allow for a self-vent option or a captured vent option? Both vent options allow you to purge excess downstream pressure and improve accuracy. A captured vent also provides a means of containment of hazardous media should a diaphragm or piston rupture.
For more information about regulators you can call us at 780-437-0640 or request a copy of our Regulator Reference Guide »