What? a difference?

[JJayG]

Here's another one of those that I believe is just semantics but someone out there may be able to shed more light on this.
Is there a difference between a Safety Valve and a pressure relief valve? They both fulfil a similar function but definitions in some cases vary quite significantly.

Any Takers ?

 

[hydtools]

I'll bite. The safety valve or pressure safety valve is a pressure relief valve named for its function in a system. The pressure relief valve is a system component which can serve a number of functions and becomes named by that function.
I suppose that a preset, non-adjustable pressure relief valve may be sold as a safety valve.

Ted

 

[kcj]

I have seen 'safety valve' used in a vague ways, apparently by spec writers not real familiar with systems, to mean saftey from over pressure (relief valve), safety from source of energy (OSHA block and vent valve), safety from motion (PO check or counterbalance), safety from temperature, and so forth.

If there is any doubt, I ask for clarification from the customer.

k

 

[dbaird]

From:

http://www.controlandinstrumentation.com/glossary/relief.html

Relief Valve

A spring loaded pressure relief valve actuated by the static pressure upstream of the valve. The valve normally opens in proportion to the pressure increase over the opening pressure. Used primarily with incompressible fluids.

Safety Valve

A spring loaded pressure relief valve actuated by the static pressure upstream of the valve and charachterised by rapid opening or pop action. Normally used with compressible fluids.

David Baird

Sr Controls Designer
EET degree.
Journeyman Electrician.