Back Pressure Valve vs Back Pressure Regulating Valve

[RJSH]

This question is pertaining to water works.
I am seeing two terms or two equipment - back pressure valve and back pressure regulating valve.
Wondering what is the difeerence between these two (in terms of inlet and outlet pressure)

 

[hsbcn]

Check out this thread; it might shed some light on your question:

http://www.eng-tips.com/viewthread.cfm?qid=237647

My focus is on corrosion-resistant, high-alloy valves for the petrochemical industry.

 

[gerhardl]

As a Scandinavian I might be wrong in my understanding of English, but I would have presumed:

a) Back pressure regulating valve:
A valve to control the back pressure. Normally from a higher upstream pressure to regulate down to a lower downstream pressure, adjusted to maintain the downstream lower pressure within a given limit at varying downstream consumption.

Upstream pressure might be at a higher pressure class or also at the same pressure class as the downstream pressure.

b) back pressure valve:
Have never seen this used, but might be an isolating valve. In this case I presume this to be further qualified with a more detailed description elsewhere in the project (as you have to do with a presure regulating valve). The description could (should?) in this case for instance give full qualities as for instance: qualified as end valve, eg valve 'droptight and secure' at full pressure according to pressure class upstream, and pipeline demounted or emptied (atmospher) downstream, and perhaps the same the other way.

The project must describe detailed verbally, with examples of typical/acceptable valves/brands/constructions, drawings or datasheets the exact meanings, giving full flow details under all conditions.

 

[zdas04]

Terminology in control devices is terribly inconsistent and confusing. I've published a couple of paper on this subject and everyone seems to agree with me and all of the valve manufacturers I've talked to have said "terminology should be consistent and comprehensible, everyone should use ours". Needless to say, this inconsistency and confused language issue is not getting any better.

In my experience both a "back pressure valve" and a "back pressure regulating valve" do the same job--maintain upstream pressure at a set point regardless of downstream pressure. They both do it with a combination of springs, diaphragms, and internal or external pilots. They are the same thing from different manufacturers.

Valves that maintain downstream pressure (nearly) regardless of upstream pressure are called "pressure regulating valves" or "regulators". They often look very similar to a back pressure valve, but the primary sensing point is on the other side of the flow arrow.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[rmw]

David used the term "...at a set point". One other differentiation I have seen is that 'back pressure valve' might be an adjustable valve that added some back pressure, but it wasn't set - rather a function of inlet pressure and flow while a 'back pressure regulating valve' did have and maintain a pre-determined set point.

rmw

PS to David: I would encourage you to bring back one of your former signature tag line and add it to your present one as a fourth line - the one that said "Two anecdotes is not data."

 

[gerhardl]

...bow to you, gentlemen, and withdraw my attempt to give a definition...

 

[zdas04]

rmw,
It does fit doesn't it. Oh well, if you're going to be preachy, might as well do it whole hog.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.
The plural of anecdote is not "data"

 

[rmw]

David,

I love it.

rmw