Pressure Rating versus Reverse Pressure Rating? 1

[rtcsp]

I understand what Pressure Rating is. What is Reverse Pressure Rating or Minimum Pressure Class?

Can a fitting have two different values of Reverse Pressure Rating, as is the case with the Pressure Rating of a relief valve?

 

[mgp]

Where did you find these terms?

Minimum pressure class looks familiar but I don't remember where I've seen it, if I have at all.
Some further info might help.

regards
Mogens

 

[CHD01]

Rupture disk manufacturers use a reversal ratio to let their customers know what the dis k will rupture at if it is installed backwards; could this be what you refer to?



The more you learn, the less you are certain of.

 

[rtcsp]

Thanks to both of you for helping/inquiring. I found the following reference to 'reverse pressure rating' in the description of a valve. Although I couldn't find the original basis of my question in Google, the context involved relief valves.

"However, the pressure rating with the FRP gate is reduced and it is not reverse pressure rated. For full pressure rating and reverse pressure rating use a titanium or other corrosion resistant alloy gate."

 

[timbones]

Never come across the term before but it could refer to a vacuum pressure rating. Not sure how that would apply to relief valves though...

tim

 

[PVRV]

CHD01,

If a differential pressure is anticipated, assuming an operating pressure equivalent to the pressure/temperature rating ornating downstream the valve (assume zero) upstream does that change a gate valve design requirements; specifically material ?

Regards

 

[pennpoint]

rtcsp
Sorry! But why have'nt you contacted the manufactuer and ask them to define this term you've stated?
It's a free trade world out there, and people use terms that support their particular point of view. They then feel they are safe from legal review.
If you do not understand the terms used by the provider of the equipment, then you are putting yourself in jeopardy.

Good Luck
pennpoint

 

[IainM]

One possibility for consideration:
Relief valves are proportional flow devices whereas safety valves are full flow devices. Relief valves are thus intended for liquid service only and are frequently used to relieve from a higher pressure to a lower one (hydraulic systems for example). Such a valve must be capable of providing isolation in a reverse flow direction if the higher pressure part of the system becomes depressured.

Possibly this is what is being referred to.
As has been said in other replies ... nothing beats asking the manufacturer what he means! Saves red faces when the new valve does not perform as intended!