Pressure relief valves for freezers

[CRH]

Hi, can some learned person tell me if there is an internationally accepted formula to determine the number of valves required for a particular sized room.
Different valve manufacturers seem to use different formula with various constants.
Thank's.

[Magoo]

Are you asking about pressure releif ports for enclosure, or refrig., system safety releif devices.

[CRH]

Sorry, for enclosures

[indian]

I dont actually know the answer but suspect there are many different answers due to the variables involved. By that I suppose I mean assumptions. As you know the pressure relief valve is designed to equalize the internal pressure of the room to atmospheric pressure outside the room. Therefore it will depend upon the temperature differential ie room temp to ambient the more you cool the air the greater the pressure drop. It will probably also depend upon how much air is circulated, volume of air ingress into the room in proportion to the volume of the actual room. So there may be variations on room volume, room temperature, ambient temperature, door size, amount of traffic(air) in out of room. There is also the matter of defrosting how much heat is input into the room by the defrost heaters and what effect does that have on the internal pressure .
I would have thought the only constant would have been the allowable pressure differential between the air in the room and the air on the outside before the room buckles or door blows open - but even here different panels, doors and latches may all have different ratings.
And after all of that thinking my answer to your question is I am thankful that someone else has the ability to work it out because I wouldnt know where to start.