Suggest you contact a firm like Portsmouth Aviation that deals with this kind of stuff. Of course depending on the exact nature of your question it may be sensitive information.
Wellman might be able to help in UK too. If it's military then the relevant department/section of the appropriate Navy should be able to help.
If nothing else you'd need to state the size of ship. If I recall there are figures on what % volume of the air needs to be replaced per unit time. Can't recall what they are though. May be in a Stanag but I'm not sure.