I have a question: In deep-sea situations, if the internal pressure is very high, can the pressure release valve be opened? If so, will water leak in when the pressure release valve is opened?
Hi @Joe22 -
The internal pressure would have to be higher than the external pressure in order for the PRV to open, by just under one atmosphere (12 psi). At depth, because the external pressure is higher and the internal pressure is still approximately atmospheric air pressure (thank goodness for o-rings) the internal pressure would need to build to 122 psi higher than external in order for venting to occur. Once venting has started, the internal pressure drops, and so the venting may also stop having equalized with the external pressure.
What typically happens in scenarios where the internal pressuure is higher than external, and the enclosure is underwater, is that a leak has already occured. Some amount of water entered the enclosure, until the internal air was compressed enough to equal the external water pressure. If the enclosure is rapidly brought to the surface from there, as the external pressure decreases, the internal pressure will try to as well, venting through the leak, and if that isn’t sufficient for the rate of change, the PRV as well.
In the same way, if a battery vented gas in an enclosure at depth, gas would only emerge when the internal pressure was higher than external, and as the enclosure was raised to the surface it would continue to vent.
Whether water can leak in a PRV that is venting is a tricky question - it shouldn’t, but it certainly could in some edge-cases? Moisture / humidity is certain to enter - and generally if you’re venting things are not going well?
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