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Yorkie88

Does a vacuum test mean you don't need to test a case empty?

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Hi all,

I recently bought a new seafrogs salted line housing, it has the double main o-ring so seems a step up in design from the old version and I've also put the VPS-100 vacuum system on it.

It held the vacuum for over an hour when testing, so would this suggest I'm good to go or should I still take it out empty to test?

 

I think I'm meant to take the vacuum off before diving.....but I remember someone saying they'd asked seafrogs and they suggested it would be ok to use in the water. What's the recommendation on that?

Cheers!

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I have used the vacuum system on all my housings without an empty housing test. The vacuum proves the same - properly sealed, no leaks. I've known NO company that recommends releasing the vacuum before the dive. Proof? Try to open or remove the port while under vacuum. Unless you are King Kong, I doubt you will be successful.

Have fun with your new gear!!

Edited by bill1946

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Don't release the vacuum, one thing it does is pre load the O-rings.  Housings are more likely to leak the surface when the O-rings are not loaded.  O-rings seal by the water pressure pressing them against the sealing surface without that pressure they are more prone to leakage.

Taking it in empty means you need to open it again which means you have to test it again, you may get some hair or something on the o-ring if you open the housing.  The whole idea of the vacuum test is to prove it won't leak, testing for an extended period is good to prove there is no slow leak.

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Thanks for the replies, I'll be trying it out this weekend!

By removing the vacuum, I mean removing the actual systems attachment as it suggests here (precautions number 2):

57_VPS-100_User_Manual_3_600x.jpg?v=1561

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I've exchanged messages with SeaFrogs support about this, and their rationale for not diving with housing under vacuum is that the increased pressure gradient reduces the housing's maximum operating depth. Since I don't dive past 30 meters, this is irrelevant for my use case, and I always dive with the vacuum valve attached and active.

One thing that should be noted is that if you pump it just to the point where it starts flashing green, you will likely have it start flashing red at depth - my best guess is that the main o-ring compresses under pressure, the front and back halves of the housing get squeezed closer together, the internal volume shrinks and the air pressure inside rises correspondingly. Having the indicator suddenly start flashing red mid-dive is quite disconcerting, so I make sure to give it a dozen extra pumps after it turns green to avoid that.

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1 hour ago, Barmaglot said:

I've exchanged messages with SeaFrogs support about this, and their rationale for not diving with housing under vacuum is that the increased pressure gradient reduces the housing's maximum operating depth. Since I don't dive past 30 meters, this is irrelevant for my use case, and I always dive with the vacuum valve attached and active.

One thing that should be noted is that if you pump it just to the point where it starts flashing green, you will likely have it start flashing red at depth - my best guess is that the main o-ring compresses under pressure, the front and back halves of the housing get squeezed closer together, the internal volume shrinks and the air pressure inside rises correspondingly. Having the indicator suddenly start flashing red mid-dive is quite disconcerting, so I make sure to give it a dozen extra pumps after it turns green to avoid that.

Good to hear it's been fine for you in the water, most of my dives are pier dives under 10m so it should be fine aswell. I noticed the lid has an o-ring so thought it must seal - I'd prefer to keep it on during the dive aswell.

 

I first tested it by stopping as soon as it went green, then it went red but I assume it was a temperature drop in the room as it was at night, pumped a few more times and it held for over an hour.

 

I wish you could switch it off without releasing the pressure but you can't have everything at that price!

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