New Housing "Airlock" Vacuum from Backscatter

How do you release the Vacuum? Sliding down the Outer part ( the one that looks moveable).

Then my assumption is that the Block-off plug is there to prevent it from sliding down.

Then I would understand the naming One-way valve!

Have I guessed it correctly???

/Erik

Erik

You must connect the vacuum pump to release the vacuum in the housing. The block off plug is used to prevent water from getting inside the valve. It is not really a one way valve as air can flow in both directions with the input fitting installed. It is a self sealing valve that seals when you remove the input fitting. The movalable part allows the input fitting to be installed and removed. You might check out our FAQ page for more details.

Bill,

Thanks for the info.

Until how deep does it go?

/Erik

i don't understand the question

Sorry.

My question is which depth rating the Valve has?

I assume that it is 60m or more.

If you dive without the plug / cap in place the spring inside the valve will protect you to a depth of about 150 feet or 80 PSI.

If you have the cap in place The seal of each fitting is rated at 4000 PSIG @ 70 °F / 275 BAR @ 21 °C which is equivalent to being at a depth of 9000 feet.

I will update our F.A.Q. page http://www.uwcamerastuff.com/housing_sentry_faq.htm to show this information.

Thanks for the info!

Ok, that is much better than I thought!

KIrk,

Did backscatter give an indication of price on electronic version?

 

 

Erol

I called backscatter and spoke with someone who said it would probably $100 over the manual version. Which does seem to be a bad price. Hopefully that is correct.

All newer Hugyfot housings come with their electronic Hugycheck vacum leak tester,

made of a red and green LED blinking green if the vacuum inside is good and a additional electronic leak detector

beeping if water is inside the housing.

I really love this additional safety margin to avoid a disaster flooding my camera and i am aware that it would be

mostly my fault if there would be a leak but i like it if the housing is adverting me - and did several times - if there is a leak.

This new system looks nice and would be a great thing to add on a housing not equpped with a vacuum leak tester.

I strongly recommend to get the electronic version as the blinking LED's will advert you if there should be a leak,
even/especially under water.
I usually load my camera/housing in the evening before and control the blinking LED's in the morning and again before i start the dive.

Chris

... snip ...

 

 

There are two other advantages of using a vacuum on a housing, which are worth mentioning. First, the slight negative pressure acts a port lock. Second, if you have a problem with a button not working at depth - you can pump out the housing and reproduce the fault on the surface where it is much easier to fix.

 

Alex

I was wondering if there would also be the additional advantage of less condensation risk. Lower pressure means lower partial pressure of water vapour, unless the pressure drop is too small to be significant.

Bart

I was wondering if there would also be the additional advantage of less condensation risk. Lower pressure means lower partial pressure of water vapour, unless the pressure drop is too small to be significant.

 

Bart

Hi Bart,

There should be less condensation risk while diving, since more humid air is sucked out, causiing less overall humidity in the Housing.

This is however only an issue for plastic Housings.

The 2nd part of condensation is when opening the Housing at the surface. The Air is generally warmer at the surface compared to the water..

With a vacuum system, more air will rush in when opening the Housing after a dive. That gives us a faster temp change, this causes a condensation as well.

If it is only a theoretical problem or a a "real" issue???

An easy way to get around this should be to leave the Camera in the Housing a bit longer than normal.

Erik

I believe a vaccum system should be standard on all housings.

Regards Mark

Yes, i believe also that it should be standard on all housings and this is

one of the main reasons that i will stick with Hugyfot.

There is one more important advantage of this system:
creating a vacuum inside the housing will suck the o-rings in their position and shape.

I believe that slightly out of shape or position o-rings are the main reason for unexplainable flooding on surface

or low depth as the external pressure don't press them on their seat/shape.

Chris

To current users of these systems; how do you prevent aspirating a few drops of water when you bleed off the vacuum to open the housing?

I guess the quick connector everyone uses is from swagelok (QM2) :

http://www.swagelok.com/downloads/WebCatalogs/EN/MS-01-138.pdf (page 12)

(without the nuts)

My mission here is done, I shall now fly away.

DIY anyone?

To current users of these systems; how do you prevent aspirating a few drops of water when you bleed off the vacuum to open the housing?

The Hugyfot housing has a screw on cap on the top and to release the vacuum you have dry the external valve assembly unscrew slowly the lower part of the valve assembly to release the vacuum. I never had issues with water get sucked inside the housing releasing the vacuum this way.

I guess the quick connector everyone uses is from swagelok (QM2) :

http://www.swagelok.com/downloads/WebCatalogs/EN/MS-01-138.pdf (page 12)

No, not everyone; Hugyfot is using their own valve assembly who got screwed inside one of the bulkheads.

There is a animation on the Hugyfot webpage demonstrating how a/their vacuum system work.

Chris

Chris, you are right. So I should say most systems showed in this topic use

the swagelok quick connector.

Here is the Hugyfot valve :

I wonder about how accurate these systems are - I certainly see the intuitive connection between confirming that the pressure inside your housing using one of these systems not changing confirms that your housing will not flood. But have there been extensive tests confirming the link between these two?

Changing the pressure inside of your housing at sea level using a pump is different than changing the pressure outside of your housing at depth using seawater.

Whats the differance?