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cneal

Went with Backscatter's Airlock

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Backscatter's Airlock was my decision for a pressure test device for my housing. It came this week and I've installed it.

 

Pro's

 

1. Completely mechanical. No batteries to go dead or electronics to fail.

2. Footprint is small and adjustable (direction). Clearly would fit in the available real estate.

 

Con's

 

1. More expensive than the Vivid, which was the primary competitor in my decision.

2. Competely mechanical, no ability to check pressure at any time.

 

Installation:

 

It was easy on the Aquatica housing. Remove a nut on a blank bulkhead. Insert the furnished fitting and tighten a nut. I don't know why it bothered me to open a hole in the housing, I open a bigger one everytime I install the Aquaview viewfinder before diving. And now and can test my work for both.

 

Use:

 

The manual pump easily reached the recommended -5 inches of mercury for a pressure test and the -10 inches for locking all ports in place. The pressure did hold overnight. And since there are no electronics or other items to evaluate it's done.

 

Note:

 

I am removing the valve for packing the housing, closing the bulkhead fitting with the included cap. Packing pressure on the valve could possibly leverage into breaking the plastic bulkhead fitting. Reintalling the valve will just take a few seconds.

 

 

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Let us know how it goes when diving -- I'm looking at that same one. I don't mind it being mechanical. I would say if you pressurize it and then check 10 minutes later then it will be good for the dive; no real reason to have a real time LED. With the flood sensor LEDs, I've noticed they usually come on just about the same time your entire rig has filled up with water, kind of like engine lights that come on right before the cylinders seize :D

Edited by johnspierce

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You could buy just the Vivid circuit board and put it inside the housing, which would give you continuous confirmation of the vacuum.

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Keep us posted on how you go using it a few times please.

I am interested in getting one of these.

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I received my Airlock last night and installed it on my Subal ND3.

 

I sent the following feedback email to Sean at backscatter this morning:

 

 

 

Sean
Some feedback on myAir Lock install last night.
Housing is a Subal ND3.
Installed the bulkhead fitting with a bit of lube on the o ring. I did not use threadlock. Originally used a crescent wrench. Is the bulkhead fitting made of metal or plastic?
The outer threaded part of the fitting was a fraction too wide for the surrounding lip of the housing casting. There was some interference once the fitting threaded in far enough and would not seat the o ring on the mating surface of the housing. My first try yielded a slow leak that would go from -10 to zero in about ten minutes. I disassembled everything, cleaned and regreased and on the second try used an 11/16 socket. The fitting actually cut some threads into the paint of the housing. I got to the original install depth and then gave an extra 1/4 turn until it completely stopped. I reassembled and pulled -10 which held perfectly overnight.
This interference may be a one off due to the position of the bulkhead hole relative to the surrounding casting, but knowing Subal, I doubt it. Had I dived the housing it would have leaked. It is important to stress that ANY loss of vacuum indicates a leak.
At -10 in/Hg my ports would still rotate but could not be removed.
The other point I would make is that when testing the stability of the vacuum, I used a synthetic cork from a wine bottle to plug the hole in the gauge where the pump handle would go, rather than the pump. It is easier to handle and eliminates the possiblity of air leaking from the pump side. You could even throw a cork in with the packaging.
FYI my math indicates that -10 in/Hg is equal to 11 FSW or 10 feet of fresh water.
The other use of this product is to tell you when your housing needs a rebuild.
Apart from the interference problem, everything is perfect. You just need to know it is a potential glitch, and hopefully the paint won't chip off.
Great product, no doubt!
ian

 

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I received my Airlock last night and installed it on my Subal ND3.

 

I sent the following feedback email to Sean at backscatter this morning:

 

 

 

Sean
Some feedback on myAir Lock install last night.
Housing is a Subal ND3.
Installed the bulkhead fitting with a bit of lube on the o ring. I did not use threadlock. Originally used a crescent wrench. Is the bulkhead fitting made of metal or plastic?
The outer threaded part of the fitting was a fraction too wide for the surrounding lip of the housing casting. There was some interference once the fitting threaded in far enough and would not seat the o ring on the mating surface of the housing. My first try yielded a slow leak that would go from -10 to zero in about ten minutes. I disassembled everything, cleaned and regreased and on the second try used an 11/16 socket. The fitting actually cut some threads into the paint of the housing. I got to the original install depth and then gave an extra 1/4 turn until it completely stopped. I reassembled and pulled -10 which held perfectly overnight.
This interference may be a one off due to the position of the bulkhead hole relative to the surrounding casting, but knowing Subal, I doubt it. Had I dived the housing it would have leaked. It is important to stress that ANY loss of vacuum indicates a leak.
At -10 in/Hg my ports would still rotate but could not be removed.
The other point I would make is that when testing the stability of the vacuum, I used a synthetic cork from a wine bottle to plug the hole in the gauge where the pump handle would go, rather than the pump. It is easier to handle and eliminates the possiblity of air leaking from the pump side. You could even throw a cork in with the packaging.
FYI my math indicates that -10 in/Hg is equal to 11 FSW or 10 feet of fresh water.
The other use of this product is to tell you when your housing needs a rebuild.
Apart from the interference problem, everything is perfect. You just need to know it is a potential glitch, and hopefully the paint won't chip off.
Great product, no doubt!
ian

 

 

C'mon Poolboy - get that housing in the ocean!

:crazy::crazy::crazy::crazy::crazy:

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Some day, all housings will come with this feature as a standard fitting!

Edited by John Bantin

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some come already and this from a long time ago ....

  • Like 1

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Backscatter's Airlock was my decision for a pressure test device for my housing. It came this week and I've installed it.

 

Pro's

 

1. Completely mechanical. No batteries to go dead or electronics to fail.

2. Footprint is small and adjustable (direction). Clearly would fit in the available real estate.

 

Con's

 

1. More expensive than the Vivid, which was the primary competitor in my decision.

2. Competely mechanical, no ability to check pressure at any time.

 

Installation:

 

It was easy on the Aquatica housing. Remove a nut on a blank bulkhead. Insert the furnished fitting and tighten a nut. I don't know why it bothered me to open a hole in the housing, I open a bigger one everytime I install the Aquaview viewfinder before diving. And now and can test my work for both.

 

Use:

 

The manual pump easily reached the recommended -5 inches of mercury for a pressure test and the -10 inches for locking all ports in place. The pressure did hold overnight. And since there are no electronics or other items to evaluate it's done.

 

Note:

 

I am removing the valve for packing the housing, closing the bulkhead fitting with the included cap. Packing pressure on the valve could possibly leverage into breaking the plastic bulkhead fitting. Reintalling the valve will just take a few seconds.

 

 

 

Hi,

 

Did you put the valve in one of your spare bulkheads for the strobe or did you put it where the Hydrophone hole is?

 

thanks,

John

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Just got back fron my first trip with the Air Lock installed. A week on Little Cayman.

 

It worked as advertised. If there is a reason to make a big deal about it, you were either caught being sloppy or failed during the dive. I don't see the latter happening.

 

John, I installed the valve on the spare strobe bulkhead. (Ikelight fitting on the primary.) It looked as if installing on the side of the housing would interfere with the zoom/focus knob.

 

Roger, the bulkhead fitting is plastic. To remove the metal one way valve you simply unscrew it from the buldhead (plastic fitting) and replace it with the supplied cap. I would suggest watching the video on the Backscatter web site. Between that and the photos on the web site all of your questions should be answered in detail. All the black bits are plastic.

 

Carl

Edited by cneal

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I spoke with Scott at Backscatter. He assured me that all the black fittings are anodized aluminum :)

 

I have confirmed this by removing my bulkhead and found that where the threads interfere with the casting on my Subal ND3, the threads are now silver.

 

Backscatter has a solution to this interference problem on my housing and will be producing bulkhead fittings that are slightly taller before the threaded portion begins.

That will clear the lip on the casting that binds the thread as the bulkhead seats. It will also allow the threaded cap or Airlock fitting to seat completely in the bulkhead which it doesn't currently do on my housing.

 

That should definitively solve this issue on my housing.

 

Ian

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got the Aquatica 5D III, installed that Airlock and well it's leaking after pumping it to -5 after 5min I have -3 then 15min later nothing. I tried listening where the pressure leakes but nothing.

Strange, I can't keep it to hold the -5 for more than 2min.

Edited by Scubanomad

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got the Aquatica 5D III, installed that Airlock and well it's leaking after pumping it to -5 after 5min I have -3 then 15min later nothing. I tried listening where the pressure leakes but nothing.

Strange, I can't keep it to hold the -5 for more than 2min.

I had the same problem...mine was getting the bulkhead O ring to seat properly due to interference with the housing casting. Is there any interference on your housing?.

 

I used a bicycle torque wrench and snugged mine down to 5 Nm, if that helps. It did cut the threads into the paint on the side of the casting.

Of course, it may be that you have another leak elsewhere, but the most likely explanation is the new fitting.

 

Also make sure there is no air leaking around the pump to gauge interface. I used a cork to replace the pump handle while assessing stability of the vacuum.

 

ian

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I would suggest spraying a soap / water mixture on the housing and watch for a bubble.

 

When I installed on my Aquatica the washer went on the inside and I used a wrench to tighten slightly. less than 1/8 turn.

 

got the Aquatica 5D III, installed that Airlock and well it's leaking after pumping it to -5 after 5min I have -3 then 15min later nothing. I tried listening where the pressure leakes but nothing.

Strange, I can't keep it to hold the -5 for more than 2min.

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some come already and this from a long time ago ....

:)

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I would suggest spraying a soap / water mixture on the housing and watch for a bubble.

 

When I installed on my Aquatica the washer went on the inside and I used a wrench to tighten slightly. less than 1/8 turn.

 

Problem is, you need to spray the solution INSIDE the housing!! :)

 

I suppose you could put a small positive pressure in with a bike pump and check for bubbles, but that does not mimic how the "o"rings are designed to work.

 

Not sure if this would produce "false positive" results:(

Edited by ianmarsh

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You got me. :aggressive:

 

Don't know how to go about finding the culprit. At least your not finding the problem using your camaera as the leak detector.

 

Problem is, you need to spray the solution INSIDE the housing!! :)

 

I suppose you could put a small positive pressure in with a bike pump and check for bubbles, but that does not mimic how the "o"rings are designed to work.

 

Not sure if this would produce "false positive" results:(

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Here is an idea.

Line the housing inside with paper towels, using some tape to hold in place.

Pump the housing down (with out camera).

Immerse briefly in fresh water.

Open and look for the wet spot!

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got the Aquatica 5D III, installed that Airlock and well it's leaking after pumping it to -5 after 5min I have -3 then 15min later nothing. I tried listening where the pressure leakes but nothing.

Strange, I can't keep it to hold the -5 for more than 2min.

The soapy water idea will not yield good results. Fill the housing with weights and paper towels. Submerge it in water for a while and open it and look for dampness. If none found reassemble it, connect up the vacuum pump, submerge the housing in water and draw a vacuum on it. If it doesn't hold vacuum it will be sucking in water where the leak is unless you have a leaky input valve.

 

I hope that helps.

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***WARNING*** I am not certain of the effects of acetone on housing materials.

 

The way to find a vacuum leak is to draw a vacuum on the vessel, then while monitoring the vacuum level spritz acetone around the seals and fittings. The acetone will work like the soapy water mixture does on pressure vessels as a leak spotter. It will get drawn in through any leak and rapidly evaporate under the vacuum, thus causing a quick jump up on the vacuum gauge. Alcohol may be able to be used in place of acetone, but I am not sure if it would evaporate fast enough to make a noticable movement in the vacuum gauge.

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