Bulging environmental seals

[Fishpie]

I made a comment in the pet peeves thread and thought that maybe it deserved its own thread.

Whenever I am on a dive boat I can't help myself from noticing the number of regulators that have enviro seals fitted also have them fitted incorrectly.

They should not bulge out, if anything they should be concave with the reg not under pressure, and flat under pressure.
The diaphragm should be in contact with the pressure transfer piston.

If you have a bulging seal it means your service tech doesn't know what they are doing.
It's very easy......the reg has to be pressurized and a thumb used to flatten the seal as the cap is tightened......simple as that.

Is it dangerous?
No.
.....but I expect there will be a small drop in IP as the reg submerges and the trapped air has to compress before the seal contacts the transfer piston.

 

[Shcubasteve]

...regulators that have enviro seals fitted also have them fitted incorrectly.

If you have a bulging seal it means your service tech doesn't know what they are doing.
It's very easy......the reg has to be pressurized and a thumb used to flatten the seal as the cap is tightened......simple as that.

I generally agree with the bold line, but your assertion is not entirely true, depends who you talk to: I have attached screen shots from the final assembly section of service manuals for an Oceanic FDX10, CDX5, Aqualung Legend, and Apeks Tec 3- Aqualung and apeks say reassemble the environmental seal with the 1st stage under pressure but oceanic no pressure.

Also not listed in the service procedures is the technique you describe with your finger.

 

[lindenbruce]

Interesting. I just had my Apek's serviced and when I picked it up today, the environmental seal was concave. Bruce

 

[Scared Silly]

Mine bulged and then white goo oozed out. The tech said the white goo was good for yer skin. Made it nice and soft.

 

[turnerjd]

Bruce, Concave is perfect. It means that the environmental seal was put on with the reg under pressure.When it is pressurised it will become flat.Jon

 

[elan]

IMHO There should be no ip drop as the outside pressure is transferred through compressing gas.

 

[Shcubasteve]

IMHO There should be no ip drop as the outside pressure is transferred through compressing gas.

+1. I agree. In fact the opposite will happen: as water pressure compresses the air in the spring chamber, the hydrostatic transfer piston will be drawn down, exerting presssure on the spring plate/diaphragm. This will result in an INCREASED IP at depth- I think its called overballancing.

 

[DA Aquamaster]

As noted above, most companies specify that the cap and external ambient chamber seal be installed with the regulator pressurized, which will result in a slightly concave appearance when it is depressurized.

You can add Scubapro to that list as well as the Mk 17 should have the external diaphragm/outer seal installed with the reg pressurized.

The important thing here is for the tech to follow the manufacturer's recommendation as it will affect the IP at depth. The effect won't be major, but doing it incorrectly will leave the reg slightly out of tune in terms of IP and peak performance.

It is however also possible that the concave appearance may disappear on a dive boat with a reg in the hot sun as the air in a sealed ambient pressure chamber will heat and expand slightly.

On the other hand, an ambient chamber that floods slightly during the dive with some remaining air in it may also bulge outward as the air in it expands with the added volume of the water. I've seen my share of customer regs with flooded ambient chambers and with salt water more or less sealed in it, it can get ugly looking after a few weeks/months. So note how yours looks when you get it back from service (most should be concave) and more importantly, if it changes and becomes bulged, check out why that may be happening and if flooded, have it looked at.

Some of the caps that retain the outer seal require special spanners to remove, but many are hand tightened (mostly those with plastic retaining caps). With those regs, you could remove the cap and diaphragm yourself to inspect it - just be sure to re-install it with the reg properly pressurized, if that is what's required, and be sure the outer seal is properly seated.