To purge or not.

[Linedog]

Sorry if this has been asked before, I have an Atomic B2 reg set. I have been told to slightly hold the purge button open when
opening my tank valve. I have also been told it makes no difference,well purge or not?

 

[Hank49]

On a piston reg, pressing the purge on the second stage and slowly releasing it after opening the tank valve theoretically lets the piston stem gently set onto the high pressure seat.
I practice it. But I haven't, nor do I know of anyone who has done real research to see if the procedure actually lengthens the life of your hp seat.

 

[FireInMyBones]

Never heard of that one. Interesting. Maybe I will give it a try.

 

[Crush]

My cavern instructor suggested that we do precisely what you describe. Being familiar with two-stage regs used on industrial compressed gas cylinders, this would be contraindicated. I don't know what the correct answer is, but I would tend to side with the cavern instructor.

 

[scubafanatic]

..an Atomic "B3" ???

 

[Couv]

If the reason behind that procedure is to prevent the first stage piston from slamming into the hp seat, then it probably makes no difference provided you open the tank valve slowly (as you should.) Why does it not make a difference? Because when you first open up the tank valve the air is slowly pressurizing an "empty" regulator and set of hoses that act to dampen pneumatic pressure.

Of course the reason could be for something totally different; I would be interested to hear it.

Cheers,

c

Edit after reading the following post #7: I agree it will not harm anything; however, I feel it isn't necessary.

 

[tech3324]

Scuba Equipment Care and Maintenance by Farley/Royer ©1988 page 64 "Mounting a Regulator to a Tank"

4) With the second(sic) stage mounted to the tank valve securely, depress the purge button, then turn the air on slightly and listen for any escaping air to build, then release the purge button and open the valve slowly.


There's no explanation for why this is recommended. I've gotten into the habit of doing it, maybe because Charlie Royer was a friend, and I don't see how it could hurt anything.

 

[herman]

I come down in the middle of this. IF and it's a big if, you SLOWLY open the tank valve and gently pressurize the reg, then I don't see it's of much benefit. On the other hand, if you open the tank valve like many do, just spin it open then it's likely a good idea. It's never a good idea to slam the internals of a regulator shut. So, while I don't personally do it ( I SLOWLY charge my regulators) it's most likely a good idea for the average diver to do so, it might not help much but it certainly will not do any harm.

 

[LeadTurn_SD]

I'm also a "slow valve opener".

In one of my owners manuals (or maybe a service manual) it was recommended to open slowly with the purge depressed slightly (no explanation given for exactly why). And this was with a diaphragm reg; but I guess the reasoning is the same: to prevent the HP seat from being damaged or prematurely worn?

Anyway, back in the 70's when I started diving I was taught to open the valve very slowly (until 2nd stage and SPG are pressurized), and the habit stuck.

Best wishes.

 

[FireInMyBones]

I'm also a "slow valve opener".

In one of my owners manuals (or maybe a service manual) it was recommended to open slowly with the purge depressed slightly (no explanation given for exactly why). And this was with a diaphragm reg; but I guess the reasoning is the same: to prevent the HP seat from being damaged or prematurely worn?

Anyway, back in the 70's when I started diving I was taught to open the valve very slowly (until 2nd stage and SPG are pressurized), and the habit stuck.

Best wishes.

I have started to open my valves slowly ever since my Advanced Nitrox class and learned about how dangerous quick flowing gas can be.