Regulator checklist and inspection

[rsingler]

Good eye, Herman. Like Luis, I was under the impression that 200-400 psi drop over 10 minutes (after closing the tank valve) would still be satisfied even for Sherwoods. However, as both of you have pointed out, a note mentioning Sherwoods is probably in order. It's been a while since I last read over the checklist, perhaps it's time for a REV 8....keep the ideas coming.

BTW, I don't have a Sherwood so if you're in an experimenting mood and want to give me a ball park figure, that would be appreciated.

Hey, couv! Sherwood's bleed rate is 13-25 cc/min for the 1sts with a bleed air valve. In that case, you'll drop more than 400 psi in a lot less than 10 min with the tank shut off. So that step doesn't count for Sherwood as others have pointed out, but you could substitute something like:
"For Sherwood 1st stages with a bleed air valve, omit Step 6. In Step 7, immerse the pressurized first stage in the bathtub and place a shot glass upside down over the bleed air valve. The shot glass should fill between 1/3 and 3/4 full of escaping air in 60 seconds, as bubbles escape from the bleed air valve."

As a separate comment, I think it would be worth leaving the whole rig pressurized on the IP gauge overnight once a year. A stable IP (creep less than 5psi over 12 hours) tells me I don't need to even bother servicing my 1st stage yet, as long as the rest of the checklist is okay, and IP recovery is brisk after I inhale from the 2nd.

Just some thoughts.

Rob

 

[halocline]

So my 2nd stage is failing the vacuum test. When I inhale, I can hear airflow.

Any suggestions on how to find the cause?

It's an Atomic ST1.

It's probably because your 2nd stages have a seat saver that separates the seat from the orifice when the reg is not pressurized. You're probably testing it with two 2nd stages attached to the first stage? Unfortunately the only way you can vacuum test this second stage is to isolate it; remove it from the 1st stage and cover up the hose outlet with your thumb.

 

[guruboy]

It's probably because your 2nd stages have a seat saver that separates the seat from the orifice when the reg is not pressurized. You're probably testing it with two 2nd stages attached to the first stage? Unfortunately the only way you can vacuum test this second stage is to isolate it; remove it from the 1st stage and cover up the hose outlet with your thumb.

Yes, two 2nds on the 1st.

Good to know! Thanks.

 

[ScubaTexas]

As a separate comment, I think it would be worth leaving the whole rig pressurized on the IP gauge overnight once a year. A stable IP (creep less than 5psi over 12 hours) tells me I don't need to even bother servicing my 1st stage yet, as long as the rest of the checklist is okay, and IP recovery is brisk after I inhale from the 2nd.

Just some thoughts.

Rob

That has been generally my approach and found it to work well. In addition, the precision of an AI transmitter with computer helps to see if there are any slow leaks (short of a water dunking) on the rest of the rig. But, leads me to wonder about the following check (#6 in the list):

6. Check for air leaks by putting regulator on a tank and with the pressure on, first listen to any leaks, then turn the tank valve off but do not purge the reg. Note the SPG pressure and leaving it undisturbed come back in 5 or 10 minutes. The SPG pressure should be close to the original value. A drop of 200-400 psi is no big deal, but a large drop in pressure indicates something is leaking beyond the normal limits. If the leak is so fast you can see the needle drop just looking at it, the leak is probably large enough to warrant fixing before you dive.

If, when the tank valve is open and left completely pressurized, you have zero pressure drop over a long period of time (8-12 hours), why is #6 necessary where you pressurize your rig and leave it with the tank valve off. Why would you have a slow leak (PSI drop) with the rig pressurized with tank valve off, but have zero leak with rig pressurized and tank valve left on? For example, with my Atomic B2 setups I have zero PSI loss when pressurized and tank valve left open for a 8 to 12 hour period, but when doing check #6 with it pressurized and valve closed, I can have about a 10 to 15 PSI loss over about 10 minutes. In any event, wanted to get a better understanding of this aspect.

 

[Luis H]

If, when the tank valve is open and left completely pressurized, you have zero pressure drop over a long period of time (8-12 hours), why is #6 necessary where you pressurize your rig and leave it with the tank valve off. Why would you have a slow leak (PSI drop) with the rig pressurized with tank valve off, but have zero leak with rig pressurized and tank valve left on? For example, with my Atomic B2 setups I have zero PSI loss when pressurized and tank valve left open for a 8 to 12 hour period, but when doing check #6 with it pressurized and valve closed, I can have about a 10 to 15 PSI loss over about 10 minutes. In any event, wanted to get a better understanding of this aspect.

The leak doesn't change just by closing or opening the tank valve. The leak would stay the same. What changes is the ability to measure or detect the leak.

When the tank valve is closed you have a very small volumes of compressed high pressure air in front of the regulator first stage. Therefore, even a small leak can be easily detected.

If the tank valve is open then you have a very large volume of compressed high pressure air in front of the regulator and even if you have a very accurate digital gauge, you may not detect a leak. A small pressure change over time could be a leak or it could be a pressure change caused by temperature change. Your gauge may be very precise, but if the change is small you may have a false reading.

Closing the valve (after pressurizing the regulator) isolates a that small volume, which will make the detection of a leak much easier to measure.


There is another very important reason to close the valve on the tank when leaving a regulator pressurized over night. If an O-ring or a hose in the regulator lets go and a major leak develops in the middle of the night, you want just the small volume of air to let go. You do not want a full tank of air let go in the middle of the night if something fails in the regulator... It can happen, it has happened, and it will happen again if it is allowed to happen... It causes a very rude awakening when a full tank of air lets go in the middle of the night. My personal experience was not related to a pressurized regulator, but the effect is similar.



BTW, I also perform the same test (as item 6) by pressurizing a regulator, then closing the tank valve and checking if there is any pressure drop (in that small volume) during a 24 hour period or much longer. That is one of the checks I do after servicing a regulator.

When I perform this overnight test, it is very hard to remember the exact pressure reading from the day before. Therefore, the easiest thing to do is to watch the pressure gauge needle to see if it moves when opening the tank valve the next day. I ignore any very small gauge movement, because that could just be a temperature change or such a small leak that I am not going to care.

I have precision digital gauges (both high pressure tank gauges and IP gauges), but I don't use them for a simple leak check.

 

[bethunec]

http://www.airspeedpress.com/newregbook.html the link does not work anymore.. so where should I go to get the resources?

 

[Couv]

http://www.airspeedpress.com/newregbook.html the link does not work anymore.. so where should I go to get the resources?

You might find something useful in this thread:

Seems that Airspeed Press has gone out of business?

Seems that Airspeed Press has gone out of business? Does anyone know any specifics? Would they sell the business and/or rights to the books? Would they sell the business and/or rights to the books? As many have experienced, their website is still up but with limited functionality. No online...

scubaboard.com

 

[buddhasummer]

http://www.airspeedpress.com/newregbook.html the link does not work anymore.. so where should I go to get the resources?

DM sent.