trusting your training over advice

[soggybadger]

Defo. I like to think that as a novice that I should not be taking unnecessary chances

 

[DA Aquamaster]

Here's what you need to do. First of all buy an intermediate pressure gauge. Mike's in London has them -http://www.mikesdivestore.com/products/beaver-inspector-intermediate-pressure-gauge?variant=606019973

Then find out what the IP is supposed to be on your reg. Somewhere in the range of 125 -140 PSI is typical (9-10 Bar). Attach that to the low pressure inflator and put it on a tank. Turn the air on and watch it while you are breathing it. It should drop a little on the inhale and then come back up and stay there until the next breath. It should not slowly creep up over that 10 BAR number. If it goes over that quickly watch out. Shut the air off and purge the second stage.

If it locks up and doesn't creep your good to go with the 1st stage. next fill your kitchen sink with water and check the cracking pressure. This is where the second starts to deliver air. Holding the second stage upside down slowly place it in the water holding it level. As you do that note how far down you have to push it into the water before it starts to allow gas to flow.

You want it around an inch (25cm) maybe a little more or SLIGHTLY less. If that's ok, dive it! Those are the two things a shop will check with a gauge set up or maybe their own sink and ruler! Along with inspecting the hoses for cracks and water in the spg there's not much more to check. The filter on the 1st stage where it hooks to the tank should be silvery or gold in color. Not black or green.

If it has hose protectors near the first stage, pull them back and look for corrosion. If you see any clean it off with white vinegar and water. Then get rid of the hose protectors. They are not needed and often cause problems.

So now for 16.50 and some of your time you just saved 74.00.

I agree with Jim in general and what he's said is good advice, but a few things should be added.

1. Those small portable IP gauges are available from numerous vendors for not much money. Dive Gear Express sells one for $7.95:

https://www.divegearexpress.com/compact-ip-gauge

I have one but I check it against the spendy IP gauge on my bench before every trip. Why you ask? Because the needle is just press fit on the pin, and if dropped the inertia of the mechanism inside the gauge can twist the stem inside the socket on the needle, while the needed is blocked firmly by the stop pin at "0 psi". I've seen mine read as much as 20 psi low after being dropped. The end result is that the needle looks fine as it is still pointing at "0", when it's actually wanting to point below zero, but it is preventing from pointing below zero by the stop pin. The end result is that if you use that gauge in that condition of reading 20 psi low to set your IP at 140 psi, your first stage will now be operating at 160 psi. Guess how I know this....

It's not hard to fix, you just need to connect it to pop the plastic lens off the gauge, connect it to a first stage with a known IP, pluck the needle off the stem and press it back on pointing at the proper pressure reading. Of course, that requires a second IP gauge to set the IP on the known IP reg in the first place.

Now, my portable IP gauge travels surrounded by soft cell foam in a small box to help prevent it getting de-calibrated if dropped.

2. Vacuum checks are also important. When I re-assemble a second stage after servicing it, before it even gets connected to a low pressure hose, I place the pad of my thumb firmly over the inlet fitting and inhale through the reg. I should hear the lever and poppet moving, I should get no air through the mouth piece, and I should not hear any leakage. That should be the case even when sucking quite hard. It will verify that the second stage doesn't have a leaking exhaust valve or diaphragm, that there are no cracks in the case, and that any O-rings sealing the openings in the case are doing their job.

I do the same thing once the first and second stages are assembled with the SPG, etc in place. I cover the inlet fitting of the first stage (either with my thumb or with an air tight rubber or o-ring sealed dust cover) and perform the same check. You'll get a very small volume of gas as you put the internal spaces of the hoses and first stage under vacuum, but once that's done you should not be able to draw any air or hear any leaks. This check ensures their are no major leaks anywhere upstream from the second stages, and it ensures gas is not leaking past the second stage seats.

3. As a pre dive check I'll connect the regulator to the tank and with the valve still closed, I'll attempt to inhale though the second stage(s). If I get any gas or hear any leaks, I've got an issue I need to address. The most common culprits are an exhaust valve that is folded over or has a piece of grit stuck on one of the spokes supporting it, or a diaphragm that is improperly seated or has a pin hole in it.

4. The next pre-dive check is to then turn the valve on, and test the second stages for normal breathing, but then connect your portable IP gauge to the inflator hose, read the IP and then turn the valve back off without purging the system. The IP should stay steady. If the IP starts to drop, you have a leak somewhere in the system.

It may be in a slight free flow/leak in one of the second stage seats, it may be a leak in one of the o-rings in the LP hose fittings, it may be a leak in the HP hose fittings, or it may be a leak in the tank valve outlet o-ring.

In some cases it's just an adjustable second stage needing to be cranked in a bit, or a non adjustable second stage needing the spring pressure or orifice adjusted slightly to account for a set in the seat.

If the IP drops very slowly over the course of a few minutes, I'll proceed with the dive but I'll be sure to conduct a bubble check, and I'll often find something like a small leak at the tank valve o-ring.

If the IP needle drops smoothly and steadily as soon as the valve is turned off, you've got a large leak you need to fix before the dive.