Regulator – Pre Dive Checks

I wanted to share some things I do to try to be a safer diver. So in this post I wanted to share some additional Regulator checks I carry out before diving and what I teach to students. Please feel free to copy these checks or if you do anything else, I would love to know. So these checks are done while kitting up/packing kit the night before. (Will cover the 5m Safety Drill/Bubble check in another post).

1) Zero Pressure Check: Remove dust cap, and before connecting to tank. Use thumb or fingers to cover/block inflator hoses. Then try breathing through each regulator, it will be hard but not impossible. By blocking the hoses you are ensuring you sucking air all the way through the 1st Stage to 2nd Stage.
Reason: To ensure you can get that last 20-30 bar out of your tank in an emergency. If you cant breath through the Reg this means your Regs have problems and need servicing ie stuck or sticky valves/seats. This might not be apparent during a normal test as there will be 200+ Bar of pressure pushing its way through the system.
Example: Suddenly it all goes wrong underwater, you are buddy breathing and making an ascent to the surface you are at 50 bar and you think that’s enough we will make it. Half way the pressure has dropped to 30 and that 30 bar is not enough to push through the system, so now you are technically out of air.

2) Normal Pressure Check: As you turn on your air slowly, keep your Reg purge button depressed, and slowly release stopping the air. Once the Tank is fully open test your regulators as you would do normally (remember to get a buddy to breath of your alternative air source at the same time).
Reason: . Idea is to lengthen the life or your HP seat/valve in your first stage, therefore reducing the possible damage before a dive – many Regulators advise this in their manuals. By both divers breathing at the same time you can ensure the Regulators are in a well maintain state to support 2 divers.

2a IP Check (Intermediate Pressure): I only do this every 3 months or so or before a long weekend of diving. You can pick up an IP gauge that plugs into your inflation hose for about £15 to £20. Most IP pressures are set between 9-10 bar (please see your Reg manual). Similar to the normal pressure test you breath from your reg watching the IP gauge. The pressure should drop then once your breath has stop it should within a couple of seconds return and stop at the IP pressure. You are looking for IP creep, this is where when you stop breathing the pressure will return to the IP pressure but then continue to slowly creep upwards.
Reason: If this is happening it means there is problem with your first stage, normally the HP seat. If this seat wears out enough you could get a free flowing first 1st stage that will push the pressure up in the hoses, either bursting them or forcing open the 2nd stages. (If you have regulators that are upstream – not very common and you will know if you have them, this could blow the over pressure valve).

3) Negative Pressure Test: Turn your tank off and keep breathing from your Regulators slowly (Ensure inflation hoses are blocked as per step 1). There are 2 parts to this, 1st closely watch your pressure gauge, you checking that the needle is not sticking at any points. 2nd You should get to stage when you cant breath any air in.
Reason: If you can still breath this means there is a fault with your Regulators. Commonly (not always) this test identifies that one of the following is ripped and letting air in, if air is getting in that means water will get in. If the hole increases in size enough you could suddenly breath in a load of water (not the best thing to happen underwater). The mouth piece, the 2nd Stage Main Diaphragm or the Exhaust Diaphragm has a hole.

4) Leak Test: Turn the tank on and then off and slowly breath your Regulators down until you pressure gauge shows 10 bar. Then simply leave your kit alone and sort out the rest of your gear. Then check your gauge after 10 mins or so.
Reason: Pressure has dropped significantly – you have a leak somewhere in your Reg set. Pressure has increased – you have a leak in your tank valve. I use 10 bar, as its enough pressure to push out of a leak but low enough that if there is a leak in the tank valve the pressure is not high enough to act as a barrier. Also when I check its easy to remember 10 out 10 is a good result. (Keen to know what pressures other divers use and why).

I hope you may have found some of this useful, and would like to know if there is anything people do differently in relation to Regulator checks.

G-SAV