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Pre-Season Checklist - Regulators

Pre-Season Checklist - Regulators

The winter is finally over and the new season is coming up fast. If you were sensible the winter period was the perfect time to have your kit serviced by a professional but if you didn't now is an opportune time to dust off your kit and give it a good going over to pick up any problems early, leaving enough time to get them sorted out.

Although nothing beats a proper service, these little guides will take you through some relatively simple but well advised kit health checks. Part 1, which you are reading now, is for checking your regulators. Part 2 is about checking Everything Else.


Dive Hoses

You can have the most expensive and finely tuned regulators in the world but if your hoses aren't cared for and regularly checked it's not going to mean a thing when your precious air is streaming out of a split or worse. A split hose could empty your cylinder a lot faster than you can reach the surface!

Check for perishing, cuts or chunks missing, particularly at the ends. If you still have hose protectors fitted, make sure you slide them down and check beneath them as any damage here can easily go unnoticed. Never pull too hard though as this can damage the different layers within the hose. If it's difficult to budge try a little warm soapy water between the hose and protector and twist clockwise (this will prevent the hose unscrewing from the first stage).

While some tiny perish cracks are tolerable, anything bigger and it is advisable to replace it. Also look for bubbles forming under the outer layer of the hoses as this is an obvious sign of a break down in the inner layers. This is most likely to happen to a high pressure hose.

With your hoses removed from the first stage check the condition of the O-rings. Make sure they aren't perished, split, too loose, or pinched when the hoses are re-attached to the first stage. The Miflex Hoses Service Box is a great collection of the O-rings and air-spools you might need.

Need a new hose? We have the full range of Miflex scuba diving hoses available in stock.

See also, Caring For Scuba Diving Hoses.

Wet Test

A very simple but often overlooked test, simply place an assembled and pressurised reg set into a bath full of water and leave it to settle for a short while.

Check that there are no bubbles flowing from first stage, any of the ports, second stage connections or high pressure gauge/instrument connections. Anything coming out of these places indicates an O-ring problem.

If there is air escaping from within the second stage, either the first stage intermediate pressure (IP) is too high (or creeping), the second stage valve seat is heavily worn and not sealing properly, or if the regs have just come back from servicing it could simply be a poorly tuned second stage.

This problem will require investigation by a trained technician.

First Stages


This is obviously something that you are not going to be able to change yourself, but if it's heavily corroded or growing things, then get your regs in for a service.

Never EVER allow water to enter the first stage, bad things could happen, especially if it is salt water. I'm sure most of you have seen what happens to metal when it comes into prolonged contact with salt water.

The following first stage checks will require an Intermediate Pressure (IP) gauge which are available in either low pressure (LP) port, or BC style quick disconnect versions. The Sonar Deluxe Intermediate Pressure (IP) Gauge would be a great choice.

First Stage IP

Most regulator manufacturers use an IP between 9 and 10 bar but others (Poseidon for instance) use higher pressures. Connect your IP gauge and check that the needle points somewhere within this range (or whatever the particular value is for your regulator). An IP lower than the recommended value will degrade breathing performance whilst a higher pressure could increase the risk of freeflows.

IP Creeping

IP creeping is a (not very) technical term used when the IP quickly climbs to the correct pressure but rather than stopping there it continues to 'creep' up until the second stage 'down stream' valve opens to release the excessive pressure (bubbles appearing from within the second stage, as mentioned in the wet test above). You should be able to leave a correctly operating reg overnight and not see any movement in the needle.

The problem is typically caused by a worn or otherwise compromised high pressure seat within the first stage. A good technician will be able investigate further, but it will likely result in a service.

IP Recovery

Another performance aspect of the first stage to bear in mind is how quickly it will return to the preset IP (intermediate pressure). When breathing from the regulator the IP should typically only drop by a couple of bar before quickly rising once inhalation has finished. If your IP is very slow to recover make sure the cylinder valve is fully open, a valve which is barely open will significantly restrict air flow into the first stage.

Obviously the response time of an entry level reg is going to be slower than an expensive high performance reg.

Second Stages

There is very little to check on a second stage. If you shake it near you ear, it shouldn't sound like it's currently being used to store your assortment of nuts and bolts, but the lever may gently tap against the diaphragm. If you can feel it swinging back and forth inside, or if the purge button has to travel more than 5 mm before air starts to hiss out, then the second stage likely needs some adjusting.

Most, if not all, regulators have some sort of built in locking system that prevents vital parts from coming undone during use, but it's always a good idea to check that you can't accidentally remove the front cover, or that the hose connection doesn't come unscrewed in your hand.

The other thing to do check that the valve seat, diaphragm and exhaust diaphragm all seal correctly. This is actually simple to do: with the first stage dust cap on, gently inhale through the mouthpiece. A correctly sealed second stage should not allow you to draw any air in and you should be able to find any leaks quickly. Don't get over excited and inhale too hard as you could dislodge or damage the diaphragms.

Check out our Diving Regulator options if you think it's time to replace your first or second stage regulator.


We know divers that seem to eat their mouthpieces, so always check the condition of yours. Check the teeth grips for missing lugs or splits plus perishing around the cable tie.

If you need to replace the mouthpiece, make sure you get the correct one as there are various sizes and fitting the incorrect size will lead to problems. Too small and you run the risk of it splitting when stretched over the opening, too large the mouthpiece could leak or actually come off the regulator.

Check the cable tie is not only tight and secure, but also that the excess has been cut off smooth without any sharp edges or points to cut your lips on.

If you find yourself chomping your way through more than one mouthpiece per year you should consider getting yourself a high quality mouthpiece such as the Apeks Comfo-Bite Anti-bacterial Mouthpiece.

Need a new mouthpiece? Check out our full range of Scuba Diving Mouthpieces.

High Pressure Gauges

Not much to go wrong here. If your wet test found bubbles trickling out of the gauge, it is likely that the air-spool swivel inside the connection will either need the O-rings lubricating, or replacement O-rings. Sometimes it's just best to replace the air-spool.

Check out our full range of high pressure gauges.

See also, Regulator Care.

If you have any specific enquiry about how to care for your dive gear, please feel free to contact The Scuba Doctor by email to or by a telephone call to 03 5985 1700.


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