Do you own an Intermediate Pressure Gauge?

[Stone]

One of the few things a diver can do (inexpensively) to monitor the health of a regulator is to check intermediate pressure (IP).

In the past two years, I have discovered creeping IP twice (on two different regs). The damage that results from creeping IP depends on the type of regulator, but I figure my first IP gauge has paid for itself a couple of times over.

<Edit>

If you are new to the thread and don't know what an IP gauge is, a short explanation is provided a few posts down.

 

[BigDiver]

My dad and I made and routinely use a IP guage. They are very inexpensive to make and are vital to knowing the "health" of your reg.

When you do chech your IP make sure that you know your particular regs optimal setting, although most are relativly the same. Also note that there are some external factors that can influence what you set it at.

 

[divedude]

I voted for the last one
How do you think we keep warm up here

 

[Stone]

The purpose of the first stage is to reduce tank pressure (up to 3000+ psi on HP tanks) to something more manageable (usually 130 to 150 psi). The second stage reduces the 130-150 psi to ambient pressure. The 130 to 150 psi is the Intermediate Pressure (IP) or Interstage Pressure (still IP). You can check the IP with a pressure gauge that has a range of 0 to 300 psi (or 0 to 400, or 0 to 500). An easy way check your IP is to attach a male quick disconnect (QD) (identical to the one on your BC inflator) to an appropriate pressure gauge and stick it in your inflator hose’s female QD. If you know what your IP is suppose to be, you can tell if your IP is high, low, okay, or creeping. In general, an IP that is not in the correct range and steady can indicate 1) a harder work of breathing (WOB) than normal, or 2) a tendency toward 2nd stage free-flow. Slowly increasing IP (creep) usually indicates a bad high pressure seat which can cause something as simple as a temporary free-flow, or as dangerous as a catastrophic failure in the first stage, second stage, or hose. The failure mode depends on the kind of regulator.

 

[scuberd]

shouldn't the yearly sevicing of your regulator fix these problems though?

 

[Iguana Don]

Yes I own one and yes I use it regurarly.

ID

 

[ChrisF]

Originally posted by scuberd
shouldn't the yearly sevicing of your regulator fix these problems though?

Seems like the anual service check should be sufficient.

If you take care of your gear, is it really that likely that the IP will get so far out of wack between anaual checkups that it will materially impact regulator performance?

 

[BigDiver]

Sure there SHOULD be no change in IP if you have your reg. serviced every year, but that is no reason not to check it. When the service is being done, there should be new parts. ei. for a balanced diaphragm, o-rings, diaphragm, disc filter,or conical filter for DIN, etc. But sometimes when the service is being done what the tech will do is examine the part and if there is no wear or damage they will not change it. There is nothing wrong with this except if they miss something it could be potential failure in the future. It may pass the IP test done by the tech, but after a few dives it could begin to creep.

So having your own IP gauge is a inexpensive and great way to know your 1st stages performance.

 

[Iguana Don]

Do you ever check th oil in your car/truck or do you just wait till 3000 miles and change it?

 

[Stone]

I got the idea to start this poll because I checked the IP on one of my regs last night and found it was creeping. When I cracked it open, I found that a backup ring was missing. The reg was last overhauled by the LDS under warranty (apparently not very well). This reg passed the tech's IP test, and several of my own IP checks over the past year, but it is my belief that the missing backup ring allowed the deformation of its associated o-ring; hence, IP creep.

The point is: If there is a problem due to workmanship or materials, no amount of diligence in taking care of your reg will help. Unless you check the IP, you won't catch a problem before it becomes symptomatic or catastrophic.

To use an analogy (although I don't have the statistics): A certain number of automobile accidents and their associated injuries and deaths occur each year due to under-inflated tires. Checking the air pressure in your tires is cheap, easy, and one of the few maintenance actions anyone can perform. The worst thing that can happen is you save some money on gas and rubber by keeping your tires properly inflated. The best thing that can happen is you save your own life.

Same thing with checking your IP. It's cheap, easy, and one of the few maintenance actions anyone can perform. The worst thing that can happen is you save some money on a hose or a missed dive. The best thing that can happen is you save your own life.