What's the small bit between the hose and the SPG for

[BlueTrin]

I bought a SPG and a hose, the SPG came with a small insert which had two rings on each side to put inside the SPG and hose.
What is it for ?
Also I only noticed now that the hose for the SPG has only a very tiny hole, I guess it does not need more to measure the pressure.

 

[Tribal]

Its to make it turn around. And HP has small holes, thats why a HP hose that bursts isn’t half as bad as a LP hose.

 

[emoreira]

The part you refer is called spool and is the piece that allows the SPG to rotate while preserving the pressure.
The SPG only needs to meassure pressure, there is no gas flow, so the small hole allows that. Besides the small hole avoids the tank to empty very fast in case the HP hose breaks.

 

[tbone1004]

@emoreira the small hole has nothing to do with the tank draining fast. That is a reduced port size in the body of the first stage that doesn't allow a high quantity of air out in the first place.

@BlueTrin the spool provides the actual sealing surfaces for the hose:gauge connection. If you put an o-ring on the end of the SPG, the hose will seal to it *same way the hose seals to the first stage body*, but it is not as secure as the spool.
The spool allows for a face connection inside the barrel of the SPG and the hose fitting itself to facilitate the swivel.

 

[Dan]

I would put a thin coat of silicon grease over those o-ring before inserting into the fitting & tightening the nuts and try not to spin / turn the SPG more than necessary to prevent premature wear of those dynamic o-rings.

You’ll see air bubbles start to appear around the fittings once the o-rings start to wear off. I replace those o-rings once for every 5 years.

 

[tbone1004]

@Dan_T bit more than a thin coat on those o-rings, though silicone will not keep them O2 clean and once the inside of that SPG has silicone in it, it can't be cleaned again.
Those o-rings are supposed to be replaced when regulators are serviced. I would also recommend keeping a few spare spools in your save a dive kit as they tend to go without warning

 

[broncobowsher]

A blown O-ring on the spool is fairly common. It is a lot easier to carry a complete spool in the save a dive kit than it is to replace the O-rings on the spool.

 

[davehicks]

Spare Spools are $1.50 each on DiveGearExpress. Buy a few for your spares kit for sure.

 

[emoreira]

@emoreira the small hole has nothing to do with the tank draining fast. That is a reduced port size in the body of the first stage that doesn't allow a high quantity of air out in the first place.

I do not agree. I've found that the hole that first stages have is way bigger that the hole in the HP hose connector. There could be several failures. One failure could be a broken HP hose. The HP hose connector remains threaded to the first stage, so the air will flow through the small hole in the HP hose connector.
Another failure could be the HP hose connector o-ring breaks, the air will flow only restricted by the small hole in the first stage.

 

[BlueTrin]

@Dan_T bit more than a thin coat on those o-rings, though silicone will not keep them O2 clean and once the inside of that SPG has silicone in it, it can't be cleaned again.
Those o-rings are supposed to be replaced when regulators are serviced. I would also recommend keeping a few spare spools in your save a dive kit as they tend to go without warning

Are you saying that I better not put silicone on it ?