VIP, O2 cleaning and time frame

[bletso]

This is why the valve should be checked every year if partial pressure blending. Some valves are worse than others. I am less worried about the cylinder as adiabatic pressure changes are less than at valve faces. The attached photo is of a valve in service a little over one year!



Dale
hydro testing

 

[halocline]

The only part of the valve that's exposed to O2 when the valve is closed (i.e. almost all the time) is the seat face, which I don't see in your photo, unless I'm mistaking something. Everything else only 'sees' O2 during the fill process itself, which in normal use (say 25-50 fills?) is very limited O2 exposure. I have a hard time believing that the damage in your photo is due to O2 exposure.

 

[bletso]

Actually the O-rings get the brunt of O2 pressure as they are the seal for the valve stem. They not only get the O2 surge pressure but torsional tearing under pressure whilst turning the knob. As far as seats try this one;



Dale

 

[halocline]

Actually the O-rings get the brunt of O2 pressure as they are the seal for the valve stem. They not only get the O2 surge pressure but torsional tearing under pressure whilst turning the knob. As far as seats try this one;

View attachment 107130

Dale

The stem o-rings only experience pressure while the valve is open, a tiny percentage of the time. The 'torsional tearing' you're referring to is simply that they're attached to a shaft that only rotates when the vale is worked; i.e. not very often. That's one reason that tank valves tend to last far longer and fail far less frequently than regulators, which open and close on each breath. I'm not denying that stem o-rings experience a large pressure gradient when the tank vale is open, and that certainly includes when the valve stem is in rotation, but zero pressure when it's closed. Interestingly, it looks like the plastic crush seals in your photo have taken the abuse; the greenish o-rings look covered in lube but not torn up.

I don't know what to make of your seat; it looks like it's smeared with lube to me, and otherwise just has the normal circular set mark. Am I missing something?

 

[bletso]

The valve seat, has been burnt and is hard as a rock probably caused by turning on the O2 too fast. I have seen a several of these, mostly OMS and Draeger valves. My friend, don't under-estimate the power of O2 under pressure. It just doesn't take much.

Dale

 

[DepthCharge]

O2 cleaning should be done annually along with the VIP.

Why? I'd prefer a data based answer if you would.

 

[davetowz]

O2 clean is kind of a misnomer...I clean a tank and valve and the do a PP blend of nitrox, diver X dives this tank and then gets it refilled in MX by resort Y. Resort Y pumps some bad stuff into diver X's tank. Yes the O@ clean punch on the vis is still valid...is the tank still O2 clean? No. Combustion requires 3 things...fuel, Oxygen, and heat. I will not PP fill a tank that has not been O2 cleaned, but cannot really trust any that I don't control, The one aspect I can control when PP blending is the heat. I fill uber slow. All tanks that might be subjected to a high O2 should be cleaned annually at the time of vis, but should not be truly considered O2 clean except for the first fill after the cleaning and inspection process.
just my .02$

 

[DepthCharge]

O2 clean is kind of a misnomer...I clean a tank and valve and the do a PP blend of nitrox, diver X dives this tank and then gets it refilled in MX by resort Y. Resort Y pumps some bad stuff into diver X's tank. Yes the O@ clean punch on the vis is still valid...is the tank still O2 clean? No. Combustion requires 3 things...fuel, Oxygen, and heat. I will not PP fill a tank that has not been O2 cleaned, but cannot really trust any that I don't control, The one aspect I can control when PP blending is the heat. I fill uber slow. All tanks that might be subjected to a high O2 should be cleaned annually at the time of vis, but should not be truly considered O2 clean except for the first fill after the cleaning and inspection process.
just my .02$

Absolutly agree. I (we)have our own compressor/booster/filter sytem. This is the only place my tanks get filled. So when it's time to do the visual, I don't O2 clean. Just do the clean after a hydro. Unless of course something looks funky during a vis. Dosen't take rocket science to keep the valve clean, or to keep anything from entering the tank.

 

[ajduplessis]

O2 cleaning should be done annually along with the VIP.

O2 cleaning should be done whenever contamination is suspected!! Bare min would be yearly. Every time you use a cylinder the status deteriorates.

 

[DepthCharge]

O2 cleaning should be done whenever contamination is suspected!! Bare min would be yearly. Every time you use a cylinder the status deteriorates.

Again, what is the proof??? Agreed, IF there is a suspicion absolutely. Otherwise, if you are using O2 compat. air and not running tanks to zero how are contaminants going to enter?