Full on, and a little off
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Bob DBF
Contributor
Few valves have a back seat. If the valve is "back-seated", without having that seat, it is more prone to jamming if fully opened 'till it stops and left there, even more likely if agressivly turned. This is one reason I was always advised to back off a valve slightly after fully opening unless I knew it had a back seat. SCUBA tank valves I have worked do not have a back seat.
Bob
----------------
DBF
OBD
In my sidemount class I was taugt "
this time fingertight, in order to have the tank fully open but gently - so that if you have to shut the valve you could do it without effort.
Turn the tank fully on and then one quarter turn back"
- and then turn it fully open again, but this time fingertight, in order to have the tank fully open but gently - so that if you have to shut the valve you could do it without effort.
Michael Guerrero
Contributor
iamrushman
Contributor
six pages of interesting reading....valve on then back... valve fully on...if it's on and it works.
Last edited:
Rich Keller
Contributor
This is about reducing long term wear on the valve. This is not a critical problem just something that can be easily addressed by turning the valve back part way. You just need to turn it back a bit every time, not exactly the same amount every time. First you do not want to leave stress applied to the parts of the valve that is preventing you from opening it further or have the valve get frozen in the open position. Second you do not want the valve resting in the same spot all the time.
AfterDark
Contributor
Thinking about it I even do it to the adjust knob on my SP 109 second stage, the outside faucets on my house, the garden hose, and thinking about it a little more I've never had anything like those things stick open on me.
are similar problems in the valve seen in the off position?
i.e. when a valve is off, it needs to be turned all the way off (as opposed to turning it back on a quarter turn). Shouldn't this cause long term wear as well since it is resting in the same spot (and for longer periods than when in the on position).
bakodiver391
Contributor
No, because the valve has a plastic seat that can deform a little to allow for repeated seating, and that is easily replaceable. Opening a valve hard open can squash and destroy the o ring, the nylon seals, or whatever combination of the two are in that particular valve (there is some variation in the design of spindle seals in various valves). I have rebuilt hundreds of valves and most of the damage is done by opening too hard and jamming.
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