Left hand threads

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gcarter

gcarter

Contributor
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gcarter:
Really? Sidemount uses left hand threads? Why?
Click to expand...

NWGratefulDiver:
Left tank has valve handle on the usual side ... right tank has valve handle on the opposite side.

Perhaps that's a subject better discussed in the side-mount forum ...

... Bob (Grateful Diver)
Click to expand...

I have to admit I have a bias against left hand threads. That said, why are they used in side mount? I would think that if you always had to deal with right hand threads, movements would be more automatic and you wouldn't have to worry about dealing with wrong threads on the wrong side.

Curious, not critical.
 
Its not any different than with a set of BM doubles, just a form of funciton for the most part.

Its easier to setup a set of tanks that are mirrored on either side of your body. If you goto MX or something, you may have to adjust your setup a bit in order to work with two standard threaded tank valves.
 
What??? BM doubles with isolator manifolds don't have left hand threads, that's why the handles turn valves off in opposite directions. They may have left hand handles, but I assure you, the threads are identical. Otherwise, manufacturers of valves would have to make two different parts. All valves turn off in the same direction, only the handle is on the opposite side. If one handle had left hand threads, they would both turn off by rolling the handle forward.
 
Oops, my bad ... Frank is correct. The handles are on the opposite side, but the threads all turn right.

That's what I get for posting before fully waking up in the morning ...

... Bob (Grateful Diver)
 
gcarter:
I have to admit I have a bias against left hand threads. That said, why are they used in side mount? I would think that if you always had to deal with right hand threads, movements would be more automatic and you wouldn't have to worry about dealing with wrong threads on the wrong side.

Curious, not critical.
Click to expand...



Explain your bias...

The use of a left and right handwheel (NOT THREADS since these are identical) in SM or Backmounted doubles or CCR is to facilitate valve operations with one's left hand and right hand.

Specifically in SM having a LH and RH valve allows this orientation with the mouth of the valve pointing towards the diver's body rather than one towards and one away.

Am I missing something here because I truly do not understand your issues and would like to.
 
Wookie:
What??? BM doubles with isolator manifolds don't have left hand threads, that's why the handles turn valves off in opposite directions.
Click to expand...

Judging by this statement:

gcarter:
I would think that if you always had to deal with right hand threads, movements would be more automatic and you wouldn't have to worry about dealing with wrong threads on the wrong side.
Click to expand...

I'm guessing he means the wheel action, rather than the threads themselves.
 
SuPrBuGmAn:
I'm guessing he means the wheel action, rather than the threads themselves.
Click to expand...

Correct ... when closing left and right tank valves, your hands are moving in opposite directions ...

... Bob (Grateful Diver)
 
Doppler:
Explain your bias...

The use of a left and right handwheel (NOT THREADS since these are identical) in SM or Backmounted doubles or CCR is to facilitate valve operations with one's left hand and right hand.

Specifically in SM having a LH and RH valve allows this orientation with the mouth of the valve pointing towards the diver's body rather than one towards and one away.

Am I missing something here because I truly do not understand your issues and would like to.
Click to expand...

I don't have an issue per se, just trying to understand what I am reading.

My bias is that when I turn a valve clockwise, I expect it to be closed, and open when turned counter-clockwise. This is a life-long ingrained habit for most people, so I am curious as to why this would be different for SM - which is what I thought I was reading. If the threads are in fact the same, then I misread and apologize for the stupid question :)
 
Yep... Misinformed rather than stupid... One way to imagine it it to put a regular cylinder on the floor and face it with the handle pointing to your left... Open and close the valve. Now walk around to the other side and face the same tank but now the handle is pointing to your right. Only diff with LH RH valves is that either way, the mouth of the valve (the hole the reg screws into) faces you.

The valve closes clockwise and opens counter clockwise in both cases.
 
Just to confused things more...the valve plugs on the left hand valves are left hand threads.
 
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