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Posted by SteveB on November 10, 2008, 7:13 pm
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> As I mentioned previously, I have two acetylene tanks, 145 CF and 397
> CF.
>
> So I bought some O/A kit that includes a regulator, among other
> things.
>
> Here's something that concerns me: the 397 CF tank, seems to leak
> acetylene from the seal between regulator and tank. The symptom of it
> is that the high pressure gauge shows pressure that declines
> relatively rapidly if I close the tank valve. I would say most
> pressure is lost in one minute. This makes me concerned since
> acetylene is explosive.
>
> Here's my findings:
>
> 1) Quick pressure loss with tank valve opened and then closed, happens
> on the 297 CF tank
>
> 2) it does not happen with the 145 CF tank, or at least it is
> extremely slow
>
> 3) The rate of loss on 397 CF tank seems to depend from how tightly I
> tighten the connecting nut. The tighter, the slower is the leak. I am
> not sure how hard I can push that brass nut, but my guess is not too
> hard. I used perhaps 50 Ft/lbs or so of force.
>
> Any thinking on this. Thanks.
In an ideal world, it shouldn't leak at all with just good snugging. Spray
some Windex on there, and that will tell you a LOT. Then look at
everything. If you can't see anything that's obviously deformed or dinged,
take it to the shop. Maybe someone before you really reefed it down and
distorted it. It could be just a little distorted enough to leak, but
appear good. Fix it. It might be as easy as getting a new nipple and
shaft. (that sounds weird, doesn't it?) That's a good place for a fire to
start. I've heard that stuff is flammable. ;-)
Steve
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Posted by Tim Wescott on November 10, 2008, 7:04 pm
Please log in for more thread options SteveB wrote:
>> As I mentioned previously, I have two acetylene tanks, 145 CF and 397
>> CF.
>>
>> So I bought some O/A kit that includes a regulator, among other
>> things.
>>
>> Here's something that concerns me: the 397 CF tank, seems to leak
>> acetylene from the seal between regulator and tank. The symptom of it
>> is that the high pressure gauge shows pressure that declines
>> relatively rapidly if I close the tank valve. I would say most
>> pressure is lost in one minute. This makes me concerned since
>> acetylene is explosive.
>>
>> Here's my findings:
>>
>> 1) Quick pressure loss with tank valve opened and then closed, happens
>> on the 297 CF tank
>>
>> 2) it does not happen with the 145 CF tank, or at least it is
>> extremely slow
>>
>> 3) The rate of loss on 397 CF tank seems to depend from how tightly I
>> tighten the connecting nut. The tighter, the slower is the leak. I am
>> not sure how hard I can push that brass nut, but my guess is not too
>> hard. I used perhaps 50 Ft/lbs or so of force.
>>
>> Any thinking on this. Thanks.
>
> In an ideal world, it shouldn't leak at all with just good snugging. Spray
> some Windex on there, and that will tell you a LOT. Then look at
> everything. If you can't see anything that's obviously deformed or dinged,
> take it to the shop. Maybe someone before you really reefed it down and
> distorted it. It could be just a little distorted enough to leak, but
> appear good. Fix it. It might be as easy as getting a new nipple and
> shaft. (that sounds weird, doesn't it?) That's a good place for a fire to
> start. I've heard that stuff is flammable. ;-)
>
> Steve
>
>
Not to mention that if you over tighten your regulator to fit, then
you'll distort _it_.
I can't see a decent welding shop _not_ wanting to make good on this.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html
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Posted by Jon Elson on November 17, 2008, 11:03 pm
Please log in for more thread options Ignoramus14646 wrote:
> As I mentioned previously, I have two acetylene tanks, 145 CF and 397
> CF.
>
> So I bought some O/A kit that includes a regulator, among other
> things.
>
> Here's something that concerns me: the 397 CF tank, seems to leak
> acetylene from the seal between regulator and tank. The symptom of it
> is that the high pressure gauge shows pressure that declines
> relatively rapidly if I close the tank valve. I would say most
> pressure is lost in one minute. This makes me concerned since
> acetylene is explosive.
>
Don't assume you know where the leak is, use
dishwashing soap and a brush to wipe it here and
there and find the exact leak location. It is
very easy. It could be the main valve fitting,
the pipe to the regulator, the regulator
diaphragm, the low-pressure side, or even the tank
valve stem.
> Here's my findings:
>
> 1) Quick pressure loss with tank valve opened and then closed, happens
> on the 297 CF tank
>
> 2) it does not happen with the 145 CF tank, or at least it is
> extremely slow
>
> 3) The rate of loss on 397 CF tank seems to depend from how tightly I
> tighten the connecting nut. The tighter, the slower is the leak. I am
> not sure how hard I can push that brass nut, but my guess is not too
> hard. I used perhaps 50 Ft/lbs or so of force.
Oh, no, we go quite a bit higher than that. Some
tank valves have mars on the sealing surface that
close up if you crank down tighter. Is this a
rental cylinder?
If it leaks, make them swap it out for a good
cylinder. Also, it could be your regulator
fitting that is marred. Inspect visually, you can
replace the fitting pretty easily.
Jon
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> CF.
>
> So I bought some O/A kit that includes a regulator, among other
> things.
>
> Here's something that concerns me: the 397 CF tank, seems to leak
> acetylene from the seal between regulator and tank. The symptom of it
> is that the high pressure gauge shows pressure that declines
> relatively rapidly if I close the tank valve. I would say most
> pressure is lost in one minute. This makes me concerned since
> acetylene is explosive.
>
> Here's my findings:
>
> 1) Quick pressure loss with tank valve opened and then closed, happens
> on the 297 CF tank
>
> 2) it does not happen with the 145 CF tank, or at least it is
> extremely slow
>
> 3) The rate of loss on 397 CF tank seems to depend from how tightly I
> tighten the connecting nut. The tighter, the slower is the leak. I am
> not sure how hard I can push that brass nut, but my guess is not too
> hard. I used perhaps 50 Ft/lbs or so of force.
>
> Any thinking on this. Thanks.