Newbie "snifting" question.

[Paul Rusco]

Hello all, I have a quick question regarding an alternative to "cracking" or "snifting" a cylinder to clear out any dust/dirt.

I'm rather reluctant to just open the cylinder like that, so would using a vacuum cleaner on the cylinder port be a viable alternative?

Also, I've read here that turning the regulator dial anti-clockwise actually turns it off, even though the dial itself gradually comes out as you do it - is this true?

Thank you,
Paul.

 

[Bsmith]

So long as the cylinder outlet thread appears clean and has no water in it put the regulator straight on. I don't crack the valve as full cylinders now come with plastic covers on the outlets. Turning the regulator adjuster anti clockwise will decrease or completely de-pressure the gas to the mig welder. The reg adjuster should be in this position before turning on a full gas cylinder.

 

[Paul.]

A blast of compressed air or nitrogen is now preferred to snifting, a vac would probably do it, if you have a small enough nozzle,

http://www.boconline.co.uk/en/sheq/...ylinder-maintenance/cylinder-maintenance.html

http://www.mig-welding.co.uk/wiki/Setting_up_the_gas

turning regulator knob clockwise will increase output pressure, anti clock reduces it, its not designed to be used as an on off tap though, use the valve for that.

 

[bpcoryton]

A blast of compressed air or nitrogen is now preferred to snifting, a vac would probably do it, if you have a small enough nozzle,

http://www.boconline.co.uk/en/sheq/...ylinder-maintenance/cylinder-maintenance.html

http://www.mig-welding.co.uk/wiki/Setting_up_the_gas

turning regulator knob clockwise will increase output pressure, anti clock reduces it, its not designed to be used as an on off tap though, use the valve for that.

tig paul,dont want to start a war of words but useing compressed air to clear a valve i my view not the best idear oxygen more so!,due to the fact it my contaminate it with oil.nitogen is ok but someone who not experienced with oxygen+oil could lead to major problems!sniffing hydrogen cylinders is best done with care though.

 

[backpurge]

tig paul,dont want to start a war of words but useing compressed air to clear a valve i my view not the best idear oxygen more so!,due to the fact it my contaminate it with oil.nitogen is ok but someone who not experienced with oxygen+oil could lead to major problems!sniffing hydrogen cylinders is best done with care though.

BCGA now advises against snifting any gas. Snifting Hydrogen has always been strongly discouraged

 

[Paul Rusco]

Thanks for the info guys, I think I'll just use my vacuum tube on the cylinder port to clean it.

Also out of curiosity I wonder why the regulator dial comes outwards as you actually close/shut it off, and goes inwards as you open it - normally (like with taps) it's the other way around hehe.

So as long as I turn the Regulator dial completely anti-clockwise until the dial is fully backed-off, and then slowly turn on the cylinder valve, then I should be alright? I just don't want to accidentally break or "shock" the regulator lol.

P.S the cylinder is Nitrogen.

 

[Bsmith]

I don't know much about the inside of a regulator, but what happens is something like, as you screw the adjuster in or clockwise, the pivot in the centre of the screw presses a diaphagm off it's seat allowing gas to enter the low press side of the reg from the high press side.
Yes, you are right about reg adjuster position when opening a new or full cylinder.
Open cylinder valve, screw adjuster clockwise until desired press is reached on the low pressure gauge (some regs have 2 gauges, 1 showing cylinder press), then you can leave it there, just turn gas off and on with cylinder valve.

 

[Will_Davis]

The regulator knob screws down onto a spiring, the spring loads a diaphragm that opens/closes a needle valve. If you screw the knob clockwise, this compresses the spring, that puts more pressure of the diaphragm and the gas pressure increase.

It is not a screw down valve!!

HTH

Will

 

[backpurge]

It is worth getting into the habit of when you have finished welding for the day, turn your cylinder off at the valve, pull the trigger on your torch to drain all the pressure out of the system and then fully wind out the pressure adjustment screw on your regulator.

This saves subjecting the regulator internals to a shock load each time you crack your cylinder open

 

[Paul Rusco]

I'll be using a Multistage two-gauge Regulator, I was wondering what is the best way to depressurise the Regulator once the cylinder valve is turned off?
It doesn't look like it has a Bleed valve on it or anything, I'm just a little concerned that there will still be a deposit of high-pressured gas left inside the Regulator when I start to unfit it from the cylinder.

 

[hotrodder]

As Backpurge said, close the cylinder valve first (this just leaves a small volume at pressure in the regulator) then pull the torch trigger to empty the reg and lines and finally back off the regulator (so the diaphragm is 1. relaxed and 2. doesn't get a shock when you next open the cylinder)

Multistage means that the pressure is reduced in two stages, the first stage is fixed and is so that the output (adjustable) stage always 'sees' the same inlet pressure regardless of cylinder contents. With single stage regs the outlet side sees varying inlet pressure as the cylinder empties

Unhooking a reg (obviously after the cylinder valve is closed) while there's still pressure in the system just results in a hissssss (like opening a bottle of soda that's been shaken)... the volume of gas is tiny and it's over in a sec or so after the regulator nut has been loosened 1/2 a turn or so

 

[Bsmith]

I just leave my reg set as it is and don't depressure it, when finished I just turn the gas bottle valve off. The gauges show the same pressures (and they are not stuck lol) the next time I go to use even if it's a week later, so obviously, no leaks, so no shock to reg.

Anyway, if you wish to depressure your reg, gas bottle valve turned off, welder switched on, unhook wire feed tension spring on welder to stop wire feed, press trigger as said. You can then unscrew reg adjuster.

 

[Paul Rusco]

I see.

So if I just switched off the cylinder valve and then say, set the Regulator to maximum outlet, would that not be an alternative way of emptying it?

Then again, if it is only a tiny amount of gas that's in there, then I assume just slowly unscrewing the Regulator until it finishes hissing will be sufficient, or would it cause damage/injury?

 

[Bsmith]

Why are you so bothered about the little bit of gas in the regulator? I wouldn't unscrew the reg unless I was going to change the gas bottle, then it's only a little gas that won't cause any harm.
If you are finishing welding for the day and you want to depressure the reg without undoing it from the bottle, do it as I said above.

 

[backpurge]

I see.

So if I just switched off the cylinder valve and then say, set the Regulator to maximum outlet, would that not be an alternative way of emptying it?

No, to depressurize the system you need to drain it downstream of the regulator. As has been said several times,after turning the cylinder valve off just pull the torch trigger for a few seconds, you are overcomplicating what is really something very simple

 

[Paul Rusco]

I apologise for all the questions regarding the Regulator and depressurising it. The reason is because I don't yet have a complete Welding set, all I have is the cylinder, regulator, flow meter and tubing - so I just wanted to test the flows/pressures of what I currently have and ergo all the Regulator questions lol.

Since I don't yet have a Welder to use, I'll just switch everything off and slowly unscrew the Regulator and let all the built-up Nitrogen hiss out like hotrodder suggested. Thank you all for the info and help, I appreciate it!

 

[Bsmith]

You could just turn the cylinder valve off then, and screw the regulator adjuster a few turns clockwise so the reg depressures at the open outlet.
No need to apologise, hope you got the answers to your questions, if not, ask again, that's how we learn.

 

[hotrodder]

Whoooooa! Welder? Nitrogen? Does not compute, nitrogen is one of the things that needs keeping out of the weld.

 

[backpurge]

No probs fella, so long as you get into the habit of always turning the cylinder valve off when you're not using it everything will be safe which always has to be you're main prority