PURGING A GAS PIPE
Sam Farrell
how does one go about it ??
.
Sam
.
Purging a gas pipe means displacing the contents of the pipe with
another medium. Usually it means removing air or air gas mixtures with
100% fuel gas,asuming we are talking about natural gas.
The method varies depending on the size of the installtion i.e
length,pipe diameters,volumes etc and in the case of large
installations it can get quite involved.
For normal domestic insalltions it is sufficient to purge from the
furthest points on each pipework leg.
joe
geoff
rell.freeserve.co.uk> writes
reaction has started
If you haven't purged the oxygen from your gas supply, once initiated
(at your cooker for example) the reaction can continue back into the
pipe in a possibly explosive sort of way
Get the drift ??
--
geoff
Ian White
possible gas/air mixture cannot "strike back" towards the supply. The
jets on a gas appliance are sized to prevent this possibility.
If there is air in the pipe, the flame tends to roar and lift off
because the gas/air mixture is too lean, until neat gas starts to come
through and then the flame settles down onto the burner. Nothing
exciting at all...
Ian White
Abingdon, England
Andrew Gabriel
Ian White <I...@ifwtech.com> writes:
>
>If there is air in the pipe, the flame tends to roar and lift off
>because the gas/air mixture is too lean, until neat gas starts to come
>through and then the flame settles down onto the burner. Nothing
>exciting at all...
If there's lots of air, the flame will blow out, so it needs someone
standing by to relight it.
--
Andrew Gabriel And...@cucumber.demon.co.uk
Consultant Software Engineer
Ian White
>In article <zvrzw7A0...@ifwtech.plus.net>,
> Ian White <I...@ifwtech.com> writes:
>>
>>If there is air in the pipe, the flame tends to roar and lift off
>>because the gas/air mixture is too lean, until neat gas starts to come
>>through and then the flame settles down onto the burner. Nothing
>>exciting at all...
>
>If there's lots of air, the flame will blow out, so it needs someone
>standing by to relight it.
>
Ian White
Abingdon, England
.
>For a given fuel gas, there is a minimum size of hole through which any
>possible gas/air mixture cannot "strike back" towards the supply. The
>jets on a gas appliance are sized to prevent this possibility.
>
It is quite possible to have a gas flame burning on an open ended pipe
which is anything from a mm to 24" and upwards in diameter..
Ian White
Of course it is... now which part of "true, but irrelevant" seems to be
the problem?
Ian White
Abingdon, England
Adam
news:k9ffW8A9...@ifwtech.plus.net...
> >>If there is air in the pipe, the flame tends to roar and lift off
> >>because the gas/air mixture is too lean, until neat gas starts to come
> >>through and then the flame settles down onto the burner. Nothing
> >>exciting at all...
> >
> >If there's lots of air, the flame will blow out, so it needs someone
> >standing by to relight it.
> >
> Good point!
Bad point!!!!!!!!!!!!! You do not keep relighting a gas supply that has air
in it. It could flashback to the meter and a big bump will be heard.
IMHO, on a normal boiler. Calculate the volume of gas in the supply pipe.
Vent the room by opening doors and widows, turn off the electricity at the
meter (no sparks) and open the tap at the pipe at the boiler. If the pipe
holds 1 cu foot have some one at the meter observing the dial to see when
the meter has turned 1 cu foot. Best go 5% over. Have the person at the
meter turn off the supply when the meter has turned the correct amount.
I used to just turn on the supply at the boiler and small the gas coming in.
A seasoned person can instantly small the difference when full gas is coming
through. No recommended.
For large gas installations a "flame trap" has to be used attached to the
pipe near the appliance. The flame trap prevents a flame from flashing back.
Flame traps ae also used in purging large new meters. Done many!
--
Our Homes Are Small & Expensive
Because We Are Not Allowed To
Build On Land That Is Plentiful.
Make Land Available For The
People To Own & Use in the UK
http://www.oneworld.org/tlio/
.
Ian White
>"Ian White" <I...@ifwtech.com> wrote in message
>news:k9ffW8A9...@ifwtech.plus.net...
>
>> >>If there is air in the pipe, the flame tends to roar and lift off
>> >>because the gas/air mixture is too lean, until neat gas starts to come
>> >>through and then the flame settles down onto the burner. Nothing
>> >>exciting at all...
>> >
>> >If there's lots of air, the flame will blow out, so it needs someone
>> >standing by to relight it.
>> >
>> Good point!
>
>Bad point!!!!!!!!!!!!! You do not keep relighting a gas supply that has air
>in it. It could flashback to the meter and a big bump will be heard.
>
>IMHO, on a normal boiler. Calculate the volume of gas in the supply pipe.
>Vent the room by opening doors and widows, turn off the electricity at the
>meter (no sparks) and open the tap at the pipe at the boiler. If the pipe
>holds 1 cu foot have some one at the meter observing the dial to see when
>the meter has turned 1 cu foot. Best go 5% over. Have the person at the
>meter turn off the supply when the meter has turned the correct amount.
>
>I used to just turn on the supply at the boiler and small the gas coming in.
>A seasoned person can instantly small the difference when full gas is coming
>through. No recommended.
>
>For large gas installations a "flame trap" has to be used attached to the
>pipe near the appliance. The flame trap prevents a flame from flashing back.
>Flame traps ae also used in purging large new meters. Done many!
>
Large systems are different from the domestic-sized systems that are
relevant to this newsgroup. Flame traps are necessary on large systems
because the gas jets are large enough to allow a flashback into the
supply or the meter. A flame trap simply consists of something like a
sheet drilled with many small holes. The individual holes are small
enough to prevent a flashback, but there are enough of them to avoid
causing an undue pressure drop.
You don't need flame traps in domestic-sized appliances because the
single hole in the gas jet is itself small and deep enough to serve the
purpose. In the case of conventional "aerated" burners you have double
protection, because any gas/air mixture that is too weak (too much air)
will never flash back through the burner ports, much less strike back to
the main gas jet.
The gas company technique after changing a domestic meter - which starts
out full of air, of course - is to turn on a cooker ring, and apply
continuous spark ignition (thanks, Andrew, for emphasising this) to keep
burning off whatever comes through, until all the air is purged out and
the burner is working normally. The flame will be roaring and unstable
at first, but any gas/air mixture that escapes the flame is so weak that
it will never be ignitable again.
Having purged most of the air from the system via the cooker, the same
can be done with the leg to the gas fire, and the leg that leads to the
boiler. It's very much slower with the boiler, because the only outlet
available at first is the pilot burner (which is why they use the cooker
first). Again, keep applying ignition continuously until the pilot flame
settles. By the time the flame failure system lets you turn on the main
burner, the gas pipe has already been purged of air and the boiler
starts as normal.
Ian White
Abingdon, England
.
>
>
>Of course it is... now which part of "true, but irrelevant" seems to be
>the problem?
>
>Ian White
>Abingdon, England
I;m sorry,is there a problem? You seem to have formed the impression
that I am contradicting you ?
Jim Easterbrook
> For a given fuel gas, there is a minimum size of hole through which any
> possible gas/air mixture cannot "strike back" towards the supply. The
> jets on a gas appliance are sized to prevent this possibility.
>
> If there is air in the pipe, the flame tends to roar and lift off
> because the gas/air mixture is too lean, until neat gas starts to come
> through and then the flame settles down onto the burner. Nothing
> exciting at all...
Not strictly relevant, but...
I have vague memories of a quite impressive demonstration of the effect
of fuel/air ratio on flame speed from a TV programme years ago (probably
Open University). The apparatus was a glass tube (about 1 inch dia?)
formed into a two feet diameter helix (about six feet long), one end of
which turned round and ran straight along the axis of the helix. The
other end was next to a pilot light. Somewhere along the tube was a gas
inlet. (All this is from memory, and might be totally wrong.)
As the tube filled with gas, the fuel/air ratio at the pilot light end
became enough to sustain a flame. This then travelled back along the
tube, picking up speed as it went. As it rounded the corner into the
straight section it became supersonic. This device made a wonderful,
accelerating, wa wa wa wa wa wa ... wa wa wa wa bang! sound, repeated at
10 or 20 second intervals. Don't try this at home, folks.
--
Jim Easterbrook <http://www.easter.mersinet.co.uk/>
Adam
> >> > If there's lots of air, the flame will blow out,
> >> > so it needs someone
> >> > standing by to relight it.
> >>
> >> Good point!
> >
> > Bad point!!!!!!!!!!!!! You do not keep relighting a
> > gas supply that has air in it. It could flashback
> > to the meter and a big bump will be heard.
> >For large gas installations a "flame trap" has
> >to be used attached to the pipe near the appliance.
> >The flame trap prevents a flame from flashing back.
> >Flame traps ae also used in purging large new meters.
> > Done many!
>
> Large systems are different from the
> domestic-sized systems that are
You probably missed the line "done many". Like a Holmes Connersville meter,
many monns ago.
> A flame trap simply consists of something
> like a sheet drilled with many small holes.
Typically a type of guause
> You don't need flame traps in domestic-sized
> appliances
I never said you did.
> (which is why they use the cooker
> first). Again, keep applying ignition
> continuously until the pilot flame
> settles. By the time the flame failure
> system lets you turn on the main
> burner, the gas pipe has already been
> purged of air and the boiler
> starts as normal.
Please read again what I wrote. What you advocate is dangerous.
M.J.Powell
Easterbrook <j...@easter.mersinet.co.uk> writes
Er...where can I get this tubing...?
Mike
--
M.J.Powell
.
Easterbrook) wrote:
>I have vague memories of a quite impressive demonstration of the effect
>of fuel/air ratio on flame speed from a TV programme years ago (probably
>Open University). The apparatus was a glass tube (about 1 inch dia?)
>formed into a two feet diameter helix (about six feet long), one end of
>which turned round and ran straight along the axis of the helix. The
>other end was next to a pilot light. Somewhere along the tube was a gas
>inlet. (All this is from memory, and might be totally wrong.)
>
Yes i think ive seen this demo before also. I come across many large
installations whereby people are carrying out work or are about to
carry out work without any regard for the need to purge. You even get
guys taking angle grinders and other cutting equipment to steel pipes
of various diameters to either cut out/dismantle permanently or to add
extra bits. Sometimes its a question of familiarity breeds contempt
and i guess we can all be guilty of this at times.
The problem is when it does go wrong and the larger the
installation,the greater the chance of a mishap.
In practice domestic installtions can often be purged successfully
just by venting an open end at the extremity of the system or
lighting a cooker at the end of the line. Chances of a mishap are
minute. Same can;t be said for long lengths of larger diameters in
industrial/commercial installations.
Occasionally i have a retraining package on fire fighting which is
quite interesting,,dealing with large volume gas fires at low and high
pressures eg from fractured mains/pipes etc,,it renews your regard for
safety.
Ian White
>> (which is why they use the cooker
>> first). Again, keep applying ignition
>> continuously until the pilot flame
>> settles. By the time the flame failure
>> system lets you turn on the main
>> burner, the gas pipe has already been
>> purged of air and the boiler
>> starts as normal.
>
>Please read again what I wrote. What you advocate is dangerous.
I did, several times. Please can you explain exactly what you think is
dangerous about the procedure I described, and how the differences in
your procedure overcome those hazards?
Ian White
Abingdon, England
Ian White
I had... but: peace.
Ian White
Abingdon, England
Thomas Prufer
<mi...@pickmere.demon.co.uk> wrote:
(Gas thing that goes bang)
>Er...where can I get this tubing...?
I think this is the principle behind those things that are supposed to
scare birds away from crops -- gas seeps into a chamber until there's
enough for it to go bang. Maybe a pilot light's always on to set it
off? Crop gun? Crow cannon? Some name like that. (No wah wah though).
Thomas Prufer
Andrew Gabriel
j...@easter.mersinet.co.uk (Jim Easterbrook) writes:
>
> Not strictly relevant, but...
>
> I have vague memories of a quite impressive demonstration of the effect
> of fuel/air ratio on flame speed from a TV programme years ago (probably
> Open University). The apparatus was a glass tube (about 1 inch dia?)
> formed into a two feet diameter helix (about six feet long), one end of
> which turned round and ran straight along the axis of the helix. The
> other end was next to a pilot light. Somewhere along the tube was a gas
> inlet. (All this is from memory, and might be totally wrong.)
This was demonstrated in a Royal Institution Christmas lecture, some
~20 years ago. IIRC, the series was about sound, and given by someone
named Taylor. In this case, the tube was straight. I'm sure the
experiment has a name, but I don't recall it now.
--
Andrew Gabriel
Alex Gray
> of fuel/air ratio on flame speed from a TV programme years ago (probably
> Open University). The apparatus was a glass tube (about 1 inch dia?)
> formed into a two feet diameter helix (about six feet long), one end of
> which turned round and ran straight along the axis of the helix. The
> other end was next to a pilot light. Somewhere along the tube was a gas
> inlet. (All this is from memory, and might be totally wrong.)
My ex-colleague at BBC Open University, Laurie Hyman, made that. We used to
work together in the preparation room at Alexandra Palace, and then in
Visual Effects at Walton Hall, as Science Projects Designers. Being in the
same room as Laurie and some of his wilder experiments for a decade was a
life-shaping experience!
Alex
Thomas Prufer
>They're called "gas guns" and they work exactly as you surmise.
Thanks - I found them on the web, but no description as to how they
work.
But they reminded me of a demonstration at school: Some saboteur had
made a well-hidden cut in a rubber hose used to connect a Bunsen
burner to the gas valve in the chemistry lab. Big blah blah about the
dangers, could blow us all up -- afterwards I found the hose,
wel-hidden cut and all, neatly replaced in the drawer with all the
other hoses, waiting for an unsuspecting user...
To graphically demonstrate that gas can burn, they had a can: one lid
left, a hole in the middle of the lid, one at the side towards the
bottom. Filled the can with gas with a hose, light the gas coming from
the hole at the top. As it burns, air goes in the side hole until the
mix inside is dilute enough, upon which the flame flashes back,
ignites the mix, and the can hits the ceiling with a satisfying bang.
Don't try this at home! Before you try this at home, remember that the
gas must be lighter than air for this to work, so propane and butane
are out.
Thomas Prufer
Chris J Dixon
>Yes i think ive seen this demo before also. I come across many large
>installations whereby people are carrying out work or are about to
>carry out work without any regard for the need to purge.
>The problem is when it does go wrong and the larger the
>installation,the greater the chance of a mishap.
>
Large power stations use Hydrogen for cooling the main
alternators. On before and after maintenance they are purged
using CO2.
A power station which had been extended only had a regulating
valve in the hydrogen line where a shut-off valve should have
been. After some maintenance work, having been boxed up again,
the electrical kit was high-voltage tested. Enough hydrogen had
seeped past the inappropriate valve for there to be a significant
explosion.
Chris
--
Chris J Dixon Nottingham UK
chris...@easynet.co.uk
Have dancing shoes, will ceilidh.
Lee
>
> Large power stations use Hydrogen for cooling the main
> alternators. On before and after maintenance they are purged
> using CO2.
>
>
> --
> Chris J Dixon Nottingham UK
> chris...@easynet.co.uk
>
> Have dancing shoes, will ceilidh.
I'm intrigued, what is the advantage of using Hydrogen as a coolant over
other gases?
Lee
Lee
Chris J Dixon wrote:
There is a link to (this ?) incident here:
http://www.abcnews.go.com/sections/us/DailyNews/blast990409.html
Lee
Tony Williams
Lee <lee.b...@virgin.net> wrote:
> I'm intrigued, what is the advantage of using Hydrogen
> as a coolant over other gases?
A very high conductivity of heat, 7x that
of ordinary air.
--
Tony Williams.
Lee
Tony Williams wrote:
Thanks! I thought it would need to be a good reason since there
are obvious disadvantages to using it as well :-(
Lee
Chris J Dixon
>The message <3A991AEA...@virgin.net>
> from Lee <lee.b...@virgin.net> contains these words:
>
>> > Large power stations use Hydrogen for cooling the main
>> > alternators. On before and after maintenance they are purged
>> > using CO2.
>
>> I'm intrigued, what is the advantage of using Hydrogen as a coolant over
>> other gases?
>
>So am I. Back in the 60s the largest generators English Electric
>built were water cooled.
>
I have worked on both EE and AEI 500 MW alternators. The stator
windings have water cooling. The whole alternator housing is
filled with hydrogen from which the heat is extracted by a number
of water-filled cooling matrices.
Despite all the No Smoking notices, I was surprised to see a guy
stationed next to an operating set being kept warm by one of
these flame-throwing paraffin heaters.
Chris
John
> Adam wrote:
> >"Ian White" <I...@ifwtech.com> wrote in message
> >news:k9ffW8A9...@ifwtech.plus.net...
> >
>
here the
proceedure as laid down in the VIPER "GAS POINT" training booklet which is
used for the ACS assessments.
For clarity a single pipe system is illustrated but where branch pipes are
present these will require purging also. Large systems will obviously
require due allowance for the increased pipe volume.
PURGING
Whenever a gas supply is made avaiable to an installation the person
making it available must ensure that all air and gas other than the gas to
be supplied is purged from the installation.
New installations and existing installations that are being commisssioned
must be purged of all air and gas/air mixtures.
THE FOLLOWING CONDITIONS APPLY:
A satisfactory soundness test must precede the purge.
No gas must be allowed to build up in a confined space.
No operation of any electrical switches, e.g. light switches, electrical
appliances etc.
No smoking or other possible ignition source is allowed in the proximity of
the purge area.
Normally a gas installer will need to purge an installation which is fed by
a meter, which measures the gas consumption by displacement. To enable the
correct purge volume to be calculated the badge capacity of the meter is
required. The volume of the meter is shown on the meter badge plate. This
can be found stamped on the front of the meter or more commonly on the
panel which houses the registration dials. A typical example is given where
a U6 meter has a volume of 0.071 ft^3/revolution (of the inner measuring
device not the test dial).
U6 meters commonly measure in cubic feet.
The purge volume is taken as five times the badge capacity. This is based
on four times the capacity for clearing the meter and it has been found
that with very few exceptions the fifth volume is adequate to ensure
clearance of the pipework in a domestic premises.
PURGE PROCEDURE
Tell the customer/occupier that purging of the gas supply is being
undertaken and draw attention to the no smoking/ignition sources
requirement.
Calculate the purge volume (from above 5 x badge capacity) In the case of
the example this will be 5 x 0.071 = 0.355 ft^3
This figure is the minimum amount of gas that should pass through the meter
to purge the meter and installation.
Ventilate the area by opening doors and windows.
Ensure the emergency control at the meter and any appliances, including
pilot lights are turned OFF.
Open a point furthest from the meter.
Turn ON the gas and allow the correct amount of gas to pass through the
meter as indicated by the index reading on the meter. On reaching the
correct quantity turn OFF the gas
On completion of the purge, seal and if neccessary test the purge point for
gas soundness with leak detection fluid.
Relight all appliances, if fitted, ensuring they burn correctly
(allow any gas to clear the property via the ventilation before doing this)
If when relighting an appliance an obvious defect is found the approriate
action must be taken for an unsafe situation.
PURGING A U6 ELECTRONIC METER
Because of the low volume of gas actually contained in an E6 meter it is
only neccessary to pass a volume of 0.010 cubic meters of gas through the
meter to purge it fully. Due allowance again being made for the pipework
system.
M.J.Powell
<r.ch...@zetnet.co.uk> writes
>> > alternators. On before and after maintenance they are purged
>> > using CO2.
>
>> > --
>> > Chris J Dixon Nottingham UK
>
>
>> other gases?
>
>built were water cooled.
But not when I worked for them in the late 40s.
Mike
--
M.J.Powell
Ian White
>Just to set the record straight for everyone else in this group I quote
>here the
>proceedure as laid down in the VIPER "GAS POINT" training booklet which is
>used for the ACS assessments.
>For clarity a single pipe system is illustrated but where branch pipes are
>present these will require purging also. Large systems will obviously
>require due allowance for the increased pipe volume.
>
>PURGING
>Whenever a gas supply is made avaiable to an installation the person
>making it available must ensure that all air and gas other than the gas to
>be supplied is purged from the installation.
>New installations and existing installations that are being commisssioned
>must be purged of all air and gas/air mixtures.
>
>THE FOLLOWING CONDITIONS APPLY:
>
>A satisfactory soundness test must precede the purge.
>
>No gas must be allowed to build up in a confined space.
>
>No operation of any electrical switches, e.g. light switches, electrical
>appliances etc.
>
>No smoking or other possible ignition source is allowed in the proximity of
>the purge area.
>
[...]
>
>PURGE PROCEDURE
>
>Tell the customer/occupier that purging of the gas supply is being
>undertaken and draw attention to the no smoking/ignition sources
>requirement.
>
>Calculate the purge volume
[...]
>
>Ventilate the area by opening doors and windows.
>
>Ensure the emergency control at the meter and any appliances, including
>pilot lights are turned OFF.
>
>Open a point furthest from the meter.
>
>Turn ON the gas and allow the correct amount of gas to pass through the
>meter as indicated by the index reading on the meter. On reaching the
>correct quantity turn OFF the gas
Thank you - that's very interesting. What is most interesting is the
vagueness about safe venting and disposal of what comes out of the pipe.
In particular the requirement to
>Ventilate the area by opening doors and windows.
is very vague.
How many doors and windows? How long for? How is the engineer supposed
to ensure that the gas/air mixture is going outside, and not further
into the building?
Above all, how can the engineer rely on the occupier to eliminate all
sources of ignition; and how is he supposed to ensure that it is safe to
re-light the appliances and pilots?
I really would like to see a detailed hazard assessment of that
procedure!
Ian White
Abingdon, England
John
> John Wrote - and apologies for quoting almost all of it:
>
> >Just to set the record straight for everyone else in this group I quote
> >here the
> >proceedure as laid down in the VIPER "GAS POINT" training booklet which
is
> >used for the ACS assessments.
SNIP
>
>
> Thank you - that's very interesting. What is most interesting is the
> vagueness about safe venting and disposal of what comes out of the pipe.
>
> In particular the requirement to
> >Ventilate the area by opening doors and windows.
> is very vague.
How so? either there is ventilation or there is not. Please also bear in
mind the actual volume of gas released as a proportion of the total volume
of the room even unventilated and its dispersed percentage of the total and
the LEL (lower explosive limit)
>
> How many doors and windows? How long for? How is the engineer supposed
> to ensure that the gas/air mixture is going outside, and not further
> into the building?
Common sense is required and if you have not got that you really should not
be working on a gas system at all. I was asked in this group about two
years ago for prging info and at the time I said I was not too sure about
encouraging this activity to the untrained. It was only the fact that
various "opinions" were being aired here that prompted me to put the
"proper" (in one training manual at least) procedure down now.
>
> Above all, how can the engineer rely on the occupier to eliminate all
> sources of ignition; and how is he supposed to ensure that it is safe to
> re-light the appliances and pilots?
He cannot rely absolutely on any human but having explained that he is
purging live gas and pointed out the risks he can only hope the occupier
has SOME sense. Personally I like to exclude the occupier from any area
where I am purging by suggesting they stand outside my defined area during
the operation. Better still send them out shopping!
>
> I really would like to see a detailed hazard assessment of that
> procedure!
"detailed hazard assessment"? - Various tomes could be written on this
theme - I haven't got the time to do this on an unpaid basis and still pay
my mortgage :-)
Ian White
>> vagueness about safe venting and disposal of what comes out of the pipe.
>>
>> In particular the requirement to
>> >Ventilate the area by opening doors and windows.
>> is very vague.
>
>How so? either there is ventilation or there is not.
Come on...
>Please also bear in
>mind the actual volume of gas released as a proportion of the total volume
>of the room even unventilated and its dispersed percentage of the total and
>the LEL (lower explosive limit)
I'm well aware of that. What worries me is the total uncertainty about
the gas concentration that this procedure is allowing to be created in
the room.
>>
>> How many doors and windows? How long for? How is the engineer supposed
>> to ensure that the gas/air mixture is going outside, and not further
>> into the building?
>
>Common sense is required and if you have not got that you really should not
>be working on a gas system at all.
I totally agree with that, but it seems that a procedure that relies
entirely on "common sense" is a poor safeguard against creating a very
dangerous situation.
[...]
>>
>> I really would like to see a detailed hazard assessment of that
>> procedure!
>
>"detailed hazard assessment"? - Various tomes could be written on this
>theme - I haven't got the time to do this on an unpaid basis and still pay
>my mortgage :-)
I certainly wasn't suggesting that you should do it... but I hope that
somebody, somewhere has.
Ian White
Abingdon, England
Adam
have a hose and flame trap to the outside. If a building can't be
adequately vented or the power switched off then you purge to outside. See
The BES catalogue for the equipment to do it. They have a section on gas
purging equipment.
One thing is certain, you don't keep relighting pilots and hope. You use
the meter dial to calculate the time needed to purge. Simple really.
cyberf...@gmail.com
> Can anyone explain please what exactly is meant by "purging a gas pipe" and
> how does one go about it ??
>
> .
>
> Sam
any body can dance...!!!!
meow...@care2.com
> On Wednesday, February 21, 2001 1:10:19 AM UTC+5:30, Sam Farrell wrote:
> > Can anyone explain please what exactly is meant by "purging a gas pipe" and
> > how does one go about it ??
Purge it of gas by blowing air thru it.
NT
Matty F
Onetap
> In article <3A991AEA...@virgin.net>,
> of ordinary air.
>
> --
> Tony Williams.
I'll have to look it up now.
