Permissable Drop?

[novicegas]

Question? You install new pipework (changing a downstream anaconda for 22 copper), on tightness testing following the install there is a 0.16MBar drop. Measured via a Gas analyser, after some remedial work (further tightning comp joint, more solder etc) this drops to 0.07mbar over two mins. Does this pass or not? and consider before you reply if a normal U-guage had been used.

 

[mcniven]

do the test with a normal ugage.

 

[diamondgas]

What was the drop before you undertook any work?

Anything less than 0.5mbar recorded electronicaly is tight I do believe ... or is it 0.25mbar? Either way what you're describing is a pass IMO Unless there's smell reported of course

 

[gaspastemania]

Doesnt temperature help alter readings??
I always prefer u gauge ,water dont lie .

 

[Barry98]

was there a smell of gas ?

 

[CMairiD]

What was the drop before you undertook any work?

Anything less than 0.5mbar recorded electronicaly is tight I do believe ... or is it 0.25mbar? Either way what you're describing is a pass IMO Unless there's smell reported of course

Perceptible movement on an electronic gauge is 0.25 if gauge reads to two decimal places or 0.2 if it reads to one place.

Water is 0.5.

 

[plumbdoctor]

obv the correct answer is fail, but if you was to turn up to that installation a week later it would pass with no smell of gas and applainces connected, tough call buddy

 

[tamz]

It is fine on both counts as less than 0.25 is classed as no perceptible movement. It is good that you asked tho I think you need another wee read through your books. It is all explained there.
Tightness testing is one of the most paramount things a gas operative does and you should be able to interpret the results without thinking.

Next time you do a test with an electronic gauge hold your hand on the pipe and see what happens.

 

[diamondgas]

Perceptible movement on an electronic gauge is 0.25 if gauge reads to two decimal places or 0.2 if it reads to one place.

Water is 0.5.

Cheers M'dear It's been nearly a year since I re done my ACS and the figures soon disappear into the ether!! lol

 

[CMairiD]

Nae bother! Have a talent for retaining esoteric information but still don't know my right from my left. Go figure!

 

[diamondgas]

Nae bother! Have a talent for retaining esoteric information but still don't know my right from my left. Go figure!

LOL ... well that brings to mind a female apprentice who never got the hang of male and female threads ?? I'd bet to this day she's still pushing beads of sweat trying to undo fittings!! LOL

Thanks for the back-up though, appreciate it

 

[Pssst]

Theoretically,no installation can be proved sound with 100% certainty unless you take account of atmospheric pressure and ambient temperature.

 

[plumbdoctor]

haha always one to throw a spanner in the works but good point

 

[gasmarc]

No drop allowed on new pipework or have i being doing it wrong , I have had a drop on a system before and got transco out and they could not find a problem

 

[tamz]

No drop allowed on new installation or existing if only pipework.
You are allowed what is called not perceptable movement which is 0.25mb on a u gauge, 0.25 on a electronic gauge with 2 decimal points and 0.2mb on an electronic with 1 decimal point. This as Pssst said, is to cover small movements caused by temperature and pressure changes.

Also never do a tightness test soon after soldering as it will show as a drop as the pipe cools.

 

[keltoyboy]

here in ireland we are not allowed to use anything electronic to do tightness testing only u gauge or j gauge...and any drop is classed as a fail on new pipework or alteration's to existing pipework....but if in doubt why not use your gas sniffer as they are super sensitive, especially around joints /fittings....!!

 

[GQuigley67]

100% allowed 0.25mbar drop

the one thing i drilled into my head was how to do a tightness test, this is the most important thing you do in gas, if i didnt know this i would be flapping all the time about a 0.25mbar drop

 

[gasmarc]

I flap about a 25mbar drop lol

 

[bantamgas]

I flap about a 25mbar drop lol

I'd bloody flap about a 25 mb drop too,i'm guessing you mean .25mb.

 

[gasmarc]

I am being silly:gettree: