tightness testing

[lion08]

hi guys im not in training but will be shortly was doing some reading on tightness testing nat gas and saw that a let by test is at 10mb for 1min and a tight test is at 20mb for 2min i was wondering what determines these numbers why 10mb for let by? and 20mb for tight test? and is a tight test the same as a standing pressure test ??

thanks in advance.

 

[Agile]

Those figures are correct. The standing pressure is not relevant and is not measured.

But we dont give DIY gas advice on this forum.

If you want to learn about gas you should go on an approved course.

Tony

 

[lion08]

thanks mate will be on a course soon but was just curious as to why these particular measurements ie 10mb and 20mb.

 

[transam]

I remember prior to the acs , when it was acops , lf u did a let bye test at 10 mbar they would have failed you think it was 18 or 19 mbar ?? than !!

 

[commercialman]

Just remember , 4 min test in total , seems we've lost 60sec somewhere along the line.

 

[bengasman]

The 10 mb and 20 mb/ 1 min, 2 min are for the same reasons as the 30 mph speed limit: somebody decided that is how it is.

 

[commercialman]

2 min are for the same reasons as the 30 mph speed limit: somebody decided that is how it is.

Not that simple , these figures are calculated/based on the max volume of 0.035 m3 , commercial tightness testing procedures will obviously differ.

 

[Biggles..]

10mb let by is a general pressure in domestic scenarios based upon 50% operating pressure.The 1 min period varies dependent upon MOP and MIP but thats not relevent in domestic.

tightness testing is normally carried out at 100% opertaing pressure, the tightness test duration is always 2 minutes as a minimum but can be plenty more.
the time is actually calculated based upon the type of gauge being used to carry out the test(GRM), the installation volume(IV) and a constant for the type of tet medium F1.

Minimum of 2 mins is calculated from 1(sg guage) X 0.035(max IV for domestic X 42(F1 for NG)

TTD = IV x GRM x F1.

other varients exist dependent upon pipework routing and its surrounding ventilation.

the temp stabilisation time that you missed also varies dependent , but minimum timing are 1+1+2.

dont think theres anything wrong with you knowing the theory,most of the RGI's probably dont.

 

[bengasman]

2 min are for the same reasons as the 30 mph speed limit: somebody decided that is how it is.

Not that simple , these figures are calculated/based on the max volume of 0.035 m3 , commercial tightness testing procedures will obviously differ.

Put your glasses on dude; I didn't say they were all the same, I said the numbers were arbitrary.


There isn't a technical reason for the numbers e.g. 2 minutes and not 1.5 or 3; it was just somebodies decision. Dito for 4 mb on an old, standard domestic situation; 3 or 5 does not make it more or less dangerous, just a number plucked out of hat.

 

[barkie1]

Lion08 if you can read up on the let-by test . It should tell you what you are testing thus why its 10 and tightness 20. Also consider what is and isn't permissable. The beat advice I can give if you still don't understand is to wait until you are doing death by PowerPoint, or ask the rgi you will shadow as part of your portfolio/training. this is as close to a answer you will get in a open forum, due to health and safety/gas regs.

If you can get hold of a copy of document IGE/UP 1B this will tell all you need to know

All the best with your training.

barkie

 

[adlplumbing]

while at the moment corgi are in my bad books
buy their books

 

[namsag]

10mb for let by is a relatively new thing as in about 10 to 15 years it used to be carried out at zero pressure.
Also in some areas of country meter governors where set at 20 and others at 21 before it got brought under one banner

 

[kpmhw13]

its 10mb due to the fact that it has been published in writing and is the only upto date guide line to follow.

 

[commercialman]

its 10mb due to the fact that it has been published in writing and is the only upto date guide line to follow.

The 10mb let by test doesn't really tell the operative much if anything , the only 'sure' way to test ECV let by would be at the ECV itself.

 

[Aquilani]

The Governor will lock out above 20 mbar so you will not be testing before this including the ECV.