MM for pressure test? I have only heard of bar/psi???

[swifters]

Can anyone advise as to the following? I have never heard of mm in a tester before?

Preparation: Temporarily seal open ends of pipework using plugs.
• Testing: Connect a 'U' tube water gauge and pump air into pipework until gauge registers
38 mm.
• Required performance: Allow a period for temperature stabilisation, after which the
pressure of 38 mm is to be maintained without loss for 10 minutes.

Many thanks

Jon

 

[justlead1]

Hi When testing soils and vent installations inches water gauge was the units used now we are using the metric system Milli Metres is the call perhaps (38 mm being about 1.1/2")

 

[swifters]

Yes, but this is a pressure reading? Never heard of that as a pressure gauge before...

 

[billybob150811]

you would be usuing a standard 4in water gauge not a pressure gauge i have always understood the test to be 38mm for 2min where did you get the info its for 10min

 

[Nat]

As I understand it 38 millimeters above the zero reading on your guage. Haven't got my u-guage to hand but maybe 5 millibar? Is this a soil test? 10 mins seems very long to me. I usually do a couple of mins.

 

[kay-jay]

hmmm i thought it was 38 mb

i stand corrected. nat is correct that it is 38mm above the zero level on the guage.

should be tested for at least 3 minutes according to building regs document H1


KJ

 

[xsjadofred]

It's 38mm because that's the depth of most trap seals.. If you test higher you can blow the water out of the traps and your test wont work 🙂

 

[billybob150811]

the depth of a trap is 75mm its 50mm for a wc and shallow seals can go down to 38mm but this has raised a question i have thought of before the cross sectional area of a test gauge is only 1 or2mm it seems whereas a 35mm trap is pi r\2 so i dont see how a trap can blow if the test is higher but your thought,s are sought on this matter its should be added this is the standard test i have had it in the spec at 60mm for five min and the test was fine although this only had 75mm deep traps on it

 

[xsjadofred]

Indeed I have thought the same thing however im sure that is the reason it's 38 mm that is what college nd my mentor told me anyway next time I do one I'll ser how high I cab test. It before a 38mm trap goes !!

 

[Nat]

Personally I wouldn't worry too much about it. On a first fix test you'e not going to have any traps anyway. Open ends will be bunged off so you can put as much pressure as you want in there (within reason!). I usually go about half way up the guage. You can tell pretty quickly if.its dropping. Nobody is going to care if you tested it with slightly more pressure than you needed to! On a final soil test with showers, basins connected I don't even bother with a guage. Just fill the pan until one of.the traps start blowing and you know you're there then just watch the level of the water in the pan.Honestly don't start stressing too much about getting 38mm on your guage you'll be.messing around for ages. Also wouldn't worry too much about times either. Every building inspector I.have performed tests for has been happy if.it holds up for about a minute or so.

 

[billybob150811]

agree with nat completely dont stress it The full test is 3 min in days of old it was called a 2 min test because you flushed the wc if it held steady the test lasted till the cistern refilled that was it Building inspecters are busy so let them make it as short as possable you dont need a gauge a slither of wood thrown in the wc will rotate clockwise if the water is going down dont do that unless they say its going down and it isnt you,ll know soon enough if he isnt a nice guy and there nothing you can do about that so why worry