Author Topic: Leak down tests  (Read 283 times)

Offline Hgye

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Leak down tests
« on: May 16, 2018, 05:18:14 PM »
I am just wondering if anyone is doing the leak down test on propane systems as per B149.1 6.22.3.

If you are doing it, how exactly are you doing it. 

Thanks!

Offline Admin

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Re: Leak down tests
« Reply #1 on: May 16, 2018, 07:30:35 PM »
Quote
Clause 6.22.3 - After an appliance(s) is connected, the new system shall be tested in the following manner:
(a) Before turning on the gas for the test, a check shall be made to ensure that any opening from which gas can escape is closed;
(b) Immediately after allowing the gas into the piping or tubing system, a test shall be made to determine that no gas is escaping by carefully watching the lowest volume test dial of the meter, or by using a pressure gauge or manometer (fluid, mechanical, or electronic) as specified in 6.22.3 (c);
(c) Where a meter is not provided, a working pressure isolated system (supply shut off) test shall be completed and the pressure shall be measured with either a pressure gauge or equivalent device calibrated to read in increments not greater than those specified in Clause 6.22.2(b), with the following exceptions:
(i) for a system where the working pressure is 0.5 psig (3.5 kPa) or less, the pressure gauge or equivalent device (e.g. a manometer) shall be calibrated to read in increments of not greater than 1 in w.c. (250 Pa); and
(ii) for a system where the working pressure exceeds 0.5 psig (3.5 kPa) but does not exceed 5 psig (35 kPa), the pressure gauge or equivalent device shall be calibrated to read in increments of not greater than 2 in w.c. of pressure (0.5 kPa); and
(iii) For this test the gas supply shall be shut off and the contained gas pressure shall be monitored for leakage indicated by a pressure drop.
(d) The test described in subsections (b) and (c) shall be of a 10 minute duration;
(e) Each appliance connection, valve, valve train, and system component shall be checked while under normal operating pressure with either a liquid solution or a leak-detection device to locate any source of a leak.

On a propane system the second stage regulator should have an outlet port that you can connect a manometer to, the same way you do on a gas valve to test the manifold pressure.  Turn the propane tank on once you have a manometer connected and see what pressure you are getting, E.g. 11" wc.  Then turn the gas off and the pressure should hold.  If the pressure starts to drop it would indicate there is a leak somewhere.

Offline walker

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Re: Leak down tests
« Reply #2 on: May 17, 2018, 05:53:26 AM »
I used a digital manometer before I pulled the plug at the inlet to the gas valve and did the leak down test from there.  I'm not sure if that would be an allowable method or not.

Offline Admin

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Re: Leak down tests
« Reply #3 on: May 17, 2018, 07:18:34 AM »
It should accomplish the same thing doing it at the gas valve as well.

Offline Porcupinepuffer

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Re: Leak down tests
« Reply #4 on: May 17, 2018, 01:41:45 PM »
Yeah the test cap on the regulator looks like an orifice with no hole in the middle on the edge of diaphragm disc. I just do the tests at the gas valve on the furnace. I like to make sure there's no out of spec pressure drop coming into the gas valve. Then I move on to checking the pressure of the furnace gas valve to get it right on the money. Being right there with the manometer gives me no good reason to be at the reg outside.

I usually find myself doing a pressure test of 15 psi and then soaping the rest at working pressures. I find it's the better way.

Offline Hgye

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Re: Leak down tests
« Reply #5 on: May 17, 2018, 03:46:41 PM »
Yeah the test cap on the regulator looks like an orifice with no hole in the middle on the edge of diaphragm disc. I just do the tests at the gas valve on the furnace. I like to make sure there's no out of spec pressure drop coming into the gas valve. Then I move on to checking the pressure of the furnace gas valve to get it right on the money. Being right there with the manometer gives me no good reason to be at the reg outside.

I usually find myself doing a pressure test of 15 psi and then soaping the rest at working pressures. I find it's the better way.

Do you do leak down tests?

Offline Admin

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Re: Leak down tests
« Reply #6 on: May 17, 2018, 04:46:55 PM »
If the pressure test passes, E.g. 15PSI for 15min, then turn on the gas and use soap to test for operational leaks at the valve train or anything downstream of the appliance gas valve.  I'm assuming by leak down test you mean to pressure test a system and come back after 24 hours.  This is not a requirement.  Using nitrogen to do such a test can be misleading as temperature will affect the pressure.

Offline NoDIY

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Re: Leak down tests
« Reply #7 on: May 17, 2018, 05:28:59 PM »
Its a good idea when doing a manometer test to bleed down your line pressure to below your operating pressure. This will ensure your shut off valve is fully closed. I drop an inch or two below operating pressure. And watch for: drop = leak and rise = passing shut off valve.

Offline Hgye

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Re: Leak down tests
« Reply #8 on: May 18, 2018, 06:09:21 AM »
I'm assuming by leak down test you mean to pressure test a system and come back after 24 hours. 

I am calling a leak down test 6.22.3, not a pressure test.

Offline Admin

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Re: Leak down tests
« Reply #9 on: May 18, 2018, 08:45:05 AM »
I do not see the words leak down test in Clause 6.22.3.

They mention a dial test, manometer test, pressure test, soap test or electronic detector test.

Which one of those tests are you trying to do?

Offline Hgye

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Re: Leak down tests
« Reply #10 on: May 18, 2018, 04:46:23 PM »
Sorry, a manometer test.  I was using the local slang.