DWV Vacuum Test - How I did it.

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This site has been incredible to me for years and here is my chance to contribute.

Here in Columbus, OH, positive pressure testing is not available for rough inspection and in my case, I did not want to perform a test with water as failure would result in water damage to the existing interior (my project was a new room addition). The city described the test requirements to me; however, did not provide guidance on how to perform the test. I was able to figure it out and wanted to post this in hopes that it may help future readers.

This thread got me started down the right road, but not quite to the finish line: https://terrylove.com/forums/index.php?threads/dwv-vacuum-test.101382/#post-755774

I needed plugs to seal up the roof vent and the toilet flange, a cleanout seal, a ball valve to cut the suction quickly, a plug with a blow-out stem, a FNPT coupling, and a vacuum gauge. The plugs and cleanout seal were easily obtained and installed. The tire pressure inflator I use for my vehicles made inflating the seal to the proper pressure a breeze. I found a PVC ball valve at the big box store and screwed it onto the trap adapter with Teflon tape. I found a negative pressure gauge on Amazon, but the pool plug with a blow out stem had a Schrader valve on it and had to be returned. This is where I was stumped for a bit. I called Grainger and the product specialist was able to get me a CHERNE Mechanical Expansion Plug: Inside Pipe, For 2 in Pipe, Male 3/8 in NPT Bypass that fit my needs, along with a coupling so that I could attach the gauge.

The test requires -2psi, which I could obtain with my shop-vac; however I found that my vacuum cleaner got me up to -3psi. To perform the test, I reset the pressure in the gauge by using the rubber stopper, used the vacuum cleaner to create the negative pressure, then closed the ball valve. Here are photos of my setup. It was actually quite easy once I had the right pieces and parts.

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Breplum

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Positive pressure option for DWV testing is part of UPC (5 psi). What code allows for negative pressure testing?
 

wwhitney

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Jeff H Young

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Glad you passed , Ive heard of vaccum test but very little and couldnt name any code that specificaly allows it , but there could be some clause of acceptable alternative testing where allowed by AHJ or something . I ran a positive air test in Elko NV back in 94, 95 It mighty have been 5 psi I wouldnt swear by it it was freezing weather thats what the inspector and a local plumber I had working for me said its done there . I see wayne has shared its amended to code to do vac test in ohio
 

MightyKC

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The vacuum test was added to the 2021 IRC.

P2503.5.1Rough plumbing.
DWV systems shall be tested on completion of the rough piping installation by water, by air for piping systems other than plastic, or by a vacuum of air for plastic piping systems, without evidence of leakage. The test shall be applied to the drainage system in its entirety or in sections after rough-in piping has been installed, as follows:

1.Water test. Each section shall be filled with water to a point not less than 10 feet (3048 mm) above the highest fitting connection in that section, or to the highest point in the completed system. Water shall be held in the section under test for a period of 15 minutes. The system shall prove leak free by visual inspection.

2.Air test. The portion under test shall be maintained at a gauge pressure of 5 pounds per square inch (psi) (34 kPa) or 10 inches of mercury column (34 kPa). This pressure shall be held without introduction of additional air for a period of 15 minutes.

3.Vacuum test. The portion under test shall be evacuated of air by a vacuum-type pump to achieve a uniform gauge pressure of -5 pounds per square inch or a negative 10 inches of mercury column (-34 kPa). This pressure shall be held without the removal of additional air for a period of 15 minutes.
 
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