ALERT: Vacuum Box Pressure Test Requirement Changed!

By October 2, 2017Uncategorized

ASTM D5641/D5641M – 16 has brought a little-known change to the industry standard on vacuum test requirements!

This new ASTM now states “For most cases, a minimum vacuum of 2 to 8 inches of mercury (1 to 4 psi) as registered on the vacuum gauge should be appropriate.” This is a substantial reduction from the “minimum vacuum of 28 to 55 kPa (4 to 8 psi)” required in ASTM D5641 – 94 (2011).

Nearly all of the project specifications our firm has dealt with this year (2017) have required a minimum vacuum test pressure of 5 psi and we have been strictly enforcing that pressure. Of countless installers we worked with, only one pointed out the change in the ASTM requirement, 2/3 of the way through the construction season.

The reduction in required pressure greatly changes the landscape of vacuum testing. Every installation crew we worked with this year did not have a vacuum box that could pull the required 5 psi when they arrived on site! Commonly, a Venturi system is required to meet the 5 psi requirement. In fact, most Shop-vac motors will only pull approximately 2.5 psi, even with a perfect seal.

Whether you are an owner, installer, certifying engineer, or technician in the field, it may be worth looking at what your project specifications say and getting an interpretation on the intent – at the pre-construction meeting or sooner!

I am curious to hear your thoughts on the change. Do you think the pressure is sufficient to adequately find leaks? Have you seen this change already or are people sticking with the age old standard of 5 psi?

Join the discussion 2 Comments

  • Fred Gassner says:

    We require 35 kPa as our standard VacBox suction requirement. Bad idea to reduce required pressure, as extrusion welds are the weakest link in the installed liner.

  • Glen Toepfer says:

    Fred, Thank you for your feedback. I have had several private e-mails/calls that echo your sentiments about the pressure being too low to be effective (and none thus far in support of the reduced pressure).

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