DIY Pressure Testing for Rain Leaks

SaltDawg wrote:
westend,

There is no answer to your question. Or, more correctly, any capacity fan would work... just a question of how long it would take.

Given zero leakage and 1600 Ft*3 volume, there is a volume of air in CF to add that would raise that pressure .2 psi... that is not CFM, simply CF.

If my arithmetic is correct, using Boyle's Law one would need to add ~21.5 Cu Ft of air at STP. Note, this is not a rate in CFM, just a volume of added air to raise the pressure.

Just intuition, and no RV experience, but experience with compartment air tests on submarines, I believe that an RV is going to be very leaky and one will need a much larger fan then some have opined.

Again, no experiece with RVs.

Thanks, that is more knowledgeable than anything I could have written.

Togger wrote:
I have done some research today regarding static pressure capability of carpet dryers (also called air movers).

From the spec sheet for Dri-Eaz air movers:

Sahara Pro X3 .25 HP 2700 max CFM. 1.28 max static pressure
Sahara HD 1.0 HP 3500 max CFM. 2.75 max static pressure

As the horsepower increases, the ability to create static pressure increases much more than the volume of air moved by the blower.

I am thinking that the horsepower of the motor is quite important to build adequate pressure. The .25 HP unit would probably lose so much CFM as it worked against the building pressure that it would never maintain adequate air flow and pressure to accomplish a test, especially in a large unit with more air leakage.

It may also be that the larger unit has a bigger cage or vane than the smaller. hence, more air delivered. Using my furnace blower, I don't notice any drag on the motor or cage but I'm sure there is some, once the air inside reaches a certain pressure.

ISTR a Forum member that used the Harbor freight $80 Portable ventilator with success. Again, just from a foggy memory, he had a plastic duct and introduced the air into a storage compartment. I'll try to dig up that thread.