Leak Check when testing

[Rick360]

I have a orifice plate bench that I built about 10 years ago and have used a lot. Before testing a port I always check for leaks on the head/adapter/bench etc by using the smallest orifice range for good resolution. Range changes are all done externally with this type bench.

With a pitot/annubar type flowbench how do you check for leaks before a test? Is there a different range tube or what? I am just curious how this is done on these benches.

Rick

[bruce]

I completely close off the part I am testing to any flow. I crank up the flow depression (which should not show any flow since its all closed off). If my bench shows any flow I know I have a leak somewhere in my setup. I then use a probe connected to a digital manometer to probe any area I think is leaking.

To test the bench itself, I simple put a solid peice of PVC over the hole turn on the bench and turn up the flow depression, if I see any velocity I know my bench itself has a leak somewhere in the piping.

A probe connected to a manometer is one thing everyone should have on their flowbench. You can use it for various things. Mine is simply a peice of stainless steel tubing. I have them in various diameters for getting into any location I need to get.

Hope this helps?

[Rick360]

With some quick calcs I find that if the inclined flow scale is 24" long and the flow range is 300cfm small leaks would be virtually impossible to see without a different scale for leak testing.

Scale Reading(In) Flow (CFM)
.001 1.9365
.005 4.33

Seems this would be very hard to see even .005" movement in a manometer.

Rick

[bruce]

I agree if you do not have fine enough resolution on your scales then you would not see that small a change. If you use a seperate static pressure U-tube manometer with a probe wand you can look for static pressure leaks in your setup. Use it like a "sniffer" and run it around all your connections or mating surfaces you will see differences if its leaking. Personally I use a digital manometer for this which shows .01 changes in static pressure. I only use the "no flow" method for initial setups if it shows flow then I start probing around for the leak. I'm using the FP setup that Mouse sells so I'm not dealing with an inclined water manometer and it shows small changes in flow. But back to your original post, yes seeing small changes is dependant on the scale your inclined manometer uses.

On a side note I plan on working on a simple inclined manometer based on a meter scale to work with a 1-1/2", 2" and 3" PVC style pitot bench. By changing the inclination you will be able to make it work for what ever scale you need with varing resolutions. I plan on taking pics of the setup and offering a kit to build one or have it prebuilt or you can just use my design and DIY. I just started thinking about it this week and picked up some parts today to get started. I've had alot of emails asking for something like this to compliment the other parts I am selling. Not sure how its going to work but I'll keep everyone up to date in another post . . . sorry for hijacking this one.