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What is size tubing is required to get a gage visual response ?

What is size tubing is required to get a gage visual response ?

What is size tubing is required to get a gage visual response ?


I am using the 2025 model Dwyer gage in a 1/4" dia tube system that can be in tube lengths of 50 ft to 600 ft.
I would like to know what tubing diameter allows the Dwyer gage to show changes in pressure when the changes in differential pressure are as small as 1" water pressure.   
My concern is that the tube I am using now may be smaller than needed for the tube lengths required.
I included a pneumatic diagram (see attached PDF) showing components and tubing sizes with approximate lengths.  Can anyone tell me what is the proper tube size in order for the Dwyer gage to respond within seconds of a change in differential pressure at the end of the long (50-600 ft) tube of 1" water  ?
I have included detailed information of the system to hopefully answer all your questions and information requests


RE: What is size tubing is required to get a gage visual response ?

It depends on whether actual water is present.

If the system is full of dry gas, the tubing can be almost arbitrarily small because the flow associated with a pressure change is very small.

Some of my friends made up a nice data collection system for boat exhausts (hot gas + water) using 1/8" OD plastic tubing, which is easy to route, easy to terminate, doesn't take up much space even in big bundles, and is cheap enough to throw away after a single test.  Unfortunately, a single droplet of water in a tube of that size makes the manometer 'sticky', and several drops can stop it from responding at all.   I like to see a minimum .25" bore throughout such a system, at least at the wet end.


Mike Halloran
Pembroke Pines, FL, USA

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