- #1
rdy4trvl
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I'd like to calculate the change in air pressure within a long tube - like the driveway hoses at gas stations.
The static pressure is zero, a vehicle drives over the hose and the increase in pressure activates a switch. I'm trying to determine the proper switch size (in PSI).
So, here is my attempt to start solving this (simple) problem...
Thanks
The static pressure is zero, a vehicle drives over the hose and the increase in pressure activates a switch. I'm trying to determine the proper switch size (in PSI).
So, here is my attempt to start solving this (simple) problem...
- The hose is 1/2" (interior diameter) by 20 feet long. I calculate the cubic inches to be 47.1 (3.14 x 1/4 x 1/4 x 240 inches).
- If a vehicle drives over the hose, (say 12" of hose is compressed flat, for simplicity), then the cubic inches become 44.7 (3.14 x 1/4 x 1/4 x 228 inches). (If the two wheels don't hit at the same time, this could certainly change the results...but let's just keep it simple for now - one wheel, evenly compressed hose.)
- Volume of air decreases from 47.1 cubic in (CI) to 44.7 CI...how is this converted to a change in air pressure (assuming 47.1 was at 0 PSI)?
Thanks