the fabricated U-tube
sensing tube / not shown is abt 1/8 dia ... i tested with a 20 foot run of sensing tube and it worked .
the sense tube fits inside a little larger tube , which fits in the biggest tubes , measurement tubes . the *U* at the bottom is the middle size to reduce radius.. filled with water and food color. i used some glue to seal where the water filled tubes joined. first effort leaked . maybe this will not
taped to a card , card with increments marked shoved in behind. Zero calibration is by sliding the increment card up or down
this should work pretty good for the OP ., will measure 10 inches of water over and under pressure. and cost very little
my intent with this device is to measure dynamic pressure at the engine air duct set into the Special Tuning chin fin on this machine.
i measured in the convergent sector of the duct , later intend to measure many other places
theoretical over pressures are :
45 mph = .67 inh20
50 mph=.83 inH20
55 mph =1.0 inH20
65 MPH = 1.4 InH20
78 MPH = 2.01 InH20
measured values in initial test
40 MPH 1.0 INH20 measured
50-55 =2.0 inH20 .. measured
i saw intermittent of 2.5 inh20 [ when i met traffic and hit the bow waves ,, 2 lane blacktop]
2" of water=0.0721 PSI
i will be testing many other places , but that will be another string
should this type of testing seem appropriate to this forum