U-tube scale compensation

[Tony]

You could always fit a much larger bore manometer tube.
That should help considerably with the viscosity problem.

The only other thing that worries me about "exotic" manometer fluids is what happens if you blow the fluid out of the manometer due to an overpressure accident ?
At least water completely evaporates, making any resulting mess disappear.
And water is cheap and available, but it can still be a real nuisance refilling the beast if you are half way through a test.

Some kind of overflow catch tank with automatic drain back would be very high on my priority list if using anything other than water.

[ccm399]

Good thoughts guys.

Happy to report back on the fluid. Tony your are correct, the inclined manometer (with it's larger res. bore) doesn't seem to be effected nearly as much.

So next issue...

This stuff is either really sensitive to temp changes or it is really hygroscopic. Since zeroing the U-tube (and verifying it to be zero a day later) the temp went up a good amount around here. The manometer now reads almost 1" high. My barn had a dehumidifier so I don't believe it is a humidity (hygroscopic) issue but who knows.

at least with water I have to add fluid. That is much easier than draining it...

Back to water for now.

Chris

[Tony]

This stuff is either really sensitive to temp changes or it is really hygroscopic. Since zeroing the U-tube (and verifying it to be zero a day later) the temp went up a good amount around here. The manometer now reads almost 1" high. My barn had a dehumidifier so I don't believe it is a humidity (hygroscopic) issue but who knows.

Could it have been due to thermal expansion ?