Hi temp Differential Pressure gages
Hi temp Differential Pressure gages
(OP)
I have a project where I need to measure air velocity via velocity pressure. The gages that we use now (Magnehelic) have a max temperature tolerance of 140F and the air exhaust can get up to 1000F. I plan on using copper tubing to help dissipate some of the heat but I wanted to know if there was a product out there that could handle a higher temp or any suggestion on better tubing to use





RE: Hi temp Differential Pressure gages
RE: Hi temp Differential Pressure gages
RE: Hi temp Differential Pressure gages
http://www.eng-tips.com/viewthread.cfm?qid=278809
Best to you,
Goober Dave
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RE: Hi temp Differential Pressure gages
RE: Hi temp Differential Pressure gages
That might work, but then - how do you ensure the water fill doesn't boil off unevenly, which it will if there is a pressure differential between the ports, leading to an error in the measurement. Also, depending on the gage, dry or non-condensing gas may be required at the sensor face, which a wet fill won't give (I know most Magne-helic gages, at least the aluminum-bodied style, will corrode horribly if exposed to moist conditions).
RE: Hi temp Differential Pressure gages
RE: Hi temp Differential Pressure gages
If you don't like wet legs and the measurement is continuous (i.e. a dP transmitter rather than a gage), you can try to heat trace the impulse legs to prevent condensation, but your gage/transmitter needs to be able to withstand the condensation temperature in that case. That route often leads to failures in practice.
A pigtail or U trap on both legs, if properly designed, can provide a dry environment to the gage while also providing a constant level of condensate in the impulse legs- by allowing excess condensate to drain back to the source piping as Compositepro mentioned. This is not an ideal option in a freezing environment unless you heat trace the U traps. Imagine, heat tracing something you want to lose heat from?! But if the ambient doesn't fall below freezing, it's relatively maintenance free.
This isn't new stuff- but it's also one of the things that people screw up most often when making DP measurements for flow or level.