Impulse piping
Impulse piping
(OP)
We have a tail end SCR Gas/Gas heater and wish to measure the pressure at the cold and hot end of both the treated and untreated sides.The problem is that the treated gas hot end is 170'C and the pressure transmitter is only good for 120'C. is there a way to work out how much impulse tubing is need to reduce the gas temperature reaching the instrument. I know the gas is static if that helps?
thanks very much
thanks very much





RE: Impulse piping
For formula,
heat transfer is given by q=m*Cp*delt, m= flow rate of gas, cp = specific heat of gas and delt = 170-120=50
Once u have got the amount of heat(q) to be removed, use it in q=h*a* delt, h= 25 W/m2-K ( still air) a= to be determined and delt= ( average wall temperature - ambient air). take a swag at wall temperature to be average gas temperature( 170+120/2= 145C)
The surface area is the outer surface area of the tubing. You can calculate length based on your tubing size.
Hope this makes sense.
RE: Impulse piping
If there are fast pressure transients, then you can also fashion the tube to act as a helmholz resonator or snubber to filter out the transients.
"Nobody expects the Spanish Inquisition! "
RE: Impulse piping
RE: Impulse piping
There are a bunch of them out there. Rosemount, Anderson-Greenwood, Hoke, Swagelock, Parker among others. I have my favorite but I don't think I can say on this forum.
RE: Impulse piping
RE: Impulse piping
I doubt there's any realistic risk of plugging, but you do have to concern yourself with condensate formation. You can either ensure that the legs are self-draining, or you can try to drain them periodically- as long as you're in a non-freezing environment.