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 ednalds Jan21-13 11:08 PM

Pressure Transmitter Installation at 410 deg C

1 Attachment(s)
Hi,

I have an application of pressure transmitter at 410 deg C max. process temperature. Transmitter can withstand only up to 350 C at Atm pressure.
The original length of tubing for maximum working Temp of 310 C is shown in the attach file (Sketch B) and We are planning to extend the length of tubing
so the temperature will decrease from 410 C (process side) to 350 C or even to 310 C (at transmitter connection). Maximum ambient air temperature is 65 deg C. Maximum pressure we are measuring is 0.6 inH2O.
Is there anyone can help me to have the formula to calcualte the length of tubing, X in the attached sketch A?

Thank you.

Regards,
Edmund

 Ryoko Jan22-13 12:30 PM

Re: Pressure Transmitter Installation at 410 deg C

I don't have an equation to solve your problem, but I can suggest some points to consider. The first is that we don't know the diameter, thickness, or material of the tube. For example, copper conducts heat very well, but stainless steel is not a very good conductor. So this suggests your pickup tube needs to be made from stainless steel. The next issue is that it's not clear if the ambient air is moving or not. Still air is a very poor conductor of heat which suggests you'll need forced air or some sort of heat sink.

I'll suggest a tube made from the smallest diameter stainless steel tube that will work for you, and have it coiled or zig-zagged against a good heat sink.

 ednalds Jan22-13 05:54 PM

Re: Pressure Transmitter Installation at 410 deg C

Hi, Ryoko.

Thanks for the response.

Here the new info I got from our design standard.
Tube Material: 316/316L SS
Tube Diameter: 1" (But we will try to propose 1/2" if needed) Sch 80
OD / ID: 3.34 / 2.43 cm for 1" dia.
2.13 / 1.39 cm for 1/2" dia
Ambient Normal maximum temperature (hottest month) is 44 deg C with an average of 37 deg C. The previous 65 deg C temp is only our design temp.
Maximum basic Wind Speed, 3 sec. gust (at 10 m above ground for 50-year mean recurrence intervals) is 155 km/hr.
The device will be installed at 13 and 14 meters above ground.
New process Temp is 420 deg C instead of 410.
Required Temperature at the end of tubing is 310 deg C.

Coiled or zig-zagged can also help to minimize the space.

Regards,
Edmund

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