Naptha High temp. pressure measurement technic

[EngMic07]

Hi Sir,

I have one naptha application noraml process temperature at 500 degC (Vapour Temp). I need to measure the Pressure for this high temp. application.

Limitation part is. I cannot lay tubing. Because long travel tubing temp. reduce will make the naptha solidify.

I have some challenging part.
1. Diaphragm type pressure transmitter cant withstand 500 degC
2. Using impulse line reduce temp. will make the naptha solidify and blocking impulse line.

Any of you guys handle this kind of application before? how you do it? or actual i should use other pressure measurement method.

 

[danw2]

What's pressure range?

A diaphragm seal connected to the pressure transmitter with capillary isolates the process and its temperature from the transmitter.

 

[EngMic07]

Hi Dawn2,

thanks for you reply.

I had checking remote seal specification. Highest with stand temperature for silicone oil inside is only 370 degc. (Some famous brand). But the client design process temp is 500 degC. Reason is to keep the naptha above boiling point..... avoid solidify...

Just wonder. We have other pressure measurement technic for this kind of application?

 

[danw2]

Oops. My mistake. I 'saw' 500°F, not 500°C.

Wika has the highest fill fluid (proprietary) rating I'm aware of and that tops out at 400°C.

 

[rcvonbrecht]

Man 500°C really puts you out there. Are you sure about that spec? Hydrocarbons tend to coke at these temperatures. This is the reason that you can't find reliable fills above 300°C they break down and release vapor which is death to pressure measurement. The gas law takes over at that point.

There are strain gauges that can operate at those temperatures but I don't know of anyone using them in pressure transducers. Also, there are questions about the functional life a strain gauge at those temperatures. I have used them and they are problematic.

 

[wmhlwx]

How about tubing with other liquid filled?

 

[Sanderposthumus]

For thermosolar industry, we have developed a diaphragm seal solution for process temperatures up to 600 degrees C.see Badotherm.com and HTDS ( high temperature diaphragm) seal. Untill now, diaphragm seal technology Goes up to 400degrees C

Let me know in case you wish more information

 

[EngMic07]

Oops. My mistake. I 'saw' 500°F, not 500°C.

Wika has the highest fill fluid (proprietary) rating I'm aware of and that tops out at 400°C.

Hi Dawn,
it ok.. thanks suggestion..

 

[EngMic07]

Man 500°C really puts you out there. Are you sure about that spec? Hydrocarbons tend to coke at these temperatures. This is the reason that you can't find reliable fills above 300°C they break down and release vapor which is death to pressure measurement. The gas law takes over at that point.

There are strain gauges that can operate at those temperatures but I don't know of anyone using them in pressure transducers. Also, there are questions about the functional life a strain gauge at those temperatures. I have used them and they are problematic. [\quote]


Hi rcvonbrecht,

it was study by the process guys. I guess it was theory to keep naptha from solidify, that why they return process temp. in datasheet. and make instrument guys life difficult.

something like strain gauge transducer? I am not sure is that any high temp. application for this.

 

[EngMic07]

New Post wmhlwx (Electrical)
29 May 13 4:08



How about tubing with other liquid filled?

Hi Wmhlwx,

I am not sure about the allowable on other liquid to mix or touch with naptha. But is that and medium can handle 500 degC without vapour?