PDA

View Full Version : Just registered in, thus newbie. RE's real knowledge reservoir. Great people.







kkwong0
15-05-2011, 12:24 PM
Hi all, Is it possible to convert temperature to pressure units?
For instance, attach a pt100 temperature sensor onto the discharge piping. retrieve the read temperature data and convert to discharge gas pressure reading.

Please advise.

thks

martinw58
15-05-2011, 07:00 PM
this will not ive you gas pressure as the discharge is superheated gas not saturated refrigerant

Magoo
16-05-2011, 04:07 AM
Hi kkwong.
welcome to the forum.
You will need a pressure transducer. Not a PT100.

kkwong0
16-05-2011, 10:12 AM
Glad to know you and thks for your prompt reponse.

Hi Martin, I'm rather agreed with you. even by simply mesuring any vapour mmHG at a 100C boiling point, it gave only 760 (29.92HG) = 14.7 psi, it's far beyond the refrigerant discharge pressure which usually read 200-200 psi (R22). The reason I ask this question is that in my area, people used to say that it's possible to convert temperature reading into pressure reading, but I don't know how they do that. I think it's a myth.

Hi Magoo, thks your your welcome msg. Actually my previous question above was a decoy, sorry!. The true story was: I'm currently developping a PLC based test control system with local and remote scada. I already have Tecsis pressure transducers to measure discharge/suction pressures, but I have also wanted to measure the compressor's oil pressure. Unfortunately I have only a small rack configuration: 3 units of 2hp hermetic compressors (for c.modulation). As you can imagine, it's almost impossible to find dispositive i.e oil pump or nipple installed allowing to fix a pressure transducer on such smal hp compressor (even for semi-herm nowdays). This is the reason why I was looking for alternative means to overcome this issue.

Suggestions and advises from you guys would be highly appreciated.
thanks a lot again Martin and Magoo
Have a nice day.

Chonchon_18
14-07-2011, 07:02 PM
Kkwong0: If you had the space, the NOSHOK 755 would be perfect for you, because it allows you to measure pressure and temperature at the same time with high accuracy. Look here: http://www.noshok.com/755-756_series.shtml

It is very expensive and too big though. Probablyh made for more industrial applications. Anyway, you have Tecsis...they seem to be partners with Noshok, and I have worked with both companies. Give Noshok a shot, they are americans, not germans, meaning they know how to help and sell you the right products!



Glad to know you and thks for your prompt reponse.

Hi Martin, I'm rather agreed with you. even by simply mesuring any vapour mmHG at a 100C boiling point, it gave only 760 (29.92HG) = 14.7 psi, it's far beyond the refrigerant discharge pressure which usually read 200-200 psi (R22). The reason I ask this question is that in my area, people used to say that it's possible to convert temperature reading into pressure reading, but I don't know how they do that. I think it's a myth.

Hi Magoo, thks your your welcome msg. Actually my previous question above was a decoy, sorry!. The true story was: I'm currently developping a PLC based test control system with local and remote scada. I already have Tecsis pressure transducers to measure discharge/suction pressures, but I have also wanted to measure the compressor's oil pressure. Unfortunately I have only a small rack configuration: 3 units of 2hp hermetic compressors (for c.modulation). As you can imagine, it's almost impossible to find dispositive i.e oil pump or nipple installed allowing to fix a pressure transducer on such smal hp compressor (even for semi-herm nowdays). This is the reason why I was looking for alternative means to overcome this issue.

Suggestions and advises from you guys would be highly appreciated.
thanks a lot again Martin and Magoo
Have a nice day.