from the instrumentation department...
Remote seal level transmitter
Engineering and workplace issues. topic
Posted by Rajesh on 9 July, 2009 - 8:47 am
Under which circumstances we will go for HP side flange mounted and LP side remote seal type transmitter? What is the difference between two side (Both LP & HP) remote seal transmitter and the earlier one?

Posted by Sushant Chanana on 9 July, 2009 - 11:29 pm

Earlier in the conventional DPT installation,usually one connect HP side directly via flange & LP side via impulse tube of 6 mm (usually copper).This kind of arrangement one can find where in the process media is not viscous e.g in boilers.

But if we need to measure DP where either the media is viscous enough to block the impulse line or the process is under vacuum conditions which can result in the leakage in the process e.g Batch pans in sugar industry.

In both cases we need remote seal at LP side.

But since we are using capillary filled with silicon oil,which has its own vapor pressure,so to tune the system and for better accuracy two seal systems are more prevalent nowadays.

However the remote seal do have some disadvantages like prone to temperature induced errors.So,proper selection of capillary fluid media is required as per your process.

Small spans are difficult to measure & response time got delayed due to longer capiliaries.

In case of any query please feel free to contact.

Sushant Chanana
sushant.chanana [at]

Posted by Roy Matson on 10 July, 2009 - 3:09 am
A typical example might be a steam condensate tank outside in freezing conditions. By using a remote seal you can avoid having to heat trace the LP side which otherwise would fill up with condensate and freeze.

Personally I try to avoid them wherever possible, they are expensive, easily damaged and more difficult to calibrate


Posted by Jari on 11 July, 2009 - 8:44 am
We have used such type transmitter configuration for liquid measurement for Liquid where boiling point of liquid was less than 40 Deg C. Incidentally I belong to country INDIA. Ambient temp is 40-45 deg c, EVEN THE CATCH POT DOES NOT HELP US.

We wanted to use Radar LT, but die-electric constant was not known & hence we have avoided the RADAR.

But DP xtrs did give us good performance & still working well.

iconcnl [at]

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