Installation factors that affect pressure transmitter. 1

[insttech]

hi i have a question for you guys, what is an installation factor that affects the pressure transmitter.
What affect would it have on the system and how would correction be achieved.
Regards, Its a question for my studies, help would be greatly appriciated.

 

[khan101]

Dear Insttech,
Here are few important factors that you should consider when buying and installing a pressure transmitter.

In normal practice, we install pressure transmitters with long impulse lines, to facilitate access. Today’s modern transmitters, however, are so much more reliable than older transmitters, that we find that most failures and maintenance are due to these lines themselves. Using short, horizontal impulse lines will reduce maintenance, eliminate hydrostatic head errors and improve dynamic response.

If you and your staff is familiar with smart technology, then buy smart transmitters. They have longer zero stability.

Select a range that your normal pressure falls between 30% and 70% of the total range.

If the installation is in classified area then buy your transmitter approved by a third party lab e.g UL, CSA and etc. according to hazardous area classification.

I am sure other users have few more things to add.

 

[jsummerfield]

I too like close-coupled transmitters but this is not always possible. The significance varies depending upon the pressure of interest and other application details.

Mount the transmitter above the taps for gas, below the taps for liquid. This is very important for very low pressure gas. Howeveer, if the hydrocarbon condensates in 1000 psig service and the transmitter is one meter below the line it will still work. Treat some hot condensible vapors such as steam differently (mounted below the tap) to permit the cool liquid to fill the impulse line as transmitters have a maximum temperature limit. Cryogenic temperatures require the opposite treatment. Mount cryogenic liquid transmitters above the taps to permit lots of ambient to boil off the liquid as a self-bubbler where the transmitter is not rated for cryogenic temperatures.

John

 

[omby]

Another point to bear in mind is that if the impulse lines are full of liquid and are exposed to freezing ambient temperatues then it may be worth lagging and trace heating them.

omby

 

[controlnovice]

Don't forget chemical seals if the product you are measuring is nasty. Most of the new instruments come with seals, but if you need to replace the instrument, a seperate seal, and valve, would be handy.

 

[ilan7]

Instalation errors are when measuring low pressure and diferential pressure.
1. Instrument range must be close to the measured value.
2. When measuring gas - the instrument need to be above the measuring line/tank. If neasuring DP, instrument usually under the pipe with the lines full with liquid.
2. When measuring liquid anways have the instrument under the process measuring point with the line full with liquid.

When measuring low pressure or Dif. Pressure, after completing the installation, the transmitter must be zero to eliminate the effect of static pressure.