Answer / www.islamqa.com

They are diffrential pressure transmitter "installation
technique" used in "level measurement"

When installing diffrential pressure transmitter we attach 2
impulse lines with high & low transmitter sides, the 1
attached to low side is empty impulse line so it is "dry
leg" or it's filled with a sealing liquid with density
greater than the process liquid so it is "wet leg".

We use "dry leg" for closed pressurized tank.

We use "wet leg" for closed pressurized tank also but if we
have the probability of process liquid condensable vapor
which will give a faulty measurement.

If we have an open tank, the Tx low side is atmospheric.

Regards,

Ahmed Sabry
Control and Instrumentation Engineer
GPC - General Petroleum Company
CELL.: 00 2 0121367310
ahmedsabry.onine@gmail.com

Answer / heri santoso

Dry and Wet leg are process connection of dp cell level
instrument used in close tank
(Wet leg)Where leg impulse connection of tx contained fill
(difference SG)with process fluid in tank.fill is a
parameter reading of tx tranduser
(Dry leg)where leg impulse connected to atm no fluid in leg
connection

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