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6.2 Piping
It is generally recognized that there are appropriate positioning relationship between the
transmitter and main process piping for accurate measurement to avoid harmful gas or liquid
accumulation.
General recognizations are;
1- Mount transmitter below main process piping for liquid or steam measurement.
2- Mount transmitter above main process piping for gas measurement.
The standard style of FCX-CII series transmitter except gauge pressure transmitter correspond to
the piping procedure 1 mentioned above. Change the vent/drain plug to correspond to the piping
procedure 2.
CAUTION
Main valve used for piping should be selected with the maximum pressure of the pro-
cess taken into account (piping parts such as main valve, etc. should be furnished by
user). If the main valve and other parts do not meet the rating, it may result in leakage
of gas or liquid which could lead to a hazard.
LH
Gas measurement
Differential pressure
source is located upper
side of main process piping
Differential pressure
source is located lower
side of main process piping
Differential pressure
source is located upper
side of main process piping
Liquid measurement Steam measurement
Upper
Upper
Lower
Within 45°upward from
vertical direction
Within 45° downward
from horizontal direction
Within 45° upward from
horizontal direction
45°
45°
45°
45°
45°
Lower
45°
Main process piping Differential pressure source
6.2.1 Piping of differential pressure transmitters
Check of high/low pressure sides of transmitter
The detecting unit of the differential pressure transmitter bears
symbols H and L which represent high and low pressure sides,
respectively.
Also, vent/drain plugs are provided at the lower process connection,
while impulse pipes are connected at the upper process connections.
Removal of protective cap
The process connection ports of the transmitter and manifold (equalizer) valve are fitted with
protective caps. Before piping, be sure to remove the caps. When removing the caps, care-
fully protect the threaded portion and sealing face from damage.
Connection of transmitter and impulse pipes
(1) When using the manifold valve, it should be fixed to the transmitter by tightening four oval
flange setbolts (7/16-20UNF), and then the impulse pipe should be connected to the manifold
valve. Tightening torque of 7/16-20UNF mounting bolt should be 30 to 40 N•m (3 to 4
kgf•m).
(2) If a manifold valve is not used, the impulse pipes can directly be screwed into the transmit-
ter. If thread size does not match between the transmitter and impulse pipes, an oval flange
should be used. Tightening torque of 7/16-20UNF mounting bolt in an oval flange should
be 30 to 40 N•m (3 to 4 kgf•m).
Position of process taps (Horizontal main process piping)
The position of the process tap is determined by the relationship between the condition, char-
acteristics and measuring point of the process fluid.
Note the following figures when planning and installing the piping.