IM 01C25R01-01E
6-1
6. INSTALLING IMPULSE PIPING
6.
INSTALLING IMPULSE PIPING
6.1 Impulse Piping Installation
Precautions
The impulse piping that connects the process outputs to
the transmitter must convey the process pressure
accurately. If, for example, gas collects in a liquid-
filled impulse line, or the drain for a gas-filled impulse
line becomes plugged, it will not convey the pressure
accurately. Since this will cause errors in the measure-
ment output, select the proper piping method for the
process fluid (gas, liquid, or steam). Pay careful
attention to the following points when routing the
impulse piping and connecting the impulse piping to a
transmitter.
6.1.1 Connecting Impulse Piping to a
Transmitter
(1) Check the High and Low Pressure Connec-
tions on the Transmitter (Figure 6.1)
Symbols “H” and “L” have been placed on the capsule
assembly to indicate high and low pressure side. With
differential pressure transmitters, connect the high
pressure side impulse line to the “H” side, and the low
pressure side impulse line to the “L” side.
With gauge/absolute pressure transmitters, connect the
impulse line to the ‘H’ side.
F0601E.EPS
Pressure
connection
“H” and “L” are shown
Process connection
Process connector
Bolt
Differential Pressure Transmitter
Figure 6.1
“H” and “L” Symbols on a Capsule
Assembly
(2) Changing the Process Connector Piping
Connections (Figure 5.1)
The impulse piping connection distances can be
changed between 51 mm, 54 mm and 57 mm by
changing the orientation of the process connectors.
This is convenient for aligning an impulse line with a
process connectors.
(3) Tightening the Process Connector Mount-
ing Bolts
After connecting an impulse line, tighten the process
connector mounting bolts uniformly.
(4) Removing the Impulse Piping Connecting
Port Dustproof Cap
The impulse piping connecting port on the transmitter
is covered with a plastic cap to keep out dust. This cap
must be removed before connecting the line. (Be
careful not to damage the threads when removing this
cap. Never insert a screwdriver or other tool between
the cap and port threads to remove the cap.)
(5) Connecting the Transmitter and 3-Valve
Manifold
A 3-valve manifold consists of two stop valves to
block process pressure and an equalizing valve to
equalize the pressures on the high and low pressure
sides of the transmitter. Such a manifold makes it
easier to disconnect the transmitter from the impulse
piping, and is convenient when adjusting the transmit-
ter zero point.
There are two 3-valve manifold types: the pipe-
mounting type and the direct-mounting type; care
should be taken with respect to the following points
when connecting the manifold to the transmitter.
Pipe-Mounting Type 3-Valve Manifold
(Figure 6.2)
1) Screw nipples into the connection ports on the
transmitter side of the 3-valve manifold, and into the
impulse piping connecting ports on the process
connectors. (To maintain proper sealing, wind
sealing tape around the nipple threads.)
2) Mount the 3-valve manifold on the 50 mm (2-inch)
pipe by fastening a U-bolt to its mounting bracket.
Tighten the U-bolt nuts only lightly at this time.
3) Install the pipe assemblies between the 3-valve
manifold and the process connectors and lightly
tighten the ball head lock nuts. (The ball-shaped
ends of the pipes must be handled carefully, since
they will not seal properly if the ball surface is
scratched or otherwise damaged.)
4) Now tighten the nuts and bolts securely in the
following sequence:
Process connector bolts
→
transmitter-end ball head
lock nuts
→
3-valve manifold ball head lock nuts
→
3-valve manifold mounting bracket U-bolt nuts
