YOKOGAWA Dpharp vigilantplant EJA Series, Manual, Page: 21 / 40

<4. Installing Impulse Piping>
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IM 01C22A01-01E
4. Installing Impulse Piping
4.1 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 piping, or the drain of a gas-filled impulse piping
becomes plugged, the impulse piping will not convey
the pressure accurately. Since this will cause errors
in the measurement 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 the
transmitter.
4.1.1 Connecting Impulse Piping to the
Transmitter
(1) Check the High and Low Pressure
Connections on the Transmitter (Figure 4.1)
Symbols “H” and “L” are shown on a capsule assembly to
indicate high and low pressure side. Connect the impulse
piping to the “H” side, and the low impulse piping to the
“L” side.
F0401.ai
Pressure
connection
“H” and “L” are shown
Process connection
Process connector
Bolt
Figure 4.1 “H” and “L” Symbols on a Capsule
Assembly
(2) Changing the Process Connector Piping
Connections
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 the impulse piping with the
process connectors when connecting the piping.
57 mm 54 mm 51 mm
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Figure 4.2 Process Connector Impulse Piping
Connection Distances
(3) Tightening the Process Connector
Mounting Bolts
After connecting the impulse piping, tighten the process
connector mounting bolts uniformly.
(4) Connecting the Transmitter and 3-Valve
Manifold (EJA110A)
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 transmitter zero point.
There are two types of 3-valve manifold: 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
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Nipple
Nipple
Process
connector
Ball head
lock nut
Pipe
Ball head
lock nut
Process connector
bolts
50 mm(2-inch) pipe
Pipes
3-valve
manifold
Impulse piping
Vent plug
(optional)
Stop valve
(low pressure side)
Equalizing valve
(balancing)
Stop valve
(high pressure side)
Figure 4.3 3-Valve Manifold (Pipe-Mounting Type)
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.)
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