Yokogawa EJA115 - Manual (Page 24)

<4. Installing Impulse Piping>
22
IM 01C22A01-01E
4.3 Process Piping Installation
Precautions
4.3.1 Connecting Process Piping to the
Transmitter
(1) Confi rming the Process Fluid Flow
Direction
The mark “ ” on the manifold indicates the direction in
which the process fl uid is fl owed (from right to left).
When connecting the process piping to the process
connector, confi rm the process fl uid fl ow direction.
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Flow direction (from right to left)
Manifold
Orifice name plate
Process connector
(low pressure side) Process connector
(high pressure side)
Process connection
(outflow side) Process connection
(inflow side)
Figure 4.9 Manifold and Flow Direction Indication
(2) Tightening the Process Connector
Mounting Bolts
The transmitter is shipped with the process connector
mounting bolts only loosely tightened. After connecting
the process piping, tighten these bolts uniformly to
prevent leaks with a torque of 39 to 49 N·m {4 to 5 kgf·m}.
(3) Removing the Process Connector Port
Dustproof Cap
The process connector port threads are covered with a
plastic cap to exclude dust. This cap must be removed
before connecting the piping. (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.)
4.3.2 Routing the Process Piping
(1) Relationship between Process Fluid
and Manifold Locations (For the vertical
impulse piping type)
If condensate (or gas) generated in the process piping
were allowed to accumulate, then it would be necessary
to remove it periodically by opening the drain (or
vent) plug. However, this would generate a transient
disturbance in the pressure measurement. Therefore, the
process piping must be routed so that any condensate (or
gas) generated in the process piping will not accumulate
in the pressure-sensing assembly of the transmitter.
NOTE
• If the process fl uid is a gas, then as a rule the
manifold must be located at the downside of the
pressure-sensing assembly.
• If the process fl uid is a liquid, then as a rule the
manifold must be located at the upside of the
pressure-sensing assembly.
(2) Pipe Size for Process Piping
Use a 15 mm (1/2-inch) pipe for process piping
connection to the process connector.
(3) Preventing Freezing
If there is any risk that the process fl uid in the transmitter
pressure-sensing assembly could freeze, use a steam
jacket or heater to maintain the temperature of the fl uid.
(4) Process Piping Connection Examples
Figure 4.10 shows examples of typical process piping
connections. Before connecting the transmitter to the
process, study the transmitter installation location, the
process piping layout, and the characteristics of the
process fl uid (corrosiveness, toxicity, fl ammability, etc.), in
order to make appropriate changes and additions to the
connection confi gurations.
Note the following points when referring to these piping
examples.
• The process piping material used must be compatible
with the process pressure, temperature, and other
conditions.
• A variety of process piping-mounted stop valves are
available according to the type of connection (fl anged,
screwed, welded), construction (globe, gate, or ball
valve), temperature and pressure.
Select the type of valve most appropriate for the
application.
Gas flow measurement
Liquid flow measurement
Union or flange
Union or flange
Stop valve
Stop valve
Manifold
Manifold
Process piping
Process piping
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Figure 4.10 Process Piping Connection Examples
(EJA115)