Meriam 70H_72H High Pressure Wet Tap Accutubes with Integral 3-Valve Head and Optional RTD - Manual (Page 24)

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4.8.1 MODELS 40H, 41H & 70H WITH DIRECT DP TRANSMITTER MOUNT
HEAD
4.8.1.1 Refer to previous sections of this manual for Accutube-to-process pipe
installation instructions.
4.8.1.2 The direct mount instrument head is designed to allow standard
industrial DP transmitters to be bolted directly onto the Accutube head.
Any transmitter with 2 1/8” center-to-center high and Low-pressure
connections can be used. Height of heads is 2.42". Gaskets are
supplied with the order. Transmitter mounting bolts (by customer)
should be 7/16”-20 UNF x 2 ¾” length.
4.8.1.3 The integral 3-valve equalizing manifold facilitates transmitter
isolation and equalization needs.
4.8.2 MODELS 42H, 43H & 72H WITH DIRECT DP TRANSMITTER MOUNT
HEAD AND INTEGRAL RTD
4.8.2.1 Refer to previous sections of this manual for Accutube-to-process pipe
installation instructions.
4.8.2.2 The direct mount instrument head is designed to allow standard
industrial DP transmitters to be bolted directly onto the Accutube head.
Transmitter with 2 1/8” center-to-center High and Low pressure
connections can be used. Gaskets are supplied with the order. Trans-
mitter mounting bolts (by customer) should be 7/16”-20 UNF x 2 ¾”
length.
4.8.2.3 The integral 3-valve equalizing manifold facilitates transmitter
isolation and equalization needs. Operation is the same as any 3-valve
equalizing manifold.
4.8.2.4 The integral 100 ohm platinum RTD is shipped fully installed into the
internal thermal well. Flexible SS sheath protects RTD wiring outside
the Accutube. Wire termination at the receiver device (typically a
smart multivariable transmitter) is left to the customer. A 5/16" -24
UNF x 1/8" tube compression fitting is supplied to complete the RTD
wiring protection. This transition fitting secures the flexible SS sheath
to the receiver's ½” FNPT conduit connection.
4.8.2.5 The RTD can be serviced or replaced, when necessary, without process
shut down or removal of the head-mounted transmitter. The internal
thermal well is completely sealed from the process. To remove the
RTD, simply disconnect the RTD wiring at the receiver device and
then disconnect the flexible SS sheath at the receiver device and at the
Accutube head. The RTD can be pulled from the internal thermal well
by the lead wires. Replacing a failed RTD is accomplished by feeding
the platinum tip down the internal thermal well until it stops. By first
measuring the distance from the Accutube head to the center of the
process pipe and comparing to the length of wire inserted, the installer
can judge whether the RTD tip has reached the bottom of the well.
Reattach the flexible SS sheath and wire the new RTD to the receiver
terminations to complete the service.
4.9 SPECIAL APPLICATIONS