Liquid Controls MA4 Meter - Manual (Page 12)

12
Pulse Output Device (POD5)
The Liquid Controls Pulse Output Device (POD) converts
the rotary motion of the Positive Displacement Meter into
electronic pulses making it possible to interface the meter
to electronic monitoring and control equipment. The
POD5 was specifically designed to interface with the MA-
4 meter and the SCAMP A™ electronics.
The POD5 mounts directly to the front cover of the MA-4
meter. The motion of the meter’s blocking rotor is
magnetically coupled through a stainless steel wall into
the electronics compartment of the POD5. This
eliminates any dynamic seal and isolates the electronics
from the process fluid in the meter.
Inside the POD5 electronics compartment an optical shaft
encoder converts the rotary motion into a high resolution,
two-channel quadrature square wave. Both outputs
switch from 5 volts in the “ON” state to zero volts in the
“OFF” state.
The POD5 electronics compartment also serves as a
conduit junction box. The POD5 has an O-Ring sealed,
threaded cover. The standard wire entrance is a 1/2-14
NPT female hub, which accepts threaded conduit or a
cable gland. A plug-in connector on the encoder
facilitates wiring of the unit. With the wiring entrance
sealed and the cover in place, the housing is
ENCLOSURE TYPE NEMA 4X weatherproof rated. In
addition, the housing is CENELEC rated flameproof, and
UL and Canadian-UL explosion-proof rated when properly
installed with approved conduit.
INSTALLATION:
The POD5 comes factory installed on the meter ready
for wiring with the conduit orientation in the up position.
The hub can be oriented in one of four possible directions;
facing up, down, left, or right. If a different orientation is
required remove the two mounting screws and pull the
POD5 from the front cover. Remove the POD5 O-ring
from the cover.
• After determining the orientation of the conduit
hub, determine which two of the four mounting screw
holes will be used to fasten the POD5 to the front of the
meter cover. It is suggested that the mounting screws
be driven into these holes first to “pre-tap” the threads in
the meter cover. This will make it easier to thread the
screws when the POD5 is in place.
•
Position the O-ring on the bottom of the POD5.
• Align the fork driver to the drive mechanism
inside the meter and guide the POD5 into the opening in
the meter cover. When the driver is properly aligned the
POD5 will go in until its mounting flange abuts the meter
cover.
•
Rotate the POD5 to the desired orientation and
thread in the mounting screws finger tight. Using a 5/16"
box end wrench, tighten the screws to the appropriate
torque as specified in the “Torque Chart” in this manual.
WIRING:
Wiring into the POD5 must enter through its conduit hub.
For explosion-proof rated installations (Class I, Div. 1)
the wiring must be enclosed in rigid conduit that is rated
for explosion-proof installation. The conduit must be
engaged five (5) full threads into the female hub on the
POD5 to meet explosion-proof standards. When a
Division 2 installation is called for, either rigid conduit,
flexible conduit such as LiquidTight, or no conduit can
be used. When no conduit is used, the instrument cable
must be brought into the conduit hub using a cable gland
to seal the wiring entrance to maintain the ENCLOSURE
TYPE 4X rating. Regardless of the type of conduit/cable
gland used, thread sealant should be applied to prevent
moisture from getting into the POD5 electrical housing.
Removing the cover of the POD5 will expose the plug-in
connector and ground screw.
! ! ! ! ! WARNING
All internal pressures must be relieved before
disassembly or inspection of the strainer, air eliminator,
any valves in the system, the packing gland, and the
front or rear covers. See “Relieving Internal Pressure”
(Page 10).