35
Please Note: The turbines have magnets built into the
fins. There are no visible magnets on the inside of the
cavity.
TO ASSEMBLE THE FLOWMETER
Place the servo, flowmeter end up, in a vice or other
suitable fixture. Set turbine in non-sensor housing. Properly
position gasket on housing. (Gasket may be reused a few
times but will eventually need to be replaced.) Pipe thread
compound is not absolutely necessary but will insure a
good seal. Be careful not to get compound inside flowmeter
or the turbine will stall. Carefully put other flowmeter
housing (sensor half) in place. (Position the housing so that
the two square lugs are lined up with each other.) Drop all
three bolts into holes. Hold lock washers in place and finger
tighten all three nuts. Nuts should be torqued to 120 in./lb.
(13.56 nw/m). Attach tag by running wire between a bolt
and the housings, and twisting.
After assembly, shaking flowmeter end-to-end should
produce a “rattling” sound (shaft end play). Blowing into
the meter from either end should cause the turbine to spin
freely. If the turbine only spins from one direction, install
the flowmeter so that the liquid flows in that direction.
Start with original calibration number and follow procedure
in Appendix B to fine-tune the calibration.
Appendix D
Flowmeter Assembly (FM-750 N)
WARNING
TO PREVENT SERIOUS INJURY, DO THE FOLLOWING
1.
ALWAYS WEAR
gloves, goggles, and other necessary
equipment when handling NH3 apparatus.
2.
DO NOT
cross thread. Use anti-seize lead base thread
compound.
3.
THOROUGHLY BLEED
hoses before disconnecting NH3
apparatus.
4.
COMPLETELY EVACUATE
NH3 apparatus before
servicing.
IMPORTANT:
Opening the flowmeter will void the Flow
Calibration value assigned to your unit. However, you may
need to take the flowmeter apart for periodic cleaning or to
remove an obstruction.
See Illustration 17
.
TO OPEN THE FLOWMETER
Disconnect the hose from servo valve to manifold. Loosen
the union hex closest to the heat exchanger. Remove the
two “U” bolts that hold the servo/flowmeter assembly to the
brackets. Unscrew the union from the heat exchanger and
remove the servo/flowmeter assembly.
Use running water to rinse the assembly of any
accumulated dirt. Remove the three flowmeter bolts,
carefully open the flowmeter and remove the turbine.
Thoroughly clean turbine and housings of any foreign
material (dirt, pieces of teflon tape, rust on magnets, etc.).
Set and spin the turbine in each flowmeter housing half. It
should spin freely. If not, remove the turbine, wipe the shaft
and try again.
Illustration 17
Complete assembly
FM750 N Flowmeter
P/N 10899
Housing FM 750 N with Sensor
Receptacle, Including Bearing
P/N 10145
Housing, Includes Bearing
P/N 10116
Turbine
P/N 14836
Teflon Gasket
P/N 10137
