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IOM BiRotor 3” to 6” R03
proper timed relationship with one another by helical
gears. They divide the volume being measured into
segments, separate each segment from the fl owing
stream momentarily, then return them to the stream.
The segments of fl ow are counted and the results
are transferred to a totalizing register or other fl ow
recording device by means of a gear train.
The BiRotor Meter is unique in that it does not use
any sliding vanes or reciprocating parts nor are there
any shock loads on the mechanism during operation
resulting from the shifting of offbalance masses.
An accuracy adjustor, located on the output of the
counter drive gearing permits the operator, at the
time of installation, to adjust the output of the mea-
suring unit to read in an exact number of units of
volume. Thus, the accuracy adjustor acts as a variable
gear changer (simi-lar to the speeding up or slowing
down of the timing of a watch) and allows an adjust-
ment of +-3% of meter throughput. The meter may
be supplied with any of several accessory items such
as high frequency pulse generator, impulse contac-
tor, automatic temperature compensator (ATC), etc.
The units provide various functions for local and/or
remote control and local and/or remote readout.
Figure 7.1 Lubricating System Schematic
Warning
Before placing the meter into service, refer to the
appropriate instruction manual for these accesso-
ry units if the meter is so equipped.
The meter has an integral positive lubrication sys-
tem (APL) to supply constant clean lubricant to the
meter’s bearings, timing gears, counter drive gears
and o-rings. The two rotors are the only moving parts
subject to the fl owing stream. The APL system, as
illustrated in Figure 1-1, is composed of a hydraulic
cylinder, relief valve, needlevalve, fi lling fi ttings and
mechanical isolating seals.
Hydraulic Cylinder
The hydraulic cylinder incorporated in the APL unit
acts as a lubricant reservoir and a segregating ele-
ment between the product being metered and the
lubricant. It contains a piston and a rod that extends
through the cylinder top for visual indication of the
lubricant level. Upstream pipeline pressure (meter
inlet) is applied to the side of the piston opposite the
lubricant supply, thus pressurizing the lubricant to
a value equal to or slightly greater than the internal
meter pressure.
Relief Valve
The relief valve incorporated in the APL unit serves
to protect the meter from excessive pressure when
charg-ing the APL system with lubricating oil. Should
the lubricant pressure exceed pipeline pressure by 30
psi (206 kPa), this valve will open, releasing a small
amount of lubricant to
atmosphere.
Crane Seals
Mechanical seals located on the rotor shaft between
the rotor and rotor bearings segregate the lubricant
from the product being metered. The seals are char-
acterized by their ability to remain effective seals
with little or not differential pressure and by their low
torque requirement. The low torque characteristic is
an important factor in providing accurate metering.