CALIBRATION
Test the flowmeter using a volumetric prover large enough to permit
the flowmeter to operate for at least one minute at normal flow rate.
Slip tube and rotary gauge reading are not sufficiently accurate for
proving flowmeters. A detailed description of an LP-Gas test proce-
dure may be found in the National Bureau of Standards Handbook
99, “Testing Liquefied Petroleum Gas Liquid-Measuring Devices”.
If a gravimetric test method is used, the conversion to gallons must
be on the basis of: (1) specific gravity determined at the time of the
test (not an assumed value), and (2) the temperature of the product
as it is passed through the flowmeter. The volumetric test method,
however, is considered to yield more accurate results and is pre-
ferred. After performing the test procedure:
1. Determine the percentage of over-or under-delivery for each test
conducted.
2. Remove the register screws and take off the register.
3. Note the numbers stamped on the “R” change gear (on register
spindle) and on the “S” (or flowmeter spindle). Locate the gear tooth
combination on the Change Gear Chart.
4. Add the step-wise increments of change in registration until the
desired amount is reached. If the flowmeter is under-registering (de-
livering too much), select a new pair of gears farther down the chart.
If the flowmeter is over-registering (delivering too little), select a new
pair of gears farther up the chart.
5. Remove the old change gears and replace them with the new
pair. Always place the change gear with the smaller number of teeth
on the “R” register shaft and the gear with the greater number of
teeth on the “S” flowmeter shaft. To remove change gears, close the
split end of the spindle slightly with a pair of pliers to permit removal
of the change gear. After slipping on the new gear, spread the ends
of the spindle slightly.
6. Reinstall the register, run several gallons (liters) through the
flowmeter, and retest.
MEASURING CHAMBER MAINTENANCE
CAUTION: Be sure meter is completely relieved of pressure
before performing any internal maintenance. Pressure must
be 0 psig (0 bar). Failure to properly depressurize and evacu-
ate the system could result in serious injury or death from ex-
plosion/fire.
Perform the following outdoors, away from buildings and
sources of ignition. Replacement gaskets should be on hand.
To Remove and Disassemble
This operation is not difficult and may be performed by any compe-
tent mechanic. No special tools are required if these few simple but
important directions are followed. Do not open the flowmeter until
you have checked over all other possible causes of erratic registra-
tion. (Refer to TROUBLE SHOOTING.)
1. Prepare a clean surface on which to place the parts as they are re-
moved. (The parts are machined to close tolerances and should be
handled with care.) Also check that a replacement gasket is on hand
before opening the flowmeter, it may need to be replaced.
2. Remove the main case cover taking care not to damage the gas-
ket, if it is to be reused.
3. Lift the measuring chamber from the flowmeter casing.
4. Remove the top plate by inserting a screwdriver in one of the slots
provided, and prying it off. Be careful not to scratch or nick any part
of the chamber.
5. Lift out the piston by its spindle. If care is taken to draw it straight,
it should come out easily. Do not force it.
6. Remove the control roller from the lower cylinder head. If the dia-
phragm or seal pin requires replacement, they may be removed by
pulling upward, using pliers if necessary.
To Clean the Measuring Chamber
The parts may be most easily cleaned of scale, embedded chips,
heavy corrosion and other foreign matter, using gasoline and a
stiff-bristle (not wire) brush. Do not use abrasives, such as emery
cloth or sandpaper. When the piston is badly corroded, replace the
whole chamber.
The sliding surfaces between the chamber and piston take on a bur-
nished finish and wear little if any. The parts of the measuring cham-
ber which may show wear after long periods of service are the
diaphragm and the control roller. These parts will not require re-
placement until the accuracy of the flowmeter fails at low rates of
flow. To change these parts, merely substitute new parts for the old,
when the flowmeter is disassembled for cleaning.
To Reassemble the Chamber in the Flowmeter
Before assembling the flowmeter, make sure all parts are clean. If
possible, flush out the flowmeter body. Assemble the parts carefully;
they should slide together easily without hammering or forcing. It is
essential that all contact surfaces between the upper and lower cylin-
der heads and the cylinder, or between the measuring chamber and
its seat in the casing, be free from nicks.
1. Assemble the diaphragm and seal pin in the chamber, if replace-
ment of these parts was necessary.
2. Place the control roller on its pin, and see that it will rotate freely.
3. Reinstall the piston, and oscillate it carefully by hand; it should
move easily without binding. If it sticks, do not force it, but remove it
and locate the cause. Do not file down the roller as this will destroy
the accuracy of the flowmeter.
4. Reinstall the top plate, and again oscillate the piston to make sure
that it is free.
5. Before installing the measuring chamber in the casing, make sure
that the seat is clean and free of nicks. Install the chamber, making
sure that the dowel pin in the main casing enters the slot in the bot-
tom housing properly and allows the chamber to rest squarely on
the seat. The top of the chamber should be flush with the gasket
seal.
GEAR TRAIN MAINTENANCE
CAUTION: Be sure meter is completely relieved of pressure
before performing any internal maintenance. Pressure must
be 0 psig (0 bar). Failure to properly depressurize and evacu-
ate the system could result in serious injury or death from ex-
plosion/fire.
Perform the following outdoors, away from buildings and
sources of ignition. Replacement gaskets and seals should be
on hand.
To Replace Gear Train Shaft Seal
1. Remove the register.
2. Remove the stuffing box nut.
3. Remove shaft seal. Inspect top of spindle to be sure it is free of
nicks or burrs which might damage the new shaft seal when it is
placed on spindle.
4. Replace shaft seal. Be sure expander and spring are in position
before inserting new seal.
5. Assemble nut and tighten down all the way.
To Replace Gear Train
1. Remove the register.
2. Remove the flowmeter main case cover, with gear train assembly
attached. Be careful to keep dirt out of flowmeter, and avoid dam-
age to the cover gasket (a replacement gasket may be necessary).
3. Remove the stuffing box nut.
4. Take off the clamp nut and remove the gear train assembly from
the underside of the flowmeter top casing.
5. Install replacement gear train, making sure that the replacement
has the same gear reduction, new seal, and new gear train is orien-
tated with anti-rotation pin. Both clamp nut and stuffing box nut
should be torqued to 200 inch lbs.
7. Before installing the top casing, inspect the gasket and replace if
necessary. Next, position the driving arm of the gear train so that it
will not rest on the piston spindle. Then reassemble the main case
cover on the main casing and secure it with the four cap screws.
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