PROBLEM

PROBABLE CAUSE & SOLUTION

Leakage past packing gland drive shaft housing from internal metering chamber

Internal seal of packing gland assembly is worn. Replace packing gland and O-ring seal.

OPERATING NOTES:

•Two common causes of packing gland leakage are thermal expansion and hydraulic shock.

•Thermal expansion can occur when two valves in a piping system, on either side of the meter, are closed at the same time and the temperature in the system rises. As little as a 1°F increase in temperature can drive the system pressure to a point that exceeds

•the maxiumum working pressure rating of the meter. To avoid any damage caused by thermal expansion, a pressure-relief valve of some kind must be installed in the system.

•Hydraulic shock occurs when a large volume (mass) of liquid is flowing through the system and a valve suddenly closes. When the flow is stopped, the entire mass of the liquid in the piping system rams into the components within the meter. The greater the length of line (more line length equals more liquid mass) and the greater the velocity of the liquid, the greater the hydraulic shock. Since the valve is usually located at the meter outlet, the meter housing, packing gland and the meter internal are subject to the full impact of such hydraulic shock. To prevent hydraulic shock, a slow closing two-stage valve should be used with the meter. On systems where mass length of line and velocity are of a magnitude that preclude the elimination of hydraulic shock with the use of a two-stage slow closing valve, an impact-absorbing air cushioning device can be added to further dampen hydraulic shock.

Leakage from the cover gasket

Gasket has been damaged due to shock pressure or cover bolts have not been tightened sufficiently. Replace gasket and tighten cover bolts correctly.

Product flows through meter but the register does not operate

Follow this procedure:

1.Check packing gland, and gear train.

2.If all meter parts are moving then problem is in register. Faulty register should be checked and repaired by trained mechanic.

3.Remove register from meter. If all meter parts are moving but output shaft of adjuster assembly is not, adjuster is worn and must be replaced.

4.If totalizer numerals (small numbers) on register are recording, but the big numerals are not moving, register needs repair.

5.Packing gland gear not turning. Replace the packing gland. This may be caused by starting the flow too rapidly.

 
NOTE: For M-60® and M-80® meters, the drive blade may be sheared.

Breaking teeth on timing gears

This may result from the following:

•Starting or stopping flow in meter too rapidly.

•Pump bypass not adjusted properly

Product flows through meter but register does not record correctly

This may result from the following:

•Adjuster not properly calibrated.

•Incorrect gear plate or gear ratio has been installed.

•Air is in the system.

No flow through meter

This may result from the following:

•Faulty non-functioning pump.

•Valve not open or not functioning.

•Meter “frozen” due to build-up of chemical “salts” or foreign material inside metering chamber. Clean the meter and inspect for damage.

Meter runs too slowly

This may result from the following:

•Valve internal mechanism faulty. Valve does not open fully.

•Meter gears or rotors partially “salted” enough to slow up rotation of parts. Clean the meter.

•Downstream restriction.

•Clogged strainer basket.

The meter counts down in reverse (the meter numbers decrease)

Reverse the direction of flow by reversing the adjuster drive gear. See Reversing the Meter Registration.