MA-4 Positive Displacement > Maintenance > Maintenance Requirements

PRIOR TO METER DISASSEMBLY

Failure to follow this pre-disassembly procedure could result in property damage, personal injury, or death.

Before disassembly of any meter or accessory component:

•All internal pressures must be relieved and all liquid drained from the system in accordance with all applicable procedures.

•Pressure must be 0 (zero) psi.

•Close all liquid and vapor lines between the meter and liquid source.

For applicable safety rules, refer to local authorities and relevant NFPA Codes.

RELIEVING INTERNAL PRESSURE

All internal pressure must be relieved to zero pressure before disassembly or inspection of the strainer, vapor eliminator, any valves in the system, the packing gland, and the front or rear covers.

Serious injury or death from fire or explosion could result in performing maintenance on an improperly depressurized and evacuated system.

Strictly follow this procedure Relieving Internal Pressure Procedure for LPG and NH3 Meters:

1.Close the belly valve of the supply tank.

2.Close the valve on the vapor return line.

3.Close the manual valve in the supply line on the inlet side of the meter. If no manual valve exists on the inlet side, consult the truck manufacturer for procedures to depressurize the system.

4.Slowly open the valve/nozzle at the end of the supply line.

5.After product has bled off, close the valve/nozzle at the end of the supply line.

6.Slowly crack the fitting on top of the differential valve to relieve product pressure in the system. Product will drain from the meter system.

7.As product is bleeding from the differential valve, slowly reopen and close the valve/nozzle on the discharge line. Repeat this step until the product stops draining from the differential valve and discharge line valve/nozzle.

8.Leave the discharge line valve/nozzle open while working on the system.

DISCLAIMER

Liquid Controls disclaims all liability for damage to meter or accessories because of corrosion, salting out of product, or separation of chemicals whether occurring during periods of use or storage.

Ensure that you are mindful of the following when performing maintenance on the meter:

•PREVENT PIPE STRAIN OR STRESS – Prevent pipe strain or stress from occurring when making meter or accessory repairs. Pipe strain and stress occurs when the pipes are not supported or are not aligned correctly to the meter. The weight of the pipes must always be supported independent of the meter. This means that the meter and accessories can be easily removed without affecting the pipes or the pipe alignment. Never leave any of the pipes hanging.

•SEASONAL METER STORAGE – If the meter is used for seasonal work, the meter should be removed from the system and thoroughly flushed with a compatible liquid at the end of each season. To flush the meter, remove the drain plug on the front and rear covers. Then flush the product from the front and rear covers. If flushing with water, extra care should be taken to drain the meter completely and dry all internal parts. Refill the meter immediately with a compatible liquid (or oil misting). Refilling is essential to preventing corrosion and ice damage that can result from any moisture that was overlooked after flushing and drying.

•DO NOT MAR OR SCRATCH – Do not mar or scratch any of the precision machined surfaces by prying or sanding parts.

•TORQUE ALL FASTENERS – Torque all fasteners such as screws and bolts in accordance with specifications listed in the Torque Chart in Reassembling the Meter.

•STONE THE MACHINED SURFACES – Stone the machined surfaces when reassembling the meter to

•assure that the machined surfaces are free of burrs and mars.

•REPAIR PULLED THREADS – Repair pulled threads with threaded insert fasteners. These can be used in many instances. Contact your full-service distributor for advice if this occurs.

•COAT THREADS WITH ANTI-SEIZE – Coat threads with anti-seize when removing and replacing bolts and castings in the meter.

•REMOVING FLANGE GASKETS – Remove flange gaskets when removing the flange assembly, always carefully scrape off the flange gaskets. Make sure that the flange surface has been scraped clean. Discard the old flange gasket and install a new flange gasket. Never reuse old flange gaskets.

•EXAMINE ALL FASTENERS – Ensure the fasteners are not bent, rusted, or have pulled threads. The threads should all appear evenly placed. If the bolts are bent, check the housing and cover for flatness. Use a straight edge to determine flatness.

•LOOK FOR GAPS – When disassembling a meter, use a feeler gauge to check for gaps between the bearing plate and housing. If you do find gaps, check the bearing plates for flatness with a straight edge. Gaps can be caused by shock problems that must be resolved. Contact your full-service distributor or the Service Department at Liquid Controls for assistance if this occurs.

•CHECK THE O-RINGS – O-Rings should be smooth. Cracked or worn O-Rings should be replaced. However, a more serious problem of shock may have occurred if the ORings look nibbled. Shock problems must be verified and resolved. Contact your full-service distributor or the Service Department at Liquid Controls for assistance if this occurs.

•CHECK THE BEARING PLATES – Check the bearing plates for flatness. Use a straight edge. Warped bearing plates can be caused by shock problems that must be resolved. Contact your full-service distributor or the Service Department at Liquid Controls for assistance if this occurs.

•WEIGHTS & MEASURES – Check with the regulatory agency that governs Weights & Measures in your area. Removing a seal wire may require Weights & Measures recalibration.