Dresser Roots Model 5 Prover Manual - The Meter and Valve ...

3. Check the Master Meter differential against the original factory differential curve supplied withthe new or recertified Master Meter. As long as the differential remains within the limit of1.0" w.c. at 50% of flow (10,000 acfh) of the value shown on the original curve, the meteraccuracy is considered unchanged. For the 5M, the differential should not exceed 0.5” w.c. at50% of flow.4. Return the Master Meter to the factory for Remanufacture & Recertification if any of thefollowing conditions are applicable: The differential does not meet the criteria in item #3 (above)at any time or after completing the recommended maintenance procedures, or reference Metertests results consistently exceed ± 0.5% as compared to the original curve.10.7 Maintenance Check ListMaster Meter Inlet ScreenInspect the Master Meter inlet screen prior to each test.1. Use a vacuum cleaner to remove debris.2. Always remove the screen from the Master Meter before cleaning with solvent orattempting to clean by blowing with air through the screen.Master Meter(s)Visually inspect the impellers for damage and dirt build-up a minimum of once each month.1. Remove from the Prover Cart before cleaning.2. A clean, lint free cloth may be used to wipe contamination from the impellers.3. Do NOT use any type of solvent to flush dirt from the Master Meter.4. Blow clean, dry compressed air through the Master Meter.P&T Adapter and the Field Meter Pressure Adapter and All Master Meter Pressure AdaptersCheck at least once a month for dust, moisture or contamination.1. Seal the non-quick disconnect end of the Adapter(s).2. Apply a pressure of 10 inches of water column to the quick disconnect end of the Adapter(s).3. Quickly open the sealed end of the Adapters and record time.4. Record the time when the pressure in the previously sealed end is equal to ambient pressure.5. If the time between steps 4 and 3 is less than two (2) minutes, the Adapter is in good condition.If the time is greater than two (2) minutes, replace the Adapter.Reference Meter Testing1. Use a Reference Meter as a standard to monitor the prover system for changes that could affecttest results. The documented history of performance is the baseline for continuous comparisons.2. When inspecting and characterizing the performance of the Master Meter(s), compare and plotthe results against the historical baseline with an acceptable tolerance (i.e., ± 0.55%).3. Perform the Reference Meter test on an occasional basis (weekly, monthly, etc.) to ensure properprover system condition and repeatability. Run tests any time Field Meter tests are consecutivelyout of tolerance or you suspect problems.4. The Reference Meter should be inspected and its performance characterized at least onceevery six (6) months by an independent verification agency to ensure the proper operation ofthe Model 5 Prover.41