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Flow Meter Actaris Manual: Gas and Liquid Positive Displacement Measurement Maintenance
Quick Answer: For most Actaris positive displacement meters, field maintenance takes 30 to 45 minutes per meter. Inspect the chamber and rotors every 12 months for liquid service and every 6 months for dirty gas service. Recalibrate after any seal break or rotor replacement. Send your gas type, pressure in bar, temperature in Celsius, and pipe size in DN to Silver Instruments for a quote on a replacement meter or spare part.
PD Meter Maintenance Basics for Gas and Liquid
Positive displacement meters trap a fixed volume in a rotating chamber. Flow rate comes from rotor speed, not from velocity. This makes them strong at low flow. A gas meter with a diaphragm or rotary piston and a liquid meter with oval gears wear in different ways. Gas service brings dust, pipe scale, and oil mist. Liquid service brings solids, polymer deposits, and cavitation damage.
Here is the thing. A clean meter is not always an accurate meter. Most Actaris models use hardened rotors and precision machined chambers. Clearance between rotor and chamber often sits between 0.05 mm and 0.15 mm. A small wear ridge on the chamber wall throws off low flow accuracy before high flow error appears. Because of this, maintenance should focus on clearance checks, not just a visual clean.
We have seen this on customer sites many times. A PD meter that looks clean on the outside can pass a high flow bench test and still fail at 2 percent of full scale. That low flow error is what custody transfer auditors notice first.
Gas Positive Displacement Meter Maintenance
Start with isolation and depressurization. Remove the inlet strainer. Blow it with dry instrument air. Check the filter mesh for holes. A 100 micron strainer on a rotary gas meter is typical for natural gas. A 50 micron strainer is common for LPG vapor.
Remove the front cover. Slowly rotate the impeller or pistons by hand. Feel for a tight spot. A tight spot often means a bent shaft or a worn bearing. Check the chamber inside surface with a bore gauge if the manual gives the reference diameter. If the local clearance exceeds 0.2 mm, plan a rotor or chamber replacement.
Check the pulse transmitter. Use a signal generator and a multimeter. For a reed switch output, confirm the pulse rate in pulses per cubic meter. Compare that value with the badge data. On a new style Actaris gas meter, the pulse weight is often 0.01 m3 or 0.1 m3 per pulse. Recalibrate or replace the index if the totalizer does not match the mechanical register.
For differential pressure, install a DP gauge across the meter at 80 to 100 percent of typical flow. The value should stay below the limit in the manual. On a DN50 rotary gas meter, a DP above 15 mbar at 80 m3/h often points to bearing wear or a clogged upstream filter. Do not just blame the process gas.
Liquid Positive Displacement Meter Maintenance
For liquid PD meters, oval gear and nutating disc types are the most common. Drain the meter only after closing the isolation valves. Flush the housing with a compatible solvent or hot water if the liquid is food grade. Check the shaft grooves and the gear teeth tips under a bright light. Scoring on gear tips often comes from abrasive solids, not from normal wear.
Measure the end float with a feeler gauge. On many DN25 and DN40 oval gear meters, end float between 0.05 mm and 0.10 mm is normal. If the rotor touches the front cover, the meter will read high at low flow and then slow down as friction builds.
In one case, a paint manufacturer in Vietnam ran a DN40 oval gear meter on solvent based enamel. The rotor seized after six months because the gear clearance was set too tight for the solids content. The fix was not a new mete
Pay attention to viscosity. A meter calibrated on diesel at 3 cP will shift when used on molasses at 500 cP. The shift does not always mean the meter is broken. It often means the meter needs a viscosity specific calibration. Send us your liquid type, viscosity in cP, flow range in kg/h, and operating temperature in Celsius. We can advise if a replacement PD meter from Silver Instruments will hold the accuracy you need.
Calibration and Seal Integrity
Calibration is not optional after opening the measuring chamber. The local weights and measures rules in many countries require a reseal and recertification by an accredited lab. In practice, an in house bench test with a master meter can catch gross errors, but it will not satisfy a custody transfer audit. Use a traceable master meter with an uncertainty of 0.1 percent or better for best results.
Check the seal points. On Actaris PD meters, the common seal points are the front cover, the pulse transmitter housing, and the calibration gearbox. If any seal is broken, document it before you remove the cover. This protects your maintenance team during a customer audit.
Maintenance Interval Examples
In a natural gas distribution skid in Southeast Asia, a 12 month interval is normal for clean utility gas. In a landfill gas or biogas line, the interval drops to 3 months because of siloxane and moisture. For liquid fuels, a diesel PD meter in a depot can run 24 months with good upstream filtration. A paint or resin meter might need cleaning every 6 months to avoid a stuck rotor.
Do not wait for the totalizer to stop. Most errors start small. A 0.5 percent drift at 2 percent of full scale is enough to fail a proving run. A rebuild at that stage is cheaper than a full replacement. But if the chamber is scored, a new meter from Silver Instruments often costs less than a full rotor set plus machining.
What You Need to Send for a Replacement Quote
We match face to face dimensions for many Actaris PD meter sizes from DN15 to DN100. Send us the serial number, meter type, fluid, pressure in bar, temperature in Celsius, flow range in kg/h or m3/h, and the connection standard. BSPT, NPT, DIN flanges, and ANSI flanges are all common. If you send a photo of the nameplate, our team can usually identify the correct model within a few hours.
Silver Automation Instruments supplies oval gear flow meters, PD meters for fuels, and gas rotary meters for industrial measurement. Contact Tel: +86-25-68650347, Whatsapp: +86-25-52155837, WeChat: +86 15365082610. Use the same number for urgent site support during business hours.
FAQ
How often should I service a gas PD meter?
Every 6 months for dirty gas and every 12 months for clean natural gas. Check the strainer, rotation, pulse output, and DP across the meter.
Can I recalibrate a PD meter after a rotor change?
Yes. Use a traceable master meter or an accredited calibration bench. The meter must be resealed after the work is complete.
What causes an Actaris gas meter to read low at low flow?
Rotor wear, chamber scoring, or a loose pulse transmitter. Check clearance and compare pulse weight with the nameplate.
Does Silver Instruments supply spare parts for Actaris meters?
We supply complete PD meters and oval gear flow meters that match many Actaris face to face dimensions. Send the nameplate photo for a quick check.
Which liquids need the most frequent PD meter cleaning?
Paints, resins, molasses, and any liquid with solids or high viscosity. A 6 month cleaning interval is common for these services.
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