Oval Gear Flow Meters
Volumetric PD (positive displacement), DN5-DN200
Accuracy ±0.5 % of rate base · ±0.2 % of rate precision tier
PN0.6 to PN40 MPa, −20 to +200 °C medium
Viscosity 0.6 to 2000 mPa·s (~1 cSt to ~2400 cSt) · diesel-oil wet-cal per JJG 667-2010
- Five models; flagship oval gear, high-viscosity, high-temperature, precision, and small-bore precision gear
- Zero straight-pipe requirement; volumetric chamber displacement is profile-independent by physics
- The oval-gear lane between turbines (clean below 10 cSt) and Coriolis (universal at 2–3× the hardware cost)
An oval-gear flow meter measures volume by direct displacement; two oval rotors meter four crescent-cavity volumes per revolution, no Reynolds dependence, no straight pipe. Catalog series identifiers across this product line: LC oval gear (DN10-DN200 flagship, LC-A/E/B/C body codes; LC-N high-viscosity; LC-T high-temperature; −J precision suffix), LW small-bore precision gear (LW-01 through LW-25), and LLT high-temperature screw-rotor by quote. Five models: DN5 to DN200, PN0.6 to PN40 MPa, −20 to +200 °C, 0.6 to 2000 mPa·s (~1 cSt = ~1 mPa·s at low viscosity, 200 mPa·s ≈ 240 cSt heavy lube), ±0.5 % of rate base. PD (positive displacement) lane between turbines (clean below 10 cSt) and Coriolis for oil, fuel, asphalt, syrup, and chemical billing. Diesel wet-cal per JJG 667-2010 (China national metrological reg, scope equivalent to OIML R 117 wet-cal).
Advantages
Where oval gear wins against turbines, EMF, vortex, and Coriolis on viscous liquid billing.
- Viscosity 0.6 to 2000 mPa·s; accuracy improves as viscosity rises Internal-slip leakage narrows when the metered liquid resists chamber leakage. The catalog error spec at 20 mPa·s transformer oil is the tightest published; at 0.7 mPa·s aviation gasoline the widest. Four published flow-range tables map each DN to the in-service viscosity range the buyer actually meters.
- Zero straight-pipe requirement Volumetric chamber displacement is profile-independent. Turbines need 10D upstream and 5D downstream, vortex needs 5–10D, and DP-orifice needs 22–50D; the oval-gear catalog explicitly publishes “no straight pipe before or after the meter required”. Retrofit projects with tight pipe runs and skid-mounted dosing loops mount oval gear where no other accurate option fits.
- ±0.5 % of rate base, ±0.2 % of rate precision tier Diesel-oil wet calibration on the factory loop per JJG 667-2010, the China national metrological verification regulation for liquid volumetric flow meters. The precision tier ships with the catalog −J suffix. Custody-grade ±0.1 % is Coriolis lane, not oval gear; the honest accuracy range, no inflation.
- Mechanical-only build needs no Ex certification Pointer and six-roller totalizer build is passive metal with no electronics; the canonical low-cost hazardous-area choice for fuel-terminal and chemical-batch service. The electronic build (LCD + 4-20 mA + RS-485 Modbus + pulse) ships with an Ex d IIBT4 transmitter housing for the hot-tap and Zone-1 configurations.
- Pulse, 4-20 mA, RS-485 Modbus RTU, and passive mechanical; all from one body A photoelectric pulse output drives PLC totalizers and batch controllers, a 4-20 mA two-wire output feeds DCS scaling, and an RS-485 Modbus RTU output reads instantaneous flow and cumulative totals direct into the operator's SCADA. The mechanical-only build is the passive backup that survives loss-of-power events.
- 5–7 business day lead time, factory direct All five models ship within the same window as the ten other meter lines on the site. Each meter ships with a diesel-oil wet-cal certificate listing DN, accuracy class, calibrated flow range, K-factor pulse coefficient, body material, and serial number traceable to the factory metrology lab.
Oval gear models
Five models cover the series. Each card targets a distinct duty; pick the closest match and the configurator inside each model page returns the build code.
Oval Gear Flow Meter
The flagship volumetric oval-gear meter for general-purpose oil, fuel, and chemical billing; catalog codes LC-A (cast iron), LC-E (cast steel), LC-B (304 SS), LC-C (316 SS). ±0.5 % of rate base, −20 to +80 °C standard pointer or LCD electronic build.
View configuration →High-Viscosity Oval Gear Flow Meter
Dedicated high-viscosity rotor build for lube oil, hydraulic oil, molasses, chocolate liquor, polymer dosing, and warmed heavy fuel oil; LC-NA / LC-NE / LC-NB catalog codes. Two viscosity range published (200–1000 mPa·s and 1000–2000 mPa·s) with full DN10–DN200 flow tables.
View configuration →High-Temperature Oval Gear Flow Meter
Thermal-extension barrel and finned heat-dissipation body for asphalt loading, hot lubricant blending, warmed heavy fuel oil, and heat-transfer fluid duty; LC-TA (thermal-extension) and LC-TE (electric heat-trace) codes; U suffix adds the steam jacket by quote. −20 to +200 °C on the pointer build, −20 to +150 °C on the LCD electronic build.
View configuration →Precision Oval Gear Flow Meter
Precision tier on the same oval-gear body footprint; the −J suffix appended to any LC catalog code (LC-A-J / LC-E-J / LC-B-J / LC-C-J / LC-NA-J / LC-NE-J / LC-NB-J) marks tighter rotor-clearance grading and segmented K-factor calibration for refinery in-plant billing, bunker terminal custody, lube blending, and any duty contracted at ±0.2 % of rate.
View configuration →Mini-Bore Precision Gear Flow Meter
Small-bore helical and spur gear sibling for chemical dosing, hydraulic test stands, lab measurement, and high-pressure precision injection; LW-15 / LW-20 / LW-25 catalog codes (LW-01 to LW-25 across the range). 304, 316L, PEEK, or PTFE wetted parts. BELZ LCD with RS-485 Modbus RTU, 4-20 mA, and pulse output from one body.
View configuration →Where oval gear wins
Series applications by service slice. Out-of-range duty goes to Coriolis, turbine, EMF, or DP primary.
| Service | Oval-gear pick | Alternative |
|---|---|---|
| Lube oil and hydraulic oil dispensing (50–500 mPa·s) | High-viscosity oval gear | Coriolis for ±0.1 % custody |
| Fuel-terminal truck loading on diesel, jet, kerosene | Flagship oval gear (mechanical build) | Liquid Turbine if clean below 10 cSt |
| Marine bunker billing on warmed HFO / IFO 180–380 | High-temperature precision oval gear | Coriolis ZLMFM for 2-phase tolerance |
| Refinery in-plant fuel-distribution custody | Precision oval gear (suffix −J) | Coriolis ZLMFM for ±0.1 % mass-direct |
| Asphalt batch loading at +150°C to +200°C | High-temperature oval gear with body jacket | Coriolis for ±0.1 % or 2-phase carry-over |
| Resin, paint, ink, polymer-additive dosing | Stainless flagship or mini-bore precision | Coriolis for shear-thinning polymer |
| Chocolate, molasses, food syrup (200–2000 mPa·s) | High-viscosity oval gear (stainless) | Sanitary Coriolis if 3-A required |
| Chemical-precision dosing on acid, alkali, IPA | Mini-bore precision (PEEK or PTFE wetted) | Coriolis for non-Newtonian or 2-phase |
| Hydraulic test stand at PN10–PN40 MPa | Mini-bore precision (DN5–DN25) | Coriolis at small-bore high-pressure |
| Lab and R&D batch flow measurement, 0.1–10 L/h | Mini-bore precision (DN5) | Mass-comparator gravimetric reference |
| Skid-builder retrofit with no straight pipe | Any oval-gear model; zero D required | Ultrasonic clamp-on if non-invasive |
| Clean water billing or fast-pipeline service below 10 cSt | Outside the operating range (high slip) | EMF LEA conductive water or Liquid Turbine |
| Abrasive slurry, drilling mud, frac fluid | Outside the operating range (jams rotors) | Coriolis ZLMFM or EMF LEA conductive slurry |
| Gas, wet gas, steam, two-phase carry-over | Outside the operating range (rotors slip) | Gas Roots for gas custody, Vortex for steam |
| Custody-transfer requiring ±0.1 % of rate | Outside the catalog accuracy range | Coriolis ZLMFM (mass-direct ±0.1 %) |
Out-of-range duty goes to Coriolis (mass-direct ±0.1 %, 2-phase tolerant) or the matching liquid-turbine, EMF, or DP primary on the proflowmeters.com/ lineup.
Series install rules.
Install rules across all five oval-gear models. Model-specific dimensions and bypass-loop sizing live on each model page.
- Install an upstream strainer on every meter; not optional A matching line filter sits upstream of every oval-gear meter per catalog Section IX rule 1. Industry practice is 100 µm mesh on standard fuel and oil duty, 40 µm sintered on chemical-dosing and precision-injection duty. The strainer is a separately priced product on the order; not bundled with the meter.
- Mount the rotor axis horizontal regardless of pipe orientation The pipe can run vertical or horizontal, but the oval rotor shaft must be horizontal so the gauge disc is perpendicular to the ground. A vertical rotor axis loads the bearings asymmetrically, the upper rotor slips differently than the lower rotor, and the meter loses its calibration. The counter face rotates in 90° steps for operator sight-line.
- Bypass loop above and below the meter for continuous-service installations Sites running 24/7 plumb a bypass with isolation valves above and below the meter so maintenance can pull the body without process shutdown. The catalog mount diagram shows throttle valve at inlet, on-off valve at outlet, bypass loop with isolation valves, and dial-plate-upwards orientation marked plainly.
- Open valves slowly to prevent water-hammer; never steam-clean the chamber Sudden valve opening upstream of a positive-displacement meter at full line pressure is the number-one cause of rotor damage and bearing-cavity deformation. Open throttle inlet slowly, then on-off outlet. For asphalt and warmed-HFO service that needs hot-tracing, specify the high-temperature build with the body steam jacket; jacket steam runs on the outer body only, never through the metering chamber.
- Flush new pipework with a straight spool before swapping in the meter Weld scale, pipe-fab swarf, and dried polymer skin from a new-build pipeline permanently score the rotor and chamber on first flow. Replace the meter with a straight spool during line flush, then swap the meter in once the pipeline runs clean. Plan for 30 to 100 kPa permanent pressure loss across the meter at rated flow; published on the catalog Δp error curve and the canonical PD trade-off against zero-D straight pipe.
Frequently asked questions
Need help sizing an oval-gear meter?
Send pipe DN, in-service viscosity, design P/T, fluid composition, min/normal/max flow, and accuracy contract. Reply in 1 day; lead time 5–7 business days.