Oval Gear Flow Meter
Volumetric billing for oil, fuel, and chemicals
±0.5 % of rate on the standard build, viscosity 0.6 to 200 mPa·s
DN10 to DN200, PN1.0 to PN6.3 MPa, −20 to +80 °C
1:10 turndown per body per viscosity range; no straight-pipe upstream or downstream
- Direct volumetric chamber count; four crescent cavities per rotor revolution, no Reynolds dependence, viscosity-tolerant
- Diesel wet-cal per JJG 667-2010, ISO 9001 cert, body-stamped K-factor, mechanical pointer or LCD electronic head
- Out-of-scope: gas / steam / wet-gas (go to vortex or gas Roots); abrasive slurry (go to electromagnetic or Coriolis); ±0.1 % custody (go to Coriolis)
- For viscosity above 200 mPa·s, medium above +80 °C, ±0.2 % precision, or DN below 10 at high pressure, see the four counterpart builds linked below
Two interlocking oval rotors · four crescent cavities per revolution
JJG 667-2010 diesel wet-cal · no straight-pipe upstream or downstream
The volumetric PD workhorse for clean liquid billing; lube oil, refined fuel, food syrup, industrial chemicals. The LC series (LC-A cast iron, LC-E cast steel, LC-B 304 SS, LC-C 316 SS) covers four body materials on one flagship footprint. Two oval rotors meter four crescent-cavity volumes per revolution; rotor count is the direct volumetric measurand. ±0.5 % of rate, 0.6 to 200 mPa·s, DN10 to DN200, PN1.0 to PN6.3 MPa, −20 to +80 °C standard pointer build. Diesel wet-cal per JJG 667-2010; ships 5–7 business days.
Benefits
- No straight-pipe requirement: volumetric chamber displacement is independent of velocity profile; install in tight skids, after elbows, or after pumps where vortex (5-10 D), turbine (10-20 D), and orifice (22-50 D) cannot fit.
- Viscosity-tolerant by design: rotor slip narrows as viscosity rises, so accuracy improves on heavy oil compared with thin gasoline; opposite of turbine, vortex, and electromagnetic behavior. The 0.6 to 200 mPa·s range covers diesel through transformer oil on a single body.
- Direct volumetric metric: rotor count drives the pulse output, the 4-20 mA, and the mechanical six-roller totalizer simultaneously. No square-root extraction, no Reynolds correction, no temperature-pressure compensation needed for the volumetric reading.
- Mechanical pointer build needs no power and no Ex cert: the passive A / A1 / Z counter delivers cumulative six-roller readout for hazardous-area liquid service without electronics in the pipe; the canonical low-cost ATEX-by-design choice.
- Diesel wet-cal per JJG 667-2010: every meter ships with a calibration certificate traceable to the China national flow standard, an ISO 9001 calibration cert, a mill cert on the wetted stainless grade, and a body-stamped K-factor.
- Lead time 5–7 business days from the factory, versus the 8–12 weeks typical at Grade-1 positive-displacement vendors on industrial-grade models.
Specifications
| Measurement principle | Volumetric positive-displacement; two interlocking oval rotors meter four crescent-cavity volumes per rotor revolution; rotor count is the direct, discrete volumetric measurand with no Reynolds dependence within the design range |
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| Reference standards | JJG 667-2010 China national metrological verification regulation for liquid volumetric flow meters (factory diesel wet-cal traceability); flange standard JB/T 79~82-1994; volumetric-PD conventions referenced in API MPMS Chapter 5.2 custody practice (reference-level, not ex-factory cert) |
| Pipe size | DN10 / DN15 / DN20 / DN25 / DN40 / DN50 / DN65 / DN80 light (PN1.6 flange) / DN80 heavy (PN2.5+ flange) / DN100 / DN150 / DN200 per the flow-range tables |
| Model code | LC series; LC-A (cast iron) / LC-E (cast steel) / LC-B (304 stainless) / LC-C (316 stainless); full build code per the §XIV selection matrix combines body material, DN, pressure, counter, transmitter, and accuracy suffix (e.g. LC-A25.2/A1-GF-I = LC-A cast iron, DN25, PN1.6 MPa, A1 counter with signal-out, GF-I 12 V pulse) |
| Pressure rating | PN1.0 / PN1.6 MPa on cast iron body; PN1.6 / PN2.5 / PN4.0 / PN6.3 MPa on cast steel and stainless body; ANSI 150 / 300 / 600 lb flange supplied to order; length and flange dimensions customisable per quote |
| Medium temperature | −20 to +80 °C on the standard pointer build; −20 to +60 °C on the standard LCD electronic build; high-temperature models (related page) extend the pointer build to +200 °C and the LCD build to +150 °C via thermal-extension pipe |
| Viscosity range | 0.6 to 200 mPa·s on this flagship build (twelve DN rows split into a 0.6-2 mPa·s low-viscosity column and a 2-200 mPa·s mid-viscosity column); 200 to 2000 mPa·s goes to the high-viscosity oval gear counterpart |
| Accuracy | ±0.5 % of rate base grade across both viscosity columns of the standard build; ±0.2 % of rate is the precision related page (suffix -J), not this page |
| Repeatability | ±0.05 to ±0.1 % typical between recalibrations on a clean, in-range service (engineering estimate by quote; PD repeatability tracks mechanical clearance stability) |
| Turndown | 1:10 per body per viscosity range on the standard ±0.5 % build; narrower on the precision ±0.2 % counterpart at certain DN / viscosity combinations |
| Flow range (DN50 example) | 6 to 24 m³/h at 0.6-2 mPa·s; 4 to 24 m³/h at 2-200 mPa·s. Twelve DN rows from 0.2 m³/h on DN10 to 340 m³/h on DN200; quote engineering for the row matching your DN and viscosity range |
| Wetted material | Cast iron (refined hydrocarbon, mineral oil, lube), cast steel (higher-pressure refined fuel), 304 stainless (mild chemical, food syrup), 316 stainless (acid / alkali / corrosive chemical); rotor in matching material on each body type |
| Connection / mounting | Flange JB/T 79~82-1994 (equivalent to HG/T 20592 at PN1.6 / 2.5 / 4.0 / 6.3 MPa); ANSI 150 / 300 / 600 lb flange by order; bolt-pattern and length customisable per quote |
| Display | Mechanical pointer with six-roller cumulative totalizer (A = passive mechanical counter, A1 = with-signal electronic counter, Z = zero-return batch counter) or LCD electronic head with instantaneous and cumulative flow |
| Output signal | None (mechanical-only A / A1 / Z counter) / GF-I three-wire pulse DC12V, square-wave high > 9 V / low < 0.5 V, max 1 km cable / GF-II three-wire pulse DC24V, > 20 V / < 1 V / 4-20 mA two-wire or three-wire analog / RS-485 Modbus RTU on the LCD electronic build |
| Power supply | Passive (mechanical-only pointer build, no power required) / DC12V loop-powered (GF-I pulse and 4-20 mA two-wire) / DC24V loop-powered (GF-II pulse and 4-20 mA three-wire) |
| Hazardous-area cert | Ex d IIBT4 on the transmitter housing (GF-I / GF-II / 4-20 mA builds); the mechanical-only pointer build is passive and needs no Ex certification; the canonical low-cost choice for hazardous-area liquid billing |
| Ingress protection | IP65 on the electronic build housing (industry-norm estimate by quote; not factory-stamped on this series; IP66 / IP67 by special order on factory confirmation) |
| Ambient temperature | −10 to +60 °C for the electronic build housing; the mechanical-only build follows the medium-temperature range only |
| Permanent pressure loss | 30 to 100 kPa at rated flow, viscosity-dependent (Δp curves: 25 kPa light gasoline at 0.7 mPa·s through 75-100 kPa transformer oil at 20 mPa·s); plan a 30-100 kPa head budget across the meter |
| Calibration | Diesel-oil wet calibration on the factory loop per JJG 667-2010 with ISO 9001 calibration certificate; water calibration is forbidden on cast-iron and cast-steel bodies (rusts the rotor and chamber wall, shifts K-factor permanently) |
| Applicable media | Clean single-phase liquid: refined hydrocarbon fuel (diesel, kerosene, jet A-1, gasoline, light fuel oil), lube and hydraulic oil at 5-200 mPa·s, industrial chemicals (alcohol, glycol, paint, ink, light organic solvent), light food syrups at room and warmed service; gas, steam, abrasive slurry, two-phase, and pulsating service are out of scope; go to the relevant counterpart series |
| Lead time | 5–7 business days from factory |
Typical applications
Four applications where the oval gear is the right positive-displacement choice.
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Refinery and terminal fuel custody
Diesel, kerosene, gasoline, and jet A-1 truck-loading billing at 0.6 to 5 mPa·s on the standard cast-iron or cast-steel build. Each pulse out is a bookkeeping unit traceable to the diesel wet-cal certificate.
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Industrial lube and hydraulic oil filling
Mineral lube dispensing, hydraulic-system top-up, and lubricant blending at 5 to 200 mPa·s on the standard build. Slip narrows with viscosity, so the heavier the oil, the tighter the reading inside the rated range.
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Chemical-process volumetric flow measurement
Alcohol, glycol, paint, ink, and light organic solvents on the 304 or 316 stainless body. The mechanical pointer build runs passive in hazardous-area service without any Ex transmitter cert overhead.
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Light food-industry general billing
Corn syrup, juices, honey, and light food liquids at sub-100 mPa·s viscosity on the stainless body. Sanitary 3-A / EHEDG / FDA cert is buyer-arranged; this is general industrial-food billing, not sanitary direct-contact custody.
Installation
Five field rules from the install section for a stable PD reading.
- Line filter upstream, gas-eliminator if air is entrained 100 µm for general oil; 40 µm sintered for chemical or precision-dosing. Air pockets over-register; the chamber displaces gas the same as liquid.
- Rotor shaft horizontal, any pipe orientation The pipe can run vertical or horizontal; the oval-rotor shaft mounts horizontal (dial face perpendicular to ground). Counter face rotates in 90° steps for sight-line.
- Throttle INLET, on-off OUTLET, open slowly Water-hammer shears rotor teeth. Sudden full-line-pressure opening is the number-one cause of rotor damage.
- Bypass loop and straight-pipe spool on commissioning Continuous-service installs need a bypass loop. On a new pipeline, fit a spool during first flush; weld slag permanently scores the rotor.
- Run 50–80 % of rated max; never steam-clean the chamber Continuous operation at max accelerates rotor wear. For hot-tracing service, go to the high-temperature counterpart (steam jacket on body shell only).
Frequently asked questions
How does an oval gear flow meter measure flow?+
Two precision-machined oval rotors mesh inside a crescent-shaped chamber. Liquid pressure-differential between inlet and outlet rotates the rotor pair; each full revolution displaces a fixed volume equal to four crescent cavities. Rotor rotation count is the direct, discrete, volumetric measurand; not a velocity inference and not a Reynolds-dependent reading. A pickup converts each revolution into a pulse for the GF output; the 4-20 mA build uses a Hall sensor; the mechanical shaft drives the six-roller pointer totalizer. Slip narrows as viscosity rises (opposite of turbine and vortex behavior). Accuracy is ±0.5 % of rate across 0.6 to 200 mPa·s with no straight-pipe requirement.
What viscosity, temperature, and pressure does this flagship oval gear cover?+
The flagship handles viscosity 0.6 to 200 mPa·s, medium temperature −20 to +80 °C on the standard pointer build (−20 to +60 °C on the standard LCD build), and working pressure PN1.0 to PN6.3 MPa depending on body material; PN1.0 / 1.6 on cast iron, PN1.6 to PN6.3 on cast steel and stainless. Pipe size runs DN10 to DN200 across twelve flow-range rows split into two viscosity range per row (0.6-2 mPa·s water-thin and 2-200 mPa·s mid-viscosity). Route 200-2000 mPa·s to the high-viscosity counterpart, −20 to +200 °C service to the high-temperature counterpart, and DN5-DN25 at PN40 MPa to the mini-bore counterpart.
What ships with the order, what is the cert chain, and what is the lead time?+
Lead time is 5 to 7 business days from the factory. Each meter ships with the diesel-oil wet-calibration certificate per JJG 667-2010 traceable to the China national flow standard, the ISO 9001 calibration certificate from the factory, the mill certificate traceable to heat number on the wetted stainless grade where applicable, the matching flange set or transit caps per the order code, and the body-stamped K-factor. The standard housing carries Ex d IIBT4 on the transmitter for hazardous-area service; the mechanical-only pointer build needs no Ex certification because it is passive. The factory does not ship API MPMS 5.2 custody-transfer cert, OIML R 117 cert, MID MI-005 cert, or 3-A / EHEDG / FDA sanitary cert; these are buyer-arranged with the relevant notified body or registered third party when the project demands them. An upstream line filter is required (separately priced, factory-matched on request) and a gas-elimination filter is required if the liquid carries entrained air.
Need a positive-displacement meter on a fuel, oil, or chemical line?
Send pipe DN, working pressure, medium and viscosity at line temperature, min/normal/max flow, required accuracy range, and output (pulse / 4-20 mA / RS-485). Engineering returns a sized model code in one business day; lead time 5–7 business days from the factory.