Oval Gear Meters - 3" to 4" Flanged

Meter Type
Positive Displacement (PD) Flow Meter designed to measure the flow of most fluids including high and varying viscosities without requiring recalibration.
How It Works
Positive Displacement Flow Meters measure the volumetric flow of fluids in pipes. As fluid flows through the chamber the oval gears rotate. Each rotation corresponds with a fixed volume of fluid that is picked up by a sensor creating a pulse signal. Electronic displays convert the pulse signal to a flow rate or totals.

Standard Features

  • High accuracy and repeatability, direct volumetric reading
  • No calibration required
  • Measures low and high viscosity liquids up to 1,000cps
  • Pressure rated up to 175 PSIG
  • No straight pipe runs required up or downstream
  • Stainless Steel or Aluminum bodies
  • Bi-directional flow measurement
  • Factory Calibration Certificate supplied with each meter
  • 1 Year Limited Warranty

Optional Features

  • Measures up to 1,000,000cps
  • Quadrature pulse output option for high resolution
  • PF option for metering pulsating flows
  • Optional Exd I/IIB Approval (ATEX, IECEx)

LCD Display Features

  • Rate of Flow, 2 Totals (1 Resettable Batch, 1 Cumulative)
  • User Configurable to GPM, LPM or any Unit of Measure
  • Factory Calibrated for 1.0 Specific Gravity
  • Field Calibratable for fluids greater than 1.0 Specific Gravity
  • Digital Display with 6 Digits Starting at 0.01 (floating decimal)
  • Totals Maximum of 99,999,999
  • Powered by 3.6V Battery (approximate 3 Year life, for display only) or may be externally powered

Electronic Options

  • Local or Remote LCD (see below features)
  • Pulse Output (Open Collector NPN)
  • 4-20mA Outputs
  • Scaled Pulse Output
  • Alarms or Batch Controlling


Connection Sizes
3" (OM080)3" (OM080E)4" (OM100)
FLOW RANGES*10 - 200 GPM (35 - 750 LPM)13 - 260 GPM (50 - 1000 LPM)20 - 400 GPM (75 - 1500 LPM)
ACCURACY (Of Reading @ 3cps - 1000cps) 
Standard± 0.5%± 0.5%± 0.5%
With RT14 Display w/ non-linearity correction± 0.2%± 0.2%± 0.2%
REPEATABILITY (Typical)± 0.03%± 0.03%± 0.03%
Aluminum Meter (A)175 PSIG (12 Bar)175 PSIG (12 Bar)145 PSIG (10 Bar)
Stainless Steel Meter (S)175 PSIG (12 Bar)--
Meters with Pulse Out Only-4 to 250°F (-20 to 120°C)-4 to 250°F (-20 to 120°C)-4 to 250°F (-20 to 120°C)
Meters with LCD Display Only14 to 140°F (-10 to 60°C)14 to 140°F (-10 to 60°C)14 to 140°F (-10 to 60°C)
Meters with LCD Display & 4-20mA Output32 to 140°F (0 to 60°C)32 to 140°F (0 to 60°C)32 to 140°F (0 to 60°C)
Meters with Mechanical Totalizer176°F (80°C)176°F (80°C)176°F (80°C)
Standard Unit Ranges3 - 1,000 cps3 - 1,000 cps3 - 1,000 cps
Low Viscosities below 3cpsContact UsContact UsContact Us
High Viscosity Ranges1,000 - 1,000,000 cps1,000 - 1,000,000 cps1,000 - 1,000,000 cps
PRESSURE DROP (At Full Std Capacity)Contact UsContact UsContact Us
RECOMMENDED STRAINER SIZE45 Mesh (350 Microns)45 Mesh (350 Microns)45 Mesh (350 Microns)
OUTPUT PULSE RESOLUTIONPulses per Gallon (Pulses per Liter) - nominal
Reed Switch10 PPG (2.65 PPL)5.68 PPG (1.55 PPL)4.15 PPG (1.10 PPL)
Hall Effect40.5 PPG (10.70 PPL)22.7 PPG (6.00 PPL)16.6 PPG (4.40 PPL)
Quadrature Hall Option20.0 PPG (5.33 PPL)11.4 PPG (3.00 PPL)8.3 PPG (2.20 PPL)
Reed Switch Output30VDC x 200mA max. [Maximum Thermal Shock 50°F (10°C)/minute]
Hall Effect Output (NPN)3-Wire Open Collector, 5-24VDC Max. 20mA Max.
Optional Outputs4-20mA, Scaled Pulse, Quadrature Pulse, Flow Alarms or Two-Stage Batch Control
Protection ClassIP66/67 (NEMA4X), Optional Exd I / IIB T4/T6, Integral Ancillaries can be supplied I.S. (intrinsically Safe)
Body - Aluminum Meters (A)AluminumAluminumAluminum
Body - Stainless Steel Meters (S)316L Stainless Steel--
Bearings - Aluminum Meters (A)nonenonenone
Bearings - Stainless Steel Meters (S)Carbon Ceramic--
Shaft - Aluminum & Stainless Steel Meters (A, S)Stainless Steel--
Rotor - Aluminum & Stainless Steel Meters (A, S)PPS--
Seals - Aluminum Meters (A)FKM (Viton™)FKM (Viton™)FKM (Viton™)
Seals - Stainless Steel Meters (S)PTFE encapsulated FKM--
Aluminum Meters13.9" (354mm)15.0" (294mm)15.3" (294mm)
Stainless Steel Meter13.9" (354mm)--

*Maximum flow is to be reduced as viscosity increases, see flow de-rating guide. Maximum recommended pressure drop is 15 PSIG (1.03 bar)


  • PTFE encapsulated FKM (Viton™) Seals
  • Buna-N (Nitrile) Seals (-40°F minimum)
  • High Viscosity PPS Rotors
  • Up to 300°F rated
  • PN16 DIN Flanges
  • N.I.S.T. Certification

Replacement Parts

  • Contact our Sales Dept.

Alternate Meters

Application Notes

  • Saturated Steam Service: Not acceptable
  • Potable Water: Not acceptable.
  • Vacuum Service: Not acceptable
  • Gaseous Service: Not acceptable
  • General Non-Suitable Services: Liquids with unfiltered solids. Note that deionized (DI) and ultra-pure waters require all stainless steel components and PTFE seals.
  • Installation: Limit display’s exposure to sun.
  • Corrosion: Before ordering, verify all materials of our flow meters are compatible with the service media(s), intermittently used cleaners, the environment, and cleaning processes in conjunction with the temperatures and pressures of the application(s) and future applications. John C. Ernst Co. does not make chemical compatibility recommendations. Compatibility is the responsibility of the user and/or specifying party.

Model Number Matrix
Model Number Matrix