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BM series flowmeters

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Avery-Hardoll flowmeters are precision made, positive displacement, liquid measuring instruments that maintain accurate metering over long periods of operation. Simplicity of design and construction together with sustained accuracy has led to the widespread use of BM Series meters on aviation refuelling vehicles as well as master meters for use in calibration throughout the world.

BM Series Meter - internal view

BM Series Meter

internal view of rotor

The BM Series flowmeter directly converts volume to rotational output with minimum scope for error and with minimal disturbance from surrounding conditions, such as turbulence from nearby valves, bends, and other system conditions.

  • Positive displacement measurement
  • 115 to 4000 LPM (30 to 1000 GPM) flow rates
  • Unequalled performance in measurement

The positive displacement principle is the ONLY accurate method of measuring fluid flow. No other technology can achieve such accuracy because measurement becomes inferred, which is indirect and subject to assumption. The Avery-Hardoll® bulkmeter directly converts volume to rotational output with minimum scope for error and with minimal disturbance from surrounding conditions, eg. turbulence from nearby valves, bends, etc.

  • The product enters the meter through the inlet manifold (1) and causes the rotor (4) to revolve by pressure on the vanes (3).
  • The proximity of the rotor (4) to the body (2) forms an efficient seal, whilst the profile of the casing ensures that the vanes (3) are guided through the measuring crescent (5), where the volume of product is accurately measured.
  • Product at line pressure fills the spaces between the inner (6) and outer (7) end covers providing pressure balanced inner end covers which are therefore protected from distortion due to changes in line pressure.
  • An extension shaft driving through a pressure tight gland in the meter front cover, transmits the rotor revolutions to the calibrating gearing (8) which drives the counter (9).
BM Series Meter - cross section

BM Series Meter - dimensions
BM Series Meter - dimensions

Manifold: Fabricated steel or ductile iron (ductile iron not available on triple capsule meters)

Body: Ni-Resist cast iron

Vanes: Carbon

Rotor: Aluminum or Ni-Resist cast iron

Outer Covers: Aluminum or Ni-Resist cast iron

Inner Covers: Ni-Resist cast iron


A full range of meter accessories are available for use with all Avery-Hardoll bulk meters listed below:

Meter accessories


  • MASTERLOAD.iQ™: The center of the CENTRILOGiQ platform and the most scale-able and versatile electronic register ever produced.
  • MASTERLOADx.iQ™: The same powerful register contained in an ATEX Zone 1 rated enclosure.
  • Mechanical Counters: Meters can be fitted with standard mechanical counters with a five large figure zeroing drum and a seven figure small non-zeroing totaliser supplied to display outputs in any of the following units:
    • Imperial Gallons
    • US Gallons
    • Liters
    • Deciliters
    • Cubic Meters
  • Ticket Printers: Slip or roll printers.
  • Mechanical Preset and Preset Valve: A mechanical preset register with five figure resettable counter is used to preset a batch to be delivered. This controls a lever operated preset valve via a mechanical linkage, providing two stage closure and precise shut off of flow.
  • Mechanical Preset with Micro-switches: Micro-switches can be fitted to the preset register to control pump start and stop as well as solenoid operated preset valves.
  • Rate of flow indicator
  • Extended Counter Drive: Provided for installations where the counter is required to be read at a height above the bulk meter.
  • Slipstream® Densitometer: Automatically calculates and reports real-time fuel densities for accurate custody transfer reporting.
  • dP Transducer: Provides accurate real-time differential pressure readings in the fueling system.
  • Additive Injection: Mechanically injects fractional proportions of additives at a pre-determined ratio.
  • Strainer: Essential to prevent damage to the meter and is available with 40, 60, 80, 100, and 120 mesh baskets with either cast iron or cast steel body.
  • Air Separator: Prevents entrained air from reaching the meter.
  • Flow Governor: Limits flow rate at a maximum meter capacity when several meters are fed from one pump.


Viscous Products

Avery-Hardoll bulkmeters can be used on all petroleum products of all viscosities. However there is obviously an increase in pressure drop with more viscous fuels which, under normal circumstances, will limit the maximum flow rate obtainable.

It is recommended that the pressure drop through a bulkmeter should not exceed 15 psi (one bar), above which the load on the bearings will start to cause wear. Consequently when using products with viscosities (at operating conditions) above 100 centistokes, it is necessary to reduce the maximum permitted flowrate. As a guide it is suggested that the pressure drop through the meter should not exceed 10 psi (0.7 bar) for continuous running at maximum speed or 15 psi (one bar) for continuous running at half speed.

Pressure Loss

The low pressure drop for the BM series of Avery-Hardoll bulkmeters is displayed below:

BM series pressure loss

Maximum working pressure: 10.5 bar (150 psi)

Test pressure: 21 bar (300 psi)

Temperature range: -28ºC to 100ºC

Volume per revolution:

  • 2.27 litres (single capsule)
  • 4.54 litres (double capsule)
  • 6.82 litres (triple capsule)

Repeatability (typically): .02%

Typical accuracy curves for basic meter build (10:1 turndown)

  • Calibration adjustment is provided to minimize the meter error at any selected flowrate. Adjustment is stepless; no gear changing is necessary; the calibration screw is easily accessible after breaking a seal and removing a sealing screw.
  • All meters are tested to 300 psi (21 bar).
  • All meters are tested before dispatch at a range of flow rates, and test certificates can be supplied if requested.
  • The fluid used for testing is odorless kerosene.
    • Specific gravity at 60/60ºF, 15/15ºC = 0.8
    • Viscosity at 60ºF, 15ºC = 2.4 centistokes.
  • Suggested correction to be made to the calibrating mechanism when used with products with different viscosities as follows:
    • Gasoline + 0.1% + means increase counter readings
    • Kerosene 0.0% - means decrease counter readings
    • Gas Oil - 0.1%
    • Fuel Oil - 0.22%

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