MASTERLOAD II™ Electronic Register

The Avery-Hardoll MASTERLOAD II™  is a powerful and versatile micro processor based electronic controller.  The unit is capable of enhancing the performance of most makes of positive displacement and turbine meters.

MASTERLOAD II™ is an intrinsically safe system, ideal for use in Category 2 hazardous areas.  The system is comprised of a pulse transmitter mounted on the meter, a display unit giving readouts of batch volume, flow rate, and a totalizer.


  • Accurate, dynamic meter calibration
  • Volume to weight conversion
  • Temperature compensation (option)
  • Two-way data interchange to cab mounted data capture systems
  • Interface to deadman system
  • Interface to accessories with 4-20 mA output
  • Flexible installation

DYNAMIC CALIBRATION: Provides accurate error correction across the entire flow range. Most meters are calibrated at only one flow rate - generally 100%. In reality, meters operate at a variety of flow rates. Masterload calibration is corrected at all flow rates to provide the highest level of accuracy. With a choice of 1, 2, 4, or 8 calibration points across the flow range - the system allows the user the flexibility to configure each Masterload to suit the requirements of his own application.  Masterload performs a curve fitting exercise to provide the required correction.

VOLUME TO WEIGHT CONVERSION:  Provides a reading in weight. Available as either a simple manually entered density figure for low cost batch conversion or a dynamic input from an in-line densitometer which when linked to temperature correction offers the highest level of accuracy.

TEMPERATURE COMPENSATION (Option):  Provides a range of temperature related displays.  Using a platinum resistance thermometer (PRT), the display may be configured to show product temperature or mean batch temperature. Alternatively, full temperature correction to standard temperature or to the IP/ASTM tables 53 and 54 may be configured.

DATA COMMUNICATION:  Data to RS422 / RS232 specification offers comprehensive two way data communication between the meters and a variety of vehicle systems allowing data flow from the meter to the system and user input passed back to the meter.  Approved to EN ISO 6551-1995 level A, MASTERLOAD II™ offers the highest level of data security available.

AUTOMATIC CALIBRATION:  When calibrated against a MASTERLOAD II™ configured reference meter, a simple infra-red connection links the MASTERLOAD II™ register under test to the reference meter system. This allows calibration to be carried out automatically, reducing down time, volume of product passed, and the potential for human error. Calibration certificates are computer generated to the IP or customer’s own specification.

DEADMAN INTERFACE: The power supply unit provides a permanent signal to the deadman circuit. If an error occurs, the signal is removed and the deadman shuts the fuelling off.


  • Display:  MASTERLOAD II™ displays batch delivery, rate of flow, and totaliser on large figure liquid crystal displays (LCD’s). These displays may easily be configured at site to show a range of alternative values such as volume corrected to reference temperature. Additional display enclosures, with either repeat or supplementary information can be installed at convenient locations. 
  • Retro fit:  MASTERLOAD II™ has been widely used to enhance the performance of most makes of positive displacement meters and can be supplied as a retrofit to existing mechanical meters.
  • Flexibility:  MASTERLOAD II™ allows the meter to be installed in any convenient position since the display unit may be mounted to suit the operator.
  • Two-way data interchange:  Allows connection to most cab mounted information and data capture systems.



  • Batch: Minimum volume - one unit, 6 figures standard units, (2 decimal places selectable)
  • Flow rate: Sampled every 0.6 secs
  • Totalizer: 8 figure
  • Remote display: Max of 3 remote displays
  • (various displayed data)
  • Interfaces: RS422 / RS232, 7 switch monitoring contacts, auto calibration port
  • ID Mode: Simple password entry

Delivery override:

  • Key Operated IP 65 Box (option)

Power supply: 

  • 12/24V DC


  • Max of 11 plug-in
  • Typical - 1 Deadman
  • Pulse output


  • 4 x (4-20mA)

Power consumption:

  • 350mA max. (excluding relays)


  • 1, 2, 4, or 8 selectable
  • Full dynamic interpolation
  • Accuracy +/- .02 at measuring condition and 15˚C if temperature compensated

Manual input:

  • Density for weight indication

Non volatile memory:

  • Data retained indefinitely

Sealing:   All units are designed for outdoor use and are sealed to specification IP 65.


  • Full wire sealing
  • Automatic error checking
  • Alarm reporting
  • Data storage for 40 transactions

Operating temperature:

  • -20 to 40˚ C


  • Temperature: -30 to 120˚C
  • Fitting: Direct drive available for most makes of meter
  • Approval: EN ISO 6551-1995 Level A
  • Channels: 3 Independent
  • Security: Sense line

Humidity: Up to 100%

Safety classification: Category 2

ATEX approvals:

  • Power supply unit (flameproof): II 2 G EEx d IIB T6
  • Certificate Number: ITS04ATEX11903
  • Display unit: II 2 G EEx ib IIB T4
  • Certificate No. BAS02ATEX2199

Temperature probe PRT

  • Accuracy: +/-0.1˚C
  • Discrimination: 0.1˚C
  • Range: -30 to 120˚C
  • Set up: Factory set (no adjustment required)
  • Alarm limits: Programmable
  • Display: ˚F or ˚C; selectable
  • Compensation 15, 20, or 31.5˚C

Location: Flexible fitting (max 50 meters between units)

Product correction tables:

  • IP/ASTM Table selection to specification IP65.
  • Generalized crude (A tables)
  • Generalized products
  • Table 54
  • Table 53