The Global Leader In Viscosity For Over 75 Years
Brookfield AMETEK

Fuel Oil

Process Viscometer Application Data Sheet


Fuel oil is used to heat and/or power large commercial and institutional buildings. The problem for plant and facility managers is the variable viscosity of delivered oil, as. inefficient burning of fuel can result if the oil does not properly atomize during combustion.

The Brookfield AST-100 inline process viscometer is designed for use in pressurized fuel oil delivery systems. Plant managers at these facilities purchase variable grades of #5 and #6 fuel oil from many diverse spot markets around the globe. Steam or electric heat exchangers are used to preheat the oil prior to combustion. Proper atomization ensures the best combustion efficiency which requires continuous and accurate viscosity measurement and control.

Problem Description

To burn fuel oil at the high volume flow rates demanded of modern boiler units, the oil must be atomized (i.e. dispersed into the furnace as a fine mist). This assures high speed vaporization and ignition. Most burners atomize oil by shearing the oil into small droplets. Burner manufacturers recommend that the oil be supplied to the burners at a specific viscosity to maintain consistent atomization. Failure to maintain proper atomization results in:

  • Dirty fuel burning due to carbon and soot buildup
  • Higher fuel consumption and costs
  • Increased stack emissions and possible fines from government agencies
  • Increases costly downtime in manufacturing and office operations


The Brookfield AST-100 inline process viscometer accurately monitors and controls viscosity and temperature in pressurized oil delivery systems. Accurate viscosity measurements are necessary to maximize the efficient atomization and delivery of a variety of paraffin-based oils, asphaltic-based oils, as well as #5 and #6 heating fuels. The AST-100 process viscometer also ensures that no fluctuations in temperature and viscosity occur. The AST-100 solution includes the following design considerations:

  • Bypass loop for viscometer installation to build in redundancy for fail-safe operation
  • Use of viscosity feedback to control the heat rate to the oil feed lie heat exchanger
  • Output from the viscometer goes to a single loop controller which instantly responds to in-line viscosity changes
  • System design can accommodate the large thermal capacitance of the oil heat exchangers and the varying oil flow rates through the heat exchanger


  • Overcomes the limitations of variable grade #5 and #6 heating fuel deliveries
  • Saves money by improving combustion efficiency by lowering fuel consumption
  • Minimizes maintenance requirements by significantly reducing clogged burner nozzles, carbonizing of burner tips and increased depositions in the burner's combustion gas passages
  • Maintains consistent burner flame patterns on warmer or colder days, weekends, and slower production times
  • Prevents wax build-up in strainers when using paraffin-based oil
  • Reduces boiler down time
  • Lowers stack emissions
  • Improves corporate profitability by reducing energy costs and investment in emissions control equipment

Return on Investment

  • Fuel savings through more efficient combustion of fuel oil
  • Reduced boiler maintenance resulting from reduced fouling and soot formation A/95-804-A1297