Fuel Oil Pumps - Suction Capacities

Single stage and double stage fuel oil pumps and their suction capacities.

Fuel Oil Pump Types

The limitation of a fuel oil pump feeding a burner may often be the suction side. With higher suction lift the "vacuum" in the suction line will evaporate the light fractions of the fuel oil - and the pump starts to choke.

There are two main types of fuel feeding pumps:

  • Single Stage Pumps: Consist of one set of pumping gears with limited lift capacity, suited for low-level lifts up to 5-10 inches of vacuum
  • Double Stage Pumps: Consist of double set of pumping gears, suited for medium-level lifts up to 10-15 inches of vacuum

Higher vacuum levels require use of separate lifting pumps and dedicated feeding reservoirs to the fuel pumps.

Pump TypeMaximum Vacuum (inches)Typical ApplicationNotes
Single Stage5-10Low-level liftsLimited lift capacity
Double Stage10-15Medium-level liftsEnhanced pumping gears
Separate Lifting>15High-level liftsRequires dedicated reservoir

Vacuum Loss Estimation

The total "vacuum" in a fuel oil suction line can be estimated as follows:

  • 1 inch of vacuum for each foot of vertical lift
  • 1 inch of vacuum for each 90° elbow
  • 1 inch for each 10 feet of 3/8 inch horizontal suction pipe
  • 1 inch for each 20 feet of 1/2 inch horizontal suction pipe
ComponentVacuum Loss (inches per unit)
Vertical lift1 per foot
90° elbow1 per elbow
3/8 inch horizontal pipe1 per 10 feet
1/2 inch horizontal pipe1 per 20 feet