OFTEC Oil Burner Types and Operation 3

Question 1

What is the role of the pre-heater in an oil burner using gas oil (Class D fuel)?

Accepted Answer

To warm the oil to reduce its viscosity for proper atomisation

Answer

Gas oil (35-second) is more viscous than kerosene. A pre-heater warms the oil before it reaches the nozzle, reducing viscosity so it can be properly atomised for clean combustion.

Question 2

What is the standard nozzle flow rate unit used for oil burner nozzles in the UK?

Accepted Answer

US gallons per hour (USgph)

Answer

Oil burner nozzles are rated in US gallons per hour (USgph), even in the UK. Common domestic sizes range from 0.50 to 1.50 USgph. This rating is measured at a standard test pressure of 7 bar.

Question 3

What safety device prevents the oil pump from building excessive pressure?

Accepted Answer

A pressure relief valve that returns excess oil to the suction side

Answer

The pressure relief valve in the fuel pump prevents dangerous over-pressurisation by diverting excess oil back to the suction (return) side of the pump. This maintains safe, consistent operating pressure.

Question 4

In a two-pipe oil supply system, what is the purpose of the return pipe?

Accepted Answer

To carry unused oil back to the tank, aiding in de-aeration

Answer

In a two-pipe system, excess oil and any trapped air are returned to the tank via the return pipe. This helps remove air from the fuel line and ensures reliable priming, especially on longer pipe runs or where the tank is below the burner.

Question 5

What is the maximum recommended length for a single-pipe oil supply to a burner?

Accepted Answer

5 metres with a maximum lift of 3 metres

Answer

Single-pipe systems are limited to approximately 5 metres total length with a maximum suction lift of about 3 metres. Beyond these limits, a two-pipe system should be installed to ensure reliable fuel delivery.

OFTEC Practice Test

OFTEC Practice Test

OFTEC Oil Burner Types and Operation 3