OBT: Unit 9 (gas) & OBT Test
Questions All Solved 2026-2027
Updated.
What term is used to describe a burner flame that moves back through the burner nozzle?
a. floating flame
b. flame lift
c. flash back
d. orange flashing flame - Answer c. flash back
through which device is fuel discharged to an atmospheric burner?
a. orifice
b. nozzle
c. zero governor - Answer a. orifice
which type of atmospheric burner produces a single large flame?
a. inshot burner
b. single or mono-port burner
c. drilled port burner
d. upshot burner - Answer b. single or mono-port burner
list four common types of multiport atmospheric burners: - Answer - drilled port
- drilled pipe
- slotted port
- ribbon port
what are the recommended minimum and maximum port diameters for drilled port
atmospheric burners?
a. max:No. 29 drill & min: No.42 drill
b. max: No. 25 drill & min: No. 40 drill
c. max: No. 20 drill & min: No 38 drill - Answer a. max: No. 29 drill & min: No.42 drill
, which type of burner has combustion air supplied by a fan or blower under sufficient pressure
to overcome the restriction of the burner and the appliance?
a. fan-assist burner
b. atmospheric burner
c. forced draft burner - Answer c. forced draft burner
which type of burner has a fan located downstream of the combustion zone?
a. fan-assist burner
b. induced draft burner
c. atmospheric burner - Answer b. induced draft burner
what provides the kinetic energy to entrain the gas required for a premixing aspirator-type
burner?
a. the gas pressure issuing from an orifice into a gas jet mixer
b. the gas pressure issuing from a nozzle into a gas jet mixer - Answer a. the gas pressure
issuing from an orifice into a gas jet mixer
what device is used to regulate gas supply to an aspirator-type burner?
a. orifice
b. zero governor
c. mixing tube - Answer b. zero governor
which type of burner provides complete premixing using mechanical mixers?
a. atmospheric burners
b. aspirator premix burners
c. blower-mix or fan-mix burners - Answer c. blower-mix or fan-mix burners
how do you correct a lifting flame on atmospheric burner?
a. correct draft position
b. increase primary air
c. reduce appliance input
d. reduce primary air
e. both c & d - Answer e. both c & d
how do you correct flash back on atmospheric burner?
a. increase burner input
Questions All Solved 2026-2027
Updated.
What term is used to describe a burner flame that moves back through the burner nozzle?
a. floating flame
b. flame lift
c. flash back
d. orange flashing flame - Answer c. flash back
through which device is fuel discharged to an atmospheric burner?
a. orifice
b. nozzle
c. zero governor - Answer a. orifice
which type of atmospheric burner produces a single large flame?
a. inshot burner
b. single or mono-port burner
c. drilled port burner
d. upshot burner - Answer b. single or mono-port burner
list four common types of multiport atmospheric burners: - Answer - drilled port
- drilled pipe
- slotted port
- ribbon port
what are the recommended minimum and maximum port diameters for drilled port
atmospheric burners?
a. max:No. 29 drill & min: No.42 drill
b. max: No. 25 drill & min: No. 40 drill
c. max: No. 20 drill & min: No 38 drill - Answer a. max: No. 29 drill & min: No.42 drill
, which type of burner has combustion air supplied by a fan or blower under sufficient pressure
to overcome the restriction of the burner and the appliance?
a. fan-assist burner
b. atmospheric burner
c. forced draft burner - Answer c. forced draft burner
which type of burner has a fan located downstream of the combustion zone?
a. fan-assist burner
b. induced draft burner
c. atmospheric burner - Answer b. induced draft burner
what provides the kinetic energy to entrain the gas required for a premixing aspirator-type
burner?
a. the gas pressure issuing from an orifice into a gas jet mixer
b. the gas pressure issuing from a nozzle into a gas jet mixer - Answer a. the gas pressure
issuing from an orifice into a gas jet mixer
what device is used to regulate gas supply to an aspirator-type burner?
a. orifice
b. zero governor
c. mixing tube - Answer b. zero governor
which type of burner provides complete premixing using mechanical mixers?
a. atmospheric burners
b. aspirator premix burners
c. blower-mix or fan-mix burners - Answer c. blower-mix or fan-mix burners
how do you correct a lifting flame on atmospheric burner?
a. correct draft position
b. increase primary air
c. reduce appliance input
d. reduce primary air
e. both c & d - Answer e. both c & d
how do you correct flash back on atmospheric burner?
a. increase burner input
