MN Boiler License Exam Questions and Answers, Latest Updated 2024/2025 (GRADED)

MN Boiler License Exam Questions and Answers, Latest Updated 2024/2025 (GRADED) what are the conditions necessary for good combustion? a) low sulfur content b) Thermal, thermocoupler, tubular c) turbulence, temperature, time 3T's - answerc) turbulence, temperature, time 3T's why is secondary air necessary in hand fired boilers? a) Necessary to burn the combustible gases b) if primary air should fail c) used only if sulfur content is high - answera) Necessary to burn the combustible gases when pressure increases on steam from a given amount of water what happens to its volume and latent heat? a) increases b) decreases c) remains the same - answerb) decreases when pressure increases on steam from a given amount of water what happens to its temperature? a) increases b) decreases c) remains the same - answera) increases when carbon monoxide (co) is formed and carbon dioxide (co2) is very high what does it generally signify? a) More "under the fire air" is needed MN Boiler License Exam Questions and Answers, Latest Update 2024/2025 b) less "under the fire air" is required c) more "over the fire" air is needed d) less "over the fire" is needed less - answerc) more "over the fire" air is needed excess air is an expression that refers to: a) overabundance of air b) theoretical amount of air c) air supplied above that theoretically required - answerc) air supplied above that theoretically required a good percentage of carbon dioxide when burning oil is: a) 12% b) 8 % c) 10% - answera) 12% what is draft on a boiler in operation? a) Flow of gases through boiler b) difference in pressure between atmosphere and furnace or firebox c) difference between atmospheric pressure and breeching - answerb) difference in pressure between atmosphere and furnace or firebox which has greater heating value per pound? a) oil b) coal - answera) oil ( BTU) (coal has ( BTU)) heavy oil must be heated before entering the burner to: a) increase carbon content b) decreased sulfur content c) get proper atomization - answerc) get proper atomization why should a daily log be kept of flue gas temperature? a) Valuable information in case of explosion b) superintendent files them c) change an operation, causing heat loss, can be detected - answerc) change an operation, causing heat loss, can be detected find SWP of a boiler 72 inches in diameter, thickness of one-half inch, tensile strength of 55,000 pounds, quadruple riveted butt and strap joint (.94) factor of safety 5: a) 14.3 b) 143.6 c) 1436 - answerb) 143.6 the total heat of steam is 1,188 BTUs, and feed water temperature is 182 degrees Fahrenheit. What is the factor of evaporation? a) 107 b) 10.7 c) 1.07 - answerc) 1.07 why would viscosity be important in fuel oil? a) more heat is recovered in water b) has more volatile hydrocarbons c) affects ease with which it can be handled - answerc) effects ease with which it can be handled why is too much air objectionable? a) Cost too high b) loss of efficiency c) corrosive effect - answerb) loss of efficiency what is a fyrite used for? a) flue gas analyzer b) combustion programmer c) water analysis - answera) flue gas analyzer absolute pressure is (ABS): a) atmospheric pressure - gauge pressure b) gauge pressure minus atmospheric pressure c) atmospheric pressure + gauge pressure - answerc) atmospheric pressure + gauge pressure when pressure of steam increases, what happens to the temperature? a) Goes up b) goes down c) remains the same - answera) Goes up find the square feet of heating surface of a flu 4" in diameter and 20' in length: a) 25'sq b) 251.32'sq c) 2513'sq d) 20.93'sq - answerd) 20.93'sq what is the minimum size of the pipes connecting the boiler to the water column? a) 3/4 inch b) 1 inch c) 1/2 inch - answera) 3/4 inch why are crosses used instead of ells on water column connections? a) Cost less b) has more strength c) line may be easily cleaned - answerc) line may be easily cleaned can you have valves between boiler and water column? a) Yes, if they are locked or sealed open b) no, they might be closed accidentally c) only if the boiler is under 100 horsepower - answera) Yes, if they are locked or sealed open can you have valves between boiler and water column? a) Yes, if they are locked or sealed open b) no, they might be closed accidentally c) only if the boiler is under 100 horsepower - answera) Yes, if they are locked or sealed open in the HRT boiler, the fuse plug is located in the rear head, _____ inches above the top row of tubes. a) 2" b) 1/2" c) 1" - answera) 2" a siphon coil (pigtail) is employed in steam gauge line protects the : a) Bourdon tube b) piping c) draft gauge - answera) Bourdon tube what type of shut off would be preferable on a pressure gauge valve that is not used a) non-return b) needle-type c) cock with a T or lever-type handle - answerc) cock with a T or lever-type handle steam gauges shall have a dial graduation of at least: a) 1 1/2 times the M.A.W.P. b) same pressure as the boilers c) 2.0 times the M.A.W.P. - answera) 1 1/2 times the M.A.W.P. what is the function of a feed water regulator? a) controls temperature of water b) control solids in the water of boiler c) control water level in a boiler - answerc) control water level in a boiler when two stop valves are used on a steam outlet line, it is good practice to have one valve : a) slow opening b) automatic non-return c) quick opening - answerb) automatic non-return is the valve stem connected to the disc on an automatic non-return valve? a) no b) yes c) only when open - answera) no what must you have between two stop valves on the steam outlet and between the header line? a) thermocoupler b) dial actuated thermostat c) drain - answerc) drain on a globe valve used on feed piping, the inlet shall be: a) immaterial b) above the valve disc c) under the valve disc - answerc) under the valve disc which valve offers very little resistance to a flow? a) gate b) globe c) check - answera) gate which valve is used where a flow in one direction only is desired? a) gate b) globe c) check - answerc) check each boiler shall have: a) only one safety valve b) two safety valves c) one or more safety valves d) two or more safety valves - answerc) one or more safety valves a boiler with more than 500 square feet of heating surface must have: a) one safety valve b) two or more safety valves c) three safety valves d) four safety valves - answerb) two or more safety valves if a boiler is fired to full capacity, the header valve being closed, the safety valves or valve should prevent steam pressure from rising above: a) 4% above S.W.P. or valve setting b) 5% above S.W.P. or valve setting c) 6% above S.W.P. or valve setting d)10 % above S.W.P. or valve setting - answerc) 6% above S.W.P. or valve setting the maximum steaming capacity of a boiler shall be based on the: a) capacity of the fuel burning equipment, air supply, draft, etc. b) ability of the fireman c) type of boiler under test d) temperature of ht boiler feed water - answera) capacity of the fuel burning equipment, air supply, draft, etc. one of mare safety valves on the boiler proper shall be set: a) at or below the maximum allowable working pressure b) not more than 6% above the maximum allowable working pressure c) not more than 10% above the maximum allowable working pressure d) not more than 15% above the maximum allowable working pressure - answera) at or below the maximum allowable working pressure if additional valves are used, the highest pressure setting shall not exceed the M.A.W.P. by more than: a) 3% b) 4% c) 5% d) 6% - answera) 3% safety valves shall be: a) positive weight b) direct spring loaded type c) combination of weight and spring d) doesn't make any difference - answerb) direct spring loaded type dead-weight or weighted-lever safety valves may be used: a) when pressure is less than 100 psi b) never c) only by permission of boiler inspector d) under 15 psi - answerb) never if it is desirable to prove the computations of the safety valve capacity it may be done in: a) two ways b) three ways c) four ways d) five days - answerb) three ways when not more than two valves of different sizes are mounted singly. the relieving capacity of the smaller valve shall not be less than _______ percent of the larger valve. a) 20% b) 35% c) 50% d) 70% - answerc) 50% the safety valve or valves shall be connected to the boiler independent of any steam connection. a) if under 100psi b) always c) if furnace is stoker fired d) if required by inspector - answerb) always no valve of any description shall be placed between the required safety valve or valves and the boiler nor on the discharge pipe between the safety valve and the atmosphere. a) if over 15psi b) if over 100psi c) without written permission from state boiler inspector d) at any time - answerd) at any time if a discharge pipe is used on the safety valve, the cross sectional area shall be: a) not less than the full area of the valve outlet b) two times the full area of the valve outlet c) three times the full area of the valve outlet d) it doesn't make any difference - answera) not less than the full area of the valve outlet safety valves shall operate without chattering and shall be adjusted to close after blowing down not more than: a) 4% but not less than 2 lbs psi b) 3% but not less than 4 lbs psi c) 6% but not less than 4 lbs psi d) 10% but not less than 2 lbs psi - answera) 4% but not less than 2 lbs psi the spring in a safety valve in service for pressure up to 250lbs psi shall not be used for any pressure more than _______ below that for which it is designed. a) 2% above or 2% b) 6% above or 6% c) 10% above or 10% d) 12% above or 12% - answerc) 10% above or 10% for pressure above 250lbs P.S.I. , the safety relief shall not have a pressure more than ______ below that that for which it is designed. a) 2% above or 2% b) 5% above or 5% c) 6% above or 6% d) 10% above or 10% - answerb) 5% above or 5% every attached super-heater shall have one or more safety relief valves: a) near the outlet b) between boiler and super-heater c) between super-heater and turbine or engine d) if steam is used to operate turbine - answera) near the outlet