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What is the purpose of a low-water cutoff on a low pressure boiler?

Learn about the importance of a low-water cutoff in low-pressure boilers to prevent water level issues, excessive pressure, and ensure safety.

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What is the purpose of a low-water cutoff on a low pressure boiler?

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  1. What is the purpose of a low-water cutoff on a low pressure boiler? • To cut off the water supply • To cut off the fuel supply • To signal that the water level is low • To prevent excessive pressure

  2. 1.a. What is the purpose of a low-water cutoff on a low pressure boiler? • To cut off the water supply • To cut off the fuel supply • To signal that the water level is low • To prevent excessive pressure High pressure boilers P 252 P 90

  3. Which of the following is exempted from specified field-pressure tests? • Liquid-line connections at the expansion valve • Suction-line connections at the accumulator • Suction-pressure control connections on the compressor • Factory-assembled parts tested at the factory

  4. 2a. Which of the following is exempted from specified field-pressure tests? • Liquid-line connections at the expansion valve • Suction-line connections at the accumulator • Suction-pressure control connections on the compressor • Factory-assembled parts tested at the factory UMC 2012 1108.1.2 P 105

  5. All of the following are features of electronic control systems EXCEPT: • slow response. • simple construction. • no moving parts. • a centrally located regulatory element.

  6. All of the following are features of electronic control systems EXCEPT: • slow response. • simple construction. • no moving parts. • a centrally located regulatory element. HVACR P 1222

  7. Refer to the figure below:What does this symbol represent when it is used on internal and field wiring diagrams for control systems? • Solid Wire • Stranded Wire • Wire junction • Cross-section of wire

  8. Refer to the figure below:What does this symbol represent when it is used on internal and field wiring diagrams for control systems? • Solid Wire • Stranded Wire • Wire junction • Cross-section of wire HVACR P 555 Symbols tab

  9. A control circuit that prevents the restarting of a compressor after the safety control resets is what? • Standing relay • Floating relay • Lockout relay • Single pole double throw switch

  10. A control circuit that prevents the restarting of a compressor after the safety control resets is what? • Standing relay • Floating relay • Lockout relay • Single pole double throw switch HVACR P 1479 Glossary

  11. Vent connectors shall rise vertically to the vent minimum pitch equal to what? • 1/8” • 1/4” • 1/2” • 1"

  12. Vent connectors shall rise vertically to the vent minimum pitch equal to what? • 1/8” • 1/4” • 1/2” • 1“ IMC 2012 803.10.5 2% = 1/4” P 81

  13. An electric heating appliance shall have a manufacturer’s label containing all except: • Btu/h • Electrical data • Manufacture’s seal or trade mark • Manufacture's date code

  14. An electric heating appliance shall have a manufacturer’s label containing all except: • Btu/h • Electrical data • Manufacture’s seal or trade mark • Manufacture's date code IMC 2012 301.9 P 21

  15. This question refers to the duct layout found on the next slide, and to the information given below:Determine the size of the galvanized metal duct using a constant velocity method with the following velocity limits: Supply, Main: 1,500 fpm Supply, Branch: 900 fpm Return: 1,200 fpmWhat is the size of Supply Duct F? The Duct is 16” deep. • 20 • 22 • 24 • 28

  16. This question refers to the duct layout found on the next slide, and to the information given below:Determine the size of the galvanized metal duct using a constant velocity method with the following velocity limits: Supply, Main: 1,500 fpm Supply, Branch: 900 fpm Return: 1,200 fpmWhat is the size of Supply Duct F? The Duct is 16” deep. • 18 • 22 • 26 • 28 Use Trane Ductulator

  17. This question refers to the duct layout found on the next slide, and to the information given below:Determine the size of the galvanized metal duct using a constant velocity method with the following velocity limits: Supply, Main: 1,500 fpm Supply, Branch: 900 fpm Return: 1,200 fpmWhat is the size of Supply Duct F? The Duct is 16” deep. • 18 • 22 • 26 • 28

  18. With the dry bulb temperature remaining constant, an increase in moisture content of the air results in • a decrease in humidity ratio. • an increase in enthalpy. • a decrease in relative humidity. • an increase in density

  19. With the dry bulb temperature remaining constant, an increase in moisture content of the air results in • a decrease in humidity ratio. • an increase in enthalpy. • a decrease in relative humidity. • an increase in density. Psychometric Chart P 678 tab page

  20. At what MAXIMUM temperature may a low-pressure boiler supply hot water? • 180° F • 212° F • 250° F • 260° F

  21. At what MAXIMUM temperature may a low-pressure boiler supply hot water? • 180° F • 212° F • 250° F • 260° F UMC Definitions: 2012 High Pressure Boiler Book P 2

  22. The heat picked up in the evaporator is approximately equal to what? • The heat of compression • The heat used to condense water vapor • The heat lost by the zone being cooled by the evaporator • The heat gained by the condenser

  23. The heat picked up in the evaporator is approximately equal to what? • The heat of compression • The heat used to condense water vapor • The heat lost by the zone being cooled by the evaporator • The heat gained by the condenser HVACR P 185

  24. A gas piping system that carries dangerous materials shall be identified by letters in what color combination? • White letters with green background • White letters with yellow background • Black letters with green background • Black letters with yellow background

  25. A gas piping system that carries dangerous materials shall be identified by letters in what color combination? • White letters with green background • White letters with yellow background • Black letters with green background • Black letters with yellow background IFGC 2012 401.5 p 29

  26. What MINIMUM passageway width is required around a boiler? • 12” • 18” • 24” • 30”

  27. What MINIMUM passageway width is required around a boiler? • 12” • 18” • 24” • 30” IMC 2012 1004.3 P 92

  28. Refer to the figure below.The term “travel” can be applied to which dimension? • A • B • C • D

  29. Refer to the figure below.The term “travel” can be applied to which dimension? • A • B • C • D Pipe Fitters P 4-9 and P 4-1

  30. A galvanized metal duct 10” wide by 16” high has a measured length of 100 feet and carries 1,000 cfm.What is the average velocity of the air in the duct? • 1,000 fpm • 1,200 fpm • 1,400 fpm • 1,600 fpm Use Trane Ductulator

  31. A galvanized metal duct 10” wide by 16” high has a measured length of 100 feet and carries 1,000 cfm.What is the average velocity of the air in the duct? • 1,000 fpm • 1,200 fpm • 1,400 fpm • 1,600 fpm

  32. All of the following are reasons for using the bottom blowdown line on a boiler EXCEPT • to control low water. • to remove sludge and sediment. • to dump or drain the boiler. • to control chemical concentration in the water.

  33. All of the following are reasons for using the bottom blowdown line on a boiler EXCEPT • to control low water. • to remove sludge and sediment. • to dump or drain the boiler. • to control chemical concentration in the water. High Pressure Boiler Glossary P 340 Can control High Water.

  34. A type L gravity vent system for a gas-fired appliance shall terminate what MINIMUM distance above the highest vent collar it serves? • 3’ • 5’ • 7’ • 9’

  35. A type L gravity vent system for a gas-fired appliance shall terminate what MINIMUM distance above the highest vent collar it serves? • 3’ • 5’ • 7’ • 9’ IMC 2012 802.6 P 80

  36. All the following are types of combustion EXCEPT • perfect. • positive. • complete. • incomplete.

  37. All the following are types of combustion EXCEPT • perfect. • positive. • complete. • incomplete. High Pressure Boiler P 169 Index also names all but Positive

  38. Air filters installed with liquid adhesives shall have what MINIMUM flashpoint? • 275° F • 300° F • 325° F • 350° F

  39. Air filters installed with liquid adhesives shall have what MINIMUM flashpoint? • 275° F • 300° F • 325° F • 350° F IMC 2012 605.1 P 70 = 325 F

  40. THIS QUESTION refers to the information found on the next slide and diagram following. Using the information and procedures in ACCA’s Manual N, calculate for winter (heating) conditions.What is the cooling load due to occupants (sensible + latent)? • Less than 10,000 BTU/hr • 10,001 to 14,000 BTU/hr • 14,001 to 16,000 BTU/hr • More than 16,000 BTU/hr

  41. The First National Bank (shown on next page) is a one-story building located in Orlando, Florida. The following information and figures are given for this bank:CONDITIONS = WALLS: All walls are 15’ high and constructed of plate glass 1/4” thick with a dark roller shade. For design purposes assume that these shades are closed tightly in the summer and opened in the winter. Neglect the effect of the frames that hold the glass.CONDITIONS = DOORS: The only doors are on the south wall. These doors are 7’ high with a combined width of 12 feet and are constructed of the same materials as the walls, including the roller shades. FLOOR: The floor is of concrete slab-on-grade construction with no edge insulation.CONDITIONS = ROOF: The roof is flat with 2 inches of insulation above a steel deck and with no ceiling suspended below. The exterior surface of the roof is a light color.CONDITION2 = OVERHANG: There is a 6’ overhang along the entire south wall. Assume that this overhang shades the south wall completely. PEOPLE: Assume 20 people, including employees and customers.CONDITION3 = LIGHTING: The lighting consists of 200 40-watt fluorescent bulbs located in the conditioned space. VENTILATION: 450 cfm. INFILTRATION: Assume neutral pressure, average construction and low exhaust cfm.DESIGN CONDITIONS: 24° North Latitude Winter SummerDESIGN CONDITIONS: Outdoor 32°F 95°F (DB); 85°F (WB)DESIGN CONDITIONS: Indoor 72°F 75°F, 50% RHUnless otherwise stated, assume all loads are calculated for 3pmNecessary data that is not given here should be taken from Manual-N.

  42. THIS QUESTION refers to the information found on the next slide and diagram following. Using the information and procedures in ACCA’s Manual N, calculate for winter (heating) conditions.What is the cooling load due to occupants (sensible + latent)? • Less than 10,000 BTU/hr • 10,001 to 14,000 BTU/hr • 14,001 to 16,000 BTU/hr • More than 16,000 BTU/hr Manual N table 10

  43. What draws the air into the burner on a low-pressure gas-fired boiler that uses high-fire and low-fire operation for the burner? • Zero-reducing governor • Vaporstat • Blower air as it is drawn through the venturi • 0.5 psi gas pressure supplied at the gas cock

  44. What draws the air into the burner on a low-pressure gas-fired boiler that uses high-fire and low-fire operation for the burner? • Zero-reducing governor • Vaporstat • Blower air as it is drawn through the venturi • 0.5 psi gas pressure supplied at the gas cock HVACR P 1252

  45. A technician is adding air to an existing gas-fired furnace. The control transformer will be required to power which additional loads? • Gas valve and thermostat heat anticipator • Fan relay and gas valve • Contactor and fan relay • High limit and fan relay

  46. A technician is adding air to an existing gas-fired furnace. The control transformer will be required to power which additional loads? • Gas valve and thermostat heat anticipator • Fan relay and gas valve • Contactor and fan relay • High limit and fan relay

  47. A boiler’s vent shall be opened when a boiler is taken off-line to prevent • superheater overheating. • excess pressure in the steam drum. • the safety valve from closing. • a vacuum from forming.

  48. A boiler’s vent shall be opened when a boiler is taken off-line to prevent • superheater overheating. • excess pressure in the steam drum. • the safety valve from closing. • a vacuum from forming. High Pressure Boiler P 59

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