Boiler Design and Operation, Exams of Engineering

Download Boiler Design and Operation and more Exams Engineering in PDF only on Docsity! 3rd Grade Engineer Final exam Questions with Answers 100% Accuracy 1. How can you lose your license? - Correct Answers Drinking on the job, sleeping on the job, negligence, unsafe work, signing a falsified license application for someone or failing to renew your license annually. 2. What must you do if you change jobs? - Correct Answers You must notify city hall if you change jobs, change address, or retire. 3. Why should you do rounds? - Correct Answers So you can find and correct problems to prevent breakdowns. Keeping permanent records will make it easy to forecast most breakdowns because you will get to know your equipment. 4. What is a steam boiler? - Correct Answers A steam boiler is a closed vessel PARTLY FILLED WITH WATER, under pressure that transforms water to steam with the application of heat. 5. What are the requirements of a good boiler? - Correct Answers 1) Simple. 2) Designed to accommodate expansion and contraction. 3) Adequate steam and water space. 4) Efficient. 5) Responsive to demands. 6) Accessible for cleaning and repair. 7) Safe. 6. Name and describe three types of heat transfer in a boiler operation. - Correct Answers RADIANT HEAT is transmitted from a hot body to a cold body by means of direct radiation. The heat from the sun reaches us by means of radiation. CONDUCTION HEAT is passed by physical contact. A coffee cup is heated by conduction when the hot coffee touches the cup. CONVECTION HEAT is carried along by a moving body such as air or water. Your living room is heated by warm air from a furnace in another location in your room. 7. What is a combustion chamber? - Correct Answers The area of the boiler where COMPLETE burning of the fuel occurs. 8. What is internally fired boiler and name four types. - Correct Answers Internally fired boilers have the grates and combustion chamber enclosed within the boiler shell. Scotch Marine, vertical fire tube, locomotive, and cast iron package boilers. 9. What is an externally fired boiler and name four types. - Correct Answers Externally fired boilers have the setting including the furnace and grates separate and distinct from the shell. HRT set in brick work, some water tube boilers, Heine, cast iron boilers set in brickwork and Sterling. 10. What are the crown sheet and its purpose? What are the tube sheet and its purpose? - Correct Answers The crown sheet in a vertical fire tube boiler holds the tubes and is thicker because it is exposed to the fire. The tube sheet holds the tubes and does not see the fire. 11. What is a water leg on a boiler? - Correct Answers It is the space between the outer shell and the furnace shell, containing boiler water. Is absorbs heat that would be wasted and increases the capacity of the boiler. The surfaces are flat, and must be stayed. 12. Is an H.R.T. boiler set level or inclined and why? Are boiler tubes set level or inclined and why? - Correct Answers H.R.T. boilers are inclined 1 to 3 inches front to rear for drainage and removal or impurities. Boiler tubes are just inclined with the boiler shell. 13. Name to ways to support and take care of expansion of an H.R.T. boiler? Which way is best? - Correct Answers It can be set on saddles equipped with rollers to permit movement of the boiler as it expands and contracts. It may also be suspended from hangers and supported by overhead beams. Hanging from beams is best, that works no hardship on the furnace walls. 14. What is a longitudinal joint? What is a circumferential joint? - Correct Answers A longitudinal joint is a seam running the length of the shell and is butt strap constructed or fusion welded. It is above the fire line to avoid overheating. A circumferential joint is a lap joint running the circumference of the drum. 15. What is the difference between a flu and a tube? - Correct Answers A tube is 4" or less diameter measured externally. A flue is 4" or more diameter and is measured internally. 16. What is a dry pipe and where is it located? - Correct Answers The dry pipe is a steam separator located within the boiler shell and connects to the steam outlet. Its upper surface is perforated. Steam enters the perforations rapidly changing its direction of flow before entering the steam outlet. This causes droplets and impurities to separate from the steam. 31. What is an Alloy? Name 5. - Correct Answers A mixture of two or more metals. Brass, steel, stainless steel, pewter, cast iron, bronze, bell metal 32. At what pressure is the use of cast iron fittings permitted? - Correct Answers 15psi or 250°F. Not to exceed either one. 33. What is meant by "factor of safety"? - Correct Answers The comparison of the tensile strength to the actual working stress. The bursting pressure divided by the working pressure. 34. What is the factor of safety for boilers, flywheel, and pipe? - Correct Answers New boilers is 4 Pre-owned boilers are constructed to ASME code are 5 Flywheels is 3 Pipe is 8 35. What is a lap joint? What is a butt joint? What is a butt strap joint - Correct Answers A lap joint is one plate over laps another plate and is joined. A butt joint is when two ends of the plate meet end to end and are joined. A butt strap joint is when two ends of the plate meet end to end and are joined by a plate. One plate is a single butt strap joint, two plates are a double butt strap joint. 36. Is the longitudinal joint the strongest part of the boiler? - Correct Answers NO! It is the strongest type joint, but any joint is the weakest part of a boiler. 37. Two boilers are made out of the same grade of steel, same thickness of plates and same type of joints. One is 30" in diameter and the other is 60" in diameter. Which will withstand the greatest pressure? Demonstrate your answer. - Correct Answers The 30" boiler-it has less total pressure on the shell. 30x30x.7854x120psi=84,823lbs total pressure. 60x60x.7854x120psi = 339,292lbs total pressure. 38. What are tube ligaments? - Correct Answers The area between the tube holes on the tube sheet. 39. What type stays are used in the heads of water tube boilers and why? - Correct Answers There are no stays. The head of the boiler drum is shaped with a die, which dishes and forms them into the shape they would take as a result of the pressure to which they will be subjected. 40. Why is a row of tubes sometimes left out of an H.R.T. Boiler? - Correct Answers To improve circulation which will reduce carry over. 41. In a fire tube boiler how are tubes secured in a tube sheet and why? In a water tube boiler how are tubes secured in a tube sheet and why? In a water tube boiler why are only some of the tube ends beaded? - Correct Answers In a fire tube boiler hey are rolled and then beaded to prevent heat damage and to prevent them from pulling out. In a water tube boiler they are rolled then flared to keep them from pulling out. For drainage of the top drums and to prevent air pockets in the lower drums. 42. Is it necessary to brace or stay a flat surface? Name three types of stays. - Correct Answers Yes, to overcome the force on heads and flat surfaces. Where there are no tubes, braces and stays must be provided to prevent bulging of the boiler plate. T stay, J stay, Y stay 43. Describe a through stay. Why are hollow through bolts used on water legs? - Correct Answers A through stay runs from one tube sheet to the other or from one flat surface to another. A rod threaded on both ends is held in place with nuts on the inside tightened against nuts on the outside of the plates. A small hole is drilled into the stay bolt so if it failed a leak will develop and be detected at once. 44. Describe a diagonal and gusset stay. Where would each be used? - Correct Answers A diagonal stay is made of flat material similar to the boiler shell and is attached directly to the boiler shell and head or tube sheet. A gusset stay consists of boiler plate riveted to the shell and head or tube sheet by means of angle iron. They are more rigid. Both are used to brace right angle surfaces. 45. Why are hand holes and manholes made oval instead of round? What are the minimum sizes for manholes and hand whole openings? - Correct Answers So they can be inserted into and removed from their respective openings in the boiler. Man whole 11x15 or 10x16 Hand hole 2 3/4 x 3 1/2 46. What is thermal efficiency and what is considered a good percentage? - Correct Answers It is the ratio of heat absorbed by the water to the heat provided by the fuel. A good percentage is 85%; some boilers made today can reach 95% 47. How do you determine boiler capacity and what is boiler heating surface - Correct Answers Total heating surface determines the capacity of the boiler. Heating surface is any area that has hot gases on one side - boiler water on the other and is MEASURED FROM THE FIRE SIDE. 48. What is furnace volume? Is furnace volume measured in square feet or cubic feet? - Correct Answers Furnace volume is the space available for complete combustion of the fuel before the products of combustion enter the heat absorbing sections of the boiler. This varies with the type of fuel used. It is measured in cubic feet. 49. What is superheated steam? Does its temperature rise? - Correct Answers It is steam that has been heated to a higher temperature, but its pressure remains the same. Yes its temperature does rise. 50. Define flash point, ignition point, and pour point. - Correct Answers FLASH POINT is the lowest temperature at which vapors of a substance will make a flash of flame but not continue to burn when exposed to open flame. IGNITION POINT is the lowest temperature at which vapors of a substance will ignite and burn continuously when exposed to open flame. POUR POINT is the lowest temperature at which liquid will flow. 51. Define combustion. - Correct Answers Combustion is a CHEMICAL REACTION between oxygen and combustibles. It is the process of rapid OXIDATION by which heat stored in fuel is released. 52. What is a rate of combustion? Does air and fuel have any relationship in figuring the rate of combustion? - Correct Answers The rate at which heat is released from a fuel. YES. When oxygen and combustibles are mixed in definite proportion at an elevated temperature, and given proper time, they will combine completely. 53. Define primary air, secondary air and excess air. Is secondary air necessary in a boiler and why? - Correct Answers PRIMARY AIR enters the furnace with the fuel and determines the rate of combustion. SECONDARY AIR creates a turbulence around the fuel to complete the burning process. EXCESS air is more than what is theoretically needed for complete combustion. YES. Secondary air is introduced above the fuel bed to burn combustible gasses. 54. What are the three T's of combustion? - Correct Answers Time, temperature and turbulence. 55. Define PSI, PSIG and PSIA. - Correct Answers POUNDS PER SQUARE INCH - pressure exerted on a surface. POUNDS PER SQUARE INCH GAUGE - pressure that is read on a gauge. POUNDS PER SQUARE INCH ABSOLUTE - gauge reading plus atmospheric pressure. 56. Could too much secondary air have a bad effect on the efficiency of a boiler? - Correct Answers YES. Excess secondary air will not enter into the reaction and will pass through the furnace wasting heat out the stack. 57. What percent of air is oxygen by volume and what percent by weight? - Correct Answers By volume oxygen is 21% By weight oxygen is 23% 75. Under what conditions must fuel oil is heated, how is it heated, and how hot is it heated? - Correct Answers #4, #5, and #6 oils need to be heated. Steam and electricity can be used to heat oil. Oil should not be heated to more than 10 degrees F below its flash point. A rule of thumb is #4-135F, #5-185F, and #6-220F 76. What is a gun type burner? Name its parts. - Correct Answers A gun type burner is an assembly found on package boilers. Blower; igniter, oil pump, transformer, oil or gas solenoid, PRV, nozzles, metering valve, dampers and fire eye. 77. You are operating on gas and the gas company calls and tells you to go to oil right away. Your oil type is #6 and its ice cold, what will you do and how will you heat the oil to operating temperatures so you can fire the boiler? - Correct Answers Call the gas company and plead for more time. Then call your boss to get help. Try to heat the lines with steam hoses, or any way you can conceive. Maybe call your oil company to bring in a tanker with heated oil, etc. Use your imagination. Don't let yourself get caught in that situation. 78. Draw a picture of low pressure gas piping to a burner. - Correct Answers The drawing must include the main gas shut off valve, a tee to the pilot with shut off valve and pilot solenoid, on to the manual reset valve, gas pressure switch, PRV with vent, main gas solenoid, mixing chamber, blower pushing through the venture, into the burner. 79. The gas meter for your boiler malfunctions and you have to shut off all gas. How can you keep your boiler online? - Correct Answers IF YOU HAVE AN ALTERNATE FUEL, hook up a bottle of propane with a regulator to the pilot. 80. Name 5 electrical devices used on a boiler. - Correct Answers Low water alarm induced or forced draft fans, oil pumps, flame controls, damper motors, flow switch, water level control lights and CCTV cameras. 81. What is natural draft? What causes natural draft? - Correct Answers When the weight of the warm air in the stack is less than the cool air around the stack it causes an upward flow pulling air through the furnace. The heavier, cool air outside the stack gives a push to the warm lighter air in the stack causing air to flow through the furnace. 82. How is the flow of natural draft controlled? - Correct Answers By dampers mounted in the breaching and/or the burner and are operated by automatic controls either electric or pneumatic. 83. Does the diameter or height of a stack have an effect on the draft? - Correct Answers YES, BOTH of them. The height determines the velocity. The diameter determines the volume. 84. How is draft measured? What is a draft gauge used for and how is it installed? - Correct Answers In inches of water with a MANOMETER or "U" GAUGE. A draft gauge is used to measure the pressure difference of the boiler room and inside the setting or firebox. One tube end is connected into the breaching and the other end is open to the boiler room. (or atmosphere) Pressure moves the liquid in the tube. The difference is read in tenths of an inch. 85. When would you employ forced draft? - Correct Answers When you fail to have sufficient natural draft through the boiler. 86. What is mechanical draft? Name and describe three types. - Correct Answers The adding of fans to make up for insufficient natural draft. INDUCED DRAFT is a fan in the breaching between the boiler and the stack PULLING air through the furnaces. The boiler operates BELOW atmospheric pressure. FORCED DRAFT is a fan at the point of air entry PUSHING air through the furnace. The boiler operates ABOVE atmospheric pressure. BALANCED DRAFT is the addiction of both forced and induced fans, and the boiler operates SLIGHTLY BELOW atmospheric pressure, about .05 to .10 inches water column. 87. What is a pressurized furnace? And why is it not desirable on large boilers? - Correct Answers A pressurized furnace has a fan placed at the POINT OF AIR ENTRY to maintain the furnace ABOVE atmospheric pressure PUSHING the products of combustion through the furnace and out the stack. Flue gases can leak into the operating areas and become a health hazard. 88. How do you control dampers on a large fan from a remote location? - Correct Answers The control panel sends a signal to pneumatic or electric actuators that move the damper linkages. 89. If maintenance was done on your boiler, it was put back in operation and the stack temperature was higher than normal, what would you look for as the cause? - Correct Answers If it was a WATER TUBE boiler it will mostly likely be defective or missing BAFFLES. If it was a FIRE TUBE boiler it could be missing TURBULATORS or blocked tubes. 90. Where are tabulators used and what is their purpose? - Correct Answers They are used in the tubes of fire tube boilers to increase heat transfer to the tubes. 91. How often should you test the low water cutoffs and fully describe two ways of safely doing this. - Correct Answers At least once a shift furiously blows down the water column and insures that the water returns rapidly and smoothly into the glass. Once a month the evaporation method is done by securing the feed pump and allowing the water to evaporate from the boiler on LOW FIRE ONLY. Do this with supervision and remain alert during the test. Once a month the slow drain method is done by securing the feed pump and SLOWLY blows down the boiler on LOW FIRE ONLY. Do this with supervision and remain alert during the test. 92. How often should you blow down your sight glass? What would you do if the glass broke while the boiler was operating? - Correct Answers Blow down the glass at the start of each shift. Put on safety equipment and operate the gauge glass shut off valves. Use tri-cocks to check water level during the repair. Open blow down for the gauge glass. Remove ALL the broken glass. After installing the new glass with new washers, VERY SLOWLY open the top shut off to warm the glass. Close the blow down. Then slowly open the bottom shut off. 93. What would cause a false level in the sight glass? - Correct Answers Sight glass valves closed, sediment accumulation, foaming because of over firing or high TDS, tilted boiler, improperly installed water column or a leaking top sight glass washer. 94. If it were -35 degrees F and you had no water showing in the boiler sight glass, your supervisor told you to keep firing, what would you do? - Correct Answers TURN IT OFF! Under no circumstances can you fire an unsafe boiler. 95. What is the smallest pipe allowed for a water column? What style fittings are used to pipe a water column and why? - Correct Answers 1" made of brass, extra heavy iron, or steel. Crosses and tees are for cleaning and inspection. 96. Describe how to pipe a water column on an H.R.T. boiler. - Correct Answers The top of the column is connected to the top of the steam shell. The bottom is connected to a point 6" below the center of the drum. The bottom of the sight glass is 3" above the top row of tubes, and at least 2" above the fusible plug. The gauge glass must be 1/2" in diameter and the blow off not less than 3/4". Crosses and tees are used instead of elbows for cleaning and inspection. 97. Draw a safety water column complete with all devices. - Correct Answers Look at phone for drawing. 98. What appliances can be connected to a water column? - Correct Answers Steam gauge, feed water regulator, damper regulators, alarms, pressure controls, any device that does not consume steam. 99. How can you determine if a water gauge glass is properly set on a fire tube boiler? - Correct Answers By filling the boiler with water to normal operating level and measuring the depth of the water to the top row of tubes. 122. How is a super heater protected? - Correct Answers Each super heater must have one or more safety valves near their outlet with the pressure set below those on the boiler insuring a constant flow of steam through the super heater. 123. A boiler designed to operate at 125 psi is now operating at 15 psi. What changes will be made to the safety valve? - Correct Answers If the change is permanent. a safety valve with a larger disk and lower pressure rating will need to be installed. 124. On an Ashton type safety valve, a screw adjustment is labeled O and S, what do these letters stand for and what adjustments can you make? - Correct Answers Open and Shut. I am not certified to make adjustments. 125. What is a surface blow off, where is it employed and why is it used? - Correct Answers A surface blow off is used to remove oil and contaminants from the surface of boiler water. The takeoff is located in the top 3-4 inches of boiler water. It controls the total dissolved solids (TDS). 126. What is a continuous blow down system, and where is it installed? - Correct Answers Based on water analysis the surface blow down is metered for a continuous flow. The take-off is located just below the NOWL in the steam and water drum. 127. How should a continuous blow-down be piped as it leaves the boiler? Why? - Correct Answers It will be piped through a heat exchanged or flash tank to recover the heat, then on to the blow-down tank. 128. When is the best time to blow down a boiler? How long do you bottom blow the boiler? What important safety procedure is observed when using a bottom blow down? - Correct Answers During light loads because more of the sludge has settled to the bottom. For about 10 seconds, depending on the type and size of the boiler. Once you have opened the valve do not take your hand off of it until you have closed it. 129. Where is the bottom blow down pipe connected to an HRT boiler? What type valves are used on the bottom blow down and in what order are they placed? How should you blow down a boiler using those values? What size piping is used in the blow down line? - Correct Answers - To the underside of the shell, at the rear of the boiler drum. - Two slow opening or one quick and one slow opening valve. - The quick opening valve is installed next to the boiler and opened first and closed last. - the pipe must be at least 1" and not greater than 2 1/2" in diameter. 3/4" is allowed on boilers of less than 100 sq. ft. heating surface. 130. What is a slow opening valve? - Correct Answers It is a screw type valve that requires at least five full turns from closed to open position. 131. What is a plug valve and why is it used on blow down lines? - Correct Answers A plug valve has a circular, tapered plug ground to fit into the valve body. There is a hole through the plug that aligns with the hole in the valve body when open. When turned closed the holes are out of line. Its shearing action cuts through scale and it will not fail open. 132. How is a blow down tank piped, how does it work and why isn't any blow down connected directly to the sewer? - Correct Answers The blow down enters the tank above the water line maintained in the tank against a splash guard. There is a vent in the top of the tank to prevent back pressure; The tank discharge line is also vented to prevent siphoning. The tank has a drain valve and a manhole for cleaning. The discharge line is opposite the inlet, resulting in the cooler water being discharged first. Flash steam and hot water directly into the sewer might injure someone and will damage the sewer. 133. What is a non-return valve? Where is it located? Why does it have a drain? - Correct Answers It is an automatic stop check valve to prevent a back-flow of steam when the boiler pressure falls below that of the header. It is as close to the boiler as possible, and between the boiler and the header valve. It has a drain to remove condensate. 134. Make a drawing of three boilers in battery showing the steam header, valves and piping. - Correct Answers Look at picture #134 135. What is a soot blower? How does it work? Name two types. - Correct Answers It is a device using jet of steam, compressed air or both to remove the ash and slag from the fire side of the tubes. It is a revolving blow-arm equipped with properly spaced nozzles. The arm is operated by a chain and wheel while the boiler is in service. Two types are automatic and manual. 136. How do you operate a manual soot blower? What happens if the condensate isn't drained from the soot-blower steam supply prior to using the soot-blower? - Correct Answers Always operate a soot-blower with the boiler on high fire. Slowly open the main steam supply to the soot-blower. Open drains on the main steam supply until the piping is good and hot. Close drains and start a slow rotation of the hand-wheel, which will open the steam to the soot-blower. Rotate the element 360 degrees without stopping and make sure the steam to the soot-blower stops. Close the steam supply and open the drain valve. Condensate in the steam supply will warp and break the elements, and when it is discharged into the fire box it will form sulfuric acid, it will pack the soot onto the tubes and will cut into the tubes. 137. How can you tell if the soot blowing had any effect on the boiler? - Correct Answers You will notice a decrease in stack temperature and draft. 138. Describe a globe valve and where is it used most often? How do you pipe a globe valve? Name 6 places for a bypass. - Correct Answers It consists of a plug or disk that is forced into a tapered hole called a seat. It can be plugged or damaged easily and has more resistance to flow there for it is not used as a steam stop valve. It is used most for throttling such as in a bypass. So the supply comes in under the disk. Bypasses are common around strainers, pumps, PRV's, traps, header valves, check valves and control valves. 139. Describe a gate valve and where is it used most often. - Correct Answers A valve with a wedge shaped gate which is raised or lowered into a passageway. The wedge shape tightens against the sides of the slot when closed. It offers little resistance to flow when fully open and should not be used to throttle. It is used most for isolating devices for repair. Or to shut off the flow to the boiler. 140. What are rising stem valves and non-rising stem valves? - Correct Answers A rising stem valve has a stem that rises as the valve opens. A non-rising stem valve has a stem that stays stationary. 141. Explain the letters SWP and WOG found on the side of a valve. - Correct Answers SWP is its maximum Steam Working Pressure rating. WOG is the maximum Water, Oil, or Gas pressure the valve may be used for. Example 140 SWP and 40 WOG 142. Describe a balanced (double seated) feed water valve and why is it used? - Correct Answers A valve with two disks and two seats. One disk opens with the pressure and one against. With the forces balanced, it opens easily. 143. What is a pressure- reducing valve (PRV)? Where is it used? - Correct Answers The PRV automatically reduces high pressure and maintains a lower delivery pressure. They are used for heating systems, cookers, city water makeup, control air, gas or oil to a boiler. 144. What is a check valve? - Correct Answers It is a valve that allows flow in only one direction. 145. Name the valves found on a boiler. - Correct Answers Safety, water level control, drain, fill, non-return, plug, check, gate, globe, butterfly, and mason valve. 146. What is a hydrostatic test? How is it performed and how often should it be done on your boiler? - Correct Answers It is a water pressure test used to check the boiler for leaks. Close, lock and tag all valves and blank or remove all safeties. Fill the boiler completely with room temperature water, VENTING ALL AIR. Inflate the water 1 1/2 times the working pressure and call for an inspector. This should be done on new boilers, after turbine cleaning the boiler tubes and any time repairs are made on the pressure vessel. 161. What are pits, what causes them and how can you determine their depth? - Correct Answers Pits are small hollow spots that could develop into holes. They are caused by oxidation. 1. Make a plaster cast of the pit and the surrounding plate. After the cast has set, it will show the depth of the pit. 2. Ultra sound. 3. Eddy Current. 162. What is a fire crack and is it considered dangerous? What is a tension crack and is it considered dangerous? - Correct Answers A FIRE CRACK goes from a rivet hole to the edge of the plate and is generally not dangerous. A TENSION CRACK goes from rivet to rivet and is very dangerous. The boiler should be removed from service. 163. How do you wash and prepare a boiler for inspection? How often is your boiler inspected? What is the most important item to check for? - Correct Answers 1. Call inspector for appointment. 2. Reduce T.D.S. with blow down so solids won't adhere. 3. Operate soot blower. 4. Shut down boiler. 5. Close, lock, and tag all valves. 6. Turn off, lock and tag electrical switches and breakers. 7. Allow boiler to cool. 8. Open VENTS and drain COMPLETELY. 9. Remove all man holes and hand holes. 10. Remove drains and blow down lines. 11. Save sample of the boiler mud for your water treated. 12. With high pressure water, wash boiler top to bottom, front to rear towards the drain. 13. Clear the scale from hand holes and drain as needed. 14. Emote plugs from water column, rod and wash piping. 15. Remove and clean BOTH low water devices. 16. Open and clean ash, slag, and soot from the fire side. 17. DO NOT WASH THE FIRE SIDE. 18. Assemble any repair records. 19. Accompany the inspector. 164. What precautions should be taken before removing a man whole cover? - Correct Answers Make sure boiler shell is vented and drained. 165. Give three reasons to vent a boiler shell. What would happen if the boiler shell was not vented when it was drained? - Correct Answers To let air out when filling the boiler with water. To break the vacuum when draining the boiler. To evacuate air from the boiler on start up. The vacuum created in the boiler shell would cause leaks, a boiler implosion, siphon treatment chemicals into the boiler or cause someone to be scalded when they remove the man whole cover. 166. When operating a boiler with a pressurized furnace, why is it so important to regularly inspect the outer skin of the boiler and how do you inspect it? - Correct Answers Pressurized furnaces are undesirable because flue gas leaking into the boiler room is a deadly health hazard. Frequently check the outer skin and gaskets for visible damage and hot spots. 167. How is a leak in the shell detected on a negative pressure furnace? - Correct Answers A smoke stick or ultrasonic test. 168. How many ways are there to patch boiler shells and drums? - Correct Answers Bolting, riveting, and welding. 169. Why are hot water systems more desirable then steam systems for heating buildings? Name two types of hot water boiler heating systems. - Correct Answers Hot water heat is more consistent because water remains its heat as it circulates and steam loses its heat rapidly as it condenses. Natural circulation and forced circulation. 170. What is a diverter fitting? - Correct Answers Fitting that meters the water flow from the supply line to the individual heating units. 171. Name 4 safety devices on a hot water boiler. - Correct Answers 1. Temperature- pressure relief valve. 2. Flow proving switch. 3. High pressure cut off switch. 4. High temperature aqua stat. 5. Flame scanners. 6. Low water cut off. 172. In hot water heat systems, how often do you test the temperature-pressure (safety) relief valve and how long is the valve held open? - Correct Answers It is tested every 30 days of boiler operation or after any period of inactivity and once a year under pressure. The try lever is lifted wide open for a minimum 5 to 10 seconds or until clean water comes out. 173. What devices insure that a pump is running in a hot water system? - Correct Answers A flow switch or a differential switch. 174. What is an aqua-stat? - Correct Answers An aqua stat is a temperature sensing device. On a heating system it is used to start and stop the burner, open a valve or start a fan. 175. If you had an expansion (compression) tank on your system, where would it be located and where would the water level be in it? Why don't all expansion tanks have sight glasses? - Correct Answers It will usually be located near the top of the system with the water level mid-way in the tank. The level will go up and down as the temperature and pressure changes. The tank may use a bladder or diaphragm eliminating the need for a sight glass. 176. You have a water boiler and you discover the sight glass on the expansion (compression) tank was completely full and the system pressure was higher than normal. What will happen next and how will you correct this? - Correct Answers His relief valve will relieve excess pressure. I would isolate and drain the tank and repair the leaks by tightening fittings and replacing sight glass washers before refilling the tank. 177. What are pumps used for? Name 5 kinds of pumps. - Correct Answers Heating water, cooling water, boiler feed lubrication, condensing water, sumps, and boosters. Centrifugal, rotary, injector, duplex, simplex and vacuum. 178. Explain how an injector works. - Correct Answers It is a device designed to lift and force water into a boiler that is operating under pressure. It operates on the principle of steam expanding through a nozzle imparting its velocity energy to a mass of water. 179. How does a duplex pump work and what is lost motion? - Correct Answers It is a steam driven, double acting, reciprocating pump with check valves on both sides of the pistons so liquid is pumped no matter which way the piston is moving. Lost motion is the distance between the lugs and nut on the back side of the "D" slide valve enabling the valve to close slowly and quietly before the pump reverses the stroke. 180. What is an air chamber and why is it used? - Correct Answers It is located on the intake or discharge of a reciprocating pump. It absorbs the shock and surges of the liquid being pumped relieving the pump from excessive strains. 181. What is a foot valve and it's purpose? - Correct Answers It is type of check valve located at the bottom end of a suction line to prevent the pump from losing prime and from running backward when shut down. 182. Describe a metering pump (power pump); list its three features and what are its uses in a power plant? - Correct Answers They are either diaphragm, piston or plunger operated positive displacement pumps used for low flow applications. Three features are accuracy of adjustment, capable of pumping wide variety chemicals and high head service. They are used for injecting cooling tower treatment, internal boiler treatment or external boiler treatment. 183. What is the difference between a piston and a plunger? - Correct Answers A plunger moves inside stationary rings installed in grooves in the cylinder. A piston has rings installed in grooves in the piston itself. It can be primed with water from another source if the foot valve is tight, by using an ejector or with a vacuum pump. ALWAYS WITH THE PUMP OFF. 202. Describe how you would align a motor to a pump. - Correct Answers The driver and the driven shaft can be aligned by using a straight-edge the length of the coupling halves, a feeler gauge between the coupling halves, a dial indicator or laser alignment. Always measure the SAME PLACE AS THE SHAFTS ROTATES TOGETHER. Proper alignment would be within .005 inch. 203. On a pump, what is theoretical lift, actual lift and practical lift? What should you limit your suction lift to? - Correct Answers Theoretical 34 ft. Actual 24 ft. Practical 14 ft. 10' to 15' with cold water. With hot water, it is necessary to bring the water to the pump with a positive head. 204. What is the pressure at the base of a pipe 1" in diameter and 1' high? What would the pressure be in a pipe 1" in diameter and 275' high? - Correct Answers A column of water 1' high exerts a pressure of .433 psi at its base. 275 x .433 = 119 psi 205. What is a lantern ring? - Correct Answers It is a spacer between the packing rings allowing liquid to be used for packing cooling and to prevent the escape of the liquid being pumped. * 206. Why use flexible couplings between the pump and the power source? - Correct Answers The pump will run quieter with less wear and will be easier to align. The flex coupling will dampen start up shock and may act as a shear if the pump seizes. 207. What should the ph. in a steam boiler be? What should the ph. in a hot water boiler be? What if your condensate return had a ph. of 6.5 and what should be? - Correct Answers ph. in a steam boiler should be 10.5 to 11.5 ph. in a hot water boiler should be 8 to 8.5, newer hot water boilers 10.5. 6.5 ph. is corrosive. Condensate ph. should be 8 to 8.5. 208. What are the advantages of a feed water heater? - Correct Answers It will lessen thermo shock damage to the boiler, it will save BTUs, and it can remove free oxygen. 209. What is a closed feed water heater? What are its advantages and disadvantages? - Correct Answers A heater in which feed water and steam are in separate compartments or spaces. The heat is transferred through a metal wall from the steam to the water. Advantage: It heats feed water to within a few degrees of the steam temperature. Disadvantage: It does not remove air from the feed water and is easily fowled. 210. What is an open feed water heater? What are its advantages and disadvantages? - Correct Answers A heater in which the feed water and steam mix. The steam gives up its heat to the feed water as it condenses. SPO 8th654 9th539 10th 556 BOW 2nd125 3rd135 4th139 Advantage: it removes most of the O² and CO² from the feed water. Disadvantage: it only heats water to about 225° F. 211. Where should the feed water pump be in relation to a feed water heater and why? - Correct Answers The pump is placed before a closed feed water heater to handle cooler water and force it through the heater so nothing becomes steam bound. The pump is placed after an open feed water heater and water must flow to the pump under a static head. A pump placed before an open feed water heater will flood the heater. 212. Which type of feed-water heater heats the water the hottest? - Correct Answers A closed feed-water heater which will often heat the water to within a degree or two of the steam heating it. 213. What type valves and in what order are used on a feed water line? - Correct Answers From the feed water tank, stop valve, pump, stop valve, automatic valve, stop valve, bypass around automatic valve with globe valve, check valve, stop valve, then into the boiler. * 214. Name three types of pipe used in steam plants. What is the temperature and pressure allowed for standard fittings? - Correct Answers Standard, extra strong, double extra strong or Schedule 40, 80, 160 125 p.m. and 450°F. 215. What type of pipe is used for superheated steam? If a boiler operating at 175 psi, has a superheated installed, what changes will be made to the cast iron valves and fittings? - Correct Answers Only schedule 160 can be used for superheated steam. No cast iron is allowed on superheated steam. They will be replaced with iron or steel. 216. If you installed a steam line that is 100' long, where would you place the anchoring? Two ways take care of expansion in steam lines? - Correct Answers I would anchor the pipe on each end with an EXPANSION JOINT in the middle with ROLLERS supporting the pipe. Expansion bends, sliding sleeves, corrugated joints. * Side note: 100’ of steel pipe will grow 5/8" per 100°F. Copper will grow ¾ to 7/8 in. per 100°F 217. Name three ways to overcome vibration in piping. Give three reasons for insulating pipe. - Correct Answers Air chambers, vibration eliminators, and support the pipe more securely. To save fuel and energy, prevent sweating and for safety. 218. What are one-pipe, two-pipe and three-pipe systems? Name the pipes in a three- pipe system. What is the main disadvantage of a one-pipe system? - Correct Answers A ONE PIPE SYSTEM has only one pipe, both steam and condensate go through the same pipe. A TWO PIPE SYSTEM the steam is in one pipe and condensate is in another. In a THREE PIPE SYSTEM the pipes can be steam supply, gravity condensate return and vacuum condensate return. The main disadvantage in a one-pipe system is that it allows air to collect in the system causing corrosion. * 219. What is a Hartford loop? - Correct Answers It is a loop of piping to protect a boiler in case of a rupture in the condensate return line. * 220. Which is larger, the steam or condensate lines and why? Should a steam line slope? Why and which way? - Correct Answers Steam lines. Steam has more volume. Yes, To prevent standing condensate. The slope should be with the STEAM FLOW and TOWARD A TRAP. 221. Describe three types of steam traps. - Correct Answers Inverted bucket: The steam and condensate enter at the bottom and flow upward into the inverted bucket. As condensate enters the trap it displaces steam in the bucket, which sinks causing the valve to open. The condensate is blown out the valve, the bucket again floats and the valve closes. Any air caught in the trap passes through a small orifice in the bucket preventing the trap from becoming air bound. Float and thermostatic: As the float rides up on the condensate it will open the valve. The valve closes as the level falls. Air will cool the trap, as it cools, the thermostatic valve will open, passing the air through. Thermostatic trap contains a bellows expanding when exposed to the heat of live steam forcing a plug into an orifice closing the valve. As condensate cools the trap the bellows contracts opening the valve discharging the condensate. 222. What device is installed upstream of the steam trap? Give two reasons for a steam trap to leak through. - Correct Answers A strainer. Dirt keeping the trap orifice open or broken internal parts. 223. What will happen when a steam trap gets stuck closed and if stuck open? - Correct Answers If closed, equipment will fill with condensate, lose efficiency and could be damaged by hammering or freezing. If open, steam will fill the condensate lines pressurizing the condensate system. IT WILL WASTE STEAM. SATURATED STEAM is saturated with heat. It contains no moisture. If heat were added it would raise its temperature and if heat were removed it would form condensate. SUPERHEATED STEAM has a higher temperature than the boiling temperature corresponding to the boiling pressure. 241. Explain the theory of electricity. - Correct Answers The theory of electricity is the flowing of free electrons when electromotive force is applied across a conductor. 242. What is current? What is electromotive force? - Correct Answers Electric current is a flow of electrons. Electromotive force is an electric pressure that frees the electrons and causes them to move along a conductor. 243. What is a conductor? What is an insulator? - Correct Answers A conductor is a substance that permits a charge flow when EMF is applied. Examples: copper, brass, aluminum, silicon, iron, steel, water. An insulator is a substance that does not carry a charge flow easily. Examples: rubber, plastic, ceramic. 244. What is resistance? How is resistance measured? - Correct Answers It is a physical property that opposes current and dissipates real power in the form of heat. Resistance is measured in ohms. 245. Define volt? Define ampere? - Correct Answers A force or pressure which causes an electron flow of one ampere through a resistance of one ohm. One ampere of current is said to flow when one coulomb of electricity passes a given point in a conductor in one second. 246. Define ohms law. - Correct Answers Current is directly proportional to a voltage change and inversely proportional to a resistance change. 247. If in a 240-volt circuit you have a 20 amp load, what will the resistance be? If you have a 2400 watt heater and a 240 volt service, what would the amperage load be? - Correct Answers E (volts) divided by I (amps) = R (ohms) 240 Volts divided by 20 Amps = 12 ohms. W (watts) divided by E (volts) = I (amps) 2400 Watts divided by 240 Volts = 10 amps 248. Using a 100' long wire, which will have more resistance; #12 or #14? - Correct Answers #14 is the smaller wire, it will have the most resistance. 249. Draw a circuit - Correct Answers Picture 250. What is alternating current? What is direct current? What are four advantages of each? - Correct Answers ALTERNATING CURRENT is a periodic current, which has an average value of zero. DIRECT CURRENT is a current with a constant value. ALTERNATING CURRENT has a value that can easily be changed with a transformer, easily transmitted over long distances, safer for domestic situations and has low line losses. DIRECT CURRENT is cheaper to produce, is used in speed controlling equipment, it can be stored chemically and works well in electronic circuits. 251. How is power measured? What is a watt? How many watts in 1 kilowatt? How many watts equal 1 horsepower? - Correct Answers Power is measured in watts. A watt is a unit of electrical power defined as a rate of doing work. 1,000 watts = 1 kilowatt 746 watts = 1 horsepower. 252. What is a voltmeter and how is it connected? What is an ammeter and how is it connected? What is an ohmmeter and how is it connected? What are the last 2 items checked before connecting any meters? - Correct Answers A VOLTMETER is for measuring voltage values and is connected ACROSS the circuit. Parallel An AMMETER is for checking amperage values and is connected IN the circuit. Series An OHMMETER is for checking resistance and is connected in the circuit WITH THE POWER OFF. Series The last items checked is the polarity of the leads and the function setting on the meter. 253. Describe a transformer? - Correct Answers It is an iron core surrounded by coils of insulated wire. The voltage is changed in exact proportion to the number of turns connected in series in each winding. It is used to step up or step down voltage in an A.C. CIRCUIT. 254. Why is oil used in transformers? - Correct Answers As a coolant, insulator and moisture barrier. 255. What is power factor? - Correct Answers It is the ratio between apparent power and actual power in an AC circuit. 256. What is an electric motor and name two types. What are the characteristics of a good motor? - Correct Answers A motor changes electrical energy into mechanical energy. Induction, synchronous and D.C. A good motor must develop enough torque to start under a load, maintain its speed under full load without overheating and have a good power factor. 257. What should be considered when selecting a motor? - Correct Answers Horsepower, voltage, RPM, F.L.A., shaft size, environmental conditions, frame size and rotation. 258. How do you reverse rotation of a single-phase motor? How do you reverse rotation of a three-phase motor? - Correct Answers On a single phase motor: 1. Shift the brushes according to marks on the motor frame or brush holder. 2. Reverse two of the wires coming from inside the motor. 3. Follow the manufacturer's instructions. On a three phase motor: Interchange two of the line voltage leads. 259. List four ways to safeguard electrical equipment? What is single phasing and give three examples why a motor would single phase. - Correct Answers Overload relays, low voltage releases, fuses and circuit breakers. Single phasing is when power on one 'leg' of a three phase motor is lost. It could be caused by a burned contact, a blown fuse, a broken wire or the power supply into the building. 260. What is a synchronous motor? - Correct Answers It is an AC machine basically the same as an alternator. The motor is locked into the same speed as the alternator supplying the power and has little or no starting torque. 261. What is an alternator? What is a generator? What is the most common way to generate electricity? How do you protect generators when shorted to ground? - Correct Answers It is a synchronous generator that delivers alternating current of a frequency directly proportional to its rotating speed. A generator changes mechanical energy into electrical energy. Steam power plants using fossil fuels and steam turbines. Fuses, circuit breakers and overloads. 262. How are ball bearing motors lubricated? - Correct Answers Remove grease plugs and pump grease through the bearing until clean grease comes out. Run the motor about one hour, wipe off excess grease and replace the plugs. 263. What is OSHA? - Correct Answers OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION is a federal agency requiring employers to provide a safe environment free of hazards likely to cause serious harm to their employees. 264. What is EPA? - Correct Answers ENVIRONMENTAL PROTECTION AGENCY is a federal agency set up to control and abates pollution in the areas of air, water, solid waste, pesticides, radiation and toxic substances.