Understanding Boiler Design and Operation, Exams of Nursing

Download Understanding Boiler Design and Operation and more Exams Nursing in PDF only on Docsity! Boiler Engineer Fall with 283 Practice Questions and answers exam How can you loose your license? Drinking on the job, sleeping on the job, negligence, unsafe work, signing a falsified license application for someone, or failing to renew license annually. What must you do to change Jobs? You must notify city hall if you change jobs, change address, or retire. Why should you do rounds? So you can find and correct problems to prevent breakdowns, keeping permanent records to forecast breakdowns, and to get to know your equipment. What is a steam boiler? A steam boiler is an enclosed vessel, partially filled with water, under pressure, that transforms water into steam with the application of heat. What are the requirements of a good boiler? 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 repairs. 7) Safe. Name and describe three types of heat transfer used in boiler operation? Radiant, Conduction, and Convection Radiant Heat -it is transmitted from hot body to 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 cup is heated by conduction when hot coffee touches the cup. Convection Heat-is carried along by a moving such as air or water. Your living room is heated by warm air from a furnace in another location in your home. What is a combustion chamber? The area of the boiler where the complete burning of fuel occurs. What is an internally fired boiler and name four types? Internally fired boilers have the grates and combustion chamber enclosed within the boiler shell. Scotch Marine, vertical fire tube, locomotive, cast iron packaged boiler. What is an externally fired boiler and name four types? Externally fired boilers have the setting including the furnace and grates separate and distinct from the boiler shell. HRT (horizontal return tube) set in the brickwork, some water tube boilers, Heine, cast iron boilers set into brickwork, and Sterling. What is a crown sheet and what is its purpose? What is a tube sheet and its purpose? The crown sheet in a vertical fire-tube boiler holds the tubes and is thicker because it is expose to fire. The tube sheet holds the tubes and does not see the fire. What is the water leg on a boiler? It is the space between the outer shell and the furnace shell containing boiler water. It absorbs heat that would be wasted and increases the capacity of the boiler. The surfaces are flat and must be stayed. Is an HRT boiler set level or inclined? Why? Are boiler tubes set level or inclined and why? HRT boiler tubes are inclined 1 to 3 inches front to rear for drainage and to remove impurities. Boiler tubes are just inclined with the boiler shell. Name two ways to support and take care of expansion of an HRT boiler? Which way is the best. 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 the best, that works no hardship on the furnace walls. 2)Compact 3)Very little setting required 4)Factory Assembled 5)Fast installation. 6) Can be made portable Disadvantages: 1)Liable to disastrous explosions because drums and joints over fire. 2)Inaccessible for inspection 3)Poor circulation. 4) Slow steamers. 5)Inefficient. 6) Pressures and capacities are limited Types: 1) HRT 2)Locomotive. 3)Scotch Marine 4)Vertical fire-tube. What type of stays are used in a wet back (Scotch Marine) type boilers? Stay bolts and through stays. These will sometimes have a tell-tale drilled int them. Describe a sectional boiler. The sectional headers are built up of vertical sections or units. A sufficient number of sections are clamped together to form the desired size boiler. These boilers can be erected in an existing building by carrying them in piece by piece. What is a super heater? What are the advantages of a super-heater? A super-heater is a device used to raise the temperature of the steam without raising the pressure. Advantages: 1) Increases the efficiency of the boiler. 2) Delivering dryer steam. 3) Drier steam can be transmitted over long distances with minimal heat loss. 4) With drier steam condensation and erosion are reduced. What is a radiant super-heater? What is a convection type super-heater? What is the third type of super-heater? Radiant super-heater is positioned to absorb radiant heat from the furnace by direct radiation, it is set over the fire. Convection super heater is placed in the gas passage of the furnace, usually between the first and second pass. Little to no radiation will reach this type. The third type is a combination Radiant and Convection super-heater. What is an economizer? What is a pre-heater? An economizer is a heat exchanger located in the breeches between the boiler and the stack designed to recover waste heat from products of combustion by preheating the feed water. The air pre-heater consists of a series of tubes or plates that have hot gases on one side and incoming air on the other. Heat in the hot gases leaving the boiler is recovered by the incoming air. Both of these devices reduce stack temperatures and increase boiler efficiency. What is a water-wall? Set of tubes containing boiler water set in the refractory. They absorb heat that would otherwise be lost to the refractory and increase the capacity of the boiler. What is the ASME code? What code information is stamped on the boiler? What is an ASME stamp? Where are code markings found on the boiler? American Society of Mechanical Engineers has written a set of minimum standards for the safe construction of pressure vessels. Stamped on the boiler shell or a plate attached to the shell and there will be: the model and serial number, safe working pressure, date of manufacture, name of manufacturer, type of material used, horsepower rating, square feet of heating surface, steam generated in pounds per hour, fuel designed for and ASME stamp. The ASME symbol will identify the boiler or accessory type. On a fire tube boiler, it may be located on the right side near the front, by the water column. On a water tube boiler, it will be located next to the manhole on the steam drum. What is the cross section of a 1" bolt? Diameter x Diameter x .7854(1/4π) 1 x 1 x .7854 = .7854 sq in. Show your work and label everything. What is an alloy? Name five. An alloy is a mixture of two or more metals. Brass, steel, stainless steel, monel, pewter, cast iron, bronze, Britannia Metal, molybdenum, babbit and bell metal. At what pressure is the use of cast iron fittings permitted? Is it necessary to brace or stay a flat surface? Name three types of stays. Yes to overcome the force on the heads and flat surfaces. Where there are no tubes, braces and stays must be provided to prevent bulging of the boiler plate. Through bolt, stay bolt, diagonal stay, gusset stay, girder stay, jaw stay,"T" stay, "J" stay, "Y" stay, crowfoot stay, palm stay, head brace, screw, vertical bar stays, end brace. Describe a through stay. Why are hallowed through bolts used on water legs? 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 was to fail, a leak will develop and will be detected at once. Describe a diagonal and gusset stay. Where would each be used? A diagonal stay is made of a 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 and are more rigid. Both are used to brace right angle surfaces. Why are hand-holes and man-holes made oval instead of round? What are the minimum sizes for hand-hole and manhole openings? So they can be inserted and removed from their respective openings in the boiler. Manhole 11" x 15" or 10" x 16" Hand-hole 2 3/4" x 3 1/2" What is thermal efficiency and what is considered a good percent? It is the ratio of heat supplied by the fuel to heat absorbed by the boiler. A good percentage is 85%, some boilers made today can reach 95%. How do you determine boiler capacity and what is boiler heating surfaces? Total heating surface determines the capacity of the boiler. Heating surface is any surface that has hot gases on one side and boiler water on the other and is measured from the fire side. What is furnace volume? Is furnace volume measured in square feet or cubic feet? Furnace volume is the space available for complete combustion of the fuel before the products of combustion enter the heat absorbing section of the boiler. This varies with the type of fuel used. Measured in cubic feet. What is super-heated steam? Does its temperature rise? It is steam that has been heated to a higher temperature but the pressure remains the same. Yes, its temperature does rise. Define flash point, ignition point, pour point. Flash point is the lowest temperature at which vapors of a substance will make a flash flame but not continue to burn when exposed to an open flame Ignition point is the lowest temperature at which vapors of a substance will ignite and burn continuously when exposed to an open flame. Pour point is the lowest temperature a which a liquid will flow. Define combustion. Combustion is a chemical reaction between oxygen and combustibles. It is the process of rapid oxidation by which the heat stored in fuels is liberated. What is the rate of combustion? Does air and fuel have any relationship in figuring the rate of combustion? The rate at which fuel is burned. Yes, when oxygen and combustibles are mixed in definite proportions at an elevated temperature, and given proper time, the will combine completely. Define primary air, secondary air, and excess air. Is secondary air necessary in a boiler and why? 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 are is more than what is theoretically needed for complete combustion. Yes. Secondary air is introduced above the fuel bed to burn combustible gasses. What are three Ts of combustion? Time, Temperature, and Turbulence. Define PSI, PSIG, and PSIA. 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 Gauge - gauge reading plus atmospheric (about 14.7) Could too much secondary air have a bad effect on efficiency of a boiler? Yes, excess secondary air will not enter into the reaction, but will pass through the furnace wasting heat out of the stack. What percent of air is oxygen by volume and weight? By volume oxygen is 21%. By weight oxygen is 23%. Define Perfect, Complete, and Incomplete combustion. Purging is forced removal of combustibles from the fire-box. Pre-purge is before it is lit. Post-purge is after the combustion cycle. What precautions are needed before a gas, oil, or pulverized coal fire is lit? Purge all combustibles before you light the pilot. The pilot must be lit before the main fuel. What are pulsations? How would you correct this condition? Pulsations are when the flame leaves the burner tip and then returns. This condition may become so severe that combustion consists of several small explosions. In pulverized coal or oil furnace it can be corrected with proper air-fuel mixture. In gas furnaces it can be corrected by increasing the draft. How do you pipe an oil supply from the tank to the burner? Oil flows from the storage tank, through the suction strainer, steam or electric driven pump, relief valve, steam or electric heater, discharge strainer, low oil pressure switch, firing rate control valve,low oil temperature switch, safety shut off valve, high oil pressure switch, on to the burner or tank return. Manual isolation valves and bypasses must be installed for all devices so the boiler stays online during repairs. What are some of the difficulties you may encounter when operating an oil fired plant? If firing #4 oil and you loose pressure, what is the first two things you would look for? When would you change a strainer? Difficulties may include: plugged strainer, improper venting of the tank, failure of the pumps, sludge, air in suction lines, vapor in the pump, oil to heavy to flow, insufficient heat, faulty atomization, low oil temperature, carbon formation worn burner tip, or low oil pressure. The first two things to look for are plugged strainer or pump failure. You would valve over to a clean strainer if the delta-P was excessive. Name three types of nozzles used in oil burners. Explain where secondary air is admitted. Rotary atomizing, steam atomizing, air atomizing, and pressure atomizing. Secondary air is admitted around the tip. Under what conditions must fuel oil be heated, how is it heated, and how hot is heated? #4, #5, #6 oils need to be heated. Heated using steam or electricity. oil should not be heated to more than 10°F below its flash point. #4 = 135° F, #5 = 185° F, #6 = 220° F What is a gun type burner? A gun type burner is an assembly found on package boilers. Parts include: blower, igniter, oil pump, transformer, oil or gas solenoid, PRV, nozzles, metering valves, dampers, fire eye, etc. You are operating on gas and the gas company calls to tell you to go oil right away. Your oil type is #6 and it is ice cold, what do you do to keep your boiler on line and how will you heat the oil to operating temperature so you can fire the boiler? Call the gas company and plead for more time. 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 in the first place. Draw a picture of a low pressure gas piping to a burner. The drawing must include the main gas shut off valve, a tee to the pilot light, shut off valve 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 to the venturi, in to burner. The gas meter for your boiler malfunctions and you have to shut-off all gas. How can you keep your boiler on line? If you have an alternate fuel, hook up a bottle of propane with a regulator to pilot. Name five electrical devices used on a boiler. Low water alarm. Induced or forced draft fans. oil pumps. flame controls. damper motors. flow switch. water level control lights. CC TV cameras What is natural draft? What causes natural draft? 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. How is the flow of natural draft controlled? By dampers mounted in the breeching and/or the burner operated by automatic controls either electric or pneumatic. Sight valves closed, sediment accumulation, foaming because of over firing, or high total dissolved solids (TDS), tilted boiler, improperly installed water column, or a leaking top sight-glass washer. If it were -35°F and you had no water showing in the boiler sight glass, your supervisor told you to keep firing, what would you do? Shut down the boiler. Under no circumstances can you fire an unsafe boiler. What is the smallest pipe allowed in piping a water column? What style fittings are used to pipe a water column and why? 1" made of brass, extra heavy iron, or steel. Crosses and Tees are used for cleaning and inspection. Describe how to pipe a water column on an H.R.T. boiler. The top of the column is connected to the top part 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 of the 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. Draw a safety water column with all devices. What appliances can be connected to a water column? Steam pressure gauge, feed water regulators, or damper regulators, alarms, pressure controls, ant device that does not consume steam. It could cause the water column to record a false level. How can you determine if a water gauge glass is properly set on a fire tube boiler? By filling the boiler with water to the normal operating level and measuring the depth of the water to the top row of tubes. How high above the top row of tubes in an H.R.T boiler must the lower gauge cock be set to have a safe amount of water at this point? At least 3" above the top row of tubes. Name three appliances that can warn you of low water. Water sight glass, low water alarms, and fusible plug. If your boiler has only one low water cut off, what is the ASME code requirement? It must have a manual reset. Side note: The City of Omaha requires one to be a manual reset even if you have two cutoffs. If there is repair work done on the boiler there must be a manual reset added. What is the purpose of a high fire limit control on a boiler? What is a modulating control? It proves that the forced fan damper has fully opened prior to starting the pre-purge period to insure adequate purge air flow. It adjusts the firing rate of the burner to maintain the boiler steam pressure. Is an automatic shut off allowed between the boiler and the warm water column? NO, only between the water column and the gauge glass. What types of valves are allowed between the boiler and the water column? Outside screw and yoke type gate valves or stop cocks, which must be sealed or locked open. Name two types of fusible plugs. Waterside and fireside. The name refers to the side it is installed in the boiler. What is a Bourdon tube? A Bourdon tube consists of a curved tube with an oval cross section. One end is attached to the frame and to the pressure connection. The other end is attached to a pointer by the means of a linkage and gears. As pressure is increased to the pressure connection the tube will tend to straighten out and its motion is transmitted to the pointer. What is a siphon tube and what is it used for? A siphon tube or pig tail loop is used to protect the mechanism of the gauge from live steam. What pressure range should a steam gauge be when use on a boiler? It should be a compound gauge at least one and a half times the maximum allowable working pressure. Where is a steam gauge attached to the boiler? How do you properly mount a steam gauge to a boiler? It is mounted either on top of the water column or on the top of the steam drum. A gauge is mounted with a siphon tube, isolation valve and test connection. Name three types of feed water regulatory systems. 1. On-off such as a float or a probe. 2. Modulating such as a thermohydrolic or thermodynamic. 3. Metering such as a two or three element. Why is boiler feed pump used on some boilers and not others? A pump is not needed if the operating pressure of the boiler is lower than city water pressure. What is the most important valve on a boiler? Open and Shut I am not certified to make adjustments. What is a surface blow off, where is it employed and why is it used? A surface blow off is used to remove oil and contaminants from the surface of the boiler water. The take-off is located in the top 3-4" of boiler water. It controls the total dissolved solids (TDS). What is a continuous blow-down system, and where is it installed? Based on water analysis the surface blow-down is metered for continuous flow. The take-off is located just below the (NOWL) normal operating level in the steam water drum. How should a continuous blow down be piped as it leaves the boiler? Why? It will be piped through a heat exchanger or a flash tank to recover the heat , then on to the blow down tank. When is the best time to blow down a boiler? How long do you bottom blow down the boiler? What important safety procedure is observed when using a bottom blow down? During light loads because more sludge has settled to the bottom. For about 10 seconds depending on the size of the boiler. Once you have opened the valve do not take your hands of of it until you have closed it! Where is the blow-down pipe connected on an H.R.T. 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 valves? What size piping is used in the blow down line? • To the under side 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 is opened first and closed last. • The valves 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. feet of heating surface. What is a slow opening valve? It is a screw type valve that requires at least five full turns from closed to open position. What is a plug valve and why is it used on blow-down lines? 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 thru scale and it will not fail open. How is a blow-down tank piped, how does it work and why isn't any blow down connected directly to the sewer? 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 and manhole for cleaning. The discharge line is opposite the inlet, resulting in cooler water being discharged first. Flash steam and hot water directly into the sewer might injure someone and will damage the sewer. What is a non-return valve? Where is it located? Why does it have a drain? 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. Make a drawing of three boilers in battery showing the steam header, valves, and piping. What is a soot blower? How does it work? Name two types. A devices using jets of steam, compressed air, or both to remove ash and slag from the fireside of tubes. It is a revolving blow arm equipped with properly spaced nozzles. The arm can be operated by a chain and operating wheel while the boiler is in service. There are two type automatic and manual. How do you operate a manual soot blower? What happens if the condensate isn't drained from the sootblower steam supply prior to using the soot blower? Always operate a soot blower with a boiler on high fire. Slowly open the main steam supply to the soot blower. Open the drains on the main steam supply until the piping is hot. Close the drains and start slow rotation of the hand held wheel which will open steam to the soot blower. Rotate the element 360° without stopping and make sure the steam to the soot blower stops. Close the steam supply and open the drain valve. Condensate in the 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. How can you tell if the soot blowing had any effect on the boiler? You will notice a decrease in stack temperature and draft. Describe a globe valve and where is it most used most often. How do you pipe a globe valve? Name 6 places for a bypass. 1) Blow down gauge, glass, and water column. 2) check operation of the feed water valves and pumps. 3) Open the vent on the boiler drum. 4) Start the boiler on low manual fire. 5) Test the flame scanner. 6) Test the low water cut off. 7) when the boiler pressure starts to build, close the vent. 8) Open the equalizer line around the header valve to warn the header. 9) Open header valve and non-return valve drains. 10) when the header is hot, open the header valve and close the drain. 11) when the boiler pressure is 80% of header pressure unscrew and wheel on the non-return valve and close the drain. 12) When the boiler pressure equals header pressure control in automatic. How do you put a second boiler on line with an operating boiler using non-return valve? 1) If the boiler to come online is hot, open the equalizing line around the header valve to warm the header. 2) Open the header valve drain and non-return valve drain. 3) When the header is hot, open the header valve and close the drain. 4) Increase the fire. 5) When the boiler is 80% of header pressure, unscrew hand wheel on non-return valve and close drain. 6) When boiler pressure equals header pressure put controls in automatic. What our bags, what causes them and can they be repaired? What are blisters, what causes them and can they be repaired? A bag is a bulge in a boiler tube, caused by overheating an area under the scale. Small bags can be heated and driven back into place. Blisters are separation of layers in the boiler steel, caused by a combination of imperfections in the boiler plate and overheating. Blisters must always be cut away and replaced. What is scale and what causes it? Why is it bad for the boiler? Scale is mineral solids in boiler water being deposited on heating surfaces. It is caused by high TDS (total dissolved solids) and improper treatment of boiler water. Scale forms an insulation layer the retards the flow of heat to the water and causes the metal to become over heated. What is corrosion and what causes it? It is the eating away of metal as the result of low alkaline water, the presence of free oxygen or both in the water. What is caustic embrittlement? It is the weakening of boiler steel as the result of inner crystalline cracks caused by long exposure to a combination of stress and high alkaline water. Name three ways of treating boiler water external of the boiler. Name three chemical tests done on boiler water. Water softener, distiller, Reverse Osmosis (R.O.), or the use of chemicals. Nitrite, phosphate, sulfite, alkalinity, conductivity, hardness, pH, and chloride. Name two of the chemicals to control scale in the boiler. Polymer, phosphates, amiens, and chelates. What is priming and how is it reduced? What is foaming and how is it reduced? Priming is boiler water being carried out of the boiler with the steam. It can be reduced by lowering the firing rate, reduce the foaming, or lower the water level in the boiler. Foaming is caused by high TDS or overfilling the boiler. It is reduced by skimming the surface of the water and better water treatment. What is water hammer? It is condensate carried along with the steam flow through the pipes striking an elbow or tee possibly rupturing the pipe. If your boiler is foaming, how can you tell where the water level is? Turn off the fire or close the steam valve. What is impingement and how can it be prevented? It is unequal distribution of flame contacting the tubes of furnace walls and can be prevented by correct operation and maintenance of equipment. How do you mechanically clean the water side of boiler tubes and what precautions should be taken? What test should be done after the cleaning? How are boiler tubes cleaned other than with mechanical mean? When cleaning fire tubes, a knocker raps the inside of the tube cracking the scale off the outside. when cleaning water tubes, a cutter head rotates inside cutting and crushing the scale. Always keep the cutter head moving! A hydrostatic test should be done after the cleaning. Sometimes acid cleaning by a qualified person is necessary after mechanical cleaning. What are pits, what causes them and how can you determine their depth? Pits are small hallow spots that could develop into holes. They are caused by oxidation. 1) Make a plaster cast of the pit and surrounding plate. After the cast has set, it will show the depth of the pit. 2) Ultrasound. 3) Eddy current. What is an aqua stat? 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. If you have an expansion 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? It will usually be located near the top of the system with water level midway 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. 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 correct this? The relief valve will relieve excess pressure. I would isolate and drain the expansion (compression) tank. I would repair the leaks by tightening fittings and replacing the sight glass washers before refilling the tank. What are pumps used for? Name five kinds of pumps. Heating water, cooling water, boiler feed, lubrication, condensing water, sumps, boosters, etc. Centrifugal, rotary, injector, duplex, simplex, and vacuum. Explain how an injector works. 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. How does a duplex pump work and what is lost motion? It is a steam driven, double acting, reciprocating pump with check valves on both sides of the pistons so liquid is is pumped no matter which way the piston is moving. Lost motion is the distance between the the lugs and the nut on the backside of the "D" slide valve The enabling the valve to close slowly and quietly before the pump reverses the stroke. What is an air chamber and why is it used? 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. What is a foot valve and its purpose? It is a type of check valve located at the bottom end of a suction line to prevent the pump from loosing prime and from running backwards when shut down. Describe a metering pump (power pump) list three features and what its uses in a power plant? 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 a wide variety of chemicals and high head service. They are used for injecting cooling tower treatment, internal boiler treatment, or external boiler treatment. What is the difference between a piston and a plunger? A plunger moves inside stationary rings installed in grooves in the cylinder. A piston has rings installed in the grooves in the piston itself. Describe a rotary pump and does a rotary pump work on the same principle as a centrifugal pump? It is a positive displacement pump. It consists of a shaft or shaft with gears, vanes, screws, lobes, and cams operating in a close fitting case.They do not use valves in their design, permitting the pump to operate more efficiently on both low and high viscosity liquids with low net positive suction head requirements. No, a rotary pump is a positive displacement pump. Give seven advantages to a rotary pump. 1) Self priming. 2) Capable of high suction lifts. 3) Handle high and low viscosity liquids efficiently. 4) Low net positive suction head requirements. 5) Wide spread ranges. 6) operate efficiently on both high and low head applications. 7) Capable of high output pressures. What are the disadvantages of a rotary pump? What will happen if the discharge valve is closed on a rotary pump? 1) Slow 2) Noisy 3) Prone to wear 4) Easily damaged. The relief valve will open, if there is no relief valve, damage to the pump may result. Describe how to determine if a centrifugal pump is running. Check the delta pressure, pressure gauge, flow switch, differential switch, sight, etc. Name two types of centrifugal pumps and describe their differences. Radial flow. A centrifugal pump in which pressure is developed by centrifugal force. Mixed flow. A centrifugal pump where the pressure is developed by both the centrifugal force and by the lift of the vanes of the impeller on the liquid. Axial flow. A centrifugal pump where the pressure is developed by the lifting action of the vanes of the impeller on the liquid. Make a drawing of a centrifugal pump and explain how it works. Impeller, impeller rings, seal rings, casing rings, casing, shaft, shaft sleeve, shaft bearings, thrust bearings, bearing end covers, packing, packing stuffing box, or mechanical seal, "O" rings Name the parts of double suction centrifugal pump. What are the merits of a centrifugal pump? 1) Few moving parts. 2) Uniform flow. What are the advantages of a feed water heater? It will lessen the thermal shock damage to the boiler, it will save BTUs, and it can remove free oxygen. What is a closed feedwater heater? What are the advantages and disadvantages? It is 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 too the water. Advantages- It heats feed-water to within a few degrees of the steam temperature. Disadvantages- It does not remove air from feed-water and is easily fouled. What is an open feed_water heater? What is its advantages and disadvantages? It is a heater in which the feed-water and steam mix. The steam gives up its heat as it condenses. Where should the feed-water pump be in relation to the a feed-water heater and why? The pump is placed before a closed feed-water heater so it is handling cooler water and forcing 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 static head. A pump placed before an open feed-water heater will flood the heater. Which feed-water heater heats the hottest? A closed feed-water heater will often heat the water to within a degree or two of the steam being used to heat it. What types of valves and in what order are used on a feed-water line? From the freed-water tank - globe valve, pump, check valve, globe valve, automatic valve with bypass, check valve, globe valve, globe valve then into the boiler. Name three types of pipe used in steam plants. What is the temperature and pressure allowed for standard fittings? Standard , extra strong, double extra strong or schedule 40, 80, 160. 125 psi and 450 degrees F What type of pipe is used for superheated steam? If a boiler is operating at 175 psi and has a super- heater installed what changes will be made to the cast iron valves and fittings? No cast iron is allowed on super-heated steam. They will have to be replaced with iron or steel. If you installed a steam line that is 100'long, where would you place the pipe anchoring? How is expansion taken care of in steam lines? I would anchor the pipe on each end with expansion joints, and in the middle are rollers supporting the pipe. Expansion bends, sliding sleeves, or corrugated joints. Name three ways to overcome vibration in the piping. Give three reasons for insulating pipe. Air chambers, vibration eliminators, and support the pipe more securely. To save fuel and energy, prevent sweating and safety. 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? A one pipe system has only one pipe, both steam and condensate go through the same pipe. In a two pipe system the steam is in one pipe and condensate is in the other. In a three pipe system has both high and low pressure steam pipes and a condensate line. In a three pipe system the names of the pipes are high pressure steam supply, low pressure steam supply, and condensate return. The main disadvantages in a one pipe system that it allows air to collect in the system causing corrosion. What is a Hartford loop? It is loop of piping to protect the boiler in case of a rupture in the condensate return line. Which is larger, the steam or the condensate lines? Why? Should steam lines slope? Why? Which way? Steam lines, because steam has more volume. Yes to prevent standing condensate. The slope should be with the steam flow and toward the trap. Describe three types of steam traps. Inverted bucket - The steam and condensate enter at the bottom and flow upward into the inverted bucket. As condensate enters the trap it displaces the steam in the bucket, which sinks, causing the valve to open. The condensate is blown out the valve, the bucket again floats as the valve closes. Any air caught in the trap passes through the small orifice in the bucket to prevent the trap from becoming air bound. Float and thermostatic - As a float rides up on the condensate it will open the valve. The valve closes as the level falls. Air will coll the trap, as it cools the thermostatic valve will open, passing the air through. Thermostatic - 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 contract opening the valve discharging the condensate. What device is installed upstream of the steam trap? Give two reasons for a steam trap to leak through. A strainer. Dirt in the orifice and broken internal parts. What will happen if a steam trap gets stuck closed? And if stuck open? If closed, condensate will fill the system and water hammer will occur. If open, steam will fill the condensate lines and pressurize the condensate receiver. It will waste steam. List six places where steam traps should be installed. After steam radiators, after heat exchangers, on drip legs along steam lines, low points in steam lines, before pressure reduction valves (PRVs), before automatic valves, on steam headers, etc. Anywhere there is large amount of condensate. How often should steam traps be tested for proper operation and list five ways of testing them? Once per year using thermometers, listening devices, temperature crayons, flow indicators and test valves. What is the difference between a gravity return system and a vacuum return system? In a vacuum return system, the condensate is returned to the boiler by means of a pump. In a gravity return system, the condensate is returned to the boiler by natural tendency for water to flow downhill. List three things a vacuum return pump on a condensate system does. It pulls standing condensate back to the receiver, it vents air from the system, and it pushes condensate to the boiler or the boiler feed tank. What is a steam separator? In a cyclone steam separator, water and solids are thrown aside by centrifugal force and drain back to the boiler. A live steam separator uses corrugated baffles to collect moisture, which is drained off with a steam trap, complete reversal of the steam flow at the lower edge of the baffle separates the moisture from the steam. What is a conductor? What is an insulator? A conductor is a substance that permits a charge flow when electromotive force is applied. Examples: copper, aluminum, silicone, iron, steel, and water. An insulator is a substance that does not carry a charge flow easily. Examples: rubber, plastic, and ceramics. What is resistance? How is resistance measured? It is a physical property that opposes current and dissipates real power in the form of heat. Resistance is measured in Ohms. Define volt. Define Ampere. A force of 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. Define Ohm's law. Current is directly proportional to a voltage change and inversely proportional to a resistance change. 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 240 volt service, what would the amperage load be? 240 volts divided by 20 amps = 12 ohms 2400 watts divided by 240 volts = 10 amps Using a 100' long wire, which will have more resistance a no. 12 or no. 14? No. 14 is the smaller wire it will have more resistance. Draw a circuit. What is alternating current? What is direct current? What are four advantages of each? Alternating current - is a periodic current which has an average value of zero. Direct current - is a current with a constant value. Alternating current: 1) has a value that can easily be changed with a transformer. 2) is easily transmitted over long distances. 3) It is safe for domestic use. 4) low line losses. Direct current: 1) Is cheaper to produce. 2) Lend itself to speed control equipment. 3) It can be chemically stored. 4) Works well in electronic circuits. How is power measured? What is a watt? How many watts are in a kilowatt? How many watts are equal to one horsepower? It 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 What is a voltmeter? What is an ammeter and how is it connected? What is an ohmmeter and how is it connected? What are the last two items checked before connecting any meters? 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). Polarity and I don't know. I'm assuming the meter is correct for the voltage. Describe a transformer. 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 used to step up or step down voltage in an AC circuit. Why is oil used in transformers? As a coolant, insulator, and moisture barrier. What is power factor? It is the ratio between the apparent power and the actual power in an AC circuit. What is an electric motor? Name two types of electric motors. What are the characteristics of a good electric motor? A motor changes electrical energy into mechanical energy. Two types of motors are induction, synchronous, DC, AC, etc. A good motor should last long, be quiet, and be serviceable. What should be considered when selecting a motor? Horsepower, voltage, RPM, full load amperage, shaft size, environmental issues, frame size, rotation. How do you reverse the rotation of a single-phase motor? How do you revers the rotation of a three phase-motor? On a single phase motor: 1) Shift the brushes according to the marks on the motor frame or brush holder. 2) Reverse two of the wires coming from inside the motor. 3) Follow the manufacturers instructions. On a three phase motor: 1) Interchange two of the line voltage leads. List four ways to safeguard electrical equipment. What is single phasing and give three reasons why a motor would single phase. With fuses,circuit breakers, verify electricity levels, confirm that supply circuits are grounded properly, and use a UPS/surge protector. For proper working of any 3 phase induction motor it must be connected to a 3 phase alternating current (ac) power supply of rated voltage and load. Once these three phase motors are started they will C02 = oil and electrical Must be inspected once a year if not used, by a licensed inspector. What is a dry sprinkler system? This a system that is charged with air usually found in places where the temperature falls below the freezing point of water. When the head opens there is a pressure drop in the line, which opens the water valve. How far are the heads apart on a sprinkler system? How much area does a sprinkler head cover? The heads are spaced 12' to 15', depending on the usage of the space and height of the sprinkler system. Each head covers about 130 to 200 square feet. If an electrical panel caught on fire in a boiler room, what are the first two things you would do? Cut power to the area, call 911 even if the fire is out. Name three types of fire protection systems. Dry sprinkler system. Dry chemical system. Halon system. Deluge system. Electronic alarm system. Wet charged system. What is a confined space? Name three. It is a space large enough to physically enter but has limited or restricted entry and exit and is not designed for continuous occupancy. Examples of confined spaces include silos, vats, hoppers, utility vaults, tanks, sewers, pipes, access shafts, truck or rail tank cars, aircraft wings, boilers, manholes, manure pits and storage bins. Ditches and trenches may also be a confined space when access or egress is limited. What is on a right to know label? Physical and Health Hazards (MSDS) 1) First aid procedures for exposures or contact. 2) Personal protection required. 3) Flammability. 4) No smoking. 5) Handling and storage instructions. 6) The chemical or common name. What does MSDS stand for and what its its purpose? Material Safety Data Sheet - and it is printed material used to relay chemical information from the manufacturer, importer, or distributor to the employer. What will you do if you have a hazardous material spill? Identify its hazards, and put on protective gear. Contain the substance, call your safety officer, and notify your boss. Explain lockout -tag out. Lock-out is the use of locks, chains, or other restraints to positively prevent the operation of specific equipment. Tag-out is attaching a danger tag to the source of power warning that the equipment may not be used until the tag is removed. What are 20 safety items to be aware of in a power plant? 1) Do not wear loose clothing. 2) Wear hand and arm protection. 3) Wear safety glasses. 4) Wear safety shoes. 5) Wear hard hat. 6) Use hand held lens for observing oil combustion fires. 7) Use low voltage drop light inside boiler shell. 8) Verify venting and drain the boiler before working on it. 9) Use proper ladders. 10) Keep all guards in place. 11) Keeps spills cleaned up. 12) Do not leave tools up on top of the ladder. 13) Know what confined spaces are and procedures for them. 14) Store oily rags in proper containers. 15) Do regular inspections of your plant. 16) Always communicate shift information. 17) Report all accidents. 18) Know where to access eye wash stations. 19) Label all containers. 20) Learn fire safety plan. 21) Learn disaster plan. 22) Observe lock out tag out. The EPA requires what record to be kept regarding underground fuel tanks? Upon request you must provide records on installation, monitoring, cathodic protection, release detection equipment calibration, maintenance, repairs, and closures. These records should never be destroyed and always kept on site. List three overfill preventions required on a fuel tank. What spill protection is required on fuel tanks? How much oil can you spill before you must call the EPA? Automatic shut off devices, overfill alarms, and ball float valves. There must be a catch basin around the opening with a capacity of 5 to 25 gallons. 25 gallons Your fuel oil tank capacity is 20,000 gallons, you have 10,000 gallons remaining and you are calling to have it filled. How many gallons will you order? Order 8,000 gallons. Never fill more than 90% full (expansion and contraction). Who is authorized to handle refrigerant? You must be EPA certified to remove or add refrigerant to a system. When taking refrigerant out of a system, what do you do with it? Ensure the person doing it is certified by the EPA. You must recover it to be either recycled or disposed of properly. It is against the law to vent it to the atmosphere.