36715905
| Frage | Antworten |
| List five daily things you would check on a cooling tower? | Conductivity, pH, Algae, Water level, Noise and Vibration |
| How do you keep a cooling tower from freezing when not in service? | You could run the pump and by-pass all the water to the basin, or drain the basin and makeup lines. |
| Describe a sling psychrometer and how to use it? | It determines relative humidity. to operate, moisten the wick on the wet bulb and whirl, when the mercury stops dropping, read both thermometer, a comparison of the two temperatures on the psychometric chart shows relative humidity. |
| Define hygrometer | a hygrometer is a device used to measure the relative humidity in the air. |
| What are phosphates and chelants? | phosphates are an internal boiler water treatment used to precipitate solids as sludge; chelants are an internal water treatment used to hold solids in suspension |
| What is condensate polishing? | high pressure system uses an ion exchange system that can withstand high temperatures to purify condensate before it returns to the boiler. |
| Name three types of corrosion in a cooling tower | water hardness, ph and algae |
| Explain the operation of a zeolite water softener | A. the backwash cycle agitates and washes the zeolite. B. the brine cycle washes away calcium and magnesium ions as a soluble chlorides and the resin beads are coated with sodium ions. C. the rinse cycle removes excess brine from the bed. D. during use the resin gives up sodium ions to attract the calcium and magnesium ions. |
| What is a polisher? | a polisher is an ion exchange process which is used to remove trace contaminants both dissolved and suspended from high purity water |
| What is a demineralizer? | Highly efficient ion exchange water softener that uses sulfuric acid and caustic soda in the regeneration process. it removes silica, co2, chloride and sulfate. a demineralizer removes practically all dissolved solids in water. |
| What’s the lowest condensate pH should be? | 8.3 |
| What are amines, and name two types? | Boiler chemicals that evaporate and go out with the steam to keep the condensate ph above acid. low pressure and high pressure amines |
| How is hardness in boiler water usually measured? | parts per million of calcium and magnesium in solution |
| How does a Lithium Bromide system work? | Four parts: generator, condenser, evaporator, absorber. System works in perfect vacuum, using water as a refrigerant and bromide as an absorber and the water vapor is condensed in the condenser then sprayed over coils in the evaporator where it again evaporates before being absorbed by bromide in the absorber section. as the water evaporates it pulls heat from the water or air to be cooled. the bromide/water solution is returned to the generator by a pump which maintains the pressure difference in the system. this system can be cheap to operate but requires constant attention |
| How do you find a leak in a lithium bromide machine? | Remove the lithium bromide and put in a small charge of r-13, and use a leak detector, or helium can be used with a leak detector. or soap bubbles |
| What are the advantages and disadvantages with lithium bromide?- | advantages: non toxic, non flammable, non explosive, and the chemically stable. Disadvantages: when exposed to air becomes corrosive, an irritant to skin, eyes and mucus membranes. |
| How do you determine the size of a receiver on an ammonia cooling unit for a large company? | The unit must be large enough to contain everything in the system, including the piping and allow for 20% expansion |
| What causes freeze back on an ammonia compressor?- | improper charge or improper operation of metering device |
| How do you test for leaks in an ammonia system? | sulfur sticks, phenolphthalein, foams, litmus paper, a burning sulfur candle will produce white smoke at the leak |
| How would you start a manually operated ammonia compressor? | Open the cross over valve, start and run the compressor for a short period of time before slowly closing the valve, the idea is not to start the compressor under full load. |
| How are gasses formed in an ammonia system? | Heat is absorbed in the evaporating coil which causes the liquid to boil until vaporization is complete. |
| How is the capacity of an ammonia compressor affected by the suction pressure, discharge pressure, and clearance? | low suction pressure, high discharge pressure and greater clearance will all decrease the compressor capacity |
| What is Pak-Ice? | ice is made using the direct evaporation of ammonia with jackets forming a cylinder with water inside it. the ice is scraped off the sides of it forms and is compressed into briquettes |
| Explain the purpose of the accumulator and how it works | it is a safety device that prevents the compressor from slugs of refrigerant; it is placed in the suction line so any liquid that flows into the accumulator will evaporate before entering the compressor. |
| . In refrigeration what is the last thing you check before connecting your test gauges? | you should check for which is the high pressure side and for the low pressure side of your system. |
| What types of compressors are used in a Freon system? | centrifugal, rotary, reciprocating, scroll, screw |
| Who can make repairs on your refrigeration system? | if it is a Freon system it must be a certified technician |
| What is a purger and where is it located on a refrigeration system? | a device used to remove air and non-condensable gases from the system, located at the highest point in the system. |
| Describe the operation of an 8 blade rotary compressor and be prepared to draw one. | The eight blade compressor is an external dive unit. a rotor with eight blades that are off set inside the cylinder, as the rotor spins, low pressure vapor from the intake ports fill the spaces between the blades. the trapped vapor is compressed and pushed into the exhaust ports. |
| How does an evaporator condenser work? | an evaporator consists of a steam coil in a tank. water is fed to the tank and a float maintains a constant level. a pump circulates and sprays water over the refrigeration condenser, a fan draws in air through the sides of the evaporative condenser housing and forces air out of the top. water droplets are cooled by evaporation and flow over the condenser. |
| Regarding refrigerant EPA compliance regulations name five? | written mission statement for compliance, policy on detailed record keeping, written purchasing, labeling and handling policy, storage and inventory policy, leak test policy |
| In regards to refrigeration what is superheat? | temperature of vapor above its boiling temperature as a liquid at that pressure |
| What damage can happen if a turbine is started to quickly? | the wheels and dummies may distort through uneven expansion |
| Reaction turbines are especially suited for what steam conditions? | nearly all conditions but are usually low pressure and exhausting into a condenser |
| What’s a reaction turbine and what’s it used for? | it is designed so there is considerable expansion in the rotating blades used for extraction for other pieces of equipment. |
| Name and explain the auxiliary device necessary for start up on a DC motor. | a starting rheostat or starting box with considerable resistance is connected in the circuit to reduce the current going to the motor, thus reducing the resistance within the motor as it starts, as it gains speed the rheostat increases the voltage until full speed is attained. |
| What do you consider the most important step in the care and maintenance of a steam turbine? | The yearly inspection |
| What could cause a turbine to be noisy? | unbalanced rotating parts, misaligned or bent shaft, scale, moisture in the steam, loose bearings, and worn parts, could could be from the machine the turbine is operating. |
| How is electricity produced in a generator? | a generator uses a magnetic field created by coils and the electric pressure produced in a conductor that is cutting through that magnetic field to produce voltage. |
| What is the function of the dashpot? Where is it located? | to slow the action of the governor to prevent hunting, it is part of the governor. |
| What is power factor? | the ratio between the apparent power and the actual power in an AC circuit |
| What is a 3 phase Y connected alternator? | it has three winding, 120 degrees apart in phase relationship, connected in a y shape. the middle point of the y is common connection of one end of each winding. the other end of each winding is a line connection. the middle point of the y may or may not be brought out as another line connection |
| What is a 3 phase alternator? | A three phase alternator is an AC electrical generator with 3 sets of windings in the stator. these windings overlap each other in a phase angle, or timing relationship, by 120 degrees with respect to each other. the rotor (field or excitation) current is DC, and adjusted to regulate the output power. |
| What is a diaphragm, and where is it located? | it is a complete set of nozzles in one stage of a turbine what is bolted into the steam chest. |
| Define gland sealing steam. | it is a low pressure steam, used in conjunction with labyrinth packing to seal the low pressure end of the condenser. |
| What is the most economical vacuum on a turbine | 28.5 is ideal |
| What is considered a perfect vacuum? | 29.92 inches of mercury |
| What are the essential steps in putting on a cold boiler on line with other operating boilers? | Blow down gauge glass and water column, open vent on boiler drum, start the burner on a low manual fire, test flame scanner, test low water cut off, when boiler builds pressure close the vent, open header valve drain and nonreturn valve drain, open equalizing line to warm header, when boiler pressure is 80% of header pressure open header valve and close the drain, unscrew the handwheel on the nonreturn valve and close the drain, when boiler pressure equalizes put controls in automatic. |
| When operating a boiler with a pressurized furnace, why is it important to regularly inspect the outer skin of the boiler? | Checking the outer skin and gaskets for visible damage from hot spots alerts that repair in needed. flue gas leaks are hazardous to health. |
| . In what unit is draft measured by? | Inches of water column |
| Name three types of oil burners? | rotary, steam or air, pressure |
| How to operate soot blower on a manually operated water tube boiler? | Run soot blower with a manually operated chain drive. |
| What is thermal efficiency and what is ideal efficiency of most boilers. | it is the ratio of heat applied by the fuel to heat absorbed by the boiler, 85% is ideal. |
| What are two types of welds on boiler construction and repair? | (saw) submerged arc welding, OAW oxyacetylene welding(smaw) shielded metal arc welding |
| Sketch a steam header valve arrangement. Draw boiler, non return valves with drains, then header |
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Boiler (binary/octet-stream)
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| . Name two low water cutoffs tests and how often should you test them? | Evaporation test and slow drain test; test them yearly or during an outage. |
| When should you bottom blow a boiler? What safety procedure must be followed when bottom blowing a boiler? | when starting up with a small amount of pressure on it, but only when the fires are out. always be in control of the valve. |
| How is a steam gauge connected to a boiler? What are two requirements? | Connected to the steam space of a boiler by a siphon, should be made of copper or brass and the shutoff should be located near by. |
| In the ASME code for boilers, what does stamp ‘A’ stand for? | Power boiler assemblies. |
| Why is welding preferred over riveting on longitudinal? | Welding longitudinal joints are stronger than riveted joints, welding eliminates areas where sludge can form |
| Why are tube ends beaded over in a steam drum? | to make sure they get completely drained and to prevent air from being expelled. |
| How do you do a dry boiler layup?- | When the boiler pressure has dropped to 100 psig it is treated with sodium nitrate and filled to the top of the boiler gauge glass then drained or desiccant lay up method uses bags of desiccant to keep the boiler dry. |
| What is return condensate percentage in feed water if the make up conductivity is 836 mho and the feed water is 172 mho, condensate conductivity is 60 mho? | 836 – 172 = 664 836 – 60 = 776 664 / 776 = 85.56% |
| How do you do a wet boiler layup? | Boiler should be filled completely to the top with deaerated water, add sodium sulfite to 250 ppm for an oxygen scavenger, to control ph add caustic soda to 450 ppm |
| How often should steam traps be tested for proper operation? And list six ways to test them. | Test them every year. They can be tested by; temperature difference, temperature crayons, flow indicators, test valves, listening devices or install sight glass and have knowledge of equipment. |
| Draw or explain connecting a safety valve. | independent of any other steam connection, as close as possible to the boiler without any unnecessary piping or fittings it shall be screwed or fastened to the boiler shell, it shall stand upright, the vent piping should be securely fastened to the building and not rigidly connected to the valve |
| What is an accumulation test and when is it needed? | it is a test to determine if the safety valve capacity is sufficient to protect the boiler. shut off all other steam outlets, increase the burner to max firing rate, the safeties should relieve all steam generated without the boiler pressure exceeding 6% of the set pressure. |
| What makes a safety valve pop? | The huddling chamber increases the total force on the disk surface as the valve lifts, or the safety has the disk held on its seat by a spring which can be adjusted to give variation in popping pressure, this is accomplished by the compression screw which forces the valve against its seat. |
| Inverted bucket trap? | inverted bucket steam trap can be made to withstand high pressures, can be used on superheated steam lines with the addition of a check valve on the inlet, used on turbine drains. |
| How often is it recommended to test your safety valves manually and how often under pressure? | You should test manually once a year under pressure. |
| What are some essential rules governing safety valves and their installation? | Each boiler shall at least one safety valve and two valves it it has more than 500ft2 or over 4000 lbs per hour steam generating capacity of heating surface. it should be set at or below maximum allowable working pressure. all safety valves shall be constructed so that failure to any part cant be obstruct the flow of steam exiting the valve |
| What is an aspirating pump | an aspirating pump automatically removes air from the liquid and discharges it to the atmosphere. |
| Is a centrifugal pump primed running or stopped? Why? | it is primed while stopped because it is not positive displacement pump |
| How does a centrifugal pump eliminate balance problems? | through the use of balancing devices to control and indicate flow in a return line, thrust bearings, double flow impellers |
| What is cavitation? | cavitation is vapor bubbles forming in the suction areas of a pump, which collapse in high pressure areas of the pump resulting in vibration and noise. |
| Name three things vacuum pump does for heating system? | remove non-condensable, increases efficiency over ejector, good at moving gas and liquid |
| What is meant by total head on a pump? | it is figured by total static head of discharge above the level of the suction water pressure at the point of discharge, and pipe friction including fittings. |
| Name three merits of a metering pump. | a wide variance of delivery volume, capable of pumping a wide variety of chemicals and generally used for heads above 200 psi |
| The gauge on a pump discharge reads 125 psi, how high is the discharge pipe? | 125/.433=288.68 ft. high |
| How high will the suction of a single stage centrifugal pump lift water? | Cold water 10-15ft. hot water should come to the pump at a positive head |
| What is the purpose of a shaft sleeve? | Shaft sleeves protect the shaft from corrosion and damage. |
| What are two types of vacuums pumps? | Rotary and centrifugal |
| What will happen to the discharge pressure of a centrifugal pump if the discharge valve is closed completely? | the pressure will usually increase and then level off |
| How would you change the discharge pressure of a single stage centrifugal pump? | install a prv, change the speed, throttle the discharge, and trim the impeller |
| What are the requirements of a good motor? | threee phases, variable frequency drive, soft start feature. |
| manifold duplex water pumps? | used for boiler feed service and is capable of handling water at high temperatures without cavitation. they are operated by two float switches set to start the water pumps at low and high water levels in the receiver |
| What is meant by on-off, positioning and metering control? | on/off is the basic type of control, then positioning is where there is more selection than just on/off and metering control is more accurate then positioning |
| how do you protect your motors from overloads? | circuit breakers and fuses |
| dealing with water column piping waht is maximum and minimum diameter? | min 1" max 2 1/2" blow off line 3/4" |
| What are the advantages and disadvantages of injectors? | advantages: simple, compact takes little or no room low initial cost thermally efficient heating the feed water no moving parts. disadvantages: easily scaled is only used for small boiler because it cannot handle high temperatures unreliable with variant loads. |
| what is the right to know label? | physical and health hazards, first aid procedures for exposure and contact. personal protection required. flammability no smoking handling and storage instructions the chemicals or common name |
| fire safety plan? | goals and priorities of the plan are to have basic awareness and appropriate response to understanding what fire is, fire in you area types and how to react. fire exit and drills, location of extinguishers and fire hoses, escape routs, rescue plan |
| how much oil can spill before you call the epa? | 25 gallons |
| what is the epa? | environmental protection agency is a federal agency set up to control and abate pollution in the areas of air water solid waste pesticides radiation and toxic substances |
| the EPA requires waht records to be kept regarding underground fuel tanks? | upon request you must provide the the epa records on installation monitoring cathode protection release detection equipment calibration maintenance repairs and closures |
| How often do you check the rectifier on a fuel tank? who can check it? What do you check? | you must inspect it every 60 days and keep records of three readings on file. a Qualified cathodic protection inspector would check the dc output. if testing a rectifier it must be done after 6 months of installation and every 3 years after. |
| list three over fill precentions requird on a fuel oil tank | automatic shut off devices on the fill, overfill and high level audible alarms, ball float valves on the vent |
| What spill protection is required on fuel tanks? | There must be a catch basin around the fill opening with a capacity of 5-25 gallon |
| What is a confined space? | a confined space has a large enough opening to physically enter bus has a limited or restricted entry or exit and is not meant for continued occupancy |
| What are five basic methods used for protection of cross contamination of potable water? | air gap no less than 1" and no more than 2 times the diameter of the pipe and atmospheric style vacuum breaker a pressure style vacuum breaker reduced pressure style back flow preventer double check valve assembly |
| What is an air ejector and what is it used for? | a device using a jet of air or stream across a suction chamber and into a venturi shaped diffuser used to prime pumps or remove non condensable from condensers. |
| Where would you use a reduced pressure style back flow preventer? | On all direct connections that may be subject to back pressure or back siphonage and there is a potential for contamination and a health hazard |
| Which way should a steam line slope and why? | horizontal runs must slope in the direction of steam flow with steam traps at all points where water may accumulate lessens the chance of water |
| What is a seat less plug blow down valve? | a seat less valve in the body it permits pressure to surround the plunger, making the valve fully balanced and hence easy |
| What are two problems if soot blowers discharge water? | avoid slugs of water which might damage blower and erode the tubes |
| What is the lining for inside a steel stack? | to help protect the stack from erosive particulates and corrosive action from acid and flue gas |
| What is lagging? And how does it affect efficiency? | lagging is an outer covering over a wall used for protecting the insulation from water or mechanical damage. To provide safety for personnel and minimize heat loss, thus improving efficiency |
| Describe an intercooler and after cooler on compressors? | an intercooler is designed to remove heat from the compressed air in between stages on a multistage compressor. an after cooler is a component that cools compressed air coming from the last stage of a compressor and also removes moisture |
| Define wire drawing? | a term applied to the reduction in steam pressure which occurs when steam passes through a throttled valve. this will cut the disk and seat of the valve. |
| If an underground fuel tank has 5,000 gallons in it already and it is a 10,000 gallon tank, how much would you order and show your work. | max of 95% full 10000*.95-5000=4500 |
| tds | total dissolved solids is a measure of the total ions in solution |
| conductivity | defined as the ability or power to conduct or transmit heat electricity or sound |
| list the six things printed on the badge of a boiler | 1 design steaming rate 2 boiler design pressure 3 boiler operating pressure 4 boiler operating temperature 5 economizer design and pressure 6 economizer design inlet temperature |
| If a boiler was erected on site what markings will be found on the tubes? | row location column location asme stamp markings |
| What is a slip ring motor used for? | they are used where the s |
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