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222 Cards in this Set
- Front
- Back
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A low pressure steam boiler has a maximum allowable working pressure (MAWP) of up to ? |
15 psi |
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The evaporation of 34.5 lb of water/he from and at a feedwater temperature of 212°F |
One boiler horsepower |
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In a firetube boiler, the heat and the gasses of combustion pass ? |
Through the tubes |
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A firetube boiler may be used _ |
In high or low pressure plants |
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Because of the large volume of water, the boiler to most likely cause a boiler explosion is? |
A firetube |
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A horizontal return tubular (HRT) boiler is a _ boiler? |
Firetube |
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As stream pressure in a boiler increases, there is a corresponding increase in the? |
Temperature |
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A sudden drop in boiler stream pressure without a corresponding drop in boiler water temperature could result in a ? |
Boiler explosion |
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The part of the boiler that has the heat and gases of combustion on one side and water on the other side is known as the ? |
Heating surface |
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The comparison, or ratio, of heat supplied in fuel to heat absorbed by water is defined as _ efficiency? |
Thermal |
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Baffles stew designed to direct the gases of combustion so that they come into close contact with the _? |
Boiler heating surface |
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The steam and drum of watertube boilers is dished (concave) to eliminate the need for ? |
Stays |
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To increase the life of a furnace refractory, some watertube boilers are equipped with? |
Waterwalls |
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Vertical firetube boilers require? |
High ceilings, less floor space, and the use of staybolts |
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In a watertube boiler, the heat and gases of combustion pass? |
Around the tubes |
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The _ boiler has a large volume of water in relation to horsepower size? |
Firetube |
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Stays and braces are needed to prevent bulging in? |
A furtive boiler (high or low pressures) |
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The _ boiler was developed to provide steam at higher pressures? |
Watertube |
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The mud drum is the lowest part of the waterside of a (n) _ boiler? |
Watertube |
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Boiler plates and stay bolts are subjected to _ stress? |
Tensile |
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Safety valve connections must be approved by the ? |
American Society of Mechanical Engineers (ASME) |
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Boiler fittings are necessary for? |
Safety and efficiency |
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The most important fitting on a boiler is the? |
Safety valve |
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To prevent failure from pressure over the MAWP, all steam boilers must be equipped with at least one? |
Safety valve |
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A safety valve will? |
Prevent the boiler from exceeding it's MAWP |
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Safety valves are designed to ? |
Pop open |
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Superheater safety valves are set to open _? |
Before the main safety valves are set to open |
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When testing a safety valve by hand, there must be |
at least 75% of the popping pressure |
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Any repairs to a safety valve should be done by the |
safety valve manufacturer or manufacturer’s authorized representative |
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The setting or adjusting of a safety valve should only be done by the |
qualified person who is familiar with the construction and operation of a safety valve |
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If it is necessary to test the relieving capacity of a safety valve |
an accumulation test is put on the boiler
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The relieving capacity of a safety valve is measured in |
pounds of steam per hour capable of discharging under a given pressure |
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The main purpose of a water column is to
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reduce turbulence in the gauge glass to get a more accurate reading of the water level in the boiler |
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Try cocks are |
a secondary means of determining water level in a boiler
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When replacing a broken gauge glass, the water level is checked by |
using try cocks
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The water column and gauge glass should usually be blown down |
once a shift
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A whistle valve is used to |
warn the operator of high or low water
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A steam pressure valve is calibrated in |
pounds per square inch
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A siphon protects the steam pressure gauge from |
high temperature of steam
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The pressure at the base of a vertical foot of water is |
0.433 psi
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The boiler vent is located at |
highest part of the steam side of the boiler
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The boiler vent is open when warming up a boiler until |
there is 10 to 15 psi of steam pressure on the boiler |
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Steam separators work on the principle of |
changing the direction of the steam flow
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The dry pipe is located in the |
upper part of the steam and water drum
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Cyclone separators are used in |
boilers equipped with superheaters |
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Saturated steam is steam at |
its corresponding temperature and pressure
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When steam is superheated the |
temperature increases with no increase in pressure |
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Superheater tubes are protected from warping or burning out by
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a continuous flow of steam |
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Soot should be
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removed from boiler tubes for better heat transfer
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Soot blowers are mainly found on
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watertube boilers
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Steam impinging on boiler tubes would
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cut through the boiler tubes in a very short period of time |
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To ensure that moisture-free steam goes to the soot blower, the steam line to thesoot blower must come off the
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highest part of the steam side of the drum
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Boilers in battery equipped with manhole openings must have _ according to ASME code
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two main steam stop valves
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Main boiler stop valves must be_ valves
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Os&Y gate
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The ASME code will allow an automatic nonreturn valve to be used as a main steamstop valve. If one is used it must be
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installed as close to the shell of the boiler as practical on the main steam line |
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The main stop steam stop valves should be gate valves because they
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offer no restriction to the flow of steam |
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When the boiler is equipped with hand-operated, main steam stop valves, to cut the boiler in on the line, the steam pressure on the incoming boiler should be
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slightly lower than line pressure |
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When a boiler is being inspected, the two main steam stop valves are
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closed,locked, and tagged
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During a boiler warm-up, to remove any condensate trapped between the two boiler stop valves the
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free-blowing drain should be open
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During normal usage, the boiler main steam line expands and contracts. To allow for this
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expansion bends are used
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According to the ASME code, boilers operating at 100 psi or over must have
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two bottom blowdown valves
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When a blowing down a boiler equipped with a quick-opening valve and a screw-typevalve, the quick-opening valve is
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open first and closed last
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If a quick-opening valve is used as a bottom blowdown valve, it must be located
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between the boiler and the slow-opening (screw-type) valve
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The maximum size of the bottom blowdown line and the surface blowdown line is |
2.5”
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Bottom blowdown lines on a watertube boiler are located on the |
mud drum
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The most accurate means of deciding the frequency of blowdown of a boiler is determined by a |
boiler water analysis
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Surface tension on the water in the steam and water drum is increased by |
impurities that float on the surface of the water |
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To protect sewer lines from the high temperature and high pressure coming from the boiler blowdown lines |
blowdown tanks are used
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A generating 20,000 lb boiler of steam/hr must be supplied with at least |
20,00 lb of water/hr |
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Oxygen and other noncondensable gases are separated from the feedwater
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in the open deaerator feedwater heater |
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The four systems required to operate a steam boiler are
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steam,feedwater, fuel, and draft
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In order to produce one pound of steam, it is necessary to evaporate
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one lb of water
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Steam that has lost its heat and has turned back into water is |
condensate |
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Steam is extracted from the turbine after it has passed through some of the turbine stages to
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be used for process work and heating |
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Water from an open deaerating feedwater heater flows
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to the feedwater pump |
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A safe and efficient boiler plant should include pump(s)
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one steam and one electric feedwater |
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A surface condenser has water
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passed through tubes to cause steam to condense, causing a vacuum |
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On the feedwater line near the boiler is a check valve and a stop valve. The valve closest to the shell of the boiler is the _valve
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stop |
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On a boiler burning low pressure gas, the volume (amount) of gas burned is controlled by the
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volume of air passing through the venturi tube |
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On the fuel oil system, the purpose of the duplex strainers on the suction line between the tank and fuel oil pump is to
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allow one strainer to be cleaned without securing the boiler |
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A draft fan located between the boiler and chimney is used in a(n)_ draft system
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induced |
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When steam is superheated it has
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more heat energy, thus producing more work |
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The vacuum on the exhaust side of the turbine
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reduces back pressure and steam flow rate |
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The open feedwater heater is located
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above the feedwater pump(s) |
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NO._ fuel oil must be heater in order to be pumped
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6 |
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Coal stokers were developed because
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handfiring was inefficient in larger-sized boilers |
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Pulverized local coal has the consistency of talcum powder so that it
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can come in closer contact with the oxygen for complete combustion |
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Draft is defined as a difference in pressure that causes
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air or gases to flow |
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Air is mixed inside of the burner register in a(n) _ gas system
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high pressure |
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Natural draft is produced by a(n)
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difference in temperature of a column of gas inside the chimney from a column of air outside the chimney |
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Pulverized coal is burned in the _ in the furnace
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suspension
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Gas leaks should be located and repaired by a
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gas company representative |
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Water weighs approximately _ lb/gal
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8.3 |
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The automatic city water makeup valve found on an open feedwater heater is used to
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maintain a water level in the feedwater heater if there are insufficient condensate returns |
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The purpose of a feedwater regulator is to
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maintain a consistent water level in the boiler
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Feedwater regulator sensing elements are located
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at the NOWL
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The sequence of the three numbers found on the data plate attached to a reciprocating feedwater pump indicates the
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diameter of steam piston,diameter of water piston, and the length of pump stroke |
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A(n)_ draft fan must be used to overcome resistance caused be gases of combustion leaving the boiler when an economizer is used
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induced
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A reciprocating feedwater pump must have a safety valve located between the
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pump and discharge valve |
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An economizer is used in large boiler plants to heat
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feedwater using gases of combustion |
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The theory of operation of a centrifugal pump is that the centrifugal force of a rotating element
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is converted into pressure
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Centrifugal feedwater pumps can be started with their discharge valves
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open or closed
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A turbine feedwater pump differs from a centrifugal feedwater pump in that it is a
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positive displacement pump
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To protect the turbine pump from excessive pressure, a(n)
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safety relief valve must be installed on the discharge line |
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The feedwater stop valve on the feedwater line is located closest to the shell of the boiler so that the
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check valve can be repaired without taking the boiler off-line
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Water temperature that is too high in the open feedwater heater could cause
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the feedwater pump to become steam bound |
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Water temperature that is too low in the open feedwater heater could cause
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oxygen pitting in the boiler |
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Aline desuperheater is typically used
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when both superheated and saturated steam are needed, with a pressure-reducing station, and with feedwater addition to desuperheat the steam
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Burning a fuel releases
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heat energy
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A clogged vent line fuel oil tank being filled with fuel oil could result in a
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buildup,which would cause an oil pressure spill
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A high suction line on a fuel oil tank is used when
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signs of sludge and water are evident in the tank |
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The purpose of the fuel oil return line is to
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circulate fuel oil during warm-up, return fuel oil that bypasses the burner, and return fuel oil from the relief valve |
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In both steam and air atomizing burners, atomization is accomplished by
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live steam and air |
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In a low pressure gas burner, a _ shuts of the gas supply if a low water condition exits
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manual reset valve
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The pneumercator is used to
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indicate gallons of fuel oil in the tank
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An indication of a dirty fuel oil strainer would be _ across the strainer
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a large pressure drop
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Duplex strainers are found on _ of the fuel pump
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both the suction and discharge sides
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Fuel oil heaters must be used when burning No. _ fuel oil
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6
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Fuel oil heaters must be protected from excessive fuel oil pressure because they are located _ the fuel pumps
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on the discharge side of
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The rotary cup burner atomizes fuel oil using
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a spinning cup and high velocity air
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In a pressure atomizing burner, atomization is accomplished by
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rotating, high pressure oil coming out of the plug or sprayer plate |
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A gas pressure regulator is used to control the
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desired pressure at the burner
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A solenoid valve is a direct-acting valve in the gas system and is used
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as an automatic gas shutoff valve |
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To prevent caking and to dry the coal entering the pulverizer
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warm air is used
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Blowers are used in a high pressure gas system to
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supply air for combustion
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The air-to-gas ratio is maintained by a(n)
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air damper, butterfly valve, and modulating motor and linkage |
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The amount of gas drawn into the air stream in a low pressure gas system is controlled by the
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Venturi effect
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Boilers are equipped with a combination gas/fuel oil burner for
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more flexible operation
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The underfeed stoker can burn
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anthraciteor bituminous coal
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Spreaderstokers burn coal
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in suspension and on grates
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To achieve complete combustion ina spreader stoker, air is introduced |
under and over the fuel bed
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The thickness of a fuel bed on a chain grate stoker is regulated by a coal
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hopper
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Pulverized coal burns
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insuspension
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The volume of gas to the burner in a high pressure gas system in controlled by a _valve
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butterfly
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In order to burn 1 lb of fuel, approximately _ lb of air are needed
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15
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Draft is measured in
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inches or tenths of an inch of a vertical water column
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Draft in the boiler is measured between two points such as the _ and _
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atmosphere;inside the boiler setting
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Pressure at the discharge side of a forced draft fan is _ atmospheric pressure
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greater than
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To reduce the heat loss of flue gases going to the chimney, boilers are equipped with
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economizers and air heaters
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The convection air heater employs a counterflow principle in which the gases ofcombustion
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move up while the air goes down
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Both air and flue gas temperatures are controlled by
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the use of bypass dampers
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If the temperature of air entering the heater gets too low, it will cause
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condensation on the gas side of the air heater |
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Airheaters must be cleaned to ensure good heat transfer by
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using soot blowers
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Airheaters can most successfully be used in plants that
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have a fairly constant steam load
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If air supplied for combustion mixes with gases of combustion, it could lead to
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a loss of air for combustion and lower boiler efficiency |
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A diaphragm draft gauge is calibrated in
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inches of water
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Mechanical draft is produced by the
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power-driven fans
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Mechanical draft can be classified as
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forced or induced
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The amount of draft available in a natural draft system is dependent on the
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height of the chimney |
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The gases of combustion leaving a boiler that has a natural draft are controlled by
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outlet dampers
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The induced draft fan is located
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between the boiler and the chimney
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Mechanical draft is used when burning
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fuel oil, coal, and gas
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Large steam boilers that are equipped with air heaters and/or economizers must use
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both forced and induced draft fans
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When using mechanical draft, it is possible to
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increase the rate of combustion
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Draft pressure maintained at a constant pressure is called a _ draft system
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balanced
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The oldest form of draft used in a boiler is _ draft
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natural
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Solid particles created in the combustion process are called
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fly ash
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The temperature at which fuel oil will give off a vapor that will ignite readily when exposed to an open flame is its _ point
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flash
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In order to determine the heating value of coal in Btu per pound, the
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ultimate analysis is used |
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The temperature at which fuel oil will give off a vapor that burns continuously is its _ point
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fire
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Rank refers to the _ of the coal
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degree of hardness
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Grade refers to the _ of the coal
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size,heating value, and ash content
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A proximate analysis of coal provides information regarding its
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moisture content, content of volatile matter, and fixed carbon and ash content |
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An ultimate analysis of coal provides information regarding
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elements present in coal
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Bituminous coal has a high _ content
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volatile
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Anthracite coal has a high _ content
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carbon
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When the temperature of fuel oil is raised, its viscosity
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is lowered
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The lowest temperature at which fuel oil will flow is its _ point
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pour
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Fuel oil with a low flash point would be
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dangerous to use
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_coal is the type of coal most likely to have problems with spontaneous combustion when being stockpiled
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bituminous
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A _fire extinguisher is the correct type to use on fuel oil fires
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foam or dry chemical
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Air that controls the rate of combustion is _ air
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primary
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Air that is supplied to the burner that is more than the theoretical amount needed to burn fuel is _ air
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secondary
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_combustion is when all fuel is burned using only the theoretical amount of air supplied
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perfect
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_combustion is when all the fuel is burned using the minimal amount of excess air
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complete
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Gases of combustion that cool on contact with the boiler heating surface before combustiobn is completed cause a(n)
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formation of soot and smoke
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Air needed for the combustion of fuel is made up of approximately _% oxygen and _%nitrogen
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21;79
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Soot and smoke are the result of _ combustion
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incomplete
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_is a combustible found in fuel
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carbon,sulfur, and hydrogen
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Carbondioxide (Co2) in the flue gas indicates
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complete combustion |
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Carbonmonoxide (CO) in the flue gas indicates
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incomplete combustion
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The Orsat has analyzer measures the percentage of _ in the flue gas
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carbon dioxide, carbon monoxide,and oxygen |
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_is a type of combustion
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complete,perfect, incomplete
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No._ fuel oil must be heated to reach the required temperature for combustion
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6
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Higher number fuel oils produce _ lower numbered fuel oils
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more Btu per gallon than
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The heating value of a fuel is expressed in
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British thermal units |
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The primary function of a combustion control is to ensure
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safe and efficient boiler operation |
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The ON/OFF control system is usually found on
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small package, firetube, and watertube boilers |
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The purpose of the boiler pressure control found in the ON/OFF control system is to
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start and stop the burner on steam pressure demand
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The ON/OFF pressure control must be connected to the
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highest part of the steam side of the boiler |
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A steam siphon ensures that _ does not enter the boiler pressure controller
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steam
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A mercury-tube pressure control will only be accurate when it is installed
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invertical positon
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The four elements that must be regulated in a combustion control system are
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fuel supply; air supply; ratio of air to fuel; removal of combustion gases |
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The two scales found on the boiler pressure control are used to
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set the operating steam pressure range of the boiler |
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The purpose of the boiler modulating pressure control is to
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regulate the high and low firing rates of the burner |
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The modulating pressure control must be connected to the
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highest part of the steam side of the boiler |
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The blower motor control continues to operate after fuel is shut off the burner during
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postpurging
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The programmer in the ON/OFF control system is used to
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control the burner firing cycle
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To eliminate the danger of a furnace explosion during startup, the firing sequence must first allow for
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a prepurge period
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The purpose of the scanner is to prove
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both the pilot and the main flame
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The scanner must be installed on the front of the boiler to sight
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both the pilot and the main frame |
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The flame sensor is sensitive to
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infrared or ultraviolet rays
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In the event of a flame failure, the programmer will
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secure the fuel, purge the firebox, and then shut down |
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The positioning combustion control system used on older boilers cannot function without _ pressure
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air
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The metering combustion control system is sensitive to changes in
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steam flow and pressure |
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Combustion air is controlled by
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inlet damper, fan intake vanes, and the fan speed
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Gases of combustion are pulled from the boiler by the
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induced draft fan
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The positioning combustion control system is sensitive to changes in the
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steam header pressure |
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The most common type of pressure control used is the _ type
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mercury-tube
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Pressure gauges are calibrated in pounds per
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square inch
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Absolute pressure is equal to
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gauge pressure plus atmospheric pressure
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A boiler steam-pressure gauge should have a range of
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1.5 to 2 times the safety valve setting |
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The boiler steam-pressure gauge must be connected to the _ of the boiler
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highest part of the steam side |
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The boiler steam-pressure gauge is protected from high temperatures by
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a siphon
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A primary reason for using thermocouples for measuring temperatures is
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to take and read the readings for remote plants carefully |
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Vacuum gauges are calibrated in inches of _ atmospheric pressure
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mercury below
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Most thermometers used in a steam plant are calibrated in
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degrees Fahrenheit
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Thermocouples measure
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temperature
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A _reading can be read using a thermocouple
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superheated steam, gases of combustion, and condensate return |
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Liquids in a tank may be measured from a remote location using a
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pneumercator
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Flowmeters measure the rate of flow of
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avariety of fluids
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The differential-pressure flow meter functions by receiving a difference ofpressure across a(n)
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venture,orifice plate, and flow nozzle
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