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39. Thirty gallons of chlorine is added per day to
treat
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2 million gallons of water when the dosage is 1.5 7. To grout the unit, you must build a wooden dam
p.p.m. and dosing solution is 10 percent. around the foundation and wet the top of the
40. The precautions that must be followed while foundation. Then fill the space with grout.
per-forming the turbidimeter test are as follows: (Sec. 26, Par. 7)
The glass tube must be placed in a vertical 8. One part of Portland cement to three parts of
position with the centerlines matched. The top sharp sand is used to make grout. (Sec. 26, Par.
of the candle support should be 3 inches below 7)
the bottom of the tube. The candle must be 9. You should allow 48 hours for the grout to
made of beeswax and spermaceti, gauged to harden. (Sec. 26, Par. 7)
burn within 114 and 126 grains per hour. The 10. To establish initial alignment of the pumping
flame must be a constant size and the same unit, you must tighten the foundation and
distance below the tube. The tube should be holddown bolts. Check the gap, angular
inclosed in a case when observations are made. adjustment, and parallel alignment. Recheck
Soot, moisture and impurities must not be alignment after each adjustment. (Sec. 26, Par.
accumulated on the bottom of the glass tube. 9)
(Sec. 24, Pars. 4, 5, and 6) 11. The unit may become misaligned because of
41. The number of gallons that a vertical type foundation settling, seasoning, or springing; pipe
pressure filter, 4 feet in diameter, can treat in 1 strains; shifting of the building structure; or
hour is: springing of the baseplate. (Sec. 26, Par. 9)
Area = π2 12. Strainer. (Sec. 26, Par. 10)
Area = 3.146 X (1/2d) 13. The pump will lose a and capacity if smaller
Area = 3.146 X (2 X 2) discharge pipe is installed. (Sec. 26, Par. 11)
Area = 3.146 X 4 14. To prime the pump, fill it with the fluid to be
Area = 12.564 or 12.6 pumped through the priming opening in the
12.6 X 3 = 37.8 pump. (Sec. 27, Par. 1)
37.8 X 60 =2268 gallons. 15. After the pump is primed and before it is
(Sec. 24, Par. 11) started, make sure that all the pump connections
42. The precaution for taking water samples that is are airtight and rotate the pump shaft by hand
common to both types of analysis is that the to be sure that it moves freely. (Sec. 27, Par. 1)
equipment (bottle, stopper, etc.) must be 16. Loose pump connections, low liquid level in the
sterilized. (Sec. 25, Pars. 3 and 4) pump, loose suction line joints, improper
43. To sterilize a bottle that is to be used for direction of rotation, motor not up to nameplate
chlorine rating 0.2 to 0.5 grams of sodium speed, and dirty suction strainer will cause the
thiosulfate is added to the sample in the bottle. failure of a newly installed pump. (Sec. 27, Par.
Then it is sterilized at a temperature below 392° 3)
to prevent decomposition of the thiosulfate (Sec. 17. The lantern ring. (Sec. 28, Par. 2)
25, Par. 4, a) 18. You must pipe clean water to the stuffing box
44. You should hold the bottle least 3 inches below when the water being pumped is dirty, gritty, or
the surface of water in a tank when you take a acidic. (Sec. 28, Par. 3)
sample. (Sec. 25, Par. 4, c) 19. Loose packing will leak excessively and tight
45. A solution of lysol, mercuric chloride, or of packing will burn and score the shaft. (Sec. 28,
bicarbonate of soda is used to rinse your hands Par. 4)
after making water tests. (Sec. 25, Par. 7) 20. When five-ring packing is used, stagger the
packing joints approximately 72°. (Sec. 28, Par.
CHAPTER 5 5)
21. Back off the gland bolts. (Sec. 28, Par. 10)
1. The amount of cement that you would mix with 22. The bellows should not be disturbed unless it is
12 pounds of sand and 24 pounds of crushed to be replaced. (Sec. 28, Par. 11)
rock is 4 pounds. (Sec. 26, Par. 1) 23. The four types of bearings found in centrifugal
2. A 1-inch space is left between the foundation pumps are grease-lubricated roller and ball
and baseplate to allow enough room for grouting bearings, oil-lubricated ball bearings, and oil-
after the baseplate is level. (Sec. 26, Par. 1) lubricated sleeve bearings. (Sec. 28, Par. 17)
3. A ¾- inch baseplate bolt requires a sleeve made 24. Overlubrication causes overheated bearings.
from 1.875-inch pipe. (Sec. 26, Par. 1) (Sec. 28, Par. 17)
4. To level the baseplate, you would place two 25. Mineral greases with a soda soap base are
wedges below the center of the pump and two a recommended for grease lubricated bearings.
below the center of the motor. (Sec. 26, Par. 3) (Sec. 28, Par. 19)
5. The angular alignment of a “spider” is checked 26. Vegetable and animal greases are not used to
at four points on the circumference of the outer lubricate pump bearings because they may form
ends of the coupling hubs at 90° intervals. (Sec. acid and cause deterioration. (Sec. 28, Par. 19)
26, Par. 4) 27. 180° F. (Sec. 28, Par. 20)
6. Angular alignment is accomplished by loosening 28. 150° F. (Sec. 28, Par. 22)
the motor holddown bolts and shifting or 29. The four drilled recesses facilitate the removal
shimming the motor. (Sec. 26, Par. 5) and
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installation of the coupling bushing. (Sec. 28, 22. Conductor. (Sec. 31, Par. 4)
Par. 24) 23. N-type germanium is made when an antimony
30. Disagree. The recessed holes should face away atom has gone into covalent bonding with
from the pump. (Sec. 28, Par. 26) germanium. The antimony in the material
donates a free electron. (Sec. 31, Par. 8)
Chapter 6 24. N-type material has free electrons which support
electron flow, whereas P-type material has a
1. Thermionic emission is a method of emitting shortage of electrons. This shortage causes
electrons from the cathode with heat. (Sec. 29, current to flow from the N-type material to the
Par. 3) P-type material. (Sec. 31, Pars. 8 and 9)
2. In a directly heated cathode, the material that 25. N-type; P-type. (Sec. 31, Par. 13)
heats also emits electrons, whereas the indirectly 26. Forward bias encourages current flow. (Sec. 31,
heated cathode has separate heating and emitter Par. 14)
elements. (Sec. 29, Par. 4) 27. 2500 watts is developed in a circuit having 100
3. The elements of a diode vacuum tube are the ohms resistance and an amperage draw of 5
amps (P = I2R). (Sec 31, Par. 17)
cathode and plate. (Sec 29, Par. 7)
4. Cathode; plate. (Sec. 29, Par. 7) 28. The base is located between the emitter and
5. The diode rectifies a.c. because current will pass collector. (Sect. 31, Par. 19)
through the tube in one direction. (Sec. 29, Par. 29. Maximum power gain is obtained by making the
8) base region very narrow compared to the emitter
6. The factors that determine the amount of and collector regions. (Sec. 31, Par. 24)
current flowing through a diode tube are the 30. The emitter is comparable to the cathode, the
temperature of the cathode and the potential base to the grid, and the collector to the plate.
difference between the cathode and plate. (Sec. (Sec. 31, Par. 29)
29, Par. 9 31. The three basic transistor circuits are the
7. Positive. (Sec. 29, Par. 11) common base, common emitter, and common
8. The capacitors will filter half-wave rectification collector. (Sec. 32, Par. 1)
by charging during the positive half-cycle and 32. The common collector circuit has a high
discharging through the load resistance during impedance input and a low impedance output.
the negative half-cycle. (Sec. 29, Par. 13) (Sec. 32, Par. 5)
9. A duo-diode is a tube containing two diode 33. The coupling capacitor is used to couple the
tubes. It may have one cathode and two plates. signal into the emitter-base circuit of the
(Sec. 29, Par. 16) transistor. (Sec. 32, Par. 6)
10. The purpose of the control grid is to provide 34. The voltage drop is 9 volts (3/4 X 12 = 9).
more sensitive control of the plate current. (Sec. (Sec. 33, Par. 1)
30, Par. 2) 35. A simple two-resistor bridge is balanced when
11. The control grid is physically located between no current flows between the wipers. (Sec. 33,
the cathode and plate. (Sec. 30, Par. 2 Par. 2)
12. Negative. (Sec. 30, Par. 4) 36. The Wheatstone bridge sends a signal to the
13. When the grid is made more negative, the amplifier, which builds up the bridge signal to
current through the tube will decrease. (Sec. 30, operate a relay. (Sec. 33, Par. 5)
Par. 5) 37. The higher temperature will unbalance the
14. Grid bias is the potential difference of the d.c. bridge by increasing the resistance in one circuit.
voltage on the grid with respect to the cathode. The signal from the bridge will be amplified and
Cutoff bias is the point at which the negative operate a relay. (Sec. 33, Par. 8)
grid voltage stops all current flow in the tube. 38. A vacuum tube voltmeter is used because it has
(Sec. 30, Pars. 5 and 7) a high input resistance. (Sec. 33, Par. 9)
15. The types of grid bias used on vacuum tubes are 39. The first step to take when using a V.T.V.M. is
fixed, cathode, and contact potential. (Sec. 30, to turn the meter on and allow it to warm up.
Pars. 8, 9, and 12) (Sec. 33, Par. 10)
16. A disadvantage of contact potential bias is that 40. The purpose of the discriminator circuit is to
bias is developed only when a signal is applied to determine in which direction the bridge is
the grid. (Sec. 30, Par. 14) unbalanced and take the necessary action to
17. The triode can be used as an amplifier because a correct the condition. (Sec. 34, Par. 1)
small a.c. voltage applied between the cathode 41. The function of the blocking capacitor is to pass
and grid will cause a change in at grid bias and a.c. to the second stage and block the high-
vary the current passing through the tube. (Sec. voltage d.c. (Sec. 34, Par. 3)
30, Par. 15) 42. When the signal in the discriminator circuit goes
18. The potential of the screen grid is positive with negative, the cutoff bias is reached on the
respect to the cathode. (Sec. 30, Par. 19) control grid. (Sec. 34, Par. 5)
19. The power amplifier handles larger values of 43. The bridge supply voltage should come from the
current than triode amplifiers. (Sec. 30, Par. 20) same phase as the discriminator supply to insure
a bridge signal that is either in phase of 180° out
20. A negative potential is applied to the suppressor
grid of a pentode tube. (Sec. 30, Par. 23) of
21. The valence ring is the outer ring or orbit of an
atom. (Sec. 31, Par. 4)
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phase with the discriminator supply. (Sec. 34, 10. The total voltage across the bridge determines
Par. 7) the position of the final control element. (Sec.
44. The discriminator circuit will conduct when the 36, Par. 3)
plate and the amplified bridge signal are both 11. The adjustments for setting up or changing a
positive. (Sec. 34, Par. 8) control sequence are made at the control panel.
45. A balancing potentiometer is used with a (Sec. 36, Par. 4)
modulating motor to bring the bridge back into 12. The nonrestarting relay is connected in the
balance when a deviation has been corrected. compressor starting circuit. It will prevent the
(Sec. 34, Par. 10) compressor from operating unless the solenoid
valve is operating. (Sec. 36, Par. 7)
13. The summer compensation schedule differs
Chapter 7
from the winter compensation schedule in that
outdoor thermostat T3 will be replaced by T1.
1. The precaution you should observe when
(Sec. 36, Pars. 10 and 11)
installing a humidity sensing element is to locate
14. When the controlled variable varies continually
it not too close to sprayers, washers, and heating
and reverses its direction regularly, the throttling
or cooling coils, but within 50 feet of the control
range is set too low. (Sec. 37, Par. 3)
panel. (Sec. 35, Par. 2)
15. With a 10 percent authority and 10° temperature
2. The outdoor thermostat sensing element is a coil
change T3 will have the same effect as a 1°
of fine wire wound on a plastic bobbin and
coated for protection against dirt and moisture. change in temperature at T1. (Sec. 37, Par. 5)
(Sec. 35, Par. 5) 16. The control point can be reset after the system
3. To check the resistance of the sensing element, is in operation by positioning the control point
disconnect the leads and connect an ohmmeter adjuster in the control panel. (Sec. 37, Par. 6)
across them. (Sec. 35, Par. 9) 17. When the amplifier output voltage is 1 volt and
4. Dirt on the sensing element will reduce the the branch line pressure is 5 p.s.i.g., the most
sensitivity of a thermostat. (Sec. 35, Par. 11) probable trouble is that the valve unit is out of
5. To reposition the crank arm on the damper adjustment. (Sec. 37, Par. 7)
motor shaft, loosen the screw and nut that hold 18. The control reference temperature is
the arm on the shaft. This will allow you to temperature measured at T1. The control
reposition the shaft in four different positions, reference pressure is the actual branch line
90° apart. The adjustment screw on the face of pressure. (Sec. 37, Pars. 9 and 10)
the crank arm provides angular setting of the 19. The control point of a compensated system on
crank arm in steps of 22 1/2° throughout any winter schedule should be equal to the set point.
(Sec. 37, Par. 14)
one of the four positions on the shaft. (Sec. 35,
20. The bridge signal is amplified and fed to a
Par. 13)
magnetic coil in the pneumatic valve. The
6. The damper motor repairs that may be made in
amount of current flowing through the coil
the field are cleaning the potentiometer or limit
positions nozzle lever over the nozzle. The
switch contacts, repairing internal connecting
position of this lever controls the amount of
wires, and replacing the internal wires. (Sec. 35,
branch line pressure sent to the controlled
Par. 15)
device. (Sec. 37, Pars. 18 and 19)
7. You can check the transformer output by
21. A faulty connection between the amplifier and
connecting a voltmeter across its terminals.
bridge will cause one or more of the tubes to
(Sec. 35, Par. 16)
remain cold. (Sec. 37, table 21)
8. If the damper motor does not respond to direct
22. The transformer output and the valve unit relay
transformer power, the most probable faults are
must be checked when the tubes light up and
broken wires, defective limit switch, or faulty
burn out repeatedly. (Sec. 37, table 21)
condenser. (Sec. 35, Par. 18)
9. The authority “pots” adjust the change in
variable required to give a certain voltage
change. (Sec. 36, Par. 2)
*U.S. Government Printing Office: 2001-628-075/40468
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