DC BOILER STATIONARY THIRD TESTING EXAM 2023-2024
ACTUAL EXAM 200 QUESTIONS AND CORRECT DETAILED
ANSWERS WITH RATIONALES|AGRADE
On the boilers that have both Quick opening and Screw type blow down valves, the
Quick opening valve must be located? – ANSWER- Closest to the boiler and
followed by the screw type valve
High pressure boilers equipped with Quick opening and Screw type valves are
blown down how? – ANSWER- By opening the Quick opening valve first and
closing it Last.
ASME Code defines a slow opening valve as what? – ANSWER- One requiring at
least 5 full 360 degree turns between full open and close position.
A 300 Horsepower boiler operating at 100psi has an average load of 75% with
80% condensate return and 5% blow down. The treatment provides a chemical
which costs $8.75 per gallon, and will treat 600 gallon. Find the amount of the
chemical needed for the day period, and the cost of the chemical for a 30 days
period? – ANSWER- Water In = Water Out
Makeup + Condensate Return = Evaporator + Blow Down
Average Evaporator Rate = 300 x 34.5 pph x .75% load = 7762, 50 pph
1 Month + .8( 7762.50 pph) = 7762.50 pph + 0500 m
1 Month + 6210 pph = 7762.50 pph + .0500 m
-6210 -6210
1 Month = 1552.5 pph + .0500
.9500 m = 1552.5 pph
.9500m .9500
1Month = 1,634.21 pph
Gallons per Month = 1634.21 / 8.33 x 24 x 30 = 141, 252.24 gallons per month
Chemical needed = 141,252.24 gallon / 600 gallon = 235, 40 gallon
Cost per month = 235, 40 gallon x 8.75 = $2,059.75
During a 24 hours operation how often should you check the water level? –
ANSWER- Once per shift
A 15 psi steam boiler produces 8000 pound of steam per hour. The
Minimum pipe size for the pipe leaving the boiler is___12__inches.
(Density is 0.037 lbs/ft3)
Equation: – ANSWER- D = 12 (C/d/h /.7854)
D = 12 (8000 / 0.037/60) = 3,603.60
D = .7854 / 5000ft = 3,927
D = 3.603.60 / 3,927 = 0.917647058
D = 0.957938963 * 12
D = 11.49 OR 12 “pipe
The boiler steam line is 350 Feet long. During start-up the pipe is heated
From 60 F to 350 F. The 350 F. The pipe wills expand__7.92__inches
Due to the change in temperature
Equation: – ANSWER- (T 1 – T2) x L x .0000065
(350 – 60) x 350 x .0000065
290 x 350 x 12 x .0000065 = 7.92
A 12″ pipe filled with water to a height of 250 feet will have a pressure of
_________at the bottom of the pipe?
Equation:
P = FT / 2.31 – ANSWER- 250 feet / 2.31 = 108.22
A “5” pipe filled with water to a height of 75 feet will have a pressure of
_________at
The bottom of the pipe?
Equation:
P = FT / 2.31 – ANSWER- 75 feet / 2.31 = 32.46
What is the flow rate, in gallons per minute, of water flowing through a 8′ pipe
At a velocity of 7 feet per second? – ANSWER- GPM = V X D²
0.4085
GPM = 7 x (8 x 8)
0.4085
GPM = 448
0.4085
GPM = 1096.69 gpm
What is the flow rate, in gallons per minute, of water flowing through a 4′ pipe At a
velocity of 12 feet per second? – ANSWER- GPM = V X D²
0.4085
GPM = 12 x (4 x 4)
0.4085
GPM = 192
0.4085
GPM = 470.01 gpm
What is the maximum pressure that a 15 x 9 x 10 duplex reciprocating pump
Can develop when operating with 125-psi steam? – ANSWER- Pw = Ps x As
Aw
Pw = 125 x (15 x 15 x 0.7854)
(9 x 9 x 0.7854)
Pw = 22089.38
63.62
Pw = 347.22 psi.
During a 24 hours operation how often should you check the water level? –
ANSWER- Once per shift
How often you checking the high limit switch? – ANSWER- Annually
What is the recommended time for a complete external inspection of a boiler? –
ANSWER- Once per shift
What is the first thing to do when shutting down a boiler? – ANSWER- Turn of the
fire