Chapter 13

An open, cylindrical tank contains a liquid to a height of 7.5 metres. If the density of the liquid is 4.5 x 103 kg/m3, what is the pressure exerted by the liquid at the bottom of the tank in kPa?
a. 331
b. 352
c. 250
d. 400

An open, cylindrical tank contains a liquid to a height of 10 metres. If the density of the liquid is 4.0 x 103 kg/m3, what is the pressure exerted by the liquid at the bottom of the tank in kPa?
a. 331
b. 392
c. 259
d. 400

A pressure gauge is located in the side of a tank at 2 m up from the bottom, which is the minimum tank level to ensure suction to the pumps. If the gauge reads 260 kPa and the level in the tank is 8 m, what is the density of the liquid in the tank?
a. 3.225
b. 4.022
c. 4.417
d. 5.332

A pressure gauge is located in the side of a tank at 3.5 m up from the bottom, which is the minimum tank level to ensure suction to the pumps. If the gauge reads 300 kPa and the level in the tank is 12 m, what is the density of the liquid in the tank?
a. 3.225
b. 4.022
c. 4.417
d. 3.6

A process solution has a density of 3.4 x 103 kg/m3 and is held in a rubber-lined tank that is 9 metres high. If the tank is exactly ⅔ full, what reading, in kPa, would the operator see on a level-indicating pressure gauge, located at the base of the tank in kPa?
a. 200
b. 235????
c. 250
d. 300

What height of water is necessary to exert a pressure of 1 kPa at a temperature of 150°C?
(note Vf = 1.0905 cm3/g)
a. 0.189 m
b. 0.234 m
c. 0.1112 m
d. 0.0034 m

The pressure at the discharge of a water pump is 150 kPa and the temperature of the water is 80°C. Find the equivalent head in metres.
a. 20.21 m
b. 12.55 m
c. 18m
d. 15.73 m

If a column of mercury has an equivalent head of 50 cm., calculate the pressure produced at the bottom of the column in kPa. Relative density of mercury is 13.6.
a. 66.7
b. 73.4
c. 81.24
d. 55

A raw water supply pump is sitting idle with its discharge valve open. The equivalent discharge head is known to be 35 metres and the water is at 70°C. What pressure, in kPa, should be indicating on the pump discharge gauge? (Given vf at 70°C = 1.0228)
a. 350
b. 336
c. 380
d. 320

A chemical in a storage tank has a relative density of 7.60. What is the equivalent head at the outlet of the tank where a pressure gauge reads 250 kPa?
a. 4.0 m
b. 5.2 m
c. 3.35 m
d. 4.55 m

A rotary pump draws oil from a waste collection sump and delivers it into a storage tank. The level in the sump is 2 m below the base of the storage tank and the level in the tank is 4.5 m. If the pump sits 1m above the tank base and discharges into the side of the tank at a height of 3 m, what is the total static head on the pump?
a. 6.5 m
b. 7.2 m
c. 5.2 m
d. 6.0 m

A pump is sitting at rest with its discharge valve open and the pressure gauge showing 210 kPa. The total static head of the pump in this situation is 11 m. If the pump takes suction from a transfer tank located 4 m above it, what is the current level in the transfer tank? The liquid is water at 42°C.
a. 6.5 m
b. 7.2 m
c. 5.2 m
d. 6.42 m????
e. 6.59 m

Static suction lift means:
a. Static that builds up due to liquid moving in a pipe
b. The vertical distance from the liquid supply level to the pump center line when the pump is above the supply level
c. The vertical distance from the liquid supply level to the pump center line when the pump is below the supply level
d. The method by which the pump lifts water
e. the vertical distance form the liquid supply level to the pump discharge point

Friction head means:
a. Friction due to the head of water in the pipe
b. The pressure expressed in metres of head required to overcome friction caused by liquid flow through piping, valves and fittings in the system
c. The sum of dynamic suction lift and dynamic discharge head
d. Friction caused by the impeller moving in the casing
e. the difference between the dynamic discharge head and the dynamic suction lift

Velocity head means:
a. The pressure, in metres of liquid head, required to give the liquid its motion through the system at a given velocity
b. The speed at which the water leaves the pump
c. The speed at which the water enters the pump
d. The distance the liquid must travel in a given amount of time
e. the speed at which the pump impeller is turning

Pressure head means:
a. The sum of static lift and suction friction and velocity head
b. Static head minus suction friction and velocity head
c. The pressure acting in the impeller of a volute type pump
d. The pressure, in metres of liquid head, in a closed vessel from which the pump takes its suction or against which the pump discharges
e. the sum of the dynamic suction lift and the dynamic discharge head

If a centrifugal pump is required to move 20 000 kg of water per hour at a velocity of 12 m/s through a 4 cm diameter line, what velocity head must be considered in the system design?
a. 7.34 m
b. 6.25 m
c. 8.1 m
d. 15 m

What is the velocity in the discharge of a centrifugal pump if the velocity head is 12 m?
a. 7.34 m
b. 6.25 m
c. 8.1 m
d. 15.34 m

A 152.4 mm diameter piping system is 50 m long and contains 3 elbows, 2 gate valves, one globe valve, and 2 tees. If flow in the system is 75 L/s, calculate the friction head.
a. 7.34 m
b. 11.37 m?????
c. 8.1 m
d. 15.34 m
e. 8.364m

Schedule 40, steel pipe, 101.6 mm diameter, is used to construct a piping system. The length of piping is 60 m and there are 4 standard elbows, 1 tee and 1 globe valve. If the flow is 25 L/s, what is the friction head of the system?
a. 14.5 m
b. 12.5 m
c. 7.7 m
d. 11.42 m??????
e. 5.54m

A vacuum evaporator has an absolute pressure of 25 kPa. The level in the evaporator is 10 m above the centerline of the pump. The pump discharges into a storage tank, located 20 m above the pump. This tank has a level of 6 m and a pressure blanket of 100 kPa (gage). Liquid velocities are 3 m/s in the suction piping and 4 m/s in the discharge line. Friction loss in the suction line is 0.5 m and in the discharge line, 1.8 m. Calculate the total dynamic head for the pump.
a. 0.45 m
b. 0.815 m???
c. 1.0 m
d. 0.75 m
Total head = 36.64m

What is the dynamic suction head for a pump that has static suction head = 8 m, suction pressure head = 12 m, suction friction head = 2 m, and suction velocity head = 3 m?
a. 15 m
b. 22 m
c. 17 m
d. 12 m

Net positive suction head helps to:
1. Prevent cavitation
2. Ensure maximum flow through a pump
3. Keep the pump speed constant
4. Prevent vapor binding
a. 2, 3, 4
b. 1, 3
c. 1, 2, 3, 4
d. 1, 2, 4
e. 1, 2, 3

In a closed system completely filled with liquid, no vapours will form as long as the liquid is subjected to a pressure that is greater than the ______ pressure of the liquid.
a. vapour
b. total
c. relative
d. density

________ happens when the pressure, at any point inside a centrifugal pump, drops below the vapour pressure of the liquid, vapour bubbles will form, creating cavities in the liquid flow.
a. Cavitation
b. Surging
c. Priming
d. Chirping

A manufacturer specifies a required NPSH of 5 m for a certain pump. To satisfy this requirement, what must the minimum pressure be at the suction of the pump if the liquid being moved is water at 120°C? (note Vf = 1.0603)
a. 253.55 kPa
b. 244.8 kPa
c. 232.52 kPa
d. 100 kPa

A boiler feedwater pump is to supply water from a boiler at 110°C. According to the manufacturer, this pump must have a minimum suction pressure of 210 kPa to ensure the required NPSH is maintained. What value of NPSH has been specified by the manufacturer?
a. 10 m
b. 8 m
c. 7.15 m
d. 6.25 m

A liquid with a vapour pressure of 110 kPa and density of 840 kg/m3 is moved by a pump that has an NPSH of 6 m. How much pressure must exist at the pump suction?
a. 134.45 kPa
b. 125.87 kPa
c. 145.23 kPa
d. 159.44 kPa