chapter 18 Flashcards
(35 cards)
An equalizing line is installed around a large gate valve in a steam header because:
a)The valve is difficult to open with pressure on both sides
b)The valve is difficult to close with pressure on one side
c)The valve is difficult to open with pressure on only one side
d)With use of the equalizing line, the valve can be used for throttling
c
The tapered plug valve is lubricated because:
a)They must prevent reversal of flow
b)They are commonly used in slurries and with fluids with high-solids content
c)Their rising stem tends to dry out and seize
d)The tapered plug has a tendency to jam in the tapered seat.
d
It is easy to determine by sight whether a ball valve is open or closed
True False
true
A check valve:
a)allows flow at regular intervals
b)allows flow in one direction only
c)allows flow in two directions
d)does not allow any flow at all
b
The by-pass around a regulating valve should contain a:
a)Non-rising stem gate valve
b)Rising stem gate valve
c)Rising stem globe valve
d)Swing check valve
c
The advantage of a rising stem steam stop valve is that:
a)you can tell from a distance if the valve is open or closed
b)It may be easily lubricated
c)The threaded part is not exposed to corrosion by the high temperature steam
d)All of the above
d
The butterfly valve:
a)Is among the most expensive types of valve
b)Is a high-pressure drop valve when open
c)Is designed for throttling service
d)Is designed for both full-flow valve and throttling service
d
Flow through a swing check valve
a)Controls how fast the check valve closes
b)Changes direction twice
c)Travels in an almost straight line
d)Closes the check valve
c
Which style of valve must be installed with attention to direction of flow in the piping system?
a)Ball
b)Butterfly
c)Globe
d)Gate
c
A globe valve:
a)is used to throttle flow
b)has a machined centre bore
c)has less restriction in line than a gate valve
d)should be operated either fully open or fully closed
a
The needle valve used as a continuous blowdown valve on a boiler is which type of construction:
a) Gate
b) Plug
c) Globe
d) Ball
c
Plug valves require internal lubrication
True False
true
Non-return valve are used on steam installations only.
True False
false
Ball valves require internal lubrication:
True False
false
Which of the following applications is a plug valve not suitable for?
a) High pressure steam
b) Gas supply industries
c) Chemical industries
d) Water treatment plants
a
The butterfly valve:
a) is a quarter-turn valve
b) Is a slow-opening valve
c) Is a safety shut off valve
d) Is a type of plug valve
a
Non-rising stem valves are:
a) Used where the contents contained in the piping system may corrode or affect the stem
b) Used where headroom is limited
c) Used where it is necessary to determine at a glance whether the valve is open
d) Allowed on hot water systems only
b
The by-pass around a regulating valve should contain a:
a)Rising stem gate valve
b) Non-rising stem gate valve
c)Swing check valve
d)Rising stem globe valve
d
A check valve:
a)does not allow any flow at all
b)allows flow in two directions
c) allows flow at regular intervals
d) allows flow in one direction only
d
which of the following types of valves is used exlusively for the throttling of steam
a. gate
b. ball
c. butterfly
d. globe
d
a ball valve contains a spherical ________ with a passage bored thorughit to control the fluid flow through the valve body
a. plug
b. ball
c. circle
d. cube
a
the maximum operating temp for butterfly valve is
a. 500c
b. 1200c
c. 1100c
d. 1500c
c
which of the following applications is a plug valve not suitable for
a. water treatment plants
b. high pressure steam lines
c. chemical industries
d. gas supply lines
b
explain the meaning of 125 SWOG as stamped on a valve body
125psi steam water oil or gas
