Introduction to Valves Flashcards
Regular inspection of a valve is important and items which require close scrutiny are the:
A) Stuffing box and spindle threads B) Disc and seat C) Steam and body D) Hand wheel and packing E) Seat and stem
B) Disc and seat
The valve that provides very fine flow control is the:
A) Check valve B) Gate valve C) Butterfly valve D) Ball valve E) Needle valve
E) Needle valve
Advantages of Butterfly valves are that they:
- Are relatively light and easy to operate
- Are self cleaning
- Provide negligible pressure drop when fully open
- Can have the disc lubricated while in operation
- Are self adjusting so alignment is not required during installation
A) 2, 4 B) 1, 3 C) 1, 2, 5 D) 3, 4, 5 E) 1, 2, 3
E) 1, 2, 3
The purpose of the non-return stop valve is to:
A) Drain condensate from the main steam header
B) Prevent the safety valve from popping
C) Prevent water from entering the steam header
D) Regulate the flow of steam from the boiler
E) Prevent the back flow of steam
E) Prevent the back flow of steam
A valve which requires specific and routine lubrication is the:
A) Check valve B) Globe valve C) Tapered plug valve D) Pressure reducing valve E) Butterfly valve
C) Tapered plug valve
A check valve is a valve that:
A) Allows flow in two directions B) Does not allow any flow at all C) Has a locking spindle D) Allows flow in one direction only E) Allows flow at regular intervals
D) Allows flow in one direction only
A valve that often contains a dashpot to cushion the action of the valve is the:
A) Lift check valve B) Pressure regulating valve C) Safety valve D) Swing check valve E) Needle valve
A) Lift check valve
A valve having minimum wire drawing and seat erosion is the:
A) Gate valve B) Plug valve C) Hand valve D) Wedge gate valve E) Globe valve
E) Globe valve
A gate valve:
- Has less restriction in a line than a globe valve
- Should be operated either fully open or fully closed
- Is used to throttle flow
- Is used for different applications than a globe valve
A) 2, 4 B) 1, 2, 3, 4 C) 1, 3, 4 D) 1, 2, 4 E) 2, 3, 4
D) 1, 2, 4
A valve that has the greatest capability of handling slurries and fluids with high suspended solids is the:
A) Plug valve B) Ball valve C) Needle valve D) Globe valve E) Gate valve
B) Ball valve
Increasing the spring tension of a pressure regulating valve will:
A) Increase the regulated pressure downstream of the valve
B) Cause the valve to go to the wide open position
C) Close the valve tight
D) Decrease the regulated pressure downstream of the valve
E) Reduce or minimize the cycling or “hunting” of the valve
A) Increase the regulated pressure downstream of the valve
Relative to valves, a frequent cause of serious accidents is due to:
A) A lack of valve maintenance B) Wrong materials of construction C) Inadequate operational training D) Manufacturing defects E) Valves being of the wrong size
B) Wrong materials of construction
When valve stem leaks are fixed by tightening the packing gland:
A) Valve packing doesn’t require maintenance
B) Use a thicker packing
C) Always tighten up bolts evenly
D) Leave some leakage to lubricate the rotating shafts
E) Tighten the packing as much as possible to prevent future leaks
C) Always tighten up bolts evenly
