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PIPING QUESTIONNAIRE - VALVE (PART 2 OF 3)

Posted by Antony Thomas at Wednesday, April 15, 2009

26. What is BlowDown Valve?
Ans Refers to a plug type disc globe valve used for removing sludge and
sedimentary matter from the bottom of boiler drums, vessels, driplegs
etc.
27. What is Breather Valve?
Ans: A special self acting valve installed on storage tanks etc. to release
vapor or gas on slight increase of internal pressure ( in the region of ½ to
3 ounces per square inch).
28. What is Drip Valve?
Ans: A drain valve fitted to the bottom of a driplet to permit blowdown.
29. What is Flap Valve?
Ans: A non return valve having a hinged disc or rubber or leather flap
used for low pressure lines.
30. What is Hose Valve?
Ans: A gate or globe valve having one of its ends externally threaded to
one of the hose thread standards in use in the USA. These valves are
used for vehicular and firewater connections.
31. What is Paper-Stock Valve?
Ans: A single disc single seat gate valve (Slide gate) with knife edged or
notched disc used to regulate flow of paper slurry or other fibrous slurry.
32. What is Root Valve?
Ans: A valve used to isolate a pressure element or instrument from a line
or vessel, or a valve placed at the beginning of a branch form the
header.
33. What is Slurry valve?
Ans: A knife edge valve used to control flow of non-abrasive slurries.
34. What is Spiral sock valve?
Ans: A valve used to control flow of powders by means of a twistable
fabric tube or sock.
35. What is Throttling valve?
Ans: Any valve used to closely regulate flow in the just-open position.
36. What is Vacuum breaker?
Ans: A special self-acting valve or nay valve suitable for vacuum service,
operated manually or automatically, installed to admit gas (usually
atmospheric air) into a vacuum or low-pressure space. Such valves are
installed on high points of piping or vessels to permit draining and
sometimes to prevent siphoning.
37. What is Quick acting valve ?
Ans: Any on/off valve rapidly operable, either by manual lever, spring or
by piston, solenoid or lever with heat-fusible link releasing a weight which
in falling operates the valve. Quick acting valves are desirable in lines
conveying flammable liquids. Unsuitable for water or for liquid service in
general without a cushioning device to protect piping from shock.
38. What is diverting valve ?
Ans : This valve switch flow from one main line to two different outlets.
WYE type and pneumatic control type with no moving part.
39. What is sampling valve?
Ans : Usually of needle or globe pattern, placed in branch line for the
purpose of drawing all samples of process material thru the branch.
40. What are blow off valve?
Ans : It is a variety of globe valve confirming with boiler code
requirements and specially designed for boiler blowoff service. WYE
pattern and angle type, used to remove air and other gases from boilers
etc.
41. What is relief valve?
Ans : Valve to relieve excess pressure in liquids in situations where full
flow discharge is not required, when release of small volume of liquid
would rapidly lower pressure.
42. What is safety valve?
Ans : Rapid opening(popping action) full flow valve for air and other
gases.
43. What is foot valve?
Ans : Valve used to maintain a head of water on the suction side of sump
pump, basically a lift check valve with integrated strainer.
44. What is float valve?
Ans : Used to control liquid level in tanks, operated by float, which rises
with liquid level and opens the valve to control water level. It can also
remove air from system, in which case, air flows out of system in valve
open condition, but when water reaches valve, float inside valve raises to
close the valve and stop flow of water. Used in drip legs.
45. What are flush bottom valves?
Ans : Special type of valves used to drain out the piping, reactors and
vessels, attached on pad type nozzles.
46. What are types of flush bottom valves?
Ans : Valves with discs opening into the tank and valves with disks into
the valve.
47. What are the uses of three-way valve?
Ans : Alternate connection of the two supply lines to a common delivery
vise versa, isolating one safety valve, division of flow with isolation
facility.
48. What are uses of four way valve?
Ans : Reversal of pump suction and delivery, By pass of strainer or
meter, reversal of flow through filter, heat exchanger or dryer.
49. What is metal seated lubricated plug valve?
Ans : A plug valve with no plastic material, where grease is applied to
contacting surfaces for easy operation.
50. What are three patterns of plug valve design?
Ans : Regular pattern, short pattern and ventury pattern.

SEE ALSO:
PIPING QUESTIONNAIRE - VALVE (PART 1 OF 3)
PIPING QUESTIONNAIRE - VALVE (PART 3 OF 3)

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