Vacuum Breaker, Quick Acting Valve, Diverting Valve, Sampling Valve, Blow Off Valve
What is a vacuum breaker?
A special self-acting valve or any 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.
What is a quick acting Valve?
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.
What is a diverting Valve?
This valve switch flows from one main line to two different outlets. WYE type and pneumatic control type with no moving part.
What is a sampling Valve?
Usually of needle or globe pattern, placed in branch line for the purpose of drawing all samples of process material through the branch.
What is a blow off Valve?
It is a variety of globe valve confirming with boiler code requirements and specially designed for boiler blow-off service. WYE pattern and angle type, used to remove air and other gasses from boilers etc.
special valves, construction of valves, parts of valve
What are special Valves?
Multi-port, flush bottom, float, foot, pressure relief, breather.
What materials are used for construction of Valves?
Cast iron, bronze, gun metal, carbon steel, stainless steel, alloy carbon steel, polypropylene and other plastics, special alloys.
What is trim?
Trim is composed of stem, seat surfaces, back seat bushing and other small internal parts that normally contact the surface fluid.
Which standard specifies trim numbers for Valves?
The standard that specifies trim numbers for valves is API 600.
What are wetted parts of the Valve?
All parts that come in contact with surface fluid are called wetted parts.
Paper-Stock Valve, Root Valve, Slurry Valve, Spiral Sock Valve, Throttling Valve
What is a paper-stock Valve?
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.
What is a root valve?
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 from the header.
What is slurry Valve?
A knife edge valve used to control flow of non-abrasive slurries.
What is a spiral sock valve?
A valve used to control flow of powders by means of a twist-able fabric tube or sock.
What is a throttling Valve?
Any valve used to closely regulate flow in the just-open position.
Selection of Valve, Functions of Valves, Isolating Valves, Non-return Valves
What are the steps in selecting a valve?
What to handle, liquid, gas or powder, fluid nature, function, construction material, disc type, stem type, how to operate, bonnet type, body ends, delivery time, cost, warranty.
What are the functions of valves?
Isolation, regulation, non-return and special purposes.
What are isolating valves?
Gate, ball, plug, piston, diaphragm, butterfly, pinch.
What are regulation valves?
Globe, needle, butterfly, diaphragm, piston, pinch.
What are non-return valves?
Check the valve.
Relief Valve, Safety Valve, Foot Valve, Float Valve
What is a relief Valve?
Valve to relieve excess pressure in liquids in situations where full flow discharge is not required, when release of a small volume of liquid would rapidly lower pressure.
What is a safety Valve?
Rapid opening(popping action) full flow valve for air and other gasses.
What is a foot Valve?
Valve used to maintain a head of water on the suction side of the sump pump, basically a lift check valve with integrated strainer.
What is a float Valve?
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 the system, in which case, air flows out of the system in valve open condition, but when water reaches the valve, the float inside the valve raises to close the valve and stop the flow of water. Used in drip legs.
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blowdown valve, breather valve, drip valve, flap valve
26. What is blowdown valve?
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?
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 1/2 to 3 ounces per square inch).
28. What is drip valve?
A drain valve fitted to the bottom of a driplet to permit blowdown.
29. What is flap valve?
A non return valve having a hinged disc or rubber or leather flap used for low pressure lines.
30. What is hose valve?
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.
Through valve, Valve operators, types of Ball Valve
What is wire drawing?
This term is used to indicate the premature erosion of the valve seat caused by excessive velocity between seat and seat disc, when valve is not closed tightly
What is a straight through Valve?
Valve in which the closing operation of the valve is achieved by 90 degrees turn of the closing element.
What pressure tests are carried out on Valves?
Shell-hydrostatic, seat-hydrostatic, seat-pneumatic
What are available Valve operators?
Hand Lever, handwheel, chain operator, gear operator, powered operator like electric motor, solenoid, pneumatic and hydraulic operators, quick acting operators for non-rotary valves (handle lift).
What are two types of ball Valves?
Full port design and regular port design, according to type of seat, soft seat and metal seat
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Through valve, Valve operators, types of Ball Valve
What is wire drawing?
This term is used to indicate the premature erosion of the valve seat caused by excessive velocity between seat and seat disc, when valve is not closed tightly
What is a straight through Valve?
Valve in which the closing operation of the valve is achieved by 90 degrees turn of the closing element.
What pressure tests are carried out on Valves?
Shell-hydrostatic, seat-hydrostatic, seat-pneumatic
What are available Valve operators?
Hand Lever, handwheel, chain operator, gear operator, powered operator like electric motor, solenoid, pneumatic and hydraulic operators, quick acting operators for non-rotary valves (handle lift).
What are two types of ball Valves?
Full port design and regular port design, according to type of seat, soft seat and metal seat
Valve body types, butterfly Valve types, Check Valve, Non-slam check Valves
What are ball Valve body types?
Single piece, double piece, three piece, the short pattern, long pattern, sandwich and flush bottom design.
Why are ball Valves normally flanged?
Because of the soft seat PTFE which can damage during welding.
What are butterfly Valve types?
Double flange type, wafer lug type and wafer type.
What are the types of check Valves?
Lift check valves and swing check valves.
What are non-slam check Valves?
Swing check valve, customary check valve, wafer check valve, shifting circle check valve, cylinder check valve, stop check valve, ball actually look at valve.
Stop Check Valve, Diaphragm Valves, BIBB Valve, Bleed Valve
where does the stop check Valve used?
In stem generation by multiple boilers, where a valve is inserted between each boiler and the main steam header. It can be optionally closed automatically or normally.
Where diaphragm Valves are used?
Used for low pressure corrosive services as shut off valves.
What is a barstock Valve?
Any valve having a body machined from solid metal (barstock). Usually needle or globe type.
What is a BIBB Valve?
A small valve with a turned down end, like a faucet.
What is a bleed Valve?
Small valve provided for drawing off liquid.
Blowdown Valve, Breather Valve, Drip Valve, Flap Valve
What is a blowdown Valve?
Refers to a plug type disc globe valve used for removing sludge and sedimentary matter from the bottom of boiler drums, vessels, drip legs etc.
What is a breather Valve?
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 1/2 to 3 ounces per square inch).
What is drip Valve?
A drain valve fitted to the bottom of a droplet to permit blowdown.
What is flap Valve?
A non return valve having a hinged disc or rubber or leather flap used for low pressure lines.
What is hose Valve?
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.
Bottom Valves, Flush Bottom Valves, Three-Way Valve, Four Way Valve, Lubricated Plug Valve
What are flush bottom Valves?
Special type of valves used to drain out the piping, reactors and vessels, attached on pad type nozzles.
What are types of Flush Bottom Valves?
Valves with discs opening into the tank and valves with disks into the valve.
What are the uses of three-way Valves?
Alternate connection of the two supply lines to a common delivery vise versa, isolating one safety valve, division of flow with isolation facility.
What are the uses of a four way Valve?
Reversal of pump suction and delivery, bypass of strainer or meter, reversal of flow through filter, heat exchanger or dryer.
What is a metal seated lubricated plug Valve?
A plug valve with no plastic material, where grease is applied to contacting surfaces for easy operation.
What are three patterns of plug Valve design?
Regular pattern, short pattern and venturi pattern.
Instrument Categories, Functions of Instruments, Diaphragm Assembly
What are instrument categories?
General, flow, temperature, pressure, level, density etc.
Which instruments are handled by the piping department?
Flame arrestor, breather valve.
What are the basic functions of instruments?
To sense, transmit, indicate, read and control
Why is a block valve used at the root of an instrument like a pressure indicator?
They are needed to isolate gauges for maintenance during plant operation and during hydrostatic testing of the piping system. They are called root valves.
Where diaphragm assembly is used?
For corrosive, abrasive, viscous fluids. Neutral fluid like glycol is used on the instrument side of the diaphragm.
Where and why is the bleed valve used in instruments?
If the conveyed fluid is hazardous or under high pressure, a branch fitted with a bleed valve is inserted between the gage and its isolating valve, to relieve pressure and/or drain the liquid before servicing the gage. It can also be used to sample or for adding a comparison gauge.
Why are control valves usually flanged?
For ease of installation and removal during maintenance.
Where is the ball control valve used?
Suitable where the nature of fluid is slurry form or handling two phase flow having particles in suspension, for non-critical and critical fluids having a fluid temperature to suit the soft seat material and where relatively low pressure drop is required across control valves. They have side-mounted actuators.
Where is the butterfly control Valve used?
Used for large size piping network handling clean fluid for low pressure drop across control valve and soft seated control valve. Metal seated valves used for higher temperatures.
How should control valve block valves be located?
They should be as close to the control valve as possible, considering drain requirement and handwheel clearance. At least one of the block valves should be placed vertically so that the spool can be removed, allowing the control valve to be removed.
Conclusion:
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