Chapter 6: Valves and Actuators Flashcards
In which of these ways can butterfly valves be installed into a piping system ?
1. Welded
2. Unions
3. Flanged
4. Wafers
Select one:
a.
1, 2
b.
1, 2, 3
c.
3, 4
d.
1, 3
e.
4
c.
3, 4
A double-seated balance valve could be described as:
Select one:
a.
Having a valve plug that moves inside a removable cage that holds down a seating ring.
b.
A valve body with cage-style trim, balanced plug, and soft seat. It is single-ported as only one seat ring is used.
c.
Passing up to twice as much fluid as a single port valve. It generally divides the flow in half through two control ports.
d.
Having downstream pressure act on both the top and bottom of the valve plug, thereby equalizing most of the forces.
e.
Being ideal for positive shut-off service.
c.
Passing up to twice as much fluid as a single port valve. It generally divides the flow in half through two control ports.
In a direct-operating, electrically operated valve:
Select one:
A.
An actuator is used in place of the plunger.
B.
The plunger is connected directly to the disc of a globe valve.
C.
The plug is energized, opening the valve.
D.
The solenoid is de-energized, thus opening the valve.
E.
The solenoid is energized, thus closing the valve.
B.
The plunger is connected directly to the disc of a globe valve.
In valve selection, an examination of the fluid to be handled is made to determine its _____ and _____.
Select one:
a.
Mass, viscosity
b.
Properties, characteristics
c.
Texture, corrosiveness
d.
Colour, odour
e.
Flammability, combustibility.
b.
Properties, characteristics
A valve with a V-shaped insert would be used as a control valve, since flow characteristics are usually more:
Select one:
a.
Straight
b.
Flat
c.
Linear
d.
Circular
e.
Mixed
c.
Linear
The outside screw and yoke valve have:
Select one:
a.
The stem threads inside of the valve body
b.
The stem threads outside of the valve body
c.
Temperature changes causing in-stem galling
d.
Threads inside the bonnet
e.
A non-rising stem
b.
The stem threads outside of the valve body
The advantages of electrical valve operators include:
They can be set up for operation from several different locations (remotely operated).
Remote indicating devices can be installed to show the position of the valve at any operating station.
Valve operating speeds (to close the valve) of two seconds for some units, to four minutes, can be reached.
Valves can be operated without personnel needing to climb ladders or enter dangerous locations.
Select one:
a.
1, 2, 3
b.
2, 3, 4
c.
3, 4
d.
1, 4
e.
1, 2, 3, 4
e.
1, 2, 3, 4
Plug valve gland types include:
1. Single gland
2. Double gland
3. Button gland
4. Bolted gland
5. Piston gland
6. Screwed gland
Select one:
a.
1, 3, 4, 6
b.
1, 4, 6
c.
1, 2, 4, 6
d.
1, 3, 4, 5
e.
2, 4, 5, 6
b.
1, 4, 6
Fluid friction loss and _____ drop are inherent losses that are responsible for a major portion of the total energy loss in many fluid-handling systems.
Select one:
a.
Pressure
b.
Temperature
c.
Flow
d.
Viscosity
e.
Volume
a.
Pressure
_____ valve bodies, in general, can be used on water service up to temperatures of about 250°C.
Select one:
a.
Brass
b.
Steel
c.
Steel alloys
d.
Cast iron
e.
Stainless steel
d.
Cast iron
A gate valve consists of a gate-like _____, actuated by a screwed stem and handwheel, which moves up and down _____ the flow.
Select one:
a.
Disc, at right angles to
b.
Stopper, within close proximity to
c.
Seal, at some distance from
d.
Device, relative to
e.
Disc, parallel to
a.
Disc, at right angles to
The diverter valve operation can be described as:
Select one:
a.
Moving the valve stem varies the proportion of liquid or gas entering each of the inlets. There is a continuous flow from the outlet regardless of the valve plug position.
b.
The inlet pressure acts equally on both valve plugs, reducing the force needed to move the valve stem. An unbalanced force will be produced if one discharge line has a higher pressure than the other discharge line.
c.
When the plug is fully down, the bottom inlet is shut off. When the plug is fully raised, the side inlet flow is shut off. Any intermediate position proportions the two inlet flows to meet the operating needs.
d.
The valve may maintain a constant level of fluid in a vessel. If the inlet flow is too high when the level is at the maximum, the excess input can be diverted to another vessel.
e.
Bringing two different flow streams together into one stream.
d.
The valve may maintain a constant level of fluid in a vessel. If the inlet flow is too high when the level is at the maximum, the excess input can be diverted to another vessel.
The eccentric plug valve is specially designed for:
Select one:
a.
Tight spaces, as the body is very small
b.
Applications when four or more systems must be connected
c.
Severe rotary applications, as it features tight shut-off with globe style seating
d.
Large oil and gas facilities
e.
Light water and air service
c.
Severe rotary applications, as it features tight shut-off with globe style seating
The butterfly valve is often used as a final control element in _____ or large _____ piping systems.
Select one:
a.
Air, water
b.
Gas, bore
c.
Water, diameter
d.
Oil, fluid
e.
Power, diameter
a.
Air, water
The following describes an angle-style valve:
Select one:
a.
It may not be used as an elbow, despite that it has inlet and outlet flanges at right angles.
b.
It often has several ports but only one plug.
c.
It is usually single-ported.
d.
It has high-pressure, double-ported globe bodies or plug type.
e.
It always has an on/off valve.
c.
It is usually single-ported
