Valves Flashcards
Functions of valves:
What are the general functions of Valves (list 5)
- Stop ______
- To ________or control _______
- To stop _________ flow
- Regulate ______
- Relieve _______ or limit ________
Functions of valves:
Stop Flow entirely
To throughtal or control the flow
To stop backflow (stop flow)
Regulate pressure
Relieve pressure or limit temperature (T and P Valve)
Marking on Valves:
Max ____ ____
Direction of ______
W.O.G =
W.W.P =
W.S.P =
Marking on Valves:
Max operating pressure
Direction of flow (if applicable)
W.O.G = water, oil, gas pressure
W.W.P = working water pressure
W.S.P = working steam pressure
Flanged Joints:
Which bolts should be put in first?
Raised face:
Full Faced Flange:
What order should bolts be tightened on to a flange?
Flanged Joints:
Which bolts should be put in first?
Raised face: Bottom bolts, so the gasket doesn’t fall down
Full Faced Flange: full sized gasket is used so bolts go throw the gasket
What order should bolts be tightened on to a flange
From Top moving clockwords 1, 5, 3, 7, 2, 6, 4, 8
Gate Valve 1
- Can you throttle it?
- Is it Good for Infrequent Use?
- When open does it cause high or low resistance to flow and turbulence?
- Does direction of flow matter?
- Does orientation to gravity ever matter when installing?
Gate Valves 1
- Made to be either on or off (not throttled)
- Good for infrequent use
- When open it causes very little resistance to flow and very little turbulence
- Can be installed going either direction
- Some can not be used well inverted
What are the 4 different disc types for a Gate valve
- Solid Wedge disc
- Flexible Wedge disc
- Split Wedge disc
- Double disc
Gate Valve Types:
Solid Wedge disc
- Most or Least popular?
- Can be used for what substances? (list 5)
- Is good with what kind of flow?
Flexible Wedge disc
- Is good for Hot of cool conditions?
Split Wedge disc
- Opens with or with out drag?
- good or bad with turbulence?
Double disc
- Fast or slow with opening?
- Not good for what substance?
- what direction cant it be installed in?
There are 4 main types of Disc
Solid wedge disc (most widely used)
- Most widely used
- Used in Steam, hot and cold water, oil, air, or gas
- Ideal for turbulent flow (has very few moving parts)
Flexible wedge disc
-Works well in cooled condition (does not pinch when the body contracts)
Split wedge disc
- The 2 discs allow it to open without drag
- Not for use in turbulent systems
Double Disc
- Quick close/open
- Not used for steam
- Can not be installed upside down
What is wire draw
Wire draw, erosion on the disc, damage to the valve seating and cavitation
Globe Valve Part 1:
- Bad or good at throttling?
- Should be used infrequently?
- Are you able to repair them?
- What do they do to pressure?
- they are at risk of what?
Globe Valves:
- Idea for Throttling
- Good for frequent use
- Easy to repair
- Large pressure drops
- Is under constant erosion
Globe Part 2:
Solid Tapered Plug disc:
- Advantages of a tapered plug are?
Solid Tapered Plug disc:
- Ideal for very minimal throttling Because of the wide surface of contact the plug has with the seat
- This helps to reduce wire draw and erosion
Globe part 3:
Conventional Disc :
- Disadvantages are?
- Advantages are?
Conventional Disc
- Has a very small seat contact (not recommended for close throttling
This can lead to wire draw and erosion
- The disc is capable of cutting through solids that are trapped in the seat
Globe Part 4:
Composition Disc:
- What is the disc made of?
- What is the advantage of this type of disc for closing?
- is this disc good or bad for close throttling
Composition Disc:
- The Disc is made of soft materials
- Any debris will be caught in the disc but will still allow for positive closure
- Not good for close throttling
Globe part 5:
- Ideal for high or low pressure? in Large or small lines?
- Is good or bad at very fine throttling?
- can it be used for steam?
Needle Valve
- Ideal for high pressure in small line sizes
- Has a very small contact area with seat
- Perfect for very fine throttling
- Used on steam quite often
Globe Part 6:
V-port Disc:
- How is it with close throttling?
- Improved ____ control
- What action is unequ to the disc?
- is it easy to repair?
V-port Disc:
- Better close throttling
- Improved flow control
- Swivel action on disc
- Easy to repair
Globe valve patterns Part 7:
organize into most to least flow restriction
- Straight Pattern Globe valve
- Y pattern Globe valve
- Angle Pattern
- Straight Pattern Globe valve: Large amount of flow restriction
- Angle Pattern: Less restriction of flow (Useful for reducing material cost)
- Y pattern Globe valve: Even less pressure loss
Check valves part 1:
- Made for _______ on and offs
- used to minimise ______
- They prevent _______ in a system
- Made for frequent on and offs
- And to minimise shock conditions
- They prevent back flow in a system
Lift Check:
- Why are they used in tandem with Globe Valves?
- Does installation orientation matter?
- Describe how water feels moving and not moving through it
Lift:
- Will often be used in tandem with Globe valves as both cause loss of pressure.
- Designed in both horizontal and vertical patterns (Must be installed in proper orientation!)
- The flow of water poshes the disc up to open it, disc falls when flow stops or reverses
Prone to wear as it could be constantly in motion
Swing Check:
- Why is it often used with Gate valves?
- May they be installed vertical why or why not?
- is it used for high or low velocity systems and why?
Swing:
- Used often in tandem with gate valves as both create little resistance to flow
- Can be installed in horizontal and vertical but when vertical the flow must be going Low to High and not High to low or the valve wont work
- To identify look for hinge pin
- Can make water hammer worse Recommended for low velocity systems
Tilt Check:
- what does the disc pivot on?
- were is the pivot point located on the disc?
- high or low resistance to flow?
Tilt:
- Disk pivots on hinge
- Hinge is above center point of pipe
- Little resistance
Spring Check:
- increases or decreases water hammer?
- is it resistant to water flow and why?
- can it be installed vertically and horizontally?
- nominally open or closed?
- used in high or low pressure applications?
Spring:
- Lessen water hammer (acts as a cushion)
- Creates lots of resistance because fluid must pass through loaded spring
- Can be installed both vertical and horizontally because of the spring
- They are usually closed when not under pressure because of the spring
- Used in pressure applications
Non-Slam Check:
- Usually made for large or small piping?
- how does it work?
- Closes before or once there reversal of water starts?
- how much tension is on the springs?
Non-slam
- Usually made for large sizes of pipe
- Consists of Two spring loaded flaps seated into a housing
- Designed to close before the complete reversal of flow which avoids water hammer in the system
- ¼ to ½ pound tension
Butterfly Valves part 1:
- how much head room is needed?
- How much resistance does it cause when open?
- Good or bad at throttling?
- Shouldnt be used for ____ throttling
- Required ____ degree turn to be fully open
- Installed in areas of minima head room
- Achieves 100% shut off when closed
- Has little to no resistance when open
- Can be used in throttling
- Shouldnt be used for close throttling
- Only requires 90 degree turn to be fully open or closed
Butterfly valves Part 2:
see notes for more?
Ball Valve:
- The least or most common valve?
- ______ degrees to turn on and off?
- how is the seal created?
- how much restriction of flow when open?
- Available in sizes ___ to ____
- good or bad at throttling?
- The most common valve used
- Easy to turn on and off with just a 90 degree turn
- Seal is created by squeezing the ball between 2 seats
- Has a high rate of flow and no resistance
- Range from ¼” to 12”
- Compact and lightweight
- Not used for throttling
What are the 4 types of ball valves?
4 main types
- End entry (most common harder to surves)
- Top entry (Ball can be removed from the top)
- Center section entry (Ball is inserted from bottom)
- 3 piece ball valve (Is attached on either end to a flange)
Solenoid Valve:
- is a _________controlled valve
- It electronically moves a ______ in the valve
- Located in _______ and _________ washers
Solenoid Valve:
- Is a electronically controlled valve
- It electronically moves a plunger in the valve
- Located in Dishwashers and clothes washers
Pressure Reducing Valve (PRV)
- What is it used for?
- What psi is it usually set at?
- turn clock wise to increas or decrease pressure?
- uses a _____ to regulate?
- What is usually built in to protect it from debris?
Pressure Reducing Valve (PRV)
- Reduces pressure and can also regulate it to keep it at a constant
- Residencial PRVs are usually set to 50 psi
- Clockwise to increase pressure down stream
- Uses a diaphragm to regular
- Usually equipped with its own strainer
Plug valves/Cocks Part 1:
Read Notes!
What valve is used for hot tapping?
Corporation stop valves
Strainers:
- used to prevent what?
- placed upstream of what devices?
- Used to remove particles that could get jammed in valves or devices that close automatically
- Used upstream of a
PRV
Backflow preventer
RP (Reduced Pressure principle)
DCVA (Double check valve assembly)
