Pneumatic Systems Flashcards
1
Q
What is this and what are the parts names?
A
Basic Pneumatic System
2
Q
For a pneumatic system should the air be cooler or hotter? Why?
A
Cooler. Because cool air is denser which makes compression more efficient and cool air holds less moisture.
3
Q
Are bends good in a pneumatic system?
A
No, they create more heat and resistence to flow.
4
Q
What are Air Receivers?
A
Store compressed air to compensate for fluctations in demand and allow system pressure to vary within reasonable limits.
5
Q
What can Air Receviers also do on Reciprocating Compressors?
A
Dampen pulsations that damage the system.
6
Q
On smaller systems what do Air Receviers also function as?
A
Smaller systems without Aftercoolers use the recevier as an aftercooler.
7
Q
What must an Air Receiver/Pressure Vessel have?
A
- Relief Valve
- Gauge
- Drain
- Connections for piping system
8
Q
Large Receivers must also have what?
A
Removeable mancover for cleaning and inspection.
9
Q
How should you install safety relief valves? Why?
A
- Vertically
- To prevent dirt and sludge build up
10
Q
How do you seal a safety relief valve?
A
- Wire and a lead seal to prevent tampering
11
Q
Can a safety relief valve’s maximum safe working pressure be exceed for any reason?
A
- Never!
12
Q
What do you set the Safety Relief Valve to?
A
The lowest maximum pressure rating of any part in the system.
13
Q
What can mosture do to a pnematic system?
A
- Air supply can freeze
- Can rust the receivers
- Harm some processes in the machine
- Harmful to lubrication
14
Q
Name three piping systems for pneumatics.
A
- The grid (dead end) systems
- The Decentralized (unit) system
- The loop system
15
Q
What kind of piping system is this?
A
The Grid (Dead End)
16
Q
What are some negatives about Grid Systems?
A
- There is only one flow path
- Work stations at the end of the system may be subject to air starvation when up stream demand is heavy.
17
Q
What is a Decentralized (Unit) System? What are the advantages?
A
- Composed of two or more compressors.
- Each compressor is close to its point of use which means less pressure drops and more uniform supply and pressure.
18
Q
What is a Loop System?
A
Two or more compressors connected feeding the same loop.
19
Q
Which piping system is most common/prefered?
A
Loop System
20
Q
Name all these parts
A
21
Q
What does FRL stand for?
A
Filter, Regulator, Lubricator Unit
22
Q
What does a FRL do?
A
After compression and before use, it is often necessary to condition the air and rid it of contaminants, adjust system pressure to match the end use and either add or remove oil.
23
Q
What is the correct order of a FRL in a line? Name these parts.
A
Filter, Regulator, Lubricator
24
Q
What are these?
A
FRL unit
25
What does this sign mean?
Filter
26
Name all the parts.
27
What is happening here?
28
What does a regulator do?
Pressure coming from the compressor is often too high so a regulator changes that.
29
What is this? Name all the parts.
Regulator
30
What type of valve is this?
Regulator
31
What does this doted line represent?
Pilot Passage
32
How does a Regulator work?
33
Why are there Lubricators on air lines?
Compressed air systems should be oil-free, except for application to power components.
34
What is this? Where is it found?
- Mist Lubricator
- FRLs
35
What is this?
Lubricator
36
How does a Lubricator work in a pneumatic system?
37
Does oil from the compressor act as an lubricant aid for pneumatic systems?
No, this is an old theroy. The oil may have been overheated by compression and lost its lubricating qualities.
38
What can gum up compressor lines/piping? What do you do to remove this?
- Oil carry over from compressors
- Thinners may help if introduced in the line and there is not too much “gumming”.
39
How do you prevent compressor oil from entering the pneumatic system?
Install an oil seperator near the discharge of the aftercooler.
40
Lubricators should be installed where in proximoty to the component they are lubricating.
As close as possible.
41
What is this?
Water Trap/ Seperator
42
What is this?
Water Trap/ Seperator
43
How does a water trap work?
44
What do these symbols mean?
45
What do these symbols mean?
46
What do these stmbols mean?
47
What are these symbols?
48
What do the numbers represent?
49
How many ports and how many positions
5/3
5 ports 3 positions
50
What are these? Label them.
DCV actuation
51
What are these? Label them.
DCV Actuators
52
What are these? Label them.
DCV Actuators
53
What are these? What does the arrow mean?
- Adjustable
54
What is this?
55
What is this?
56
What is this?
57
What is this?
58
What is this?
59
Are Pressure Regulators Normally Open or Normally Closed
Normally Open
60
Are Sequence Valves normally open or normally closed?
Normally Closed
61
What is this?
62
What is this?
63
What is this?
64
What is this?
65
What is this?
66
What is this?
67
What is this?
68
What is this?
69
What is this?
70
What is this?
71
Rotary Actuators are divided into those with ____________ motion and those with ______________ rotation.
- Continous
- Limited
72
Arrow vs no arrow means?
Variable vs Fixed
73
What is this?
74
What is this?
75
What is this?
76
What is this?
77
What is this?
78
What is this?
79
What is this?
80
What is this?
81
What is this?
82
What is this?
83
What are two basic types of Pressure Regulators?
Non-venting and venting
84
What is this?
Pressure Regulator
85
What is the purpose of a Pressure Regulator?
To reduce compressor pneumatic feed and maintain the line pressure to the set point required by the actuators.
86
What is this?
Pressure Regulator
87
What is the Non-Venting Regulator used for?
To reduce downstream line pressure.
88
What is this?
Non-Venting Regulator Symbol
89
What is the difference between Venting and Non-Venting Pressure Regulators.
Venting Regulators also act as relief valves for the downstream section of the circuit to prevent any possiblity of an increase in pressure in this secton.
90
Are Venting Pressure Regulators capable of being full flow relief valves?
No, they are not adaquate for critical applications. Full flow relief valves should be installed whenever large volumes of air must be released.
91
What is this?
Venting Pressure Regulator
92
How does a Venting Pressure Regulator Work?
The diaphram spring pushes down. The poppet valve spring pushes up to keep the poppet stem sealed against the diaphram. When back pressure builds too high the pilot directs the pressure to the diaphram breaking the seal between the two and allowing air to escape.
93
What could be the reasons for an increase in pressure resulting in needing a Venting Pressure Regulator?
- External loads acting on the cylinder
- Thermal expansion of the air
- Buildup of pressure due to leakage
94
How do Pnuematic Spool Valves and Hydraulic Spools differ?
Their methods of sealing.
95
What are Hydraulic and Pnuematic Spools also called?
Directional Control Valves (DCV)
96
How do Hydraulic Spools seal?
The spool and the bore are lapped to precise tolerances.
97
How are Pneumatic Spools sealed?
Pneumatic Valves use packed bore, packed spool or sliding plate design.
98
Why are Lapped designs not used in Pneumatic Spools?
Because of their need for constant lubrication.
99
What type of Spool is this?
Pneumatic Spool
100
How are DCVs identified?
- Number of Ports
- Number of Positions
- Method of Activation
101
What is a solenoid?
An electrical device added to the end of a DCV to control the positions.
102
How does a solenoid work?
A wire coil is wraped around a plunger inside. The coil is electrically energized, it builds a magnetic field which pulls the iron plunger into the coil. This moves the DCV.
103
What is this?
Shuttle Valve
104
What is a Shuttle Valve used for?
Automatically select the higher of two pressure sources to supply a pneumatic signal.
105
Where is a Shuttle Valve commonly used?
In circuits when either of two DCVs must be able to operate a single actuator.
106
What is the purpose of a pnuematic Flow Control Valve?
Control the speed of an actuator.
107
What is this?
Fixed Flow Control Valve
108
What are these? Name each.
- Flow Contol Valves
109
What is the most common flow control valve for smaller pneumatic actuators?
Why?
- Needle Valves
- They have the finest control because of the tapered needle and fine threads on the valve stem.
110
Which flow control valves are used in large systems?
Why?
- Ball Valves and Globe Valves
- Ball Valves have the advantage of little or no restriction across the valve of the straight through flow path.
- Globe changes the flow path to change direction several times as it passes through, which also causes a restriction to flow along with an accompanying pressure drop.
111
What is this process called?
Metering Out
112
What is this?
Quick Exhaust Valve
113
Where are pneumatic Quick Exhaust Valves found?
On the end caps of cylinders.
114
What tool uses a Quick Exhaust Valve?
Jack Hammer. The Quick Exhaust allows for rapid extension on the hammer blow.
115
When would it be approapriate to use Excess Flow Valves?
Why?
- When there is 100 meters of line
- At the reciever
- When the air hose is larger then 1/2 inch.
- To limit pressure in the event of fitting or hose failures. This minimizes hose whipping while under pressure.
116
What is this?
Excess Flow Valve
117
Is a Excess Flow Valve normally open or normally closed?
Normally Open
118
How does a Excess Flow Valve work?
When excess flow surges, the poppet is pushed forward closing the valve. A spring pushes back the poppet into place when the flow has returned to normal.
119
What are three types of Cylinders?
- Single Acting
- Double Acting
- Double Rod (non-differential)
120
What are two types of Single Actings Cylinders?
- Single Acting Cylinder with Spring Return
- Single Acting Ram Cylinders
121
What are Rodless Cylinders used for?
Strokes of up to 10 meters in length.
122
What is this?
- How does it work?
- Rodless Cylinder
- Consists of a long cylinder with a free- floating piston inside. Compressed air on both sides moves the piston. Magnets mounted on the piston are used as a magnetic coupling to connect the piston to a carriage mounted on the track.
123
What is this?
Label it.
Pneumatic Cylinder
124
For proper operation of piston rods there must be what?
A positive seal across both the piston and the rod gland.
125
What are these?
Name them.
Common Piston Sealing Rings
126
What kind of seals do Rod Seals commonly use?
U-cups, V-rings and other lip type seals
127
What is used to limit the amount of stroke with a cylinder?
Threaded Rod screwed into or out of the cylinders cap. The rod acts as a stop
128
What is a stop tube?
What does it do?
- A metal collar that fits over the piston rod.
- Its purpose is to keep the piston seperate from the rod gland bushing when a long stroke cylinder is used. This reduces the side loading on the bushing.
129
What is this demonstrating?
Label it.
How a Stop tube works.
130
How does a cushion work on a piston?
The cushion spear or sleeve plugs the main exhaust port which forces the remaining air to travel through a small restiction. This results in compression of the remaining air which slows piston travel dramatically in a short distance.
131
What kind of valve is commonly used to adjust the cushion.
What does this do?
- Needle Valve type flow contol
- Allows the last bit of pressure to bleed off in a controlled manner.
132
What is this demonstrating?
How cushions work in a cylinder.
133
What are the basic types of air motors?
Piston
Vane
Turbine
134
What is this?
Vane Motor
135
What are the normal operation speeds of a vane motor?
3000 - 9000 rpm
136
In from highest to lowest what are the common rpm speeds for air motors?
- Turbine (Up to 500,000 rpm)
- Vane Motors ( 3000 - 9000 rpm)
- Axial Piston ( 5000 rpm )
- Radial Piston ( 1000 rpm )
137
What are some common problems with cylinders?
- Dried out lubrication,
- Corrosion,
- Gumming
- Deterioration of rubber parts
- Bad piston seals.
138
What should you be cautious of with a clogged/restricted filtter?
The gauge may read properly in pressure but there could be a drop in flow.
139
What safety procautions must be followed with vertical cylinders?
Must be let down or mechanically blocked to prevent movement before preforming any work on or around them.
140
Absolute Pressure Minus 14.7 describes what?
PSIG
141
What is the fuction of a reciever?
- Store compressed air
- Cool the compressed air
- Allow contaminated air to settle out its impurities
142
Lobe type compressors are best suited for pumping _________ quantities of gas or air at relatively ________ pressures.
- Large and Low
143
How is compressor flow measures?
Cubic Feet Per Minute
144
What are the two basic groups of compressors based on in principle?
Dynamic and Positive Displacement
145
What is the unit of measurement for a Vaccum?
Inches of Mercury (Hg)
146
What is Atmospheric Pressure at Sea level?
14.7 PSIA
147
What is Dew Point?
The temperature at which the water condenses.
148
Deliquescent Dryers use what to dry air?
Chemicals
149
What is the purpose of flow control or metering valves?
Control the speed of actuators
150
What is the common working pressure for air tools?
90 PSI
151
What is often done to a check valve to ensure it operates properly in a vacuum?
The spring is removed to reduce back pressure.
152
What is 1 PSI equal to in Vacuum Hg
1 PSI = 2.04 Hg
153
Simplest form of a directional control device is?
Check Valve
154
Answer.
D)
