TPC 309 Flashcards
In a pneumonia system, force must be present at all times for the system to function. What is this force?
Compressed air
What is the formula for work
Work = force x piston travel
What does Charles law state
If the volume of a confined quantity of gas remains the same, the change in the pressure of the gas varies directly with a change in the absolute temperature of the gas
If the original force is applied to the large piston instead of to the small piston, the force exerted on the small piston…
Decreases, but it’s amount of travel increases
If the kinetic energy increases and the total energy remains the same, the potential energy of the air moving in a reduced flow passage is reduced. If the potential energy is reduced…
The pressure of the air is also reduced
Positive-displacement compressors that are capable of compressing air to relatively high pressures are commonly used in pneumatic power systems. What is one kind of these devices
Reciprocating piston
What opens the valves on a reciprocating compressor
The negative pressure allows the air at atmospheric pressure to open the valves
What do cooling components allow for in compressors
The need for less power because the cooling between stages reduces the volume of air that is compressed in the second stage
What are the two functions of compressor lubricating oil
Reduce friction and improve the transfer of heat in the compressor
What does unloading allow for in large compressors
It does not compress air and is easier to start
Single stage vane compressors are capable of developing up to what psi discharge pressure
50 psi
What speeds do screw compressors operate at
Between 3000 and 12000 rpm
Impeller compressors also known as blowers are designed to…
Move high volume and low pressure air
What compressors require more horsepower per cfm
Centrifugal compressors
When trying to control the centrifugal compressor output what is the most effective way
Speed variation, however many compressors lose efficiency when the speed is reduced too much
What can change the amount of water content in pressurized air
Humidity and temperature
Water cooling is economical for what type of compressors
Medium-sized single stage compressors operating more than 8 hours a day and for larger compressors or any that operate more than 10 hours a day
What do air receivers allow for
The capability to balance off available compressor capacity against much larger peak air-flow demands that occur
Centrifugal separators also known as inertial separators work in what way
The inertia of a heavy moving particle to aid in the separation, the heavier a particle is and the faster it is moving, the more it tends to travel in a straight line, therefore when it is force into a circular path it has a natural tendency to move outward
If it stops 100% of a given particle size, this size is referred to as…
Absolute rating
Wetted air filters have a slightly higher initial cost than dry filters but…
They can be cleaned many times
Fine lubricators are especially effective in what systems
Complicated piping systems and intermittent equipment operation
To avoid turbulence in inner walls of an air piping system what should you do
The inner walls should be smooth and piping should not change direction more than necessary, also the number of fittings should be kept to a minimum
The slope when installing air lines should be what
1in for every 10ft as well as in a downward direction in the direction of air flow
What pipe thread is used for pneumatic piping
NPT, ( national pipe thread )
What can the number of primary system connecting ports be?
Two, three, four, and five
What valve is a two way valve and is excellent for high pressure service
A needle valve
What are the benefits of a spool valve
It is easy to operate even with high pressures because the internal forces balance each other
What are 4 way valves used for
To simplify pneumatic circuits
What is a five way valve
It is a special four way valve with five external connections
The poppet is held against the valve seat how
By the force of the adjustable poppet spring
What is cracking pressure
The pressure at which the valve initially opens, is determined by the adjustment of the spring
A diaphragm relief valve responding to increasing air pressure opens much faster than what
A poppet valve
When does a regulator valve close
When the discharge pressure increases
A diaphragm valve will control difference in psi how
By modulating continuously to maintain desired pressure
It is difficult to adjust a separate pressure-relief valve to operate at pressures just above regulator pressure settings , what is used
A built in relief valve is desirable for this application
Thrust is greater when the piston is moved to the left than when it is moved to the right most standard pneumatic cylinders are
Double acting
What is a spring return cylinder
A modified single acting cylinder is equipped with an internal sprint
Many single and double acting cylinders are equipped with and exhaust flow control metering valve , what does this do
This valve restricts the amount of exhaust air that can pass from the cylinder through the valve and governs the speed at which the cylinder can retract
Pivoted cylinder mountings are classed as being…
Trunnion or Clevis and have no rigid support
What is used to check if a control valve is capable of handling the air of a cylinder
The capacity coefficient
What is stalling torque
The force necessary to stop the motor once it is running
The maximum power output is obtained how
At the medium speed and medium torque output
How does a axial position motor work
Compressed air entering the inlet port acts on the piston against a wobble/cam plate attached to the offset shaft causes the cam plate to rotate this motion is transferred through gears to the output shaft
