TPC 309 Basic Pneumatics Flashcards
In compressed air systems, what provides force that performs work?
Compressed Air
What is the formula for work?
Work = Force * Distance
What is Charles’ Law?
Gas pressure inside a sealed container is proportional to the gas temperature.
How does force amplification not violate the work formula?
Force amplification = Distance Reduction
Air flowing through narrowed cross section does what to air speed and pressure?
Air Speed increases, Air Pressure Decreases
What type of compressor is a reciprocating compressor?
A positive displacement type compressor
What opens the inlet in a reciprocating compressor?
Atmospheric pressure overcoming the vacuum inside the compressor chamber
What is the purpose of a compressor intercooler?
Reduce the power requirements of the compressor
(When air is compressed, it heats up expanding the air, once it is cooled it can be further compressed without overheating the compressing chamber [causing leaks] and allows moisture to condense out of the compressed air)
Purpose of Lubrication in a compressor
To improve cooling
Advantage of unloading a compressor
Run without delivering air (so that the compressor can get up to temp)
What pressure can a single stage vane compressors achieve?
up to 50 PSI
What is the typical speed of a rotary screw compressor.
3K to 12K RPM
What is the general purpose of an impeller type compressors
High air volume, low air pressure
What is a downside of a centrifugal compressor?
Requires more power.
How to reduce air output of a centrifugal compressor?
Speed variations
Does have trouble with large reductions to speed, because compressor efficiency drops drastically.
Does compressed air carry more or less water vapor?
Compressed air carry less water vapor (Water is in-compressible)
Most common way to remove water from compressed air
Cooling the air
Where are water cooled aftercoolers used?
For large compressors that is on >10 hours a day
What does a desiccant do?
Absorb Moisture
Main Purpose of a compressed air receiver?
Maintain Pressure at peak demand.
Operation of an inertial separator depends on what?
Rapid change in the direction of air flow.
What is the smallest airborne particle?
An Aerosol
What size rating of the filter specifies the size of particle above which cannot pass through a filter with 100% certainty?
Absolute Rating
What is the advantage of a wetted filter compared with a dry filters?
Wetted filters can be repeatedly cleaned.
Under what circumstance should a fine mist lubricator be used in a pneumatic system?
If the air is intermittent and the distance to equipment is long
Laminar airflow in a piping system is turbulent by what?
Constrictions in the pipe.
What conditions cause great pressure losses inside a pneumatic system?
If the air is at low pressure and at great friction.
What should the geometry of a compressor discharge line be?
Pipe run should slope downwards 1 inch towards discharge every 10 feet
When should you use pipe joint compound when connecting NPT-Threaded pipe?
Always
If an air hose is not completely depressurized when it is disconnected, what is the greatest hazard?
Sudden blowing of dust or chips
How many ports does a 4-way valve have?
Four
What is a good throttling valve and what effect does it have on compressed air pressure?
Needle valve is a great throttling valve and it causes high pressure loss in the line.
How does spool based Directional Control Valve work in a high pressure pneumatic system?
Spool slides from one position to another (there are only 2) easily inside a high pressure system
An advantage of four-way valve over 2 or 3 way valves
Simplifying the controls
A valve w/ 5 ports and 2 exhaust ports is classified as what type of valve?
3 Position
The cracking pressure of a simple poppet-type relief valve is determined by
Spring adjustment
Why does Diaphragm-type relief valve responds very quickly to a pressure change
Large pressure-sensitive area
Only purpose of pressure relief valve
Protect the system from damage
What does A increase in pressure on the secondary side of a pressure relief valve cause that same valve to do?
Slightly closes
What is the best way to guard against excessive pressure on the secondary side of a pressure regulator
To use a regulator with a built in relief valve
In a single-rod double acting cylinder, is the force extending the rod greater or is the force retracing the rod greater?
The force extending the rod is greater.
An internal spring is sometimes used to return the piston in what type of pneumatic cylinders?
Single rod, single action
Main purpose of an exhaust flow control metering valve
Limit Return stroke speed
What does a cylinder that must be free to pivot require
Trunnion or clevis
You can determine whether a control valve can deliver air rapidly another for a cylinder by calculating what rating of the valve?
Capacity Coefficient
What is the highest amount of torque a pneumatic motor can exert on a load?
Stalling Torque
Horsepower of a pneumatic motor varies with what?
The speed and the torque of the motor shaft
At what speed of a pneumatic motor does the highest horsepower output occur?
Medium motor speeds
How does an axial-piston pneumatic motor transmits force from the piston to the output shaft
Cam plate and gears
How Air pressure of 100 PSI can create hydraulic pressure of 1000 PSI
If an air piston drives a smaller diameter hydraulic piston.
