Test 3 - Pneumatics Flashcards
In a pneumatic system, the compressed air provides the force to ???
- perform work
The inertia of an object is its ???
- resistance to movement
The abbreviation PSIG means ???
- pressure per square inch, gage
Which of the following factors determines the amount of work done by a pneumatic cylinder?
- cylinder stroke
- air pressure
- cylinder bore
- all of the above
What type of energy is produced by an air compressor?
- pneumatic
Using the formula P1 x V1 = P2 x V2, find P2 if P1 = 100 (psig), V1 = 100, V2 = 10. (remember to do all calculations in psia.)
- 1,132 (psig)
What happens when heat is applied to gas contained in a cylinder?
- the pressure increases
The force that permits a small amount of pressure to move a larger object is called ???
- pneumatic leverage
If the small piston in a pneumatic system having a 2.5-to1 leverage increase travels 5 inches, how far will the large piston travel?
- 2 inches
Bernoulli’s principle states that the total energy (potential + kinetic) of a gas always ???
- remains constant
To be efficient, a positive displacement compressor must decrease the air’s ???
- volume
Dynamic compressors increase air pressure by ???
- accelerating the air
The discharge valves of a compressor are opened by ???
- compressed air
In which of the following ways are discharged valves closed?
- air pressure
- spring pressure
- intake pison stroke
- all of the above
In multistage compressors, the required air pressure is created by compressing the air in ???
- two or more unequal cylinders
Of what benefit is the use of an intercooler in a multistage compressor?
- decreases horsepower requirements
Air-cooled compressors are usually constructed with ???
- cooling fins
Water or liquid intercoolers are usually patterened after which of the following?
- shell and tube heat exchangers
What lubrication method is used for heavy-duty compressors?
- pressurized
When a compressor is relieved of all internal pressure, it is said to be ???
- unloaded
What is the maximum discharge pressure of a single-stage sliding vane compressor?
- 50 psi
What type of compressor will deliver large amounts of oil-free air at approximately 100 psi?
- rotary dry screw
The compressing lobes of a wet screw compressor are driven without ???
- timing gears
Impeller compressors are frequently referred to as ???
- blowers
Impeller compressors use the same operating principle as ???
- gear pumps
What type of positive displacement compressors is best suited for light-duty applications?
- disphragms
A centrifugal compressor is classified as a ???
- dynamic compressor
The impellers of dynamic compressors rotate at high speeds to ensure
- efficient operation
The most effiecient method of controlling the output of a centrifugal compressor is by ???
- speed cariation
The term used to describe the measured capacity of a compressor after it is installed is ???
- actual cubic feet per minute
The most common contaminants in the air are dirt and ???
- water vapour
When washing a primary air filter, be sure to use ???
- a recommended solvent
What term is used to compare the amount of moisture in the air to what it could contain?
- relative humidity
The amount of moisture that can be held in air decreses as the ???
- pressure increases
What term best describes the condensation temperature of water vapor?
- dew point
Which of the folowing is the best method of removing vapour from compressed air?
- condensation
Which method of heat transfer is used in a shell and tube heat exchanger?
- counterflow
What else can be used if the desired dew point temperature for a pneumatic system cannot be obtained with an aftercooler?
- a second cooler
- a refridgerated dryer
- a chiller
- all the above
Most moisture separators remove liquids from a pneumatic system by ???
- mechanical separation
What type of air dryer uses a chemical agent that absorbs moisture from the air?
- deliquescent
What type of contaminant separation takes place when a stream of air is slowed down?
- gravity
Because of their ability to stop large particles, inertial separators are used as ???
- pre-filters
Contaminant particle size is measured in ???
- microns
A strainer or filter is classified by the ???
- size of particle it stops
The largest percentage of a given particle size that a filter will stop determines its ???
- nominal rating
What occurs when part of the filter medium breaks off and is carried along with the air?
- medium migration
The most efficient way of removing large particles from the airstream is by using a ???
- surface filter
Which type of filter primarily uses a medium that collects moisture on the medium surface?
- adsorption
What type of oil is used to lubricate pneumatic equipment?
- uncontaminated
The best point in a pneumatic system to place lubricating equipment is after the ???
- regulator
What is commonly used to carry or contain the compressed air in a pneumatic system?
- hose
- pipe
- tubing
- all the above
The streamline or laminar flow of air in a pipe is necessary to ???
- improve efficiency
Selected air lines should be large enough in diameter to minimize the ???
- pressure drop
How does a change in air pressure in a pipe affect the pressure losses?
- decreased pressure, higher losses
The pressure loss through fittings and valves is calculated in terms of ???
- feet of straight pipe
Which of the following is commonly used to construct the main headers in a pneumatic system?
- pipe
What should the rate of slope for compressed air piping be?
- 1” inch / per 10’ feet
Flared connections that have long-shouldered nuts are used to ???
- provide support
Most nonmetallic tubing used in pneumatic lines is limited to conditions of ???
- 100 psi and 190°F
Which of the following is provided by hoses that connect pneumatic equipment?
- vibration insulation
- noise insulation
- flexible connections
- all of the above
A manually operated flow control valve may be further identified by which of the following?
- number of control positions
- type of control element
- number of connecting ports
- all of the above
Manually operated stop or isolating valves (globe, gate, or ball) are classed as ???
- two-way valves
The high-pressure losses in a needle valve are caused by the ???
- valve seat
What is the most common method of actuating automatically operated flow control valves?
- electric solenoids
The amount of air that can pass through a direct-acting, two-way, solenoid-operated valve is limited by the ???
- spring force
An automatic check valve can be further classified as a ???
- two-way, two-position valve
A three-way valve is constructed with three ???
- primary connections
Two-position, three-way valves are usually held in a nonactuated position by ???
- a spring
Compressed air returbing through a four-way valve after it has done work is usually directed to the ???
- atmosphere
In how many directions can air flow in a nonactuated two-position, four-way valve?
- two
The primary purpose of all the pressure controls in a pneumatic system is to ???
- limit air pressure
Which of the following types of valves control the maximum allowable pressure limit in a pneumatic system?
- safety
What is the best location for a pressure regulating valve in a pneumatic system?
- at an air station
Pressure relief valves are usually adjusted to open at what pressure level?
- above the control valve setting
Initially, at what pressure does a relief valve open?
- cracking
Which of the following types of relief valves provides the smoothest relief control?
- diaphragm
When ordinary non-precision regulators operate, they ???
- modulate slightly
Remote-controlled regulators will not function without ???
- regulated pilot air
Which of the following types of valves is used to regulate a high volume air line?
- booster relay
Air hoses used to blow chips are required by Federal law to have pressure regulators set at a maximum pressure of ???
- 29 psi
The service life of a pneumatic cylinder is improved with ???
- lubrication
The major difference between pneumatic and hydraulic cylinders is the ???
- absence of return lines
A cylinder that produces work only on its return stroke is called a ???
- single-acting cylinder
Piston travel speed is commonly controlled by ???
- metered outlet air
Piston rings (or cups) and seals of pneumatic cylinders are usually made of ???
- synthetic materials
A pneumatic cylinder furnished with the mounting lugs or feet is classified as being ???
- fixed, noncenterline mounted
The amount of motion in a pivoting cylinder should be restricted to prevent the ???
- piston rod from bending
Which of the following items must be considered when determining the size of a cylinder required to move a particular load?
- pressure losses
- coefficient of friction
- weight of load
- all of the above
When selecting a cylinder, always make sure that the cylinder ports are the same size as the ???
- control valve ports
Mechanical show can be prevented in a pneumatic cylinder by using ???
- cushioning devices
What type of energy is produced by a pneumatic motor?
- mechanical energy
Pneumatic motors are classified according to their ???
- driving elements and principle of operation
All pneumatic motors are constructed with a mechanical seal and operate on the principle of ???
- positive displacement
Pneumatic motor torque is classified under which of the following categories?
- starting torque
- running torque
- stalling torque
- all of the above
The horsepower output of a pneumatic motor is calculated on the basis of the motor’s ???
- torque and speed
Which of the following is most important to consider when selecting a pneumatic motor?
- air consumption
An advantage of pneumatic motos over hydraulic motors is that they are ???
- portable
Which of the following basic construction designs is used for pneumatic motors?
- axial piston
- rotary piston
- rotary vane
- all of the above
The direction of rotation in a pneumatic motor is reversed by means of ???
- reversing the airflow
A vane pneumatic motor is usually used to power ???
- portable grinders
