Fans, Exhausters, And Air Compressors Flashcards
What is Boyles law?
If temperature of a gas stays constant, the pressure varies inversely as its volume.
What is Charles law?
If the pressure remains constant, the absolute temperature varies directly with its volume.
What is isothermal compression?
It occurs when the temperature is held in a gas as it is compressed.
What is adiabatic compression?
It occurs when the heat of compression is held in a gas as it is compressed.
What are the two types of fans.
They are axial flow ( move air in a parallel line with the propeller shaft. Centrifugal types ( air enters at or near the center of a rotating impeller and is thrown outward radially from the impeller axis. )
What happens to a gas if the absolute temperature is doubled?
Its volume will be doubled if the pressure stays constant. If the temperature of a gas is doubled its pressure at the same volume will be doubled.
How do you figure the quantity and pressure of a centrifugal fan?
It is determined by the size and speed of the fan rotor or impeller, the air density, and the fan damper opening.
How do you find discharge volume?
The load or output of a constant speed fan is varied by the means of fan dampers. When other things are constant the discharge volume of a centrifugal fan varies directly as the speed, the discharge pressure varies as the square of the speed and the fan load varies as the cube of the speed.
What happens to the fan impeller if it is unbalanced or bent?
As the speed of the rotor increases, the greater centrifugal force moves the center of gravity further from the axis of rotation further from the axis of rotation and increasing the unbalanced or whipping action.
How do you vary the load or output of a constant speed fan?
They are varied by means of fan dampers. When other things are constant, the discharge volume of a centrifugal fan varies directly as the speed, the discharge pressure varies as the square of the speed, and the fan load varies as the cube of the speed.
What are common causes of rough fan operation?
Common causes of unbalanced or rough and operation are worn rotor blades, misalignment, weak foundation, bent shaft, worn bearings and dirt on the rotor blades.
What are the ways to eliminate water in air systems?
The most common ways are drains traps separators air dryers
What should be done to large air compressors before they are started?
They are generally unloaded while starting and stopping, to reduce the starting torque and permit more gradual stopping; their output is controlled to match air usage
What is it called when air is saturated with water vapour?
This is the condensation point also known as the dew point. When air is cooled or condensed water droplets form in the pipe carrying the air. Did you point varies with pressure and temperature the higher the temperature the more moisture the air can hold.
