Self-tests For Last Two Modules Flashcards
In a deliquescent dryer, which way does the flow normally go?
upward
What is relative humidity?
A comparison of the amount of water a sample of air holds to the maximum amount it could hold if saturated.
Dew point is the temperature to which air must be lowered in order for _________________
condensation of water vapour to begin
Regenerative dryers often use a portion of the dried air for regeneration of ________________
the saturated desiccant bed
What are desiccants often made of?
- activated alumina
- granular and bead type silica gel
- molecular sieves
True or False: There are forms of energy other than electricity that can be very harmful and equipment must be locked out to prevent injury
True
As a sample of air that is partially saturated cools, relative humidity _________
rises
True or False: It takes more energy to change the phase of a volume of liquid to a vapour without a change in temperature than it does to increase its temperature 1* without any phase change.
True. It takes 1BTU to increase the temperature but 970 BTUs to change its phase from liquid to vapour
Name the 4 categories of dryers
- Adsorption
- Absorption
- Refrigeration
- Mechanical
When working on a dryer, you must _____________ and _______________ the complete system, as well as lock out the compressor whenever possible.
When working on a dryer, you must depressurize and isolate the complete system, as well as lock out the compressor whenever possible.
The energy of compressed air in the lines can cause severe whiplash when one end of a hose is let free. This can be overcome with an ________________ that stops flow through the line if excessive flow occurs
excessive flow valve
______________ cylinders must be let down or mechanically blocked to prevent movement before performing any work on or around them
vertical
Piping should be sized to minimize __________________ by being large enough with as few bends as possible
pressure drop
The purpose of a __________ in a pneumatic system is to lower the dew point so that it does not cause problems in the system
dryer
The _____________ can be used anywhere in the system that moisture might fall out
cyclone separator
____________________ are used to store compressed air to take up fluctuations in demand and allow the system pressure to vary within reasonable limits
Air recievers
The purpose of the _____________ is to bleed off excess system pressure before it becomes too extreme
Safety relief valve
Leaks waste energy (from compression) which increases expenses while reducing ____________________________
the performance of air tools and equipment
Most compressed air systems run for long distances. This allows the air to cool below its _____________, which causes moisture to fall out of the air stream
Dew Point
Flow control valves control the ____________ and therefore the speed of the actuator
volume
Pilot operation refers to valves that are operated with _____________
air pressure
What does internally piloted mean?
The air pressure within the valve is used to perform the shifting function
The 3/2 valve can be used if the air needs to be release when __________________
the valve is closed
A typical application of a 3/2 valve is the operation of a __________________ acting cylinder
single
A ____________ acting cylinder is a common application of a 4/2 valve
double
The _________________ is used to automatically select the higher of two pressure sources to supply a pneumatic signal
shuttle valve
What is the first item to check in a malfunctioning system?
Whether there is a supply of air at sufficient flow and pressure
