3rd 6th month 2 Flashcards
as air flows in a pipe and the diameter decreases, the speed of the air ___ and the pressure _____
increases
decreases
reciprocating air compressor intake valves are forced open by
atmospheric pressure
the impeller (blower) compressor delivers air at
high volume and low pressure
method of decreasing output of a centrifugal compressor is _____ but this will not work if the reduction is _____
speed reduction
too large
the greater pressure losses occur because airflow at ____ is affected by ____
low pressure
greater friction
when disconnecting high pressure lines be careful of
blowing of dust or chips
to guard against excessive pressure on the secondary side of a pressure regulator is to us a
pressure regulator with a built in relief valveq
hoursepower output wanes with the _____ of the shaft
speed and torque
highest power of output of a pneumatic motor occurs at
meduem speed
unloading the compressor
run without delivering air
single stage compressor are capable of delivering up to
50psi
screw compressors operate at speeds between
3000 and 12000 rpms
two disadvantages of centrifugal compressors
more horse power
higher speeds
as air is compressed, moisture capacity is
decreased
water cooled after coolers are typically used with ______ compressors that run ___
large capacity
10 or more hours a day
the operation of an internal seperator depends on a
rapid change in direction of airflow
a fine line lubricator is for ______ and ____ range lines
intermittent
long
what type of turbine has variable vane design and can be used for both pumping and generating
deriaz
the minimum velocity of water in a power canal to prevent the deposit of silt is
2-3ft per sec
to prevent negative pressure in a penstock where pipe is being used, what is installed in the pipline
airvents
always use pipe joint compound for
npt threaded pipe
valve that has five connecting ports, two are exhaust ports
four way valve
the only purpose of a pressure relief valve is to
protect the system from damage
an increase in pressure on the secondary side of a pressure regulating valve _______ the valve
slightly closes
exhaust flow metering valve limits
return stroke speed
the highest torque a pneumatic motor can exert on a load is its
stalling torque
a well designed protective relay system should provide 3 basic operational caracteristics
reliability
selectivity
speed
the circuit diagram usually gives the following 3 items of info about current and voltage, eliminate 1: location direction polarity magnitude
magnitude
the ground and neutral point on a 3 phase system are the same point. t/f
false
Polyphase rotating equipment may be protected against single phase operation by using a
phase-balance relay
