What important function(s) does an air receiver perform? - answer Dissipates heat,
Dampens compressor pulsations, Act as water and oil trap
On a compressed air system a safety valve would generally be installed on the: -
answerAir receiver
Variable air volume system: - answerTypically use VFDs to save energy
In figure 1.3, a full call for cooling would be at what branch pressure to the damper
motor? - answer3 psig
A ratio relay would be used to. - answerControl the sequence of actuators.
When an actuated device is said to be normally open, that means the device is open
with: - answerNo control pressure is applied
In figure 1.4, the hot water valve has an 8-12 psig spring range, the damper motor has a
3-8 psig spring range. The calibration point of the thermostat is: - answer8 psig
When you are setting up an instrument, you should know all of the following except: -
answerThe rate of flow of the control agent
Which of the following is an example of a control with a readjusted set point: -
answerSubmaster controller
In figure 1.5, the branch pressure from the temperature controller increases in pressure
as the: - answerControlled variable decreases in temperature
The departure of the control point from the set point, or the amount of that departure is
described as: - answerDeviation
The action of a control that increase its branch pressure as the controlled variable
increases: - answerDirect acting
In figure 1.3 maximum heating would be at what branch pressure to the damper motor?
- answer13 psig
In figure 1.0, if the hot water control valve was N/O instead of N/C, what would the
control action be? - answerDirect acting
, A three way mixing valve: - answerHas two inlets and one common outlet
What will be the typical range of a current sensor: - answer4 - 20 mA
In figure 1.4, with a loss of control branch pressure this system will fail on: - answerFull
cooling
If you decrease the percentage of proportional band on a receiver controller you would
in effect: - answerIncrease the psig/degree fahrenheit output of the control
The temperature-resistance characteristic of a thermistor is _________ : - answerNon-
linear
A reasonable consumption of control air for a thermostat would be: - answer30 - 40
scim
A static pressure regulator senses the pressure in the plenum, the sensor that indicates
this pressure to the regulator is called: - answerStatic tip
An instrumentation system is designed to: - answerPerform a specific function in a
specific process
If we lost control power in figure 1.2, the room temperature would: -
answerFall/decrease in temperature
Which of the following sensors have only two positions: - answerDigital
The sensing element on a humidstat is said to be made on a hygroscopic membrane.
All of the following materials are considered hygroscopic except: - answerCarbon Steel
A pneumatic controller takes air from the main at a ________ pressure and delivers it to
the actuator at a _________ pressure: - answerConstant, variable
Current outputs produce _____ signal distortion over long wire distances. - answerLow
A three-way diverting valve: - answerHas two outlets and one common inlet
A normally closed pressure electric switch is made when: - answer
In figure 1.4, the heating valve is piped: - answerNormally closed
The intensity of heat is expressed in terms of: - answerDegrees Fahrenheit, Degrees
Fahrenheit
Psychrometry refers to the relationship between: - answerTemperature, pressure and
moisture content of air
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