BOMA - Instrumentation & Controls 100
correct solutions 100%
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: -
ANSWER-Air receiver
Variable air volume system: - ANSWER-Typically use VFDs to save energy
In figure 1.3, a full call for cooling would be at what branch pressure to the damper
motor? - ANSWER-3 psig
A ratio relay would be used to. - ANSWER-Control the sequence of actuators.
When an actuated device is said to be normally open, that means the device is open
with: - ANSWER-No 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: - ANSWER-8 psig
When you are setting up an instrument, you should know all of the following except: -
ANSWER-The rate of flow of the control agent
Which of the following is an example of a control with a readjusted set point: -
ANSWER-Submaster controller
In figure 1.5, the branch pressure from the temperature controller increases in pressure
as the: - ANSWER-Controlled variable decreases in temperature
The departure of the control point from the set point, or the amount of that departure is
described as: - ANSWER-Deviation
The action of a control that increase its branch pressure as the controlled variable
increases: - ANSWER-Direct acting
In figure 1.3 maximum heating would be at what branch pressure to the damper motor?
- ANSWER-13 psig
In figure 1.0, if the hot water control valve was N/O instead of N/C, what would the
control action be? - ANSWER-Direct acting
A three way mixing valve: - ANSWER-Has two inlets and one common outlet
What will be the typical range of a current sensor: - ANSWER-4 - 20 mA
