BOMA - Instrumentation & Controls Questions and Answers Rated A+

BOMA - Instrumentation & Controls Questions and Answers Rated A+ What important function(s) does an air receiver perform? 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: Air receiver Variable air volume system: 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? 3 psig A ratio relay would be used to. Control the sequence of actuators. When an actuated device is said to be normally open, that means the device is open with: 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: 8 psig When you are setting up an instrument, you should know all of the following except: The rate of flow of the control agent Which of the following is an example of a control with a readjusted set point: Submaster controller In figure 1.5, the branch pressure from the temperature controller increases in pressure as the: Controlled variable decreases in temperature The departure of the control point from the set point, or the amount of that departure is described as: Deviation The action of a control that increase its branch pressure as the controlled variable increases: Direct acting In figure 1.3 maximum heating would be at what branch pressure to the damper motor? 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? Direct acting A three way mixing valve: Has two inlets and one common outlet What will be the typical range of a current sensor: 4 - 20 mA In figure 1.4, with a loss of control branch pressure this system will fail on: Full cooling If you decrease the percentage of proportional band on a receiver controller you would in effect: Increase the psig/degree fahrenheit output of the control The temperature-resistance characteristic of a thermistor is _________ : Non-linear A reasonable consumption of control air for a thermostat would be: 30 - 40 scim A static pressure regulator senses the pressure in the plenum, the sensor that indicates this pressure to the regulator is called: Static tip An instrumentation system is designed to: Perform a specific function in a specific process If we lost control power in figure 1.2, the room temperature would: Fall/decrease in temperature Which of the following sensors have only two positions: Digital The sensing element on a humidstat is said to be made on a hygroscopic membrane. All of the following materials are considered hygroscopic except: Carbon Steel A pneumatic controller takes air from the main at a ________ pressure and delivers it to the actuator at a _________ pressure: Constant, variable Current outputs produce _____ signal distortion over long wire distances. Low A three-way diverting valve: Has two outlets and one common inlet A normally closed pressure electric switch is made when: In figure 1.4, the heating valve is piped: Normally closed The intensity of heat is expressed in terms of: Degrees Fahrenheit, Degrees Fahrenheit Psychrometry refers to the relationship between: Temperature, pressure and moisture content of air An advantage of screw type compressors is that they: Deliver almost pulse-free flow Which of the following is more advantageous for transmission of signals: Current signal Refer to figure 1.2, contactor coil-1 pulls in an electric strip heater on a cold air duct to a room. The pneumatic room thermostat operates ps-1. The