Ch 7. Metering Devices

Modern centrifugal chillers are likely to use which of the following type of metering device?

*A) Orifice plates* B) Low side floats C) High side floats D) TEV's

Which of the following best describes the operation of a high side float?

*A) Feed the evaporator when sufficient quantity of refrigerant has been condensed* B) Feed the evaporator as refrigerant pressure decreases C) Feed the condenser as refrigerant is needed D) Maintain the level of condenser water in the cooling tower

How would reducing the length of a capillary tube affect a unit's operation?

*A) High evaporator pressure* B) High condensing pressure C) High evaporator temperature D) Reduce evaporator capacity

What will happen if an expansion valve meters too much refrigerant into a DX coil?

*A) Possibility of liquid in the compressor* B) Evaporator temperature will be too cold C) Reduced system capacity D) Possible motor burnout

In addition to evaporator pressure, what other forces influence the operation of an automatic expansion valve?

*A) Spring pressure* B) Condensing pressure C) Cut-in pressure D) Design pressure

If the ball float of a "low side float metering device" was punctured and sunk to the bottom of the float chamber, how would the system be affected?

*A) The suction pressure would rise* B) the head pressure would rise C) the suction pressure would fluctuate D) The compressor would stop immediately

An electric expansion valve is being sued in a refrigeration system contains a halocarbon refrigerant. Which of the following power sources would be used to operate this valve?

A) 6 volts AC or DC B) 12 volts AC C) 18 volts DC *D) 24 volts AC or DC*

High pressure drop is produced as refrigerant travels through the metering devices orifice. Which of the following best describes where this component is located?

A) At the valve's inlet B) At the valve's diaphram *C) At the valve's seat* D) At the top of the valve's system

Which of the following metering devices are designed to maintain constant superheat?

A) Automatic expansion valve B) High side float *C) Thermal expansion valve* D) Capillary tube

A horizontal shell and tube cooler is equipped with a float mechanism to control the refrigerant's liquid level in the shell of the cooler. If the equalizer line at the top of the float chamber should become obstructed, which of the following is likely to take place?

A) Compressor will tend to over speed B) Liquid level in the cooler will keep alternately rising and falling C) Cooler will continue to operate normally for a considerable length of time *D) Liquid level in the cooler will not correspond to that in the float chamber*

How would a partially blocked orifice affect the operation of a thermostatic expansion valve?

A) Flood the evaporator *B) Starve the evaporator * C) Low superheat D) Increase refrigerant velocity

If the ball float of a high side float metering device is punctured and sinks to the bottom of the float chamber, how will the operation of the system be affected?

A) Flood the evaporator B) High suction pressure C) Low head pressure *D) Starve the evaporator*

1) Which of the following best describes the state of the refrigerant at the leaving side of the metering device?

A) HPL B) HPV *C) LPL* D) LPV

In addition to controlling the flow of refrigerant to the evaporator, what other task is performed by a metering device?

A) Increase compressor capacity B) Filter refrigerant *C) Separate the high side of the refrigeration system from the low side* D) Shed load as load increase

Which of the following determines the amount of refrigerant passing through an orifice plate?

A) Number of orifice plates in the system *B) Difference between high side and low side pressure * C) Number of stages in the compressor D) Operation of the economizer

In a flooded evaporator equipped with a low side float the operation of the float mechanism is determined by the rate at which:

A) Refrigerant is condensed *B) Refrigerant evaporates* C) Chilled water discharged D) Superheat is produced

Which of the following metering devices requires that the refrigeration system be maintained at a critical charge?

A) TEV B) Low side float *C) High side float* D) Orifice plate

If an automatic expansion valve is mistakenly installed in a system that operates at variable loads, what is likely to take place when the valve experiences a high load condition?

A) The system will operate satisfactorily. B) The compressor will be damaged *C) The evaporator will be starved* D) The evaporator will be over-fed

Which of the following metering devices have no means of adjustment?

A) Thermostatic expansion valve and automatic expansion valve B) Automatic expansion valve and capillary tube C) Automatic expansion valve and orifice plate *D) Capillary tube and orifice plate.*

Which feature distinguishes a manual metering device from a globe valve?

A) Valve seat B) Valve stem *C) Needle Point* D) Outlet diameter