How do Automatic Expansion Valves work?
By evaporator pressure which opens the valve and spring pressure which closes the valve.
When does a faulty check valve cause the most damage ?
On Start-Up
When does High Condenser or Head pressure occur ?
During a loss of pressure due to a clogged pump strainer.
What can happen to a unit if the TEV's sensing bulb falls off the suction line ?
Flood the evaporator and raise the suction pressure.
What three components are part of the Pump Down Cycle.
Thermostat, Solenoid Valve and Low Pressure Control Switch.
What is the proper Start Up Sequence of chiller system ?
Check oil, start chill water pump, start condenser water pump, Cooling Tower fans, and start Chiller
How does a reciprocating machine cycles multistage compressors On and Off ?
With the Low Pressure Control Switch.
Which refrigerant has the best refrigerant effect ?
AMMONIA
At what temp is the leaving water temp in an Induced Draft Cooling Tower that is operating efficiently ?
Between the Dry and the Wet bulb temperatures.
What is another way that a system can create an increase in Head Pressure ?
A sudden decrease in the supply of Cooling Tower water.
How does a reciprocating compressor un-loader work ?
By keeping the compressor suction valves open.
At what point of the compressor is R-22 vapor charged from?
From the Suction side of the compressor.
What is the percentage amount of lubricant that should flow in a system ?
It should not exceed 10 %
What is one of the problems caused to a compressor at the presence of liquid refrigerant in the crankcase ?
Oil Foaming
What is the main reason for installing an Oil Separator on the Discharge Line ?
To return oil back to the compressor crankcase.
A sudden decrease in pressure can cause the Foaming of Oil in a Reciprocating compressor....
When the Splash System for Lubrication is used.
What is the main function of oil in a refrigerant ?
To lubricate the compressor inner parts and reduce the wear and friction of the compressor.
Where is the Oil Separator located ?
On the Discharge line as far from the compressor as possible.
What is the purpose of the Filter Dryer ?
To remove moisture, contaminants and non-condensables from the refrigerant
Which of the following elements control the flow of liquid refrigerant into the evaporator. The Solenoid valve or the TXV.
The TXV, TEV or AEV are the only refrigerant flow controls. The Solenoid valve is a Safety mechanism and does not do that.
How is Constant Evaporator Pressure maintain ?
With and Automatic Expansion Valve.
What happens when Oil Logs on the low side ?
The evaporator may not respond to adjustments of the TEV, TXV or AEV.
High Head Pressure can also be caused by....
Non-condensables in the refrigerant.
What happens to the Horsepower of a system when the Head Pressure increases ?
Horsepower also increases.
What happens to the Horsepower as the Suction Pressure increases ?
Horsepower will decrease.
High Head Pressure is a sign of:
Non-condensables in the system.
What is used to prevent rusting from a system that uses Brine solution. ?
D-Chromate Tablets.
A Yellow torch in a Halide Torch is caused by:
A clogged sample tube.
Why are 2 compressors used in a cascade system ?
To operate at very Low temperatures and avoid high compression ratio.
The main reason why a Pressure Relief valve is better than a fusible plug is because:
The fusible plug can not be re-seated because it melts.