STATIONARY ENGINEER UPDATED EXAM SCRIPT
QUESTIONS AND SOLUTIONS RATED A+
✔✔Absolute Humidity - ✔✔Absolute Humidity
The weight of water vapor in a given amount of air space. Absolute humidity is
measured by grains per cubic foot.
✔✔Atmospheric Pressure - ✔✔Atmospheric Pressure
The weight of a 1 square inch column of the earth's atmosphere. At sea level this
pressure is 14.696 pounds per square inch.
✔✔Chilled Water System - ✔✔Chilled Water System
Type of air conditioning system that has no refrigerant in the unit itself. The refrigerant is
contained in a chiller, which is located remotely. The chiller cools water, which is piped
to the air conditioner to cool the space.
✔✔Condensation - ✔✔Condensation
The process by which a gas is changed into a liquid at constant temperature by heat
removal.
✔✔Condensation Point - ✔✔Condensation Point
The temperature at which the removal of any heat will begin a change of state from a
vapor to a liquid.
✔✔Condenser - ✔✔Condenser - A device that transfers unwanted heat out of a
refrigeration system to a medium (either air, water, or a combination of air and water)
that absorbs the heat and transfers it to a disposal point. There are three types of
condensers
✔✔3 Condenser Types - ✔✔air-cooled condensers, water-cooled condensers, and
evaporative condensers. The evaporative condenser uses a combination of air and
water as its condensing medium. Most residential systems have an air-cooled
condenser.
✔✔Condensing Unit - ✔✔Condensing Unit
Part of a refrigerating mechanism which pumps vaporized refrigerant from the
evaporator, compresses it, liquefies it in the condenser and returns it to the refrigerant
control. The outdoor portion of a split system air conditioner contains the compressor
and outdoor coil ignoring the reverse cycle operation, also the outdoor in a heat pump
system.
✔✔Economizer - ✔✔Economizer
In a chiller with a two-stage centrifugal compressor, the discharge from the first stage
impeller and the inlet to the second stage impeller are at a pressure level approximately
half way between the cooler pressure and condenser pressure. With this arrangement,
, an economizer may be used. This is a shell within which refrigerant liquid from the
condenser drops down to the interstage pressure, flashing off some of the refrigerant
which is drawn directly into the second stage impeller. This reduces the amount of
refrigerant which has to be compressed by the first stage impeller, improving the
refrigeration cycle efficiency.
✔✔Enthalpy - ✔✔Enthalpy
Heat content or total heat, including both sensible and latent heat. The amount of heat
contained in a refrigerant at any given temperature with reference to -40°F.
✔✔HeatPump - ✔✔Heat Pump
An air conditioner that contains a valve that allows it to alternate between heating and
cooling.
✔✔Humidity - ✔✔Humidity
The amount of moisture in the air.
✔✔Relative humidity - ✔✔Relative humidity
The ratio of the amount of vapor contained in the air to the greatest amount the air could
hold at that temperature. Normally expressed as a percentage.
✔✔Super-Heated Vapor - ✔✔Refrigerant vapor heated beyond its saturation point.
✔✔Vacuum Pump - ✔✔A pump used to remove air and moisture from a refrigeration
system at a pressure below atmospheric pressure.
✔✔Water Cooled System - ✔✔Water Cooled System
A type of air conditioning system that uses freon as a refrigerant and water as a
condensing medium. Typically, the water-cooled condenser is located inside the air
conditioner with the rest of the refrigeration components. Water is piped to the unit from
a cooling tower or other suitable source.
✔✔Zoning - ✔✔Zoning
The practice of providing independent heating and/or cooling to different areas in a
structure. Zoning typically utilizes a system controller, zoning dampers controlled by a
thermostat in each zone, and a bypass damper to regulate static pressure in the supply
duct.
✔✔Bolwdown Tanks - ✔✔Blowdown Tanks: Manage Temperature and Pressure
Boiler blowdown tanks are used to reduce the pressure and temperature of the
blowdown from a boiler. IN most states, it is unlawful to discharge blowdown directly
into the sewer system. They typically require boiler blowdown to be reduced to a
temperature of 140° F at a maximum pressure of 5PSIG.
✔✔BDS Blowdown Separators - ✔✔BDS Blowdown Separators
QUESTIONS AND SOLUTIONS RATED A+
✔✔Absolute Humidity - ✔✔Absolute Humidity
The weight of water vapor in a given amount of air space. Absolute humidity is
measured by grains per cubic foot.
✔✔Atmospheric Pressure - ✔✔Atmospheric Pressure
The weight of a 1 square inch column of the earth's atmosphere. At sea level this
pressure is 14.696 pounds per square inch.
✔✔Chilled Water System - ✔✔Chilled Water System
Type of air conditioning system that has no refrigerant in the unit itself. The refrigerant is
contained in a chiller, which is located remotely. The chiller cools water, which is piped
to the air conditioner to cool the space.
✔✔Condensation - ✔✔Condensation
The process by which a gas is changed into a liquid at constant temperature by heat
removal.
✔✔Condensation Point - ✔✔Condensation Point
The temperature at which the removal of any heat will begin a change of state from a
vapor to a liquid.
✔✔Condenser - ✔✔Condenser - A device that transfers unwanted heat out of a
refrigeration system to a medium (either air, water, or a combination of air and water)
that absorbs the heat and transfers it to a disposal point. There are three types of
condensers
✔✔3 Condenser Types - ✔✔air-cooled condensers, water-cooled condensers, and
evaporative condensers. The evaporative condenser uses a combination of air and
water as its condensing medium. Most residential systems have an air-cooled
condenser.
✔✔Condensing Unit - ✔✔Condensing Unit
Part of a refrigerating mechanism which pumps vaporized refrigerant from the
evaporator, compresses it, liquefies it in the condenser and returns it to the refrigerant
control. The outdoor portion of a split system air conditioner contains the compressor
and outdoor coil ignoring the reverse cycle operation, also the outdoor in a heat pump
system.
✔✔Economizer - ✔✔Economizer
In a chiller with a two-stage centrifugal compressor, the discharge from the first stage
impeller and the inlet to the second stage impeller are at a pressure level approximately
half way between the cooler pressure and condenser pressure. With this arrangement,
, an economizer may be used. This is a shell within which refrigerant liquid from the
condenser drops down to the interstage pressure, flashing off some of the refrigerant
which is drawn directly into the second stage impeller. This reduces the amount of
refrigerant which has to be compressed by the first stage impeller, improving the
refrigeration cycle efficiency.
✔✔Enthalpy - ✔✔Enthalpy
Heat content or total heat, including both sensible and latent heat. The amount of heat
contained in a refrigerant at any given temperature with reference to -40°F.
✔✔HeatPump - ✔✔Heat Pump
An air conditioner that contains a valve that allows it to alternate between heating and
cooling.
✔✔Humidity - ✔✔Humidity
The amount of moisture in the air.
✔✔Relative humidity - ✔✔Relative humidity
The ratio of the amount of vapor contained in the air to the greatest amount the air could
hold at that temperature. Normally expressed as a percentage.
✔✔Super-Heated Vapor - ✔✔Refrigerant vapor heated beyond its saturation point.
✔✔Vacuum Pump - ✔✔A pump used to remove air and moisture from a refrigeration
system at a pressure below atmospheric pressure.
✔✔Water Cooled System - ✔✔Water Cooled System
A type of air conditioning system that uses freon as a refrigerant and water as a
condensing medium. Typically, the water-cooled condenser is located inside the air
conditioner with the rest of the refrigeration components. Water is piped to the unit from
a cooling tower or other suitable source.
✔✔Zoning - ✔✔Zoning
The practice of providing independent heating and/or cooling to different areas in a
structure. Zoning typically utilizes a system controller, zoning dampers controlled by a
thermostat in each zone, and a bypass damper to regulate static pressure in the supply
duct.
✔✔Bolwdown Tanks - ✔✔Blowdown Tanks: Manage Temperature and Pressure
Boiler blowdown tanks are used to reduce the pressure and temperature of the
blowdown from a boiler. IN most states, it is unlawful to discharge blowdown directly
into the sewer system. They typically require boiler blowdown to be reduced to a
temperature of 140° F at a maximum pressure of 5PSIG.
✔✔BDS Blowdown Separators - ✔✔BDS Blowdown Separators
