Stationary Engineer Test Questions with Complete Solutions

Stationary Engineer Test Questions with Complete Solutions Cl2 - ANSWER Chlorine boiler - ANSWER equipment that provides hot water or steam for various uses PRV - ANSWER PRESSURE RELIEVE VALVE NOWL - ANSWER Normal operating water level BTU - ANSWER British Thermal Unit absolute pressure - ANSWER gauge pressure (psi) + atmospheric pressure (14.7 psi) at sea level air changes per hour - ANSWER The hourly ventilation rate divided by the volume of a space. For perfectly mixed air or laminar flow spaces, this is equal to the number of times per hour that the volume the space is exchanged by mechanical and natural ventilation. Air conditioner - ANSWER An appliance, system, or mechanism designed to dehumidify and extract heat from an area. Chiller - ANSWER A device that removes heat from a liquid via a vapor-compression or absorption refrigeration cycle. This cooled liquid flows through pipes in a building and passes through coils in air handlers, fan-coil units, or other systems, cooling and usually dehumidifying the air in the building. Chillers are of two types; air-cooled or water-cooled. Air-cooled chillers are usually outside and consist of condenser coils cooled by fan-driven air. Water-cooled chillers are usually inside a building, and heat from these chillers is carried by recirculating water to a heat sink such as an outdoor cooling tower. Condenser - ANSWER A component in the basic refrigeration cycle that ejects or removes heat from the system. The condenser is the hot side of an air conditioner or heat pump. Controller - ANSWER A device that controls the operation of part or all of a system. Dry Bulb Thermometer - ANSWER Dry bulb temperature is the temperature of air measured by a thermometer which is freely exposed to the air while it is shielded from radiation and moisture. It is usually thought of as air temperature, and it is the true thermodynamic temperature. It is a measurement of heat intensity independently of humidity and a dry bulb thermometer is used to measure it. Economizer - ANSWER An HVAC component that uses outside air, under suitable climate conditions, to reduce required mechanical cooling. When the outside air's enthalpy is less than the required supply air during a call for cooling, an economizer allows a building's mechanical ventilation system to use up to the maximum amount of outside Enthalpy - ANSWER For a given sample of air, a measure of the total heat content (the sum of the heat energy of the dry air and heat energy of the water vapor within it). It is typically used to determine the amount of fresh outside air that can be added to recirculated air for the lowest cooling cost. psychrometric - ANSWER The study of the behavior of air-water vapor mixtures. Water vapor plays an important role in energy transfer and human comfort in HVAC design. Radiation - ANSWER The transfer of heat directly from one surface to another (without heating the intermediate air acting as a transfer mechanism) smoke damper - ANSWER A damper or adjustable louver designed to augment the ventilation of a space during a fire. subcooling - ANSWER A The condition where liquid refrigerant is colder than the minimum temperature required to keep it from boiling which would change it from a liquid to a gas phase. Subcooling is the difference between its saturation temperature and the actual liquid refrigerant temperature. VAV - ANSWER variable air volume An HVAC system that has a stable supply-air temperature, and varies the air flow rate to meet the temperature requirements. Compared to constant air volume systems, these systems conserve energy through lower fan speeds during times of lower temperature control demand. Most new commercial buildings have VAV systems. VAVs may be bypass type or pressure dependent. Pressure dependent type VAVs save energy while both types help in maintaining temperature of the zone that it feeds. Abbreviated VAV. Absolute Humidity - ANSWER 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 - ANSWER 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 - ANSWER 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 - ANSWER Condensation The process by which a gas is changed into a liquid at constant temperature by heat removal.