BOMI- AHU, Water Treatment & Plumbing (Questions & Answers) Rated 100% Correct!!

According to ASHRAE Standard 62-1989, how many cubic feet per minute of air exchange should maintain an acceptable IAQ (indoor air quality) level? - The air exchange rate should be 15 cfm per person to maintain acceptable indoor air quality in a reception area. In office space and conference rooms, the standard is 20 cfm per person. At what pH level does descaling discharge have to be before being emptied into a river or stream? - Descaling discharge emptied directly into a river or stream needs to be neutralized to a pH level between 7 and 8. At what pH level should boiler water be maintained? - Boiler water should be maintained at a pH of 10.1 to 11. BRI (building-related illness) - Specific, diagnosable illnesses whose symptoms can be identified and whose cause is directly attributed to airborne building pollutants. Briefly describe a split system. - The evaporator coil of a split system is located inside the AHU. A filter protects the evaporator coil from dirt and debris. Copper tubing is used to connect the condenser unit (located outdoors) to the evaporator unit. The suction line of a split system is insulated to prevent sweating. The compressor is usually located in the condensing unit. Briefly explain how an air-water system works. - Air-water systems deliver air at one temperature through the ducts and water at a different temperature through pipes. In the winter, the water system will deliver the warmth while the air system cools. These roles are reversed in the summer because the water system always handles the heavier temperature load while the air handler works on the humidity and ventilation. Define absolute pressure - Gauge pressure plus standard pressure gives psia (pounds per square inch absolute), or absolute pressure.Define AHP (air horsepower) - The amount of work a fan performs to move a specific volume (or weight) of air at a specific speed. Define bioaerosols. - Mold, fungus, bacteria, animal feces, insect body parts, plant parts, or any part of a living or once-living organism Define building pressurization. - Building pressurization is the measured difference in static pressure between the inside and the outside of a building. Define carryover. - Carryover happens when the water level is too high and particles of liquid water from the boiler are transported into the steam lines (which should contain only steam). Carryover is harmful because these small water droplets can cause damage to the steam pipes as they move around in the lines. Keeping the water as free from contaminants as possible controls this. Define conduction - Conduction is the direct transfer of heat from one body to another. The substances have to be in physical contact with each other, but there is no movement of the material itself. Define galvanic action. - Galvanic action occurs when two dissimilar metals are in contact in the presence of an electrolyte. An electric current will flow from one metal to the other. The metal passing the current is the anode, and the metal receiving the current is the cathode. In this process, the anode will react, while the cathode will gain mass. Define heat - Heat is energy that flows from one object to another. Heat always travels from an object with more heat to an object with less heat until both bodies are the same temperature. Define ionic bond. - Atoms that transfer electrons create ionic compounds by making ionic bonds. An ion is an atom that completely gives up or takes electrons when it bonds.Define latent heat - Latent heat is the energy that is used or released during a change of state. Latent heat cannot be felt or measured with a thermometer because it is hidden within a substance. Define mechanical efficiency - The ratio of a fan's AHP to its BHP. This value stays the same through all of a fan's different operating speeds. Because of friction and turbulence loss in the fan itself, BHP is always greater than AHP. Define relative humidity - RH (relative humidity) describes the amount of water vapor held in the air. Define static pressure - Static pressure is generally used to describe duct pressure. Static pressure is the pressure of the air being pushed against the inside walls of a closed duct by the fan.