UNIT 77 EXAM QUESTIONS

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UNIT 77 EXAM QUESTIONS

Actual Qs and Ans Expert-Verified Explanation

This Exam contains:

-Guarantee passing score -42 Questions and Answers -format set of multiple-choice -Expert-Verified Explanation Question 1: What is difference between a viscous impingement filter and a standard filter?

Answer:

Viscous filters are treated with a sticky substance to trap and hold dirt

Question 2: The steam grid humidifier works by

Answer:

introducing live steam into to air stream through a grid of orifices Question 3: What filter would be appropriate for a large industrial air handler?

Answer:

a large fiberglass roll filter

Question 4: The two main types of fan drives are

Answer:

Direct drive and belt drive

Question 5: How is the airflow adjusted on most commercial air handlers?

Answer:

by adjusting the sheave on an adjustable pulley Question 6: Why do air-handling units require field adjustment during the commissioning phase?

Answer:

to match the blower performance to the system requirements Question 7: Types of humidifiers used with commercial air-handling equipment include

Answer:

steam grid, steam pan, and direct water spray Question 8: What is the RPM of a fan that uses a 4 in motor pulley, 8 in fan pulley, and a motor RPM of 1,750?

Answer:

875

Question 9: Where are unit ventilator fan coil units installed in schools?

Answer:

below window level in each classroom

Question 10: Three types of fan blades used with centrifugal fans include

Answer:

Forward-curved, backward-curved, and backward-curved airfoil

Question 11: The three common types of axial fans are

Answer:

propeller, vane axial, and tube axial Question 12: When is a forward-curved centrifugal blower motor most likely to draw high amps?

Answer:

When there is no restriction to the airflow in or out of the blower

Question 13: The two basic types of fans used in most air-handling units are

Answer:

centrifugal and axial Question 14: Why should ultraviolet germicidal lamps NOT be handled with bare hands?

Answer:

the oil from your fingerprints can lead to premature failure of the lamp Question 15: The most common fan used for moving air through ductwork in residential air conditioning is

Answer:

Forward-curved centrifugal

Question 16: Larger fan coil units are commonly used to condition

Answer:

schools

Question 17: What is a HEPA filter?

Answer:

a very high efficiency filter Question 18: This type of fan is commonly used on condenser motors because because it moves high volumes of air in low static conditions

Answer:

propeller Question 19: What fan performance characteristics are shown on a typical fan curve?

Answer:

Pressure drop, efficiency, and horsepower

Question 20: The two broad types of fan designs are

Answer:

centrifugal and axial

Question 21: The major components of an air-handling unit include

Answer:

Fan and motor, heating and cooling coils, air filter, dampers

Question 22: Airflow through an axial fan is

Answer:

parallel to the fan shaft Question 23: The advantage of the backward-curved centrifugal fan over the forward-curved centrifugal fan is that

Answer:

Backward-curved fans are non-overloading Question 24: The most common fan used for moving air across outdoor condenser coils in residential air conditioning is

Answer:

Propeller

Question 25: Hot water heating coils should be piped

Answer:

for counter flow so that the warmest water meets the warmest air Question 26: What happens if the steam trap at the outlet of a heating coil is stuck in the closed position?

Answer:

steam flow through the coil will stop and the air temperature will be too low

Question 27: A central station air-handling unit

Answer:

is used for large systems and is assembled on site using separate components

Question 28: The components of a commercial fan coil unit include

Answer:

a fan, a water coil, a filter, a fresh air supply, and a control system