Practice Quiz: Commissioning DFMAs

Question 1

Before commissioning a DFMA, what key documentation and approvals must be in place?

Answer 1

Proper permits, product approval, and a signed-off engineering design.

These documents ensure compliance and safety in the commissioning process.

Question 2

If a make-up air unit uses a forward curved fan and the external static pressure is overestimated, what can be the result?

Answer 2

Too much airflow and over current the fan motor.

Overestimating static pressure can lead to improper airflow and potential damage to the system.

Question 3

What are two options available to correct issues with airflow if the unit is supplying too much air?

Answer 3

• Making adjustments with sheaves and belts
• Using a variable frequency drive (VFD)

These methods allow for better control of airflow without extensive modifications.

Question 4

What is the primary advantage of using a Variable Frequency Drive (VFD) for airflow adjustment during Testing, Adjusting, and Balancing (TAB)?

Answer 4

It allows for quick and accurate TAB by enabling speed adjustments without ordering and installing new belts and sheaves.

VFDs enhance efficiency and flexibility in managing airflow.

Question 5

For kitchens that communicate directly with the seating area, the exhaust capacity cannot be less than 90% of the supply air according to B149.1-7.20.14. (True/False)

Answer 5

True

This regulation ensures proper ventilation and safety in kitchen environments.

Question 6

The total air replacement of an installation in a spray booth shall not exceed the total exhaust capacity of the booth. (True/False)

Answer 6

True

Adhering to this guideline is crucial for maintaining safety and environmental standards.

Question 7

Before firing the main burner on site, what are three critical checks that should be confirmed regarding the unit’s installation?

Answer 7

• Confirm wiring is per drawings
• Gas pressure aligns with rating plate
• Valve train complies with code

These checks ensure the safe and efficient operation of the burner.

Question 8

During the commissioning procedure, what two important checks should be performed on the blower motor?

Answer 8

• Check for correct voltage and overload protection
• Check for correct rotation

These checks are essential to ensure the blower motor operates safely and effectively.

Question 9

During the commissioning procedure, a leak test of the valve train should be performed with the test firing cock open. (True/False)

Answer 9

False

The leak test should be performed with the test firing cock closed to ensure accurate results.

Question 10

What is the typical (and maximum) discharge air temperature setting for a DFMA?

Answer 10

72 degrees Fahrenheit (max 75 degrees)

Proper temperature settings are crucial for system efficiency and comfort.