Quality Assurance Flashcards
7 cards from real ASHRAE practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Quality Assurance flashcards as text
Which ASHRAE standard covers measurement, testing, adjusting and balancing of building HVAC&R systems?
Answer: Standard 111
ASHRAE Standard 111 covers TAB procedures and the measurement methods used for them.
With the proportional balancing method for air distribution, what happens to the terminal with the lowest percentage of design flow?
Answer: It is left as the reference with its damper wide open
The terminal with the lowest flow ratio is the index, so its damper stays fully open and the others are adjusted to match it.
Which traverse method is commonly used to measure average velocity across a duct cross-section with a Pitot tube?
Answer: Log-Tchebycheff traverse
Log-Tchebycheff (or equal-area) traverses place readings so they account for the velocity profile across the duct.
Before starting air balancing, which condition should the TAB technician confirm?
Answer: Filters are clean and dampers are in their normal operating positions
Dirty filters or closed dampers change system pressure and give misleading balance results.
When balancing a hydronic coil fitted with a calibrated balancing valve, what is measured to find the flow rate?
Answer: Differential pressure across the valve
The flow rate is calculated from the pressure drop measured across the calibrated valve using the manufacturer's flow coefficient.
A capture hood reading on a supply diffuser may need correction mainly because of:
Answer: Back pressure the hood adds to the outlet
The hood adds resistance that can reduce outlet flow, so back-pressure compensation or correction factors are used.
A TAB specification commonly allows terminal airflows within which tolerance of design?
Answer: ±10%
Many TAB specifications and industry procedures allow terminal outlets within about ±10% of design airflow.