Volume 5 Unit 2 Flashcards
The pressure of moving air is always measured in the direction of airflow. What kind of pressure is this?
Negative on the blowing side
Where should you expect the static pressure (SP) to become more negative in a ventilation system?
At the inlet to the fan
Less resistance and better contaminant capture in a ventilation system happens by using _____
A flange or tapered hood
Which type of velocity refers to the speed of air at a point in front of a hood that is needed to pull contaminants into the hood?
Capture
What are two parameters at a given point in ventilation systems that are needed to calculate the airflow volume (Q)?
Area and velocity
In dilution ventilation, a slight negative pressure is desirable when _____
An adjoining room is normally occupied
The cubic feet per minute (cfm) through a cross-sectional area of a ventilation booth is the same as _____
Velocity
What circumstance would result in a high K factor?
A high occupational exposure limit
The purpose of using splitter vanes, multiple takeoffs, or baffles inside of a local exhaust hood is to provide _____
A reduction in system resistance
Other than good contaminant control, what is the biggest advantage of local exhaust over dilution ventilation?
Lower operating costs
In a routine survey, ventilation system data collected during the routine assessment should be compared to _____
Data collected during the baseline survey
What determines the capture velocity that must be used for a properly designed canopy hood?
Number of open sides
What instrument is used to take face velocity measurements and actually converts velocity pressure (VP) to velocity readings?
Swinging vane anemometer
What important procedure must you follow to obtain accurate readings with a velometer?
Hold the probe parallel to the airflow
What may be indicated by a very strong flow coming in an open door of a room containing a local exhaust system?
Adequate makeup air
What is the first step you take when conducting a static pressure (SP) check on your routine ventilation test?
Find the first measurement point
Velocity pressure (VP) when measured across the duct is _____
Weaker along the sides and becomes stronger as you near the center
What is the purpose of the eight tiny holes on the outside of a pitot tube?
Sense static pressure (SP)
The range of acceptable values for the airflow volume (Q) on routine tests is within what percentage of the baseline value?
10%
During your indoor air quality (IAQ) investigation, you document several drip pans with standing water. Which recommendation would be most desirable?
Replace filters
When conducting an indoor air quality (IAQ) investigation, what would be considered an ideal range for carbon dioxide (CO2) within a building?
1000 ppm or less
