How many CFM do I need for a fume hood?
Table of Contents
How many CFM do I need for a fume hood?
The recognized acceptable minimum volumetric rate (CFM) of air for fume hood exhaust is typically cited from National Fire Protection Association’s NFPA 45 recommendation of 25 CFM per interior square foot of work area.
How does air flow in a fume hood?
The primary function of a fume hood is to capture, contain and remove airborne contaminants. Definition: Airflow into a hood is achieved by an exhaust blower which “pulls” air from the laboratory room into and through the hood and exhaust system. This “pull” at the opening of the hood is measured as face velocity.
How is fume hood flow measured?
The calculation for the CFM of a fume hood is obtained by multiplying the FACE OPENING (window of the fume hood) and the FACE VELOCITY. The FACE OPENING value is the maximal open Width x Height for your fume hood while FACE VELOCITY references the capture distance i.e. depth of the fume hood.
How do you measure fume hood velocity?
Assessing face velocity results
- Check airflow velocity meter type.
- If possible, verify readings with another air velocity meter or by checking air volume using a pitot tube traverse of the exhaust duct.
- Supply voltage is correct.
- Exhaust unit inlet and outlet conditions are suitable.
What is the OSHA recommended fume hood face velocity for fume hood air flow rates?
Fume hoods shall be balanced with an inward flow, to a minimum of 100 feet per minute (fpm) face velocity across the opening, with a minimum of 70 fpm at any point.
What is the lower limit for the linear air velocity through a fume hood?
e. In general, a hood’s face velocity is recommended to be between 0.3 m/s (60 fpm) and 0.5 m/s (100 fpm).
What is the required face velocity of a fume hood?
100 feet per minute
Fume hoods shall be balanced with an inward flow, to a minimum of 100 feet per minute (fpm) face velocity across the opening, with a minimum of 70 fpm at any point.
How do you calculate face velocity?
Face velocity is measured in m/s and can be calculated as the volume flow rate (m³/s) divided by the face area (m²).
How much linear hood face velocity air flow is adequate for laboratory ventilation?
In general, a hood’s face velocity is recommended to be between 0.3 m/s (60 fpm) and 0.5 m/s (100 fpm).
