How New-Tech applies NFPA-45


ASPS™ Sash Operator The Automatic Sash Positioning System is a sash closer for any vertically rising fume hood sash.
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Applying NFPA-45 to Phoenix Usage Based Controls^®
& the NEW-TECH™ Automatic Sash Positioning System

NFPA-45: Standard on Fire Protection for Laboratories Using Chemicals, 2004 Edition*

8.4.6 Chemical fume hood face velocities and exhaust volumes shall be sufficient to contain contaminants generated within the hood and exhaust them outside of the laboratory building.

8.4.7 The hood shall provide containment of the possible hazards and protection for personnel at all times when chemicals are present in the hood.

A.8.4.7 Laboratory fume hood containment can be evaluated using the procedures contained in ASHRAE 110, Method of Testing Performance of Laboratory Fume Hoods. Face velocities of 0.4 m/sec to 0.6 m/sec (80 ft/min to 120 ft/min) generally provide containment if the hood location requirements and laboratory ventilation criteria of this standard are met.
In addition to maintaining proper fume hood face velocity, fume hoods that reduce the exhaust volume as the sash opening is reduced should maintain a minimum exhaust volume to ensure that contaminants are diluted and exhausted from a hood. The hood exhaust airflow should not be reduced to less than 127 L/ sec/m2 (25 ft³/min/ft²) of internal hood work surface even when the sash is fully closed except where a written hazard characterization indicates otherwise. This characterization should be performed in accordance with ASHRAE 110, Method of Testing Performance of Laboratory Fume Hoods.

When using fume hoods, the face velocity is typically controlled at 100 fpm over the travel of the sash for open sash containment per the NFPA-45 A.8.4.7. The only exception to the 100 fpm is when the hood is fully closed at which time a minimum 25 CFM/ sq. ft. of work surface (or 50 CFM/ft of sash for a 24-inch deep work surface) is required. The minimum airflow equates to about 20% of the maximum airflow when the fume hood sash is fully open. This minimum ensures that when the fume hood sash is closed the fumes do not build up inside the hood.

8.8.3 Chemical Fume Hood Sash Closure.

8.8.3.1 Laboratory hood sashes shall be kept closed whenever possible.

8.8.3.2 When a fume hood is unattended, its sash shall remain fully closed.

A.8.8.3 Users should be instructed and periodically reminded not to open sashes rapidly and to allow hood sashes to be open only when needed and only as much as necessary.

Typically, during the day, fume hoods are only attended 5% of the working hours yet left open 100% of the time. This 5% equates to less than 30 minutes a day that a person needs to have there hands inside a fume hood. For this reason the Phoenix Usage Based Controls^® (UBC) was developed to save energy and the New-Tech™ Automatic Sash Positioning System (ASPS™) was developed to improve safety and save energy.

The Phoenix UBC will reduce the 100 fpm to 60 fpm (a 40% reduction in airflow) when the fume hood is unattended. However, this reduction cannot reduce the minimum airflow of 50 CFM/ft of sash when the hood is closed. So the only time the UBC system is utilized is when the sash is open and unattended which does not meet NFPA-45 8.8.3.

The New-Tech™ ASPS™ closes the fume hood sash when the fume hood is unattended thus the minimum airflow of 50 CFM/ft is achieved with any VAV fume hood airflow control system (a 80% reduction in airflow). Ensuring that the fume hood sash is closed when the fume hood is unattended complies with NFPA-45 8.8.3, provides maximum containment and energy savings.

The New-Tech™ ASPS™ doubles the energy savings compared to UBC System and the ASPS™ meets NFPA-45 8.8.3 without the need for periodically reminding and instructing the users of fume hoods to shut the sash. The New-Tech™ ASPS™ also opens the fume hood sash and controls the opening speed to optimize containment per the NFPA-45 A.8.8.3.

For more information about the Phoenix Usage Based Controls® (UBC) please see http://www.phoenixcontrols.com/Laboratory.html#UBC