Engineering Controls and Laboratory Design

1. Engineering Controls and Laboratory Design Session 4 Laboratory Safety Training

2. Types of Laboratories • Academic vs. Industrial • Research vs. Instructional • Similar functions housed togeather vs. building for entire departments • Future flexibility, diversity.

3. Engineering and Architectural Principals • Laboratory buildings present difficult challenges • Very little assignable space (65%) • Energy hog, conditioned air, elec. needs, services, fire protection life safety issues, Architects must balance beauty with safety. Engineers must balance conserving energy with safety. Both must balance users needs and cost with safety.

4. Organizations Regulating Laboratory Design • Southern Building Code (SBC) • Building Officials and Code Administrators (BOCA) • National Fire Protection Assoc (NFPA) • Standard Fire Protection Codes

5. Basic life safety design components • Labs should be designed to provide at least one, usually two clear means of egress. • The building should have at least two clearly marked means of egress at opposite ends of the building for occupancies up to 500 persons (3 for 500-1000). • Doors must swing in the direction of the exit travel

6. Basic life safety design components • Travel distance must not exceed 200 ft (with no fire suppression, 250 with). • 1 hour fire rated corridors, stairwells, • Storage not permitted in these areas. • Self closures on doors. • Areas of refuge. • ADA compliance issues ramps.

7. Basic life safety design components • Emergency power for signs, lights, equipment. • Chemical Storage room requirements • Class I Division 2 requirements (normally contained flammable liquids).

8. Fire Protection Systems • Fire Protection Systems • Sprinkler systems • Co2 systems • Inergen (N2 Ar, Co2) • Dry Chemical systems

9. Fire Detection Systems • Automatic and Manual stations are required. • Networked systems. • Visual and audible. • Fire extinguishers.

10. Other Issues/Equipment • Backflow prevention on the clean water (potable) side. Contamination can occur during pressure differentials of a piece of tubing in a sink under water flush several toilets and the pressure drops on the dirty side causing a back flow of water.

11. Other Issues/Equipment • Chemical resistant casework, typically epoxy coating. • Flammable storage cabinets. • Acid storage cabinets. • Glove boxes. • Local exhaust ventilation for equipment, processes.

12. Other Issues/Equipment • Biological safety cabinets • Class I-III (glove boxes) partial to 100% exhaust. • Emergency eyewashes and safety showers. • Must tempered and require no more than 10 sec to reach.

13. Other Issues/Equipment • Compressed gas storage. • Vacuum, air, compressor issues. • Waste issues.

14. Ventilation • All labs using chemicals require 100% out side air. The number of air changes per hour (ACH) are recommended by various organizations. • Regulated by organizations like ANSI (American National Standards Institute), ASHRAE (American Society Heating Refrigeration, Air Conditioning Engineers), NFPA (National Fire Protection Association), OSHA

15. Ventilation Cont. • Because of the requirement for 100% outside air and the number of exhaust point and exhaust volume mechanical systems are one of the largest costs. • Variable air volume systems were designed to minimize these cost. • Constant air volume hood systems with set backs

16. Types of Hoods • Constant Air • VAV • Auxiliary air • Recirculated Air (bad bad bad)

17. Constant Air Volume Hoods • Known also as bypass hoods • Face velocity changes as sash is opened but total exhaust remains constant. • Advantages: • Simpler to maintain. • Can be manifolded or have individual fans. • With off time set backs can be more efficient

18. Constant Air Volume Hoods • Disadvantages • Can be inefficient in smaller labs with several hoods.

19. Variable Air Volume Hoods • Maintain a constant face velocity independent of the size of the sash opening • Tracks room pressurization (to keep room negative) to fume hood exhaust. • Manifolded system, redundant fans. • Reduces possibility of reentry into building.

20. Variable Air Volume Hoods Cont. • Potential cost savings by allowing a reduction of supply air when sash is shut. • Hoods exhaust 1000-1200 cfm • 8-10 ach, at $6-8/cfm of conditioned air can get very expensive.

21. Variable Air Volume Hoods Disadvantages • Initial cost high. • Many control points to track, potential for malfunction. • Difficulty in maintaining sophisticated controls. • When the system goes down the entire building is not exhausted.

22. Auxiliary Air Hoods • Advantages • Unconditioned air is deposited into the hood at the face. Saves on conditioned make-up air. • Disadvantages • Researcher is either cold or hot while standing at the hood. • Requires a separate supply system. • Difficult to balance, maintain containment.

23. Recirculated Air Fume Hoods • Should never be used, recirculates fumes after passing air through a filter.

28. Single Hood - Single FanCAV System

29. Multiple Hood - Single Fan CAV System

30. Multiple Hood - Multiple FanVAV System

31. Minimum hood standards • All hoods must be tested to the ANSI//AIHA Z9.5 standard. Requires a manufacturers test, as installed test and as used test. Minimum face velocity must be be 80-120 fpm, optimum 100 fpm at 18” sash opening. • Flow monitors should be installed on all new hoods with a visual or audible alarm

32. Minimum hood standards • ANSI/ASHRAE 110 , smoke visualization and tracer gas tests are recommended to identify hood performance and containment.

33. Hood installation • Fume hoods should be placed in the back corner of the room away from turbulence and diffusers. • Not near the means of exit. • Away from windows.