hse-ls-05 fume hood training handout.pdf

HSE/LS-05: Lab Ventilation and Fume hood Training A part of 30Hrs Lab Safety Training HSE Department The Petroleum Institute

HSE/LS-05: Lab Ventilation and Fume hood Training

HSE/LS-05: Fume hood Training Handout

Slide 1 The Petroleum Institute

30-hr Lab Safety Training


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Slide 2

• Outline the importance and specifics of laboratory ventilation

• Discuss usage and functions of fume hoods

• Explain the features various types of fume hoods

• Apply safe work practice while using fume hoods

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Slide 3

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Slide 4

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Laboratory ventilation is the single most important factor used to protect people from airborne hazards. Ventilation systems can be separated into two categories:

Room ventilation (general ventilation)

Local ventilation

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Slide 5

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Laboratory room ventilation is comprised of an air supply and an exhaust system. The supply system introduces clean air into the room and the exhaust removes contaminated air.

Return Air

Supply Air

Laboratory

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Slide 6

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Based on the volume of space in a laboratory and the volume of air exhausted, an exchange rate can be determined. This exchange rate is expressed as – air exchanges per hour (ACH/hr).

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Slide 7

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• The higher the exchange rate, the faster airborne contaminates are exhausted or eliminated.

• Air exchange rates for laboratories range from 6 to 12 per hour based on chemical use.

• 98.4% of the air will be exchanged by fresh air within one hour.

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Slide 8

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• Laboratories should exhaust air at a higher rate than supplied so that the room is under negative pressure to surrounding rooms and corridors.

• Negative pressure prevents air from migrating from the laboratory into adjacent areas.

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Slide 9

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Most laboratory ventilation systems are designed to function with doors and windows closed. Therefore, laboratory doors should not be propped open and windows should remain shut.

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Slide 10

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Slide 11

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Local exhaust ventilation systems capture or contain contaminates at their source.

These contaminates are typically exhausted through a roof stack.

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Slide 12

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Chemical fume hood

Slotted hood

Canopy hood

Snorkel

Glove box

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Slide 13

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Used to capture less toxic vapors and gases used on a counter top. Air is drawn across the work surface and exhausted through the slots.

The biggest drawback is that the capture area is limited, typically within 24 inches of the slots.

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Slide 14

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Used to capture less toxic vapors and gases that are heated and rise. The canopy is located over the source of emission.

The biggest drawback is that the canopy does not capture contaminates unless they rise into the hood.

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Slide 15

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Captures less toxic substances located next to the intake. The main benefit is that it can be moved or located as needed.

The biggest drawback is that the capture area is small, typically within 24 inches of the intake opening.

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Slide 16

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- isolates and exhausts highly toxic materials. The box maintains negative pressure to prevent migration of contaminates.

The biggest drawback is that the work area is small and the manipulation of materials can be difficult.

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Slide 17

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Slide 18

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The primary safety system used to protect the laboratory worker from exposure to chemical vapors, fumes and toxic gases.

It also provides some protection to the laboratory worker from fires and explosions.

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Slide 19

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Baffles

Airfoil

Sash

Flow Sensor

Face

Gas Connections

Safety Glass

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Slide 20

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Slide 21

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• Conventional Fume Hood

• Bypass Fume Hood

• Auxiliary Air Fume Hood

• Walk – in Hood

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Slide 22

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All air enters through the hood openings from the bottom of the sash, the sides of the hood and the work surface. The lower the sash or smaller the opening, the higher the face velocity.

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Slide 23

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As the sash is closed, some air enters through a bypass grille instead of through the sash opening. This helps maintain a constant face velocity. The bypass is usually located above the sash.

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Slide 24

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This hood is similar to a conventional hood with the exception that a portion of the make-up air is provided by a separate air duct or canopy located directly above the fume hood.

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Slide 25

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A fume hood that functions properly will meet the following criteria:

The face velocity will average 0.4-0.8 meter per second with the sash open 18 inches

Air flow will flow evenly across the work surface

The hood will be structurally sound with no cracks in the safety glass

Sashes will slide properly, no parts will be missing and baffles will be open

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Slide 26

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BMM and HSE evaluate fume hoods on an annual basis. Stickers that indicate the most recent evaluation date are located on the sash.

If you suspect your fume hood is not working properly, cease operations in the hood and call BMM or raise a Help desk request

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Slide 27

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Slide 28 1. Mark a line with tape 6 inches behind the sash and keep all chemicals and equipment behind that line during experiments.

This will help to keep materials from escaping the hood when disturbances like air currents from people walking past the hood, etc., interfere with airflow at the face of the hood.

Bad placement of materials Good placement of materials Best placement of materials

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Slide 29

2. Provide catch basins for containers that could break or spill, to minimize the spread of spilled liquids.

3. Keep the sash completely lowered any time an experiment is in progress and the hood is unattended.

Note: Lowering the sash not only provides additional personal protection, but it also results in significant energy conservation.

4. Never use a hood to control exposure to hazardous substances without first verifying that it is operating properly.

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Slide 30

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5. Everyday, check flow indicators to make sure the fume hood is

functioning properly

6. If you have an older hood that has not been upgraded with a flow

indicator, hang tissue paper from the sash and observe the direction

and strength of flow

7. Contact or raise a Help Desk, if the hood is not functioning properly

8. Know the physical, chemical and toxicological properties of all

chemicals you use

9. Conduct all operations that generate contaminates at or above OSHA

exposure limits inside the fume hood

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Slide 31 10. Visually inspect the baffles (openings at the top and rear of the hood) to be

sure that the slots are open and unobstructed. For optimum performance,

adjust the baffles when working with high temperature equipment and/or

heavy gases or vapors. See figure below for suggested baffle positions.

Normal baffle position - all open.

Slot position for high temperature equipment, such as hot

plates. Lower slot is minimized since heated vapors tend to rise.

Slot position for heavy gases and vapors. Upper

slot is minimized.

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Slide 32

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Slide 33

11. Do not block slots. If large equipment must be placed in the hood, put it on blocks to raise it approximately 2 inches above the surface so that air may pass beneath it. See figure below.

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Slide 34

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12. Do not use the fume hood as a chemical waste disposal mechanism

13. Do not store chemicals or apparatus in the fume hood

14. The Fume Hood as a Storage Device

• Materials requiring ventilated storage (e.g., volatile and highly toxic, or odorous substances) may be stored in a hood if they are properly segregated and the hood is posted to prohibit its use for experimental work. (if the hoods not in active use)

• Storage of materials should be eliminated altogether. (if the hoods are actively in use for experimentation)

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Slide 35

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15.Keep the sash at the lowest possible

position and use the sash as a

shield

16.Keep the slots in the hood baffle

free from obstruction

17.Keep laboratory doors closed,

except when lab design requires the

doors to be open

18.Do not place your head or any

unprotected part of your body inside

the hood when contaminates are

present / generated

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Slide 36

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19.Minimize foot traffic and rapid movement

past the face of the fume hood (to prevent air

turbulence)

19.Do not remove the sash or safety glass except

when necessary for apparatus set- up. Replace

the sash and safety glass before use

20.Do not use a fume hood with a damaged sash or

cracked safety glass

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Slide 37

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22. Label the fume hood if the sash is to remain closed for an operation

23. Keep the fume hood clean and free of debris

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Slide 38 Conclusion

http://www.youtube.com/watch?v=nlAaEpWQdwA

In this presentation we have:

• Covered the importance and specifics of laboratory ventilation

• Discussed usage and functions of fume hoods

• Explained the features various types of fume hoods

• Outlined safe work practice while using fume hoods

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Slide 39

Presentation by:Team HSE

The Petroleum Institute

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hse-ls-05 fume hood training handout.pdf

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