Reviewed and Approved By:

PSFC Supervisor

PSFC Supervisor

Catherine L. Fiore, PSFC Safety Officer

Standard Operating Procedures for Use of Caustics and Acids Other Than Hydrofluoric

Author: P. Thomas/A. Eckmann

Version: 1.6

Date: February 10, 1997, Revised 12/4/1998 by C. Fiore

Persons Responsible: Paul Thomas - NW16-130

Bob Childs - NW21-109

Ed Fitzgerald - NW21-107

Introduction:

This document outlines the hazards involved with the use of acids, alkalies, and any caustic or corrosive materials. It details procedures to be followed to minimize the risk of exposure of Plasma Science and Fusion Center employees during etching, cleaning, and electropolishing procedures utilizing these chemicals. These procedures are appropriate for the handling and use of most caustic, corrosive, and irritating materials.

Scope:

This procedure covers employee safety during the handling, and use of highly caustic chemicals during etching, cleaning, and electropolishing procedures. Generally these procedures range from the use of a few milliliters or less of concentrated acids and alkalies to prepare small volumes of solution, to the preparation of up to two liters of concentrated solutions.

Safety Analysis:

Failure to follow this procedure could result in severe skin and eye irritation or burns from direct contact with acids and alkalies. Alkalies such as sodium hydroxide, potassium hydroxide, and ammonium hydroxide penetrate tissues more rapidly than acids and may cause irreversible eye damage if eye contact occurs. Alkali and acid vapors are irritating and may be corrosive to the respiratory system.

Definitions:

Primary Irritant - Capable of causing tissue damage and burns resulting from direct contact.

Responsibilities:

The supervisor or responsible person shall designate employees who are required to work with acids and alkalies, and train them regarding the health and physical hazards and appropriate work procedures. The supervisor or responsible person shall ensure that necessary personal protective equipment and spill control supplies are available to employees. The supervisor or responsible person shall ensure that operations utilizing acids and alkalies are performed in accordance with good work practices in adequately ventilated areas.

Assumptions:

Employees shall be familiar with the hazards associated with acids and alkalies and with appropriate spill and emergency procedures described in this document. The user shall be trained in the use of appropriate personal protective equipment. If respiratory protection is to be used, such protection shall have been obtained through the Industrial Hygiene Office and employees shall have received fit tests and appropriate medical examinations.

Hydrofluoric acid has unique health and physical hazards and requires special handling, spill control, and first aid procedures. Procedures for the use and handling of hydrofluoric acid are covered in a separate SOP document.

Required Supplies:

• Protective gloves. Gloves shall be worn whenever acid and alkali solutions are handled. Lightweight PVC gloves should be sufficient to prevent incidental contact with dilute solutions. Heavy nitrile or other impervious gloves shall be worn whenever concentrated solutions are dispensed. Discard gloves if any holes or leaks develop.

• Eye and Face Protection. Splash-proof chemical goggles, or safety glasses with side shields and face shields are required when dispensing or handling concentrated acids and alkalies. Safety glasses are required when using or handling more dilute acid or alkali solutions. Contact lenses may not be worn unless splash-proof chemical goggles are also used.

• Protective Clothing. A lab coat, in addition to protective gloves, is the minimum required protection for handling acids and alkalies. Impervious aprons shall be worn while transferring acids or alkalies in quantities greater than 10 milliliters.

• Spill Materials. Neutralizing, absorbent materials should be obtained to control spills. Appropriate spill control materials may be obtained from VWR. Sweeping compounds may be added to dry corrosive powder spills, which may then be carefully scooped or swept up to avoid raising dust. An appropriate container for holding any spill clean-up materials is also required. Spill pillows are available to members of the Alcator Group in the Alcator vacuum shop, NW21-167.

General Procedures:

1. Prior to initial assignment to the operation, read the Material Safety Data Sheet and become familiar with the hazards of corrosive acid and alkali materials.

2. Perform operations involving the use or transfer of acids and alkalies inside a laboratory fume hood whenever possible. If a laboratory fume hood is not available, perform operations in a well-ventilated area.

3. Do not use acids or alkalies while wearing open-toe footwear, or shorts. (These items of apparel are not appropriate for laboratory work at any time.)

4. Determine what the appropriate spill materials are by referring to the MSDS, or by consulting with the Industrial Hygiene Office, the Chemical Hygiene Officer, or the supervisor. Locate appropriate spill control materials and ensure that an adequate supply is available, including an appropriate container to hold any contaminated spill clean-up materials.

5. Ensure that an eyewash and safety shower are located nearby to flush the eyes or skin in the event of contact. If there is not an eyewash in the immediate vicinity of the operation, another employee who can rapidly escort the affected employee to an eyewash shall remain in the general vicinity of the operation.

6. Breakable containers of acids and alkalies must be carried in non-breakable secondary containers.

7. Wear protective goggles, face shield, gloves, lab coats, or other protective clothing and equipment as required by the job.

8. Always add acid to water, not the reverse. If the reverse is done, violent spattering and breakage of glass containers may occur.

9. Do not leave tongs, stirrers, caps etc., which have been contaminated with acids or alkalies where other people may pick them up or otherwise come into contact with them. Be careful not to contaminate work surfaces with these materials. If the outside surfaces of chemical storage containers become contaminated, flush the residue with water and dry the container before putting it away.

10. Any unattended containers must be labeled including the chemical identity of the material and the associated health and physical hazards. If it is infeasible to do this and containers must be left in an area unattended by the user, place a placard or sign adjacent to the container indicating the identity and hazard information.

11. Cap acid and alkali containers securely and store them on low shelves to minimize the risk of accidental breakage.

12. DO NOT store strong acids and strong alkalies together. If an accident results in rupture or breakage of the containers and they come into contact, they will react violently.

13. DO NOT store oxidizing corrosive materials including nitric acid and bleach, together with flammable solvents. The cleaning solution formed by adding sulfuric acid to sodium dichromate is a very strong oxidant which can violently react with organic matter. It ignites on contact with alcohol or acetic acid, and containers involved in fires may explode violently. Severe, slow-healing burns are caused by contact with sulfuric acid/sodium dichromate solution.

14. When the work has been completed and personal protective equipment has been removed, wash hands thoroughly with soap and water.

15. If a spill occurs, clean it up immediately in accordance with procedures described in this document. Note that laboratory furnishings (e.g., benches and sinks) sold as "acid resistant" withstand an acid spill unscathed for only a few seconds.

Training:

The supervisor or responsible person shall supply this procedure to affected employees and verify that they understand it. Employees should understand the health and physical hazards of acids and alkalies. The difficulty of rinsing alkalies from tissue and the ability of alkalies to inflict irreversible damage to the eyes, and the incompatibility of oxidizing acids or caustics with organic solvent should be emphasized.

Spill Procedures:

1. Refer to the product Material Safety Data Sheet for proper spill clean-up procedures.

2. Do not attempt to clean up any large spills, especially if the vapors from the spill result in noticeable eye or respiratory irritation. For large spills, restrict access to the spill area and dial 100. Small spills may be cleaned up by the person who caused the spill.

3. Do not attempt to clean up any spills without wearing gloves, eye, and face protection. Acids and alkalies may contaminate footwear during clean-up of a spill. If there is any possibility of contamination of footwear while cleaning up the spill, obtain shoe coverings or rubber boots.

4. Control the spill with an appropriate neutralizing agent. Scoop the material into a suitable container. Vermiculite or sweeping compound may be used to facilitate the clean up of dry alkali powders.

5. Carefully rinse contaminated areas with water. Sponges used to absorb the rinse water should be added to the spill clean-up wastes. Paper towels may only be used to wipe up dilute acids since strong acids may cause oxidation and heating of organic materials such as paper.

6. Label the waste container and contact the Safety Office (ext. 3-4736) for pick up of the spill clean-up materials.

First Aid Procedures:

1. Any splash or exposure of the skin should be immediately, thoroughly flushed for 5 - 15 minutes. Do not allow contaminated clothing to remain in contact with the skin. If skin irritation or dermatitis develops, the affected individual shall be examined at the MIT Medical Department and referred to Environmental Medical Services for a follow-up.

2. In the event of eye contact, 15 minutes of flushing with water is required. This is especially important with alkalies, which soak down deep into tissues. It is necessary to wash repeatedly in order to get strong alkaline materials out. The affected individual will likely require assistance to hold the eyelids open during the flushing. If any eye contact with concentrated acids or alkalies occurs, the affected individual shall be examined at ophthalmology (dial ext.3-4481). Dial 100 for emergencies.

3. If an individual has lost consciousness, dial 100 for emergency assistance.

4. In the unlikely event that an individual ingests acids or alkalies, immediately call the Medical Department or dial 100 for emergency assistance.

Waste Disposal Procedures:

Acid and alkali solutions may not be put down the drain, whether or not they have been neutralized. Any questions on this subject may be directed to Bill vanSchalkwyk of the Safety Office (ext. 3-4736).

Place acid and alkali wastes into clearly labeled, appropriate containers designated for this purpose. Do not mix different kinds of acids together unless instructed to do so by the supervisor with approval from the CHO. Unfilled waste containers must be held in a satellite accumulation area in accordance with MIT and PSFC hazardous waste procedures, then disposed of accordingly. See the PSFC Hazardous Waste Procedure.

References:

• MIT Accident Prevention Guide, Chapter 8. Hazardous Materials, Section 8-1, Acids and Alkalies

This page maintained by Catherine L. Fiore FIORE@PSFC.MIT.EDU