Reviewed and Approved By:
Catherine L. Fiore, PSFC Safety Officer
Author: B. Childs/A. Eckmann
Date: August 3, 1992, Updated 11/25/98 by C. Fiore
Persons Responsible: Bob Childs - NW21-109
Frank Silva - NW21-105
Paul Thomas - NW16-130
Other PSFC Supervisors
This document outlines the hazards involved with the handling and use of halogenated organic solvents. It details procedures to be followed to minimize the risk of exposure of Plasma Science and Fusion Center employees to solvent vapors and toxic combustion products associate with the use of halogenated solvents. Halogenated solvents routinely used at the PSFC include:
- 1,1,1-Trichloroethane (also referred to as Chlorothene)
- Freon TF (1,1,2-Trichloro-1,2,2-trifluoroethane)
Dichloromethane (also referred to as methylene chloride) and 1,2-dichloroethane (also referred to as ethylene dichloride) may be used for Plexiglass gluing operations. Trichloroethylene is used at the PSFC for specific small-scale cleaning operations. Both methylene chloride and trichloroethylene have been designated as human carcinogens by the International Agency for the Review of Carcinogens (IARC). Ethylene dichloride has been designated as a suspect human carcinogen by the National Toxicology Program (NTP).
In addition, many products found in the PSFC laboratories contain halogenated solvents. These include a number of flux removers and cleaners contained in aerosol spray cans; some paints and spray paints; Spotcheck Zyglo penetrants, developers, and cleaners; and many "Dust-off" type sprays.
Halogenated solvents are widely used because they are essentially non-flammable, and do not present a fire and explosion risk. However, when combustion does occur in an atmosphere containing halogenated solvent vapors, the vapors may decompose and react with the air to form highly toxic gases.
This procedure covers employee safety during the handling and use of halogenated solvents used for cleaning and general precautions to be followed when using and handling other products containing halogenated solvents.
Failure to follow this procedure could result in primary skin and eye irritation from direct contact with halogenated solvents; skin defatting or dermatitis from prolonged or repeated skin exposure to halogenated solvents (when the fatty layer of the skin is damaged, an individual becomes more susceptible to dermatitis, and many chemicals may be readily absorbed through the skin); central nervous system depression from exposure to high concentrations; kidney or liver effects from chronic exposure to elevated concentrations; and heart arrythmias from exposure to high concentrations of Freon. There are some variations in the specific potential toxic effects associated with different Freons. Trichloroethylene, methylene chloride and ethylene dichloride are potentially carcinogenic compounds. Many halogenated solvents are much heavier than air and rapidly replace oxygen in a confined area, which could lead to oxygen deprivation. Acutely toxic gases can be generated when halogenated solvents come into contact with open flames and hot surfaces. Most halogenated solvents cause mild to severe eye irritation but do not cause irreversible eye injury.
Primary Irritant - primary irritant causes reaction by direct contact with the skin, eyes, or respiratory system if the concentration and exposure time are sufficient.
Skin Defatting Agent - skin defatting agent causes deterioration of the fatty layer of the skin with prolonged or repeated contact.
Carcinogen - Any substance which may cause the development of cancerous growths in living tissue.
Note: Use of the word solvents in this procedure is defined to mean halogenated solvents.
The supervisor or responsible person shall designate and train employees who use halogenated solvents or products which contain halogenated solvents. The supervisor or responsible person shall ensure that necessary supplies are available to clean up spills of such solvents. The supervisor or responsible person shall ensure that all halogenated solvents and products which contain halogenated solvents are used in accordance with good work practices in adequately ventilated areas.
The supervisor or responsible person shall be familiar with the hazards associated with the handling and use of halogenated solvents and products containing such solvents, and appropriate spill and emergency procedures described in this document.
Procedures involving the use of halogenated solvents or products containing halogenated solvents shall only be performed in well-ventilated areas.
All disposal of waste materials will be done in accordance with MIT and PSFC hazardous waste procedures.
Protective Gloves - Protective gloves are not recommended for protection against Freon. The lightweight PVC gloves should be used only for damp wiping of previously cleaned parts. Under no circumstances should these gloves be immersed in or washed with liquid solvent. These are not recommended where substantial skin contact with the solvent will occur, for example, when hands are submerged in the solvent. Heavier Nitrile gloves are required for immersion or prolonged or repeated contact with the solvents and during the clean-up of chemical spills.
Glasses -Ordinary safety glasses are sufficient for small-scale operations. Splash-proof chemical goggles shall be worn when transferring volumes greater than 500 ml or when operating open surface tanks, such as the "coffin" degreaser located in NW21-167. Employees who wear contact lenses or who do not wear glasses must be provided with splash-proof chemical goggles when handling solvents.
Spill materials - Paper towels or adsorbent materials such as spill control pillows, chemical resistant gloves (Nitrile), and a suitable container, e.g., the polyethylene bag provided with the spill pillows.
Perform cleaning inside a laboratory fume hood whenever possible. Squeeze solvent onto a cloth and wipe the surface to be cleaned. Use a drip pan to collect any run-off. Paper towels or lint-free wipes may be used to wipe the workpiece. When cleaning is complete place the used cleaning materials in a bag labeled with a properly coded red tag in a satellite accumulation area for disposal through the safety office. Don't place any rags or towels in the trash.
Don't allow the excess solvent which has collected in the drip pan to evaporate to dryness in the fume hood. Place the used solvent in a designated, properly labeled waste container in a satellite accumulation area. Don't mix different kinds of solvents in waste containers unless instructed to do so by the supervisor.
Soaking workpieces in metal trays or other containers for cleaning purposes shall be performed inside a laboratory fume hood whenever possible. If a laboratory fume hood is not available, such procedures shall be performed in open, well-ventilated areas. A label shall be affixed to any container used for this purpose, indicating the identity of the solvent, and the health hazards. Pre-printed labels for specific solvents are available in the Stockroom. If this is not feasible because cleaning of the outside surface of the container is required, a sign may be placed next to the container indicating this information. The only exception to this labeling requirement is if:
When the cleaning is complete, the workpiece may be allowed to evaporate to dryness in the laboratory fume hood.
Do not allow the spent solvent to evaporate to dryness in the fume hood. Place the used solvent in a designated, properly labeled waste container in a satellite accumulation area. Do not mix different kinds of solvents in waste containers unless instructed to do so by the supervisor.
Often the outside surfaces of equipment be contaminated with oil when such equipment drained in order to change the oil. This can be minimized by carefully following the equipment manufacturer instructions for draining the pump oil. In any event, drain as much oil from the equipment as possible BEFORE cleaning the outside surface with solvent.
If it appears that it will be necessary to clean the outside surface of the equipment by washing it with solvent, OBTAIN A SUFFICIENTLY LARGE DRIP PAN TO CATCH the solvent run-off. Do not collect the solvent run-off in the same drip pan with the oil. If necessary, empty the oil into an appropriate waste oil container, and wipe the excess oil from the drip pan prior to squirting solvent onto the equipment. Where possible, use paper towels wetted with the solvent to wipe off the surface, rather than squirting it directly with the solvent.
When cleaning is complete place the used cleaning materials in a bag labeled with a properly coded red tag in a satellite accumulation area for disposal through the safety office. Place the used solvent in a designated, properly labeled waste container in a satellite accumulation area. If the waste solvent is heavily contaminated with oil, do not mix it with cleaner waste solvents. Obtain guidance from the supervisor or CHO if necessary.
Place the solvent and the part to be cleaned into a beaker and place the beaker in the ultrasonic cleaner bath. Make sure the ultrasonic cleaner is filled with the appropriate medium. Turn the ultrasonic cleaner on and operate until the part is sufficiently cleaned. Remove the part while the ultrasonic mechanism is still operating. When finished, immediately place the waste solvent into a designated, properly labeled waste container in a satellite accumulation area. Do not leave an unlabeled beaker containing solvent in the ultrasonic degreaser.
Solvents may be transferred by pouring from 1 gallon containers. These may be secondary containers filled from a horizontally positioned drum with a self-closing spigot. In the latter case, a funnel shall be used. Transfer from upright 55 gallon drums using a pressurized transfer device may only be done under the supervision of Bob Childs and is covered under the separate SOP document , "PSFC-CH-91006 Transferring Halogenated Solvents to and from 55 gallon drums".
Place the part into a basket or other holding device and submerge it in the solvent reservoir. When the parts are clean, remove slowly while the ultrasonic mechanism is still operating. Hold the basket so that the excess solvent drips back into the solvent reservoir. Allow the parts to dry in an area equipped with local exhaust ventilation, if possible. When finished, turn off the ultrasonic mechanism and cover the solvent reservoir with a fitted lid. If the solvent has to be removed, it shall be done with a solvent transfer pump under the supervision of Bob Childs. Use of the solvent transfer pump is covered under the separate SOP document , "PSFC-CH-91006 Transferring Halogenated Solvents to and from 55 gallon drums".
Users shall read the labels on the aerosol cans and be aware of the hazardous components of the such products. Spray aerosols shall be used inside laboratory fume hoods whenever possible, and their use outside of a laboratory fume hood shall be in designated approved areas.
Use of this degreaser involves the transfer of up to 80 gallons of halogenated solvent. This work shall be performed under the supervision of Bob Childs and is covered under the separate SOP document , "PSFC-CH-91006 Transferring Halogenated Solvents to and from 55 gallon drums".
Methylene chloride and ethylene dichloride are used in eyedropper quantities to glue Plexiglass. These chemicals shall be purchased in quantities of 500 ml or less, however, there may be larger containers within the PSFC which can be used up. When transferring methylene chloride from a larger container into an eyedropper bottle, perform the transfer inside a laboratory fume hood. Ensure that secondary containers of methylene chloride are labeled with the chemical identity and the associated health hazard warnings. Users should be advised of the health hazards of these chemicals.
The supervisor shall supply this procedure to affected employees and verify that they understand it. The potential generation of acutely toxic gases when halogenated solvents come into contact with open flames and hot surfaces should be emphasized. Employees should understand the health hazards of routinely using halogenated solvents.
The major hazard of large spills is the potential build-up of vapors which are heavier than air, resulting in an oxygen-deficient atmosphere. Therefore, spills are most hazardous in poorly ventilated areas. Notify the supervisor immediately of any large spills. Spills of less than 5 gal. may be cleaned up if there is local exhaust ventilation operating adjacent to the spill and the supervisor has been notified. For large spills, shut off any ignition sources, and call the Industrial Hygiene Office at 3-2596. If there is personal injury or a strong threat of personal injury, dial 100. Do not let anyone enter the spill area.
Nitrile gloves are the minimum required protective equipment for cleaning up spills. Contain the spill with absorbent spill pillows or other appropriate absorbent materials. If none are available in the immediate vicinity, emergency supplies can be obtained from NW21-167. Small spills of a few milliliters may be absorbed or wiped up using paper towels. After absorbing any excess liquid, clean-up materials should be placed in a the plastic bag provided with the spill kit or suitable container and labeled as hazardous waste. The Safety Office (x3-4736) should be called for a pick-up.
In the event of skin contact, the affected area should be washed with soap and water (preferably the pink lanolin containing liquid soap). Contaminated clothing should be removed since wet clothing may hold chemicals in contact with the skin. If skin irritation or dermatitis develops, the affected employee shall be examined at the Medical Department.
In the event of eye contact, flush the eye of the affected employee with water for 15 minutes. The affected employee shall be examined at MIT Ophthalmology. If an employee has lost consciousness, dial 100 for emergency medical assistance. In the unlikely event that an individual ingests the solvent, dial 100 for immediate transport to the MIT Medical Department for examination.