CHEMICAL PROTECTIVE CLOTHING —Do We Understand It?
HAZARDOUS MATERIALS
In recent years, the fire service has become more and more involved with mitigating incidents involving the release of hazardous materials and wastes. In response to this involvement, departments have been budgeting for and receiving approval to procure chemical protective clothing and equipment. The fact that so many departments have gotten the green light to purchase this expensive equipment in these times of tight budgets supports the contention that the public is genuinely concerned about hazardous chemicals.
And a genuine concern of the fire service should be just how effective their protective clothing is.
CHEMICAL SUIT MISCONCEPTIONS
Chemical protective clothing is that clothing designed to afford a known amount of protection against a known type, concentration, and length of exposure to a hazardous substance. Hazardous substance, in this context, is any material that may acutely or chronically effect the human body through limited or prolonged exposure (inhalation, absorption, and/or ingestion).
Chemical protective clothing does not allude to a miraculous garment that allows the wearer to wander about like Superman in any type of hazardous environment. It does not permit the wearer to literally swim in a wide variety of hazardous substances, impervious to all chemical harms.
We feel that the term “chemical protective clothing” has become an abused, misunderstood phrase in the fire service. No garment, we repeat, no garment is designed nor intended for the wearer to go wading about unconcerned in a myriad of hazardous substances.
Exactly what does chemical protective clothing mean and what protection does it afford?
WHAT ACTUALLY IS CHEMICAL PROTECTIVE CLOTHING?
In reality, there exists a wide selection of various types of chemical protective clothing constructed of a variety of materials and suited for specific types of hazardous exposures. Even a suit constructed of a certain material, designed to afford protection against a certain hazard, is limited in that protection. Various factors such as temperature, thickness of the suit material, and concentration of the hazardous substance play major roles in the suitability of any garment in a given situation.
A term we constantly hear is “acid suit.” Forget you ever heard that expression and think from now on in terms of “chemical splash suit.” Chemical protective clothing (chemical splash suit) is a protective garment designed to protect the wearer in case he is accidentally splashed with a hazardous substance. Again, chemical protective clothing is not designed to go wading about, knee deep, in who knows what.
Chemical protective clothing, totally encapsulated suits, onepiece coveralls, two-piece pants and jacket, or whatever, is designed to afford a limited amount of skin protection in the event the garment is accidentally contacted by a hazardous substance.
When the wearer of chemical protective clothing is exposed to a hazardous substance by direct contact, the accepted procedure is to leave the hazard area, decontaminate the garment, and inspect the garment for any obvious damage or indication that its integrity may be suspect (see “Exposure Suit Inspection Procedures,” FIRE ENGINEERING, February 1985). If the garment is suspect, it should be subjected to a thorough inspection and test before being either placed back in service or appropriately disposed of.
Under emergency conditions, personnel may be required to expose themselves to a hazardous substance far beyond what may be defined as a “splash” condition. One such case involved a railroad car containing 20,000 gallons of 37% hydrochloric acid. The substance was leaking through a hole the size of a person’s thumb in the center of the tank.
Circumstances dictated that the car not be moved and that it be patched as soon as possible due to the close proximity of a highway and homes. Remote patching or product transfer was not feasible; the only way to effect adequate patching of the tank car was for someone to lie under the car, across the railroad tracks, thereby allowing the acid to leak on him. Prior to attempting this task, the type and level of chemical protective clothing was carefully considered. Even though satisfied that the garment material was adequate to afford protection from leaking hydrochloric acid, there were frequent interruptions in the patching procedure to decontaminate and inspect the garment.
If you are faced with a situation that may require direct contact with a hazardous substance, you must implement sufficient safety procedures, including:
- Avoidance of prolonged exposure;
- Adequate decontamination procedures;
- Garment inspection after decontamination and before re-entry;
- Sufficient backup garments in the event of garment failure;
- Defined and limited exposure intervals between decontaminations and inspections.
The 1984 Department of Transportation’s (DOT) EMERGENCY RESPONSE GUIDEBOOK divides protective clothing into two categories, full protective clothing and special protective clothing and equipment. By their definition, full protective clothing means “. . . protection to prevent inhalation of, ingestion of, or skin contact with hazardous vapors, liquids and solids. It includes a helmet, self-contained breathing apparatus, coat, pants, rubber boots, and gloves customarily worn by firefighters. This turnout clothing may not provide protection from vapors, liquids, or solids encountered during hazardous material incidents.”
Special protective clothing is defined by the DOT guidebook as . . clothing and equipment that will protect the wearer against the specific hazard for which it was designed. This special clothing may afford protection only for certain chemicals and may be readily penetrated by chemicals for which it was not designed. Do not assume any protective clothing is fire resistant unless that is specifically stated by the manufacturer.”
LEVELS OF PROTECTION
The highest level of chemical protective clothing consists of a fully encapsulated chemical-resistant suit, chemical-resistant gloves and boots, and a positive pressure self-contained breathing apparatus (SCBA). This level of protection should be worn when maximum protection is needed against substances that could damage the surface of the skin and/or be absorbed through the skin.
A lesser level of protection against chemicals consists of positive pressure SCBA, chemical-resistant clothing, and chemical-resistant gloves and boots. The chemical-resistant clothing may consist of overalls and a longsleeved jacket; coveralls; a hooded, oneor two-piece chemical splash suit; or disposable chemical resistant coveralls. This level of protection provides a high level of protection to the respiratory tract, and a reasonably high degree of protection to the skin.
The lowest level of chemical protective clothing consists of the same non-encapsulating clothing as described above, but instead of the positive pressure SCBA, a fullface, air-purifying, canister or cartridge equipped respirator is worn. Since this level of protection, common in industrial applications, does not provide the highest level of respiratory protection, it should only be worn after type(s) of air contaminant(s) is identified and concentrations measured.
The level of protection required is determined after:
- Positive identification of the hazardous substance is made;
- The hazards and quantities of the substance are assessed;
- The role of the personnel entering the hot zone is established;
- The likelihood of contact with substance is determined.
Positive identification of the hazardous substance is of primary importance before selecting chemical protective clothing. This positive identification may be accomplished through a combination of shipping papers, labels, markings, and/or responsible authority. A responsible authority may be the shipper, transporter, or consignee of a spill occurring in shipment, or it may be a plant operator, supplier, or plant employee.
In most instances, positive identification of a hazard may not be possible without approaching the hazard; and if you must approach the hazard, you must don chemical protective clothing.
However, if we don’t know the identity of the hazardous substance that we want to protect ourselves from, the selection of the proper garment is difficult. In such a situation, in addition to wearing the chemical protective garment, we must depend on certain basic precautions to avoid contact with the chemical:
- Any approach should be made from an upwind, upgrade position, avoiding direct contact with substance or vapor.
- The length of exposure, if any, should be kept to an absolute minimum.
- Decontamination should be effected as quickly as possible after exposure.
SELECTING CHEMICAL CLOTHING
Once the hazard has been identified, then the proper type and level of protective clothing can be selected. If your department only has one type of chemical protective clothing, the selection becomes somewhat simplified. However, we should all know and understand exactly how well our chemical protective clothing will hold up against specific hazards.
Whether you now own or intend to purchase chemical protective clothing, you should contact your safety supply house or manufacturer for chemical resistance information for your particular garment. General chemical resistance charts may not be adequate. Different formulations in the manufacture of a material, variations in thickness or construction standards will affect the garment’s ability to hold up when exposed to certain chemicals. There are some general guidelines that can be followed when selecting chemical suits, such as avoiding wearing rubberized materials when mitigating an incident involving solvents, but, to be safe, you should acquire chemical resistance information from the manufacturer.
CHEMICAL SUIT CONSIDERATIONS
If you are about to purchase your first set of chemical protective clothing, you will find that a single material such as butyl rubber, neoprene, or polyvinyl chloride (PVC) will probably not be adequate for all your needs. However, budget restrictions may allow for the purchase of only one type of chemical protective clothing. If that is the case, be sure that your training emphasizes the limitations as well as the capabilities of your chemical protective clothing.
In addition to the chemical resistivity of the material that the protective clothing is constructed of, there are other factors to consider. For example, the strength of the material to withstand tears, punctures, abrasions, etc., must be tempered with its ability to remain flexible. It is not inconceivable to manufacture a garment with materials so thick that it would be like the days of King Arthur, where a winch was used to mount the knight on his horse. Though the wearer might be well protected, he would most likely be unable to accomplish any tasks requiring manual dexterity. Special care should be taken in this area when selecting gloves, as manual dexterity with one’s hands is critical. Any seams that are sewed should be covered with a coating of the same material as the suit construction. Don’t accept a glue or other adhesive that gives the appearance of protecting the seams; oftentimes it will decompose upon contact with some hazardous substance against which the garment is intended to protect the wearer.
A flap should cover the zipper when it is secured.
The garment should have some type of loop or other device attached which will permit it to be suspended for testing and inspection. Experience has shown that garments stored by rolling, hanging, or laying flat last longer than those that are folded or stuffed into storage containers.
You should consider the ability of the garment to withstand the effects of degradation and penetration as well as permeation.
Degradation is usually the obvious physical damage that occurs where a substance has contacted the suit, boot, or glove. Penetration can be likened to a sharp or pointed object penetrating a garment. Permeation is a property of the material that can be described most easily by considering a series of actions that occur. The first step in permeation is that of contact; a hazardous substance has contacted the outer surface of the garment. Some time after contact, breakthrough of the outer surface occurs. The liquid or vapor of the hazardous substance begins to be absorbed by the material of the garment. The next step is transition, the movement of the hazardous substance through the protective material towards the inner surface of the garment. Finally, breakthrough of the inner surface occurs. The hazardous substance has now been completely absorbed through the material and can now come into contact with your inner garment and/or your skin.
This permeation rate (break-through of outer surface, absorption, and breakthrough of inner surface) depends upon:
- The substance in question;
- The concentration of the substance;
- The protective clothing material used;
- The thickness of the protective material used.
Generally, the manufacturer of the material or the manufacturer of the garment can provide you with the permeation rate for their products when exposed to specific hazardous substances. It is impractical for manufacturers to test their garments for permeation rates for all hazardous substances. We advise you to acquire whatever permeation information manufacturers have and submit this information to an outside consulting firm (unless the expertise exists inhouse) to evaluate probable permeation rates for common chemical families such as organic acids, inorganic acids, chlorinated solvents, etc. This will help you make an intelligent selection of chemical protective clothing.
For example, if a nine mil thick neoprene material will withstand direct exposure to a concentrated form of chemical “X” for four hours, and an eleven mil thick PVC material will withstand direct exposure to the same chemical for two hours, the choice would be the nine mil thick neoprene, even though the PVC is thicker.
The manufacturer may provide longer exposure times for thicker materials. When ordering chemical protective clothing, you can often specify material thickness.
SELECTING PROPER PROTECTION
The choice of chemical protective clothing of course depends upon your needs and unfortunately your budget; and we do not recommend the purchase of one type of suit vs. another. However, when purchasing chemical protective clothing, we do recommend selecting several different types of chemical suits made of different materials in order to assure that the proper garment will be available for almost any incident. This option can be very expensive when purchasing encapsulated suits, and, as a result, many departments choose what they feel to be a multi-use economical material for their encapsulated suits and two or three other materials for their nonencapsulated protective clothing.
Some of the most common suit materials include viton, neoprene, butyl rubber, and PVC, with a wide variety of coatings over some of these suits. These materials are by no means the only materials available, but they are among the most common used.
The most expensive, but also most versatile, suit is probably the viton. Some viton suits have been priced at a cost four times that of butyl rubber. A large number of departments are purchasing the butyl rubber encapsulated suit primarily for its flexibility (relative to multiple uses) and durability.
Tyvek undergarments normally are worn in lieu of street clothes under protective outer garments to prevent potential contamination of street clothes. The Tyvek garments are disposable and relatively inexpensive, and some “coated” Tyvek suits are effective as chemical protective clothing, offering adequate protection from some chemicals. Again, you must know the type(s) and concentration(s) of hazards you expect to encounter as well as what these “coated” suits are recommended for.
SUMMARY
The various levels of protective clothing are determined by the level of respiratory and skin protection that is needed. Before selecting a type and material of protective clothing, consider factors such as:
- Permeability rate for specific hazards;
- Thickness of the protective material;
- Cost;
- Ease of decontamination;
- Ease of cleaning (dirt and grease removal);
- Aging resistance;
- Flexibility.
Normally, outside assistance in the form of a consulting service is advised in order to provide guidelines for selecting protective clothing materials.
We do not believe that cost should be a prime factor in the selection of chemical protective clothing, but cost and budget restrictions are a fact of life. If cost precludes purchasing the “best,” it may not preclude purchasing an adequate garment.
