Handle PPE decision with care.

Inside This Story:

* This article addresses the delicate approach to selecting proper personal protective equipment, including the required steps to choose the appropriate fabric for your foundry.

* Flame resistant fabrics are explored, including how to properly handle them.

Selecting proper personal protective equipment (PPE) is not an easy decision for a foundry to make. No easy answers exist because there is not one universal solution for the industry. Newly-designed fabrics are easing the strain somewhat, but careful planning and research are still essential.

Various strategies for protecting workers around hot metal areas have been tested over the years. Clothing design techniques (shirts without pockets, pants without cuffs, slip-on boots, etc.) and special materials (treated cotton, wool, leather, etc.) have been used to increase protection. High risk areas have called for specialized protective wear (primary garments) such as spats, coats, face shields and specialized fabrics. But there has been no easy way for the industry to fully protect its personnel, especially when some plants are melting both ferrous and nonferrous metals. Serious burns and fatalities have occurred because clothing has ignited and failed to self-extinguish. With no solutions readily available, many characteristics must be taken into consideration when selecting a fabric.

Hazards

Hot metal workers face the most danger from molten metal splash and garment ignition. Molten metal that sticks to clothing can burn skin even if it does not penetrate the fabric. Some workers also must deal with electric are flash fires and corrosive chemicals, making it essential for clothing to provide protection against many different accidents.

The foundry industry has commonly relied on 100% cotton and leather to protect employees in and around the hot metal areas.

In the past, workers have been hesitant to wear flame resistant (FR) fabrics. So, in response to the growing need for flame resistant garments, 100% cotton fabrics were subjected to FR treatment coatings that left them sticky and rubbery with a smelly finish.

Today, most fabrics are inherently flame resistant. But there is not a single FR fabric that can be used for all types of hot metal or all exposures in the different metalcasting industries. To complicate matters, many laundry service vendors and manufacturing suppliers continue to bring inappropriate products into the market without fully understanding the unique needs of the foundry industry or the limits of the materials. Many fabrics are highly flame resistant but are known to be unsuitable for use with molten metals.

Suitable garments and fabrics must effectively shed molten metal and provide burn protection to the underlying skin. They must provide adequate protection against radiant heat without causing heat stress to the wearer. In the event of molten metal splash, garments must not ignite or continue to burn. Garment ignition can occur when FR treated fabrics have had the treatment removed by excessive of incorrect laundering.

Molten metals require careful evaluation to ensure the proper FR fabric is chosen for the appropriate use. For example, the 'Green" Proban/Indura (known as FR-7A or Indura cotton) is widely used in the red metals industry (work with ferrous and copper-based alloys). But the treated cotton is not suitable for use in the white metals industry (work with molten alum[num) because chemical treatment causes aluminum) to stick to the fabric. Despite that, it is among the most popular FR garments offered by vendors/suppliers in many aluminum plants.

Primary and Secondary Protective Garments 

Primary protective garments are the first line of defense and are worn over secondary garments. They include chaps, spats, gloves, over-trousers, coats, hard hats, etc. Correct use of primary garments will eliminate damage to secondary garments. But primary protective garments are unpopular due to comfort issues--particularly, the heavy aluminized garments. New, lightweight primary protective garments are currently under development.

Secondary protective clothing refers to basic FR work clothing. It is considered a major part of PPE. [t is designed for continuous wear in the workplace. One of its important FR characteristics is the ability to self-extinguish after removal from the ignition source, whereas 100% untreated cotton garments will not self-extinguish. Some industrial plants expect workers to wear secondary or basic protective clothing only when performing hazardous tasks. Secondary protective clothing should be worn at all times, but it should not be a substitute for primary protective garments.

Test Methods & Requirements

Test methods around the world vary, but their purposes are essentially the same--the measurement of fabric performance properties. It is essential that fabrics pass the Vertical Flame Test ASTM 191 A Method 5903, which measures the char length and after flame before and after 25 launderings. The ASTM F955-85 Molten Metal Splash Test also is important. It revolves pouring 2.2 lb of molten metal over the fabric at an angle between 60-70[degrees]. Heat sensors at the back of the fabric record heat transfer and indicate if a burn has occurred. This test method is now under review because it is very severe and all single-layer, lightweight fabrics will register a skin burn.

AFS uses the following as reference documents in its PPE guidelines:

* OSHA 1910.132, which legally requires the employer to conduct a hazard analysis and provide adequate protection;

* ASTM F 1002 and ASTM F955, which are considered only performance measurement standards that aren't mandatory.

Given the increasing locus on safety and liability, binding regulations are sure to evolve soon. This is happening in other industrial areas; such as Flash Fire Protection.

Comfort Issues

After FR fabrics meet all the test criteria, they must still gain acceptance from the workforce. In the past, protection level was in direct proportion to fabric weight. Those who work in humid temperatures, do extensive physical labor of are exposed to high levels of radiant heat have previously not accepted FR fabrics because more protection means heavier clothing--and often poor breathability and lack of comfort. But new fabric developments indicate it is possible to provide protection with lightweight, inherently FR breathable garments.

Treated & Untreated Fabrics

There is a perception, particularly in the hot metal industries, that heavyweight cotton is suitable as protective clothing. While it does provide reasonable splash protection as well as comfort, metal splash or electric are can easily ignite cotton.

Once ignited, it provides a vast amount of fuel for a garment. Cotton will not self-extinguish and will increase the extent of injury.

Woven fabrics, mainly 100% cotton, typically treated by passing the fabrics through a series of chemical baths in batches and then dried through a continuous oven. While the FR treatments have improved dramatically over recent years, the treatment can still be removed by incorrect or excessive laundering. This makes it difficult to determine when the garment is no longer flame resistant.

While Proban/Indura treatments on PPE work for ferrous metals, they cause nonferrous metals to stick to the fabric and rapidly burn through.

Zirpro treated wool provides excellent protection against molten metal splash, however, wool is unpopular because it can be uncomfortable and difficult to clean. The Zirpro treatment is now on the gray list in Europe. Because of ecological issues, this treatment is likely to be withdrawn in the future.

If foundry industry management decides to use treated FR fabrics, it must ensure it has a competent laundry service provider. Many laundry service providers are not successful in preserving the FR integrity of treated fabrics. An effective tracking system can monitor garment laundry cycles for deterioration.

Inherently FR Fabrics

In contrast to the treated fabrics, inherently flame resistant fabrics consist of FR fibers and yarn. The FR properties can't be removed by laundering. Although many of these fabrics are extremely FR and durable, most are not suitable for use in the hot metal industry because hot metal splash causes the fabric to soften and allows adhesion to occur.

Flame resistant garments should be designed and produced to cater to the expected hazards within the hot metal industry and should have the following features:

* garments should fit correctly and be loose enough to help with air circulation;

* garment design should ensure full body and skin coverage, and the styling should not trap metal;

* correct sewing thread is important, and the garment closures should permit easy and rapid removal;

* primary protective garments should have no external pockets;

* layering of garments provides a greater level of protection than having a single, heavyweight layer.

Once the decision is made to equip employees with the correct PPE, serious consideration must then be given to how these garments will be cleaned and maintained. Home laundering should not be an option because most common household washing powders, detergents and fabric softeners can remove the flame resistant properties on treated fabrics. On inherently FR fabrics, they can cause a build up of film, which could support ignition. The transmission of workplace contaminants into employees' homes also is receiving far greater attention. If garments become damaged for any reason, they must be mended correctly to ensure all protective properties are retained and that their life is maximized.

While no easy answers exist, newly developed fabrics may provide some help for the industry. Still, selecting PPE is a delicate process because the correct choice can drastically reduce the possibility of serious injury. But in order to put out the fires before they start careful consideration and research must be done up front.

Geoff Wynn, Technical Consulting Services, Geraldine, New Zealand Merci Flores-Magari, Protective Apparel Team, Syracuse, New York AFS Environmental, Health & Safety Div. Safety & Health Committee (10-Q)