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The protective clothing worn by the personnel involved in this situation was designed for structural fire fighting and could not be expected to protect the user from exposure to a molten metal fire. It is significant to note the performance of the protective clothing and equipment and the protection that it did provide, recognizing that there is no standard for protective clothing for the actual situation that was encountered.

All of the injured personnel, except the Assistant Chiefs Aide, were wearing a basic ensemble consisting of black nomex turnout coats, leather helmets, leather gloves, 3/4 length rubber boots, and self-contained breathing apparatus. The Aide was wearing a station uniform without protective clothing or SCBA.

Turnout Coats - Most of the turnout coats were several years old and appear to have been purchased prior to the adoption of the NFPA standards for protective clothing. Only one coat, worn by a younger firefighter, had a label indicating compliance with NFPA Standard 1971. Most of the coats did not have labels to identify the constituent materials or construction standards and appear to date back to the 1970s. The outer shells are black Nomex, approximately 7.5 oz. per square yard, some impregnated with neoprene to make the outer layer impermeable. (The materials appear to be generally acceptable with respect to the NFPA standards that were first adopted in 1975.)

Most of the liners appear to be needlepunch Nomex with neoprene moisture barriers and several had webbing sections in the armpit areas to allow for ventilation. One coat had a quilted liner, with no moisture barrier, but was worn under an outer shell that incorporated a neoprene moisture barrier in the shell. Another coat was worn with a nylon winter liner, in addition to the regular liner.

One coat was worn with no inner liner; only the outer shell provided protection to the user. Wearing a structural fire suppression coat in this manner is a dangerous practice, as much of the thermal protection provided by a turnout coat depends on the insulation provided by the liner.

The damage to the coats indicates that they withstood the initial fire ball created by the hydrogen explosion, without significant damage or failure. This fire ball probably lasted for only a second (or a fraction of a second) and the turnout coats would be expected to provide reasonably good protection to the body from this type of exposure. Bums could be anticipated anywhere the protection of the coat was compromised, however, such as an unsecured collar closure. The coat that was worn without a liner could be inadequate to prevent bums from this type of exposure.

Where the coats were splashed with molten sodium, it burned or melted through the outer shell and continued to penetrate into the liner material. The degree of damage indicated the pattern of molten sodium impact on the individual coats. The two lieutenants who were in the room with the sodium drum were directly splashed by the molten metal, which burned large sections of the coats and liners and penetrated through to the station uniforms, resulting in large areas of third degree bums to their bodies. In each case the major bum areas coincided with their orientation toward the drum.

Most of the other members were splashed or splattered by varying amounts of molten sodium, depending on their distance from the drum. The splatter patterns were visible where the sodium burned through the coats and into the liners. In most cases the sodium did not bum all the way through the liners; however, the heat of the burning molten sodium would be sufficient to cause second or third degree bums to the skin in these areas.

Boots - All of the personnel wore 3/4 length rubber boots, some in the extended position and some in the folded down position, as noted from the damage to the boots. This is believed to have contributed to some leg and thigh bums on the firefighters who had their boots turned down. There was no evidence of molten or burning sodium on the boots, however the exposed surfaces were coated with sodium oxide.

Helmets - The helmets were all leather and also appeared to be several years old. Due to the absence of labels it was impossible to determine their vintage or specific design features; however, none appeared to meet any of the newer editions of NFPA Standard 1974. Most of the helmets had been retrofitted with chin straps, but many were found to be secured around the brim of the helmet instead of being used to hold the helmets in place. All of the helmets are believed to have been blown off the wearers’ heads by the explosion, exposing their heads and the retaining system of their SCBA face masks to the fire.

The helmets were also fitted with Bourke eyeshields, but all of the eyeshields appeared to be in the flip-up position, indicating they were not in use when the explosion occurred. It was impossible to determine if the ear flaps had been in use at the time of the explosion, because the liners and ear flaps of several helmets had burned away.

Gloves - The gloves that were examined were leather and appeared to comply with current or recent editions of NFPA Standard 1973. The gloves protected the hands of the members who were wearing them. At least one member had removed a glove and suffered serious bums to that hand. Some wrist bums were reported where the knit wristlets bunched-up and allowed some penetration of molten metal.

Station Uniforms - Most of the personnel were wearing non-fire retardant station uniforms under their protective clothing. The Newton Fire Department was in the process of issuing fire retardant (FR) station uniforms, complying with NFPA Standard 1975; however, they were being phased-in and only one of the injured personnel is believed to have been wearing an FR uniform. Most of the personnel still wore the previous issue uniform items, which were cotton/polyester blends. (One label indicated a 65 percent polyester content and 35 percent cotton content on a particular item.) Some also wore items of non-uniform clothing.

The objective of the fire retardant station uniform standard is to avoid materials that could contribute to a bum injury by igniting or melting. The one FR uniform that was worn in this incident showed no evidence of damage, while most of the non-FR items showed some damage where they were most directly exposed to the molten sodium. The non-FR station uniforms of the two most seriously burned members were seriously damaged.

It is doubtful if the FR clothing would have made a significant difference in the bum injuries to the members who were splashed directly by molten sodium. In the cases where burning sodium splattered on turnout coats and burned into the liners, the bums might have been reduced if the members had been wearing FR uniforms. The most significant area of exposure for the station uniforms was the upper legs, thighs, and buttocks, where the uniform pants provided the only protection, particularly where the members had their boots folded down.

Evidence of the heat content of the molten metal could be seen in a pair of eyeglasses that were found in the shirt pocket of one of the firefighters. Molten sodium had burned through the coat and liner, penetrated the outer layer of the shirt material, and then penetrated through the lens of the eyeglasses, leaving a metallic luster on the inner and outer surfaces.

Breathing Apparatus - The self-contained breathing apparatus included both Scott 4.5 and Scott 2A units, depending on the company to which the individual was assigned. The shoulder and waist straps on some of the 2A units melted from heat exposure and released from the wearers’ bodies. (The straps had not been upgraded from the original black webbed material that has been noted in previous incidents to be susceptible to very rapid melting when exposed to flames.) There was also damage to the low pressure breathing tubes on some of these units, including one which separated at the regulator fitting. The face masks on the 2A models stayed in place on the users heads, since the heavy rubber “spider” straps resisted the heat exposure.

The Scott 4.5 units have fire resistant shoulder and waist straps and no problems were noted with the main harnesses; however, the facepiece retaining systems on these units were compromised by heat exposure. The netting and the single take-up straps that hold the facepiece on the user’s head were exposed to the fireball when the helmets were blown off and the straps and/or the netting failed on all of the 4.5 units. This released the facepiece from the user’s head. On one unit the lens also separated from the rubber body of the mask along the upper part of the facepiece. Some of the bums to the face, neck, and ears were particularly severe.

The facepieces of the members who were close to the explosion were completely coated with a mixture of sodium and sodium oxide which made them opaque and impossible to see through. The members trying to escape from the fire had to remove their facepieces to see anything. Where molten sodium landed on the lenses, it penetrated through the plastic material leaving a metallic coating on the inside and outside. Also, on one of the 4.5 SCBAs that was splashed directly with molten sodium, the facepiece mounted regulator was completely destroyed, including the metal parts.

All of the SCBAs were equipped with Personal Alert Safety System (PASS) devices; however, they did not appear to have been turned on at the time of the explosion. The PASS devices that were examined were still functional, but showed signs of heat exposure while in the off position. No one reported using or hearing an alarm from a PASS device.

Comment - Protective clothing and breathing apparatus that is designed for structural fire suppression does not provide adequate protection for exposure to molten metals. Molten metals, particularly burning molten metals, present a much more severe danger than ordinary structure fires. Only special protective clothing, designed to resist very high temperatures and to shed molten metals, should be used where there is a potential of coming in any contact with molten metals. There is no practical protective ensemble that would offer adequate protection for an individual splashed by burning molten sodium. Firefighters should avoid situations where there is a danger of being splashed by any molten metal.

The Newton Fire Department was in the process of evaluating newer protective ensembles, which incorporate protective trousers (bunker pants) instead of 3/4 length rubber boots. This level of protection is required by current NFPA standards; however, the acceptance of the concept has been slow in some geographic areas, particularly in New England. The analysis of the injuries in this incident clearly indicates that the bum injuries would have been less extensive if the personnel had been wearing ensembles that meet the current editions of the NFPA standards.

The currently accepted level of protective clothing for structural fire suppression includes protective coats and pants, foot protection, gloves, helmets with chin straps, full ear and neck protection, fire resistant station uniforms, self-contained breathing apparatus, and PASS devices. Most of the items used by the members involved in this incident did not meet current design standards or were used improperly, or both. A full protective ensemble, meeting the standards for structural fire suppression, could prove adequate for an incident involving a small amount of burning molten metal, where the risk of coming in contact with molten metal is remote. This level of protection should be limited to situations where the greatest risk would be to come in contact with a few droplets of molten metal, which would not penetrate the outer shell of protective coat and pants. In this type of situation a faceshield should be used over the SCBA face mask for extra protection from metal splatter on the face mask lens.

In a situation where a significant amount of molten sodium was involved and splashed directly on the firefighters, even a full set of modem structural protective clothing would not have been adequate to prevent injury. However, the degree of injury could have been reduced if the clothing had met current standards or if all the clothing that was available had been worn properly. The only way to avoid injury would have been to avoid the risk by taking no action to extinguish the fire.

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