Vapor-protective Level A encapsulated suits are the ultimate defense against lethal chemical and biological agents. They are completely airtight, relying on heavy-duty, gas-tight zippers (often made of urethane or metal teeth with a rubber overlay) to seal the worker inside. These zippers are precision instruments, and the most common, fatal mistake workers make is forcing them closed-and failing to manage the "Balloon Effect."
When a worker is inside an airtight suit, their body heat and exhalation create positive pressure. The suit inflates like a balloon. If the worker tries to zip the suit while it is fully inflated, the urethane fabric pulls violently against the zipper teeth, misaligning them. Forcing the slider over misaligned teeth destroys the airtight seal, creating a microscopic channel that allows toxic vapors to infiltrate the suit. Worse, if the zipper is forced, the teeth can crush or the slider can jump the track, causing a catastrophic "blowout" where the zipper splits open while the worker is in the hot zone, instantly exposing them to the lethal atmosphere.
The Usage Protocol: Before zipping, the worker must vent the air. This is done by crouching and hugging the knees, forcing the trapped air out through the suit's one-way exhaust valves. The suit must be completely deflated before attempting to engage the zipper.
Furthermore, the zipper must be meticulously lubricated using *only* the manufacturer-supplied lubricant (usually a specialized silicone or wax stick). Never use petroleum jelly, Vaseline, or WD-40, as these degrade the urethane coating and cause the slider to gum up. Apply the lube to the leading edge of the teeth and the inside of the slider. Close the zipper slowly and smoothly with firm, even pressure. If you feel resistance, stop immediately. Do not muscle it. Re-vent the suit, check for fabric caught in the teeth, and try again. In chemical protection, the zipper is the weak link; treat it with mechanical sympathy, or it will fail you when you need it most.
