Multiplace Delivery System

Monthly Hyperbaric Safety Notice: August 2006

100% Cotton & Cotton / Polyester Blends in the Chamber

NFPA 99 2005 edition 20.3.1.5.4.2⁽¹⁾ allows us to use garments of 100% cotton or a cotton blend of polyester and cotton in class A and class B chambers if we meet the fire protection as specified in 20.2.5. ⁽²⁾ NFPA 20.2.5 deals with the facilities fire suppression system. An example is the requirement to be able to activate the FSS from the main panel.

The choices of textiles should be based on ignition temperature and static producing properties. (1)

The ignition point of 100% cotton fabric is documented at 450 f / 250c. ^{(3) (4)} The ignition point of blends is harder to determine, there have been no studies that I have been able to find. Most communications have referred me to the burning point of cotton as a guide. ⁽⁵⁾ With the exception of the lighting in our chambers we are not using anything in the multiplace or monoplace chambers that produces 450 f / 250 c.

A spark from static electricity has not produced ignition in 100% cotton, cotton blends, polyester and a variety of other material commonly found in clinical chambers. This has been demonstrated at various pressures and oxygen concentrations. The concern is with gaseous combustibles. ⁽⁶⁾

The risks of increased oxygen in the chamber require us to use caution when operating the chamber and exclude items that produce sparks, heat and burnable vapors. ⁽⁷⁾ The main risks have been items with those properties brought into the chamber. 100% cotton or poly / cotton blends in and of themselves do not create those risks. Wool, silk, and synthetic materials do produce static and are prohibited from the chamber. I have experienced static in the poly / cotton blends but was unable to produce a study, there are so many types of blends. For use in the hyperbaric chamber it is probably better to aim for the lowest possible amount of polyester in the blend. It is unlikely that a single static spark will ignite a poly / cotton blend unless there are flammable vapors present. The textiles used in the chamber do provide a fuel source and cotton will burn differently than the blends, with different end results. There is a concern with the amount and type of fuel present in the chamber. There will always be a source of fuel in the clinical hyperbaric chamber. All unnecessary items should be taken out of the chamber before pressurizing. Reclothing the patients in the hyperbaric supplied attire is essential. Street clothes are not acceptable because of the increased risks. There could be “forgotten” cigarette lighters, hand warmers, grease / oil from the car etc in or on the clothing. By reclothing you also have the opportunity of making sure that aftershave, perfume, make-up and those types of products that may produce a burnable vapor are washed off.

The current trend in the hospital linen supply is away from 100% cotton and more towards 65/35 poly cotton blends. With the change in the NFPA standard we have considered continuing to cloth the staff in 100% cotton and have the patients wear 50/50 poly cotton blends. This has proven problematic. 100% cotton scrubs have been difficult to find and expensive. The linen room has had to pull 50/50 poly cotton scrubs by hand as a special order. The sheets and linens are bulk items for several area hospitals and it is difficult to verify the content of the fabric. Our current policy is to allow 100% to a maximum of 65/35 poly/cotton blend textiles in the chamber. Our patients wear hospital-supplied linen of 100% cotton to 65/35 poly/cotton blends. The bedding continues to be the hospital-supplied linen. We work closely with the linen supply room to insure our needs are met (maximum of 65% poly). The staff scrubs are 100% cotton to 65/35 poly / cotton blends and different color(s) to distinguish between patient, and staff.

Key Points

The NFPA 99 2005 edition, chapter 20, 20.3.1.5.4.2 Allows the use of garments made from 100% cotton or a blend of polyester and cotton in class A and B chambers if the fire protection specified in 20.2.5 is met.
Choices of textiles should be based on the ignition temperature and static producing properties. Ignition point of cotton is 450 f / 250 c / blends are assumed to be essentially the same.
Static spark has not produced ignition in cotton or cotton blends at various pressures and oxygen concentrations.

Key Operational Issue

You can use 100% cotton or Cotton / Poly Blend in the class A chamber if you have a fire suppression system that meets NFPA 99, 2005, chapter 20.

References:

Excerpt NFPA 99 20.3.1.5.4
Excerpt NFPA 99 20.2.5
Physical Constants for investigators, Tony Café, T.C.Forensics PTY Inc.
Excerpt American Pyrotechnics Ass.
Personal communications; Technical services of the National Fire Protection Association & the Department of Energy also Steve Wood RT CHT, Dick Clark CHT, Greg Raleigh CHT
Section IV Fire in the hyperbaric environment, 3, Static Electricity, Steve Wood, Hyperbaric Facility Safety: A Practical Guide, Wilbur T. Workman
SectionIV Fire in the hyperbaric environment, 2, Role of Oxygen in Hyperbaric Safety, Harold Beeson and Bill Hamilton, Hyperbaric Facility Safety: A Practical Guide, Wilbur T. Workman

Contributing Author: James Bell, CHT, EMT

James Bell Jim has over 25 years experience in the operation and maintenance of multiplace hyperbaric chambers. He serves as safety director and lead hyperbaric technologist at Hennepin County Medical Center, in Minneapolis, Minnesota, USA. Jim is a certified hyperbaric technologist, and an Undersea and Hyperbaric Medical Society facility accreditation surveyor.

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