What is the evidence for limiting linens in a monoplace chamber to a minimum of 50% cotton/polyester blend? I understand the fire risks of synthetic fibers, but why is the cutoff 50%?
Thank you for your question. The UHMS Hyperbaric Oxygen Safety Committee (SC) can provide information, but ultimately the responsibility the lies with the Medical Director and Hyperbaric Safety Director of your facility.
Regarding: Concerning evidence for limiting linens in the monoplace to 100% cotton or minimum 50% cotton/poly blend.
The SC recommends submission of the question to the National Fire Protection Association, NFPA, 99 Health Care Facilities Code (http://www.nfpa.org). The NFPA has a process for the formal interpretation of these types of questions. There are several members of the SC that are also committee members of NFPA 99. Therefore, we need to add the disclaimer that this is our opinion and not a formal interpretation of the NFPA code. Testing has been completed on 55/45 cotton/poly blend fabric by the UHMS Ad Hoc Materials Testing Advisory Committee (MTAC) with more testing scheduled for January 2017. MTAC is expected to publish results is mid-2017.
Please see an excerpt below copied from the 2015 NFPA 99, Health Care Facilities Handbook:
188.8.131.52.4.1 Except where permitted in 184.108.40.206.4.3, silk, wool, or synthetic textile materials, or any combination thereof, shall be prohibited in Class A or Class B chambers.
220.127.116.11.2.2 Garments permitted inside of chambers shall be as follows:
(1) Garments fabricated of 100 percent cotton or a blend of cotton and polyester fabric shall be permitted in Class A chambers.
(2) Garments fabricated of 100 percent cotton, or a blend of cotton and polyester fabric containing no more than 50 percent polyester, shall be permitted in Class B chambers.
Why is this important?
The intent of this paragraph is to make common textiles an option in hyperbaric chambers. The amount of polyester is limited in Class B chambers to reduce the amount of static electricity. In general, cotton generates less static charge than synthetic material. However, pure cotton tends to produce lint, and accumulated lint or dust in a hyperbaric chamber is an easily ignitable fuel. Selection of textiles for the hyperbaric chamber should be based on a variety of factors, including comfort, lint production, ignition temperature, static-producing properties, and fuel load of the material. The percentage of polyester in a cotton/polyester blend can have an effect on all of these factors.
Historically, all synthetic fabrics were prohibited in the chamber. However, previous editions of NFPA 99 allowed an “antistatic blend of cotton and polyester” because of one specific fabric – a blend of cotton and polyester with steel fibers, originally intended for surgical scrubs – whose conductive properties made it a good choice for hyperbaric garments. The polyester in the fabric was deemed acceptable because the conductive properties of the fabric actually afforded some protection from static production that cotton fabric did not. Unfortunately, this particular fabric is no longer made. Selection of textiles has always been about balancing various safety concerns. Further guidance on selecting appropriate textiles can be found in A.18.104.22.168.4.3.
For the 2015 edition of the code, a differentiation was made between the garments permitted inside of Class A and those permitted in Class B chambers. There is now a maximum limit on the percentage of polyester permitted in blends that are allowed in Class B chambers. This is based on the different risks for each type of chamber. Class A chambers typically maintain an oxygen concentration below 23.5 percent and have fire suppression capability; the opposite can be said for Class B chambers.
A.22.214.171.124.4.2 Selection of textiles for the hyperbaric chamber should be based on a variety of factors, including comfort, lint production, ignition temperature, static-producing properties, and fuel load of the material. The amount of polyester in a cotton/polyester blend will likely have an effect on all of the factors.
Historically, all synthetic fabrics were prohibited from the chamber. Previous editions of this code allowed an “antistatic blend of cotton and polyester” because of one specific fabric – a blend of cotton and polyester with steel fibers to make it conductive. This blended fabric was intended for surgical scrubs, but its conductive properties made it a good choice for hyperbaric garments. The polyester in the fabric was acceptable because the conductive properties of the fabric actually afforded some protection from static production that cotton fabric did not. This particular fabric is no longer made. Selection of textiles has always been about balancing various safety concerns; primarily fire-resistance and static production. For further guidance on selecting appropriate textiles, see A.126.96.36.199.3.
188.8.131.52 All other fabrics used in the chamber, such as sheets, pillow cases, and blankets, shall conform to 184.108.40.206.4.1 and 220.127.116.11.4.2”
Neither the Undersea and Hyperbaric Medical Society (UHMS) staff nor its members are able to provide medical diagnosis or recommend equipment over the internet. If you have medical concerns about hyperbaric medicine you need to be evaluated by a doctor licensed to practice medicine in your locale, which can provide you professional recommendations for hyperbaric medicine based upon your condition. The responsibility of approving the use of equipment resides with the physician and safety director of the facility. Information provided on this forum is for general educational purposes only. It is not intended to replace the advice of your own health care practitioner and you should not rely upon it as though it were specific medical advice given to you personally.