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SCBA Information

Quick Tips #193

Ranging in price from $3,000.00 to over $10,000, a pressure-demand SCBA (Self-Contained Breathing Apparatus) represents a substantial financial investment to employers. Before purchasing an SCBA, decisions must be made to ensure the SCBA selected is appropriate for its intended use. The type of application, the length of the application and the anticipated frequency of the application are all variables an employer must examine before purchasing an SCBA to make sure they're getting the correct product.

In the hierarchy of respiratory protection, SCBAs provide the highest level protection available. They offer respiratory protection against toxic gases and oxygen deficiency. The wearer is independent of the surrounding atmosphere because he or she is breathing with a system that is portable and admits no outside air.

Type of Application

When it comes to choosing an SCBA, the employer must first consider the intended application for the product. If the SCBA will be used for firefighting purposes, then a National Fire Protection Association (NFPA) 1981 compliant unit is necessary. If firefighting is not the application, then a basic National Institute for Occupational Safety and Health (NIOSH) compliant SCBA is most appropriate.

Industrial SCBAs

For applications other than firefighting, non-NFPA compliant SCBAs are a more economical alternative for employers. A NIOSH compliant industrial SCBA is appropriate for industrial confined space applications, applications where the levels of contaminants exceed the immediately dangerous to life or health (IDLH) concentrations, situations where the contaminant(s) and/or the contaminants concentration are unknown and oxygen deficient (oxygen concentrations below 19.5%) environments.

NFPA 1981

NFPA 1981 compliant SCBAs are required for firefighting applications. All NFPA compliant SCBAs also meet the NIOSH requirements for basic industrial SCBA protection. NFPA 1981 contains testing and material component requirements for SCBAs to ensure the units will withstand the environments in which firefighters must perform. One of the obvious requirements of NFPA 1981 is that the harness materials on an SCBA must be heat and flame-resistant.

In September of 2002, the NFPA adopted a revision to their 1981 Standard (NFPA 1981, 2002 Edition) that supersedes the requirements of the previous 1997 edition of NFPA 1981. Many of the 2002 edition changes affect the compliance testing of the SCBA. Two major inclusions in the revision are requirements for a heads-up display (HUD), and a rapid intervention crew universal air connection (RIC/UAC). All NFPA 1981–2002 edition compliant SCBA must include these features.

The requirement for the HUD calls for a light-emitting diode (LED) indication of approximately full, three-quarter, one-half and one-quarter remaining cylinder air supply information be visible inside the facepiece. The SCBA wearer must receive a flashing visual notification of the one-half and one-quarter cylinder supply. The HUD must be equipped with a separate and distinct LED low-battery indicator. All LEDs must be bright enough to be visible by the wearer in ambient bright light, but not too bright to distract the wearer when operating in low-light areas.

The purpose of the RIC/UAC is to have all SCBA equipped with a common style connector for use in emergency situations for recharging the air supply of a trapped firefighter.

NFPA 1981 was updated in 2007 to include a new requirement that mandates that all SCBA for emergency services personnel also be certified by NIOSH as CBRN (chemical, biological, radiological and nuclear). Other improvements are enhanced requirements for voice communications and more vigorous water immersion and heat testing.

CBRN

The tragic events of 9/11 spurred NIOSH to establish testing and performance criteria for SCBAs intended for responding to CBRN agents. In January 2002, NIOSH began accepting approval applications from SCBA manufacturers who have developed SCBAs to meet the new NIOSH guidelines.

A CBRN agent approved SCBA must meet the following specifications:

  • NIOSH approval of the SCBA under 42 CFR Part 84, Subpart H
  • Compliance of the SCBA to NFPA 1981 for open-circuit self-contained breathing apparatus for firefighters
  • Approval of the SCBA to 42 CFR Part 84.63(c) special tests

Under 42 CFR Part 84.63(c) two special tests are defined. The two tests cover the following:

  • Chemical agent permeation and penetration resistance against distilled mustard and sarin
  • Laboratory respirator protection level (LRPL)

In the chemical agent permeation and penetration test, all components of the SCBA except the air cylinder must resist distilled mustard and sarin chemical agents. The SCBA is tested on an upper-torso manikin connected to a breathing machine operating at an air flow rate of 40 liters per minute.

The LRPL test is essentially a compilation of quantitative fit tests for 25–40 test subjects. The test subjects have a variety of facial sizes and shapes and represent a cross sample of the general population. To pass the LRPL test a SCBA must score a LRPL of 500 or greater on a minimum of 95% of the test subjects.

For more detailed information on the CBRN requirements visit the Centers for Disease Control and Preventions (CDC) NIOSH Web.

NFPA 1981 was updated again in 2013. The significant changes in this revision include the following 4 areas:

  • New performance and test requirements for Emergency Breathing Safety Systems (EBSS)
  • Addition of the Speech Transmission Index (STI) method for measuring speech intelligibility
  • New lens radiant heat resistance performance requirements and test method
  • New convection lens heat and flame resistance performance requirements and test method

Length of Application

Another important point to take into consideration when selecting an SCBA is the amount of time the SCBA-required task will take. NIOSH approved SCBAs are available with supply tanks capable of providing 15, 30, 45 or 60 minutes of breathing air. A NIOSH approved SCBA should not be confused with NIOSH approved egress or escape units. While both systems incorporate tanks of breathable air, egress units provide air for a shorter duration, typically either 5–10 minutes, and are intended strictly for escaping from a toxic or oxygen deficient environment. Unlike egress units, SCBAs are approved for entering toxic or oxygen deficient environments.

Unless an employer has a need for a 60 or 45-minute supply of breathing air, the 15 or 30-minute systems offer the advantages of cost and comfort. Because the air supply tanks are smaller on the 15 and 30-minute systems, they're generally less expensive and pack fewer pounds than 60-minute units. Even a couple of pounds can make a dramatic difference in comfort when it comes to strapping on an SCBA to complete a task

Frequency of the Application

Comfort also comes into play when considering how often the SCBA-required task occurs. If the SCBAs is only used in an emergency situation, such as shutting down a leaking valve or performing unexpected maintenance in a confined space, then comfort would not be as crucial as it would be in situations where the SCBAs is used on a regular basis. If an SCBA is used regularly, wearer comfort becomes a top priority. With SCBAs, greater comfort generally equates to less weight.

Two methods are used to reduce the weight of SCBAs. Both weight reduction techniques involve the SCBA cylinders. Manufacturers either reduce the weight of the cylinders by making them out of lighter materials or by packing more air into smaller cylinders; sometimes they combine both techniques.

Cylinder Materials

Originally SCBA cylinders were manufactured from steel. To reduce cylinder weight, aluminum became the material of choice for cylinders. Eventually manufacturers began to combine synthetic materials with aluminum to reduce the weight even further. These cylinders are generally referred to as composite cylinders. Within the composite category, there are hoop-wrapped and fully wrapped cylinders.

In more recent times, kevlar and carbon composite cylinders have been developed. Carbon cylinders are the latest and lightest in the evolution of SCBA cylinders. Unfortunately for the employer, as the weight of the cylinder decreases the cost of the SCBA generally increases. The lighter weight cylinders also have a shorter service life and require more frequent testing than their aluminum counterparts.

All SCBA cylinders require periodic testing. The frequency of the maintenance depends upon the cylinder material. For more information regarding hydrostatic testing and service life of SCBA cylinders see Quick Tips #307: SCBA Cylinder Hydrostatic Testing.

Many fire departments and some dive shops have the equipment and trained personnel to perform the hydrostatic testing on SCBA cylinders. The SCBA manufacturer, or the distributor it was purchased through, should be able to direct you to a test facility in your area.

High Pressure vs. Low Pressure

The other method of making SCBAs lighter is to pack a larger volume of air into a smaller cylinder. There are three pressure options available: high-pressure SCBA cylinders that can be pressurized to 4500 PSI, medium-pressure cylinders that can be pressurized to 3000 PSI and low-pressure cylinders that can be pressurized to 2216 PSI. Of the three classes, high-pressure and low-pressure are the most common options for SCBAs. Medium-pressure cylinders are most commonly used for scuba diving.

Both 60 and 45-minute SCBAs use high-pressure cylinders exclusively. The high-pressure is required in order to provide 60 or 45 minutes of breathing air in a tank that can be worn with relative comfort.

30-minute SCBAs are available in either high or low-pressure. The advantage of a high-pressure 30-minute SCBA is that it's lighter, because of its smaller tank, than a 30-minute low-pressure SCBA. The disadvantage of the high-pressure 30-minute system is that it's more expensive than its low-pressure counterpart.

Refilling is another drawback to high-pressure systems. It's a bit more difficult to locate a facility capable of refilling the high-pressure tanks. Local fire departments are the best bet when it comes to the high-pressure tanks; low-pressure tanks can typically be refilled at scuba dive shops or your local fire department.

Other Types of SCBAs: A Brief Overview

This document has focused strictly on pressure-demand SCBAs because they're the most commonly used SCBAs for industrial tasks. There are three other basic types of SCBA: demand SCBAs, oxygen-cylinder rebreathers and self-generating type SCBAs.

Pressure-demand SCBAs are necessary for conditions where the possible inward leakage (caused by negative pressure during inhalation that is always present in demand systems) is unacceptable. These systems provide positive pressure to the SCBA facepiece during both inhalation and exhalation.

Because demand SCBAs do not incorporate a constantly pressurized facepiece, inward leakage of the facepiece is more likely to occur in this type than in pressure-demand SCBAs.

Oxygen-cylinder rebreathers use a relatively small cylinder of compressed oxygen, reducing and regulating valves, a breathing bag, facepiece and chemical container to remove carbon dioxide from the exhaled breath of the wearer. Oxygen-cylinder rebreathers are approved by NIOSH for 45 minutes, one-hour, two-hours, three-hours or four-hours of protection.

Self-generating type SCBAs are similar to oxygen rebreathers except that they do not include an oxygen cylinder. The supply of oxygen for the wearers breathing air comes solely from the chemical container in the system. The container takes the exhaled breath and moisture and separates out the oxygen, which goes into the breathing bag and then the facepiece.

Sources

www.cdc.gov/niosh/topics/respirators/

http://www.nfpa.org/index.asp

(Rev. 5/2014)


Find even more information you can use to help make informed decisions about the regulatory issues you face in your workplace every day. View all Quick Tips Technical Resources at www.grainger.com/quicktips.

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Please Note:
The content in this newsletter is intended for general information purposes only. This publication is not a substitute for review of the applicable government regulations and standards, and should not be construed as legal advice or opinion. Readers with specific compliance questions should refer to the cited regulation or consult with an attorney.


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