Selecting Grade-D Breathable Air Systems For (SAR) Supplied Airline Respirator Systems

Do you know the type of information required for selecting and implementing Grade-D breathing air systems?

These guidelines should help you to make critical safety & health decisions.

The Hazard evaluation

It is imperative to review results of your hazard assessment with your safety department to identify the location as well as the hazard types. This initial phase of your decision making process is by far the most important to assure proper selection for airline respirator & breathing air systems you will be using.

Choosing Respirators

Choosing an appropriate airline respirator requires the assistance of properly trained distributors of safety equipment or the manufacturer’s professionals.

An important thing to consider is that airline respirators are positive pressure (SAR) supplied air respirators. An airline respirator may be one of 2 different device types which are known as pressure demand or constant flow. Constant flow airline respirators (CF) usually come with a tightly fitting mask or hood design which may be used for sandblasters and painters. These respirators function with low air pressure usually from 5 to 30psi. Pressure demand airline respirators (PD) usually come with a tightly fitting mask or the special version may include a 5 min. escape breathing air cylinder. These escape units are used in IDLH locations (Immediate Dangerous to Life or Health). PD respirators function at a higher air pressure which is from 60 to 120psi. When choosing & designing breathing air systems, federal regulations – NIOSH / OSHA - require airline respirators to be supplied with 4 cubic ft. of air / minute (CFM) minimum to be delivered to the individual worker. If your job requires sandblasting or the paint hood type respirators, they require a minimum of 6CFM. Federal standards require a maximum (CFM) air flow not exceeding 15 CFM to the individual airline respirator.

Calculating CFM requirements

The number of workers needing airlines along with air tools used will determine what size of air compressor you need to deliver breathing air for your worker’s airline respirators. Multiply the amount of workers by the needed flow rate per respirator to determine your air compressor size. The selected compressor must deliver the proper air consumption to each respirator as well as the tools used which determine the overall CFM capacity of the compressor. Add 10 to 15% output capacity CFM to the compressor system to cover any unplanned air consumption requirements. Always calculate an average air flow requirement for every worker approximately 10 to 12CFM per worker.

Air Source Selection

Breathable Air Supply

Air Source Choices 1 & 2 require the utilization of Grade D air filtration systems. Grade D means filtered air which is specified by (CGA) Compressed Gas Association & OSHA accepted. Breathing Air System components -

1. The Air Source can supply air from gas, diesel or electric compressors.

2. Grade D air Filtration with CO Monitor – Fixed or portable Grade D air filtration units provide breathing air to your workers. Choose an air filtration system that provides automatic drains that remove oil & water. The system should have separate filters for removing oil & water, and a separate filter with charcoal for odor and taste removal. Your filtration system should be based on the CFM capacity of your unit & not the number of airline workers. Many manufacturers only supply filtration units which deliver the required minimum of 4CFM to a respirator, but workers may need 15CFM for respirator hoods. The highly toxic & hazardous element of the Grade D breathing air system is Carbon Monoxide. CO monitor devices are set to alert workers at 10ppm for high CO. This alarm enables workers to determine the cause is for high CO. Always calibrate your CO monitor before using to assure the monitor provides accurate readings.

3. Air Distribution- Filtered air needs to be at the required PSI to operate your respirator - air regulators, pressure gauges, safety relief valves and respirator couplings are all essential elements.

4. Respirator - The last part of a Breathing Air System consists of an airline respirator which is attached to Air Distribution fittings using a hose - respirator hose must not be over 300 feet in length from your Air Distribution location.

Air Choice #3 requires workers to use pressure demand (PD) airline respirators if your air source is delivered from compressed air cylinders. These high pressure air cylinders with breathing air may be rented from gas distributors or your own tanks may be filled with a compressor.