The Suburban Manufacturing Group manufactures filtration and drying systems for compressed air. A part of the product line is a compressed air filtration system for use with supplied air respirators (SARs). You have asked for OSHA's interpretation on addressing air quality and clarification on various designs or configurations of currently marketed breathing air systems.
Please be aware that OSHA does NOT approve or endorse any specific equipment, products, or manufacturers' designs.
Therefore, questions about specific equipment or diagrams will only be answered in general terms. Below are your paraphrased questions and our responses, including feedback, when possible, on your proposed system.
Here are the questions OSHA addresses in this LOI:
Have the specifications for Grade D air changed since its 1989 incorporation into OSHA's Respiratory Protection standard, 29 CFR § 1910.134?
What is the acceptable dryness of air?
A supplied air respirator (SAR) is being used in an ambient temperature of 70°F and is receiving air from a compressed air system maintaining a system pressure of 120 psig. A drying system, as a part of the industrial compressed air system, is utilized to provide a dew point in the compressed air at or below 40°F. Would this dew point meet OSHA regulations?
Does 29 CFR § 1910.134(i)(4)(iii) apply to compressed air systems used for supplied air respirators?
Does OSHA deem the requirements of 29 CFR § 1910.134(i)(4)(iii) to be too dry for SARs?
Can "exceed" be defined, as used in 29 CFR § 1910.134(i)(4)(iii)? Does it mean that the moisture content has to be at -50°F or lower? Does it mean that the dew point cannot be below -50°F?
To achieve a -50°F dew point at 1 atmosphere, an air system operating at 120 psig should then have a dew point of -13.4 °F at 120 psig; would this then be the minimum dew point to meet specification?
Can "suitable" be defined, as used in 29 CFR § 1910.134(i)(5)(iii), that compressors used to supply breathing air to respirators must have "suitable in-line air-purifying sorbent beds and filters to further ensure breathing air quality. Sorbent beds and filters shall be maintained and replaced or refurbished periodically following the manufacturer's instructions?"
Would OSHA consider incorporating the specifications identified by the International Organization of Standardization (ISO) 8573-1? This ISO 8573-1 establishes clear limits regarding particle size and quantity, dew point, and oil content, and could provide a little more clarity.
Is there a standard for allowable materials and piping configurations? For instance: can compressors use a flow control device (such as a regulator) that restricts the flow in one direction? Is there a maximum distance allowed between the wall-mounted breathing air filtration and the operator's mask? What type of pipe or hose can be used with the breathing air filtration unit and individual respirable air connections (plumb rigid, etc.)?
At what point is the air going to a NIOSH-approved hose and respirator assembly deemed breathing air quality in order to satisfy OSHA standards?
If the NIOSH-approved, belt-mounted, in-line filters provide the final filtration to meet the Grade D breathing air specification, without which the air would not meet the criteria, are these systems then meeting OSHA standard and NIOSH policy?
According to NIOSH's Respirator User Notices, only the system's NIOSH-approved hose is technically useable for breathable air as long as the hose and filter are NIOSH-approved and the required NIOSH-approved, belt-mounted, in-line carbon filter is used to remove the odors in the air system. Is this system design allowed under OSHA regulations or standards? Is there a specific OSHA regulation or standard that states an employer must have a NIOSH-approved hose to run from a wall-mounted filter to a belt filter?
What is OSHA's interpretation of a system with a standard (or NIOSH-approved) breathing (Grade D air quality) air hose connected to a belt-mounted flow control device that contains a work line, where the work line disconnect couplers are different from the couplers for the breathing air disconnect? Stated differently, if the connection points for the respirable air and pneumatic tool (work line) are separated with different couplers, would this design be considered appropriate and acceptable by OSHA? Does it allow for the potential health and safety hazard stated by NIOSH?
Would OSHA consider incorporating the concerns identified by NIOSH, related to system contaminants in respirable air, in its regulations?
What are OSHA's requirements for the use of matched or paired hoses, masks, or hoods? Should all pieces be manufactured by the same company?
NOTE: I have provided some links to ANSI's online store or FREE access to out-of-date ANSI standards that OSHA still references.
