Recreational diving instructor conditions

Employers must ensure that no recreational diving instructor or guide exceeds a depth of 130 feet of sea water (fsw) or a maximum oxygen partial pressure of 1.40 ATA, whichever exposes the diver to less oxygen. Additionally, as detailed in Appendix C to Subpart T of Part 1910, the diver's oxygen exposure duration must not exceed the 24-hour single-exposure time limits specified by the 2001 NOAA Diving Manual or the 1995 DSAT Oxygen Exposure Table.

If you are operating under the alternative conditions of Appendix C to Subpart T of Part 1910 and do not have a decompression chamber on-site, you must make several key arrangements before each day's diving operations.

• Verify Resources: Confirm that a hospital, qualified health-care professionals, and a rescue service (like the Coast Guard) are available.
• Communication: Ensure the dive site has a way to alert these resources in a timely manner.
• Transportation: Make sure transportation to a suitable decompression chamber is readily available and can deliver an injured diver within four hours.
• Oxygen: Have portable, medical-grade oxygen equipment available at the dive site, with enough supply to last until the injured diver reaches a decompression chamber.
• Personnel: Have at least two attendants qualified in first-aid and administering oxygen treatment available at the dive site.

Yes, an employer of recreational diving instructors and diving guides can be exempt from the requirement to provide a decompression chamber if they comply with all of the alternative conditions outlined in Appendix C to Subpart T of Part 1910. These conditions include specific requirements for diving equipment, breathing gas mixtures, dive profiles, emergency procedures, and diver training. The exemption applies to the decompression chamber requirements found in 1910.423(b)(2), 1910.423(c)(3), and 1910.426(b)(1).

Employers must ensure that diving equipment, whether open-circuit SCUBA or a rebreather, contains an open-circuit emergency-egress system, commonly known as a "bail-out" system. According to Appendix C to Subpart T of Part 1910, this system must have the second stage of the regulator connected to a separate supply of emergency breathing gas, which must be air or the same nitrox mixture used during the dive. Alternative configurations are permitted, such as the emergency-egress system specified in 1910.424(c)(4) for open-circuit SCUBA.

Employers must provide training that enables each diver to work safely and effectively using equipment supplied with nitrox breathing-gas mixtures. As required by Appendix C to Subpart T of Part 1910, divers must be able to demonstrate proficiency in critical tasks, including:

• Recognizing the effects of breathing excessive carbon dioxide (CO2) and oxygen (O2).
• Taking appropriate action after detecting excessive levels of CO2 and O2.
• Properly evaluating, operating, and maintaining their diving equipment for the conditions they will encounter.

The fraction of oxygen (O2) in the nitrox breathing-gas mixture must be greater than that of compressed air (exceed 22% by volume). Under the conditions specified in Appendix C to Subpart T of Part 1910, the oxygen level must never exceed:

• For open-circuit SCUBA: A maximum fraction of 40% O2 by volume or a maximum O2 partial pressure of 1.40 ATA, whichever exposes the diver to less oxygen.
• For a rebreather: A maximum O2 partial pressure of 1.40 ATA.

Each rebreather must have a continuously functioning carbon dioxide (CO2) sensor in the breathing loop that is approved by the manufacturer. According to Appendix C to Subpart T of Part 1910, this sensor must be integrated with a visual or auditory alarm that is readily detectable by the diver and remains continuously activated when the inhaled CO2 level reaches or exceeds 0.005 atmospheres absolute (ATA). The employer must also ensure the sensor is calibrated daily according to the manufacturer's instructions.

Employers must calibrate the oxygen (O2) sensors on closed-circuit rebreathers before each day's diving operations, and more often if necessary, following the sensor manufacturer's instructions. As detailed in Appendix C to Subpart T of Part 1910, the calibration equipment and procedures must be accurate to within 1% of the O2 fraction by volume. Sensors that fail to meet this accuracy requirement must be replaced.

You must determine the oxygen (O2) fraction of the breathing-gas mixture before the start of each day's diving operations. This analysis must be performed using an O2 analyzer that is accurate to within 1% of the O2 fraction by volume, as required by Appendix C to Subpart T of Part 1910.

Yes, you must have a hard copy of the no-decompression tables readily available at the dive site, even if the divers are using dive-decompression computers. The required tables are specified in Appendix C to Subpart T of Part 1910 and include those published in the 2001 NOAA Diving Manual or the 1994 DSAT No-Decompression Tables.

When using an oil-lubricated compressor to mix high-pressure air with oxygen (O2) to create nitrox, several requirements from Appendix C to Subpart T of Part 1910 must be met:

• The compressor manufacturer must document that the compressor is suitable for mixing with the highest O2 fraction being used.
• Only uncontaminated air (containing no hydrocarbon particulates) may be used.
• The high-pressure air must be filtered to produce oxygen-compatible air, using a filter system documented by its manufacturer as suitable for this purpose.
• The employer must continuously monitor the air downstream from the filter for hydrocarbon contamination.
• All equipment using the nitrox mixture under high pressure (exceeding 125 psi) must meet the O2-service requirements in 1910.430(i)(1) and (i)(2).