Surface-supplied air diving requirements

Surface-supplied air diving is limited to 190 feet of seawater (fsw) except that dives with bottom times of 30 minutes or less may go to 220 fsw. The standard sets these limits at 1910.425(b)(1).

• Stay within the stated depth limits unless another provision of the standard specifically allows otherwise.

A decompression chamber must be ready for use at the dive location for any dive outside the no-decompression limits or for any dive deeper than 100 fsw. This requirement appears in 1910.425(b)(2).

• "Ready for use at the dive location" means the chamber must be available on-site at the location where the dive occurs so it can be used immediately if needed.

A bell is required for dives with an in-water decompression time greater than 120 minutes, except when heavy gear is worn or when diving is conducted in physically confining spaces. See 1910.425(b)(3).

• If the planned in-water decompression exceeds 120 minutes, plan to use a bell unless one of the two stated exceptions applies.

Each diver must have continuous tending whenever they are in the water. The standard states this requirement at 1910.425(c)(1).

• In practice, continuous tending means a responsible person or team member is assigned to watch and monitor the diver at all times while the diver is submerged, maintain communications, and be ready to respond to emergencies.
• Continuous tending is a direct requirement; employers should assign and train attendants to meet it.

When diving in enclosed or physically confining spaces, a diver must be stationed at the underwater point of entry. This is required by 1910.425(c)(2).

• The stationed diver is there to assist entrants, control entry, and provide immediate help in case of trouble in tight or confined diving areas.

The diving operation must have a primary breathing gas supply sufficient to support divers for the duration of the planned dive, including decompression. This requirement is in 1910.425(c)(3).

• Employers must plan gas volume and delivery capacity to cover the entire dive profile and decompression schedule.

For dives deeper than 100 fsw or outside the no-decompression limits, the standard requires specific additional protections: a separate dive team member to tend each diver, a standby diver available while a diver is in the water, a diver-carried reserve breathing gas supply for each diver except when heavy gear is worn, and a dive-location reserve breathing gas supply. See 1910.425(c)(4).

• These subrequirements are spelled out at 1910.425(c)(4)(i)-(iv).

Yes; a separate dive team member must tend each diver in the water for dives deeper than 100 fsw or outside the no-decompression limits. This one-to-one tending requirement is in 1910.425(c)(4)(i).

• Plan staffing so each underwater diver has a dedicated attendant available for monitoring and immediate assistance.

Yes; a standby diver must be available while a diver is in the water for dives deeper than 100 fsw or outside the no-decompression limits. See 1910.425(c)(4)(ii).

• The standby diver must be ready to enter the water to assist or rescue the working diver if needed.

A diver-carried reserve breathing gas supply must be provided for each diver on dives deeper than 100 fsw or outside the no-decompression limits, except when heavy gear is worn. This requirement is in 1910.425(c)(4)(iii).

• If heavy gear prevents carrying a reserve, that specific exception applies; otherwise each diver should carry an independent reserve supply.

A dive-location reserve breathing gas supply means the dive site must have an additional reserve supply of breathing gas available at the location for dives deeper than 100 fsw or outside the no-decompression limits. This is required by 1910.425(c)(4)(iv).

• The reserve at the location is intended to support emergency needs not met by the diver-carried or primary supplies.

For heavy-gear diving deeper than 100 fsw or outside the no-decompression limits, an extra breathing gas hose capable of supplying breathing gas to the diver must be available to the standby diver, and an in-water stage must be provided. See 1910.425(c)(5)(i)-(ii).

• These requirements address the special needs and rescue capability when divers wear heavy gear.

An extra breathing gas hose capable of supplying breathing gas to the diver in the water must be available to the standby diver during heavy-gear dives deeper than 100 fsw or outside no-decompression limits. This requirement is in 1910.425(c)(5)(i).

• Ensure the hose is fitted and ready so the standby diver can quickly provide gas to a distressed diver.

An inwater stage must be provided to divers in the water during heavy-gear diving deeper than 100 fsw or outside the no-decompression limits; the standard requires this at 1910.425(c)(5)(ii).

• The standard requires the presence of an inwater stage but does not prescribe a specific design in this text; employers must provide an appropriate inwater support platform or system for heavy-gear operations.

A diver-carried reserve breathing gas supply must be provided whenever the diver is prevented by the configuration of the dive area from ascending directly to the surface, except when heavy gear is worn or where physical space does not permit. See 1910.425(c)(6).

• If the diver cannot make a direct ascent due to obstructions or the environment, plan for a carried reserve unless one of the stated exceptions applies.

Diving "outside the no-decompression limits" triggers multiple additional protections, including having a decompression chamber ready at the dive location, separate tenders for each diver, a standby diver, diver-carried and dive-location reserve breathing gas supplies, and for heavy-gear dives, extra hose and an inwater stage. These requirements are found throughout 1910.425, specifically 1910.425(b)(2) and 1910.425(c)(4)-(6).

• Plan dive profiles and staffing to meet these additional requirements whenever decompression obligations exist.

The standard allows two exceptions to the diver-carried reserve breathing gas requirement: when heavy gear is worn and when physical space does not permit carrying the reserve. See 1910.425(c)(4)(iii) and 1910.425(c)(6).

• If an exception applies, employers must still meet other protective requirements in the standard (for example, dive-location reserves, standby diver, or inwater stage as applicable).

For dives expected to exceed 100 fsw and require decompression, employers must plan for on-site decompression chamber availability, one-to-one tenders for each diver, a standby diver, diver-carried reserves unless excepted, dive-location reserve gas, and for heavy-gear dives an extra gas hose and an inwater stage. These requirements are in 1910.425(b)(2)-(3) and 1910.425(c)(4)-(6).

• Staffing and equipment must be documented in the dive plan so that all required personnel and systems are in place before the dive begins.