Provides training required to competently and safely utilize breathing gases containing helium for dives that require staged decompression, utilizing nitrox and/or oxygen mixtures during decompression to a maximum depth of 60 msw / 200 fsw. The objective of this course is to train divers in the benefits, hazards and proper procedures of utilizing custom oxygen / helium / nitrogen mixtures as breathing gases. Gas mixes are not to have any less than 18% oxygen. 

Upon successful completion of the course, graduates may engage in technical diving activities utilizing trimix mixtures without direct supervision as long as the diving activities, areas of activities, and environmental conditions approximate those of training, and oxygen percentages are 18% or higher.

A student must:

• Be a minimum age of eighteen (18)
• Have a minimum certification of TDI Advanced Nitrox Diver & TDI Decompression Procedures Diver or equivalents
• Show proof of a minimum of 100 logged dives.

Training Material & Equipment Required:

• TDI Extended Range Entry Level Trimix Diver manual
• Bottom mix cylinder
  • Cylinder volume appropriate for the planned decompression on bottom mix
  • Dual outlet valve, double manifold or independent doubles
  • Labelled in accordance with TDI standards
• Suit inflation cylinder (required for Drysuit divers only)
• Decompression mix cylinder(s)
  • Cylinder volume should contain a minimum of 1.5 times the gas required for the planned decompression
  • Labelled in accordance with TDI standards
• Regulators
  • Primary & primary redundant regulators required on all bottom mix cylinders
  • Submersible pressure gauge required on all primary & bottom mix cylinders
  • A contingency use long hose second stage should be designated and appropriately rigged to facilitate air sharing at depth if necessary
  • It is strongly recommended that 3 required regulators be all DIN or all yoke
• Redundant depth & timing devices
• Air decompression computers allowed for use as depth & timing devices
• Buoyancy compensator appropriate for equipment configuration
• Redundant light system if needed for site conditions
• Ascent reel with lift bag/surface marker buoy
  • Appropriate for maximum planed depth
  • Lift bag with at least 50 lbs of lift
• Exposure protection appropriate for local diving condition
• Slates/wetnotes
• Helium analyzer
• Two line-cutting devices
• Other equipment requirements may apply, check with instructor