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Hose Routing for Twin Tanks

posted Mar 4, 2012, 12:07 AM by Derek Quek   [ updated Jul 22, 2013, 2:52 AM ]
In technical and extended range diving, twin tank sets are used to provide not only additional gas for longer bottom time, but also redundancy in case of failures in the gas supply system.

Hose Routing Considerations

Considerations for your hose configuration will determine what kind of functionality will be available during failure of one or more points in the gas delivery system. Here are some key points that a diver should consider:

  • Primary and secondary regulators should come from different 1st stages to cater for 1st stage failure. If there is a BCD and drysuit inflator, they should similarly be on different 1st stages.
  • Most important connections should be connected to the right post: a ceiling rub/roll-off will turn the tank valve toward the “on” position, in the worst case, breaking the knob and resulting in a full on position. These connections would be the primary 2nd stage and the BCD inflator.
  • The lesser important connections would go to the left post. This would be the secondary 2nd stage and the SPG, and drysuit inflator.
  • Minimise hose ‘cross-overs’ where possible.
  • Minimise hoses sticking out of your profile as this increases risk of snagging onto coral, wreck, etc. Hoses leading downward from the 1st stage are ideal.
  • A team-wide standardised hose configuration will make it easier for a buddy to spot problems or render assistance.

Suggested hose lengths

Back Gas:
Primary reg 7ft/210cm
Secondary Reg 24"/60cm (22" ideal for singles*)
SP Gauge 24"/60cm (22" ideal for twins*)
BCD inflator 24"/60cm (22" ideal for singles*)
*Although shorter hoses may be ideal in some configurations, but a negligible extra 2 inches would provide better flexibility between single and twins configurations.

SP Gauge 6"/15cm
Primary reg 39"/100m *
*This reg length allows the hose to route around your neck to reduce front clutter during travel/deco.

Based on the above considerations, the diagram on the right offers some suggested hose connection configurations for Apeks first stages.