Info Are Pony Bottles Dangerous?

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A pony bottle can be dangerous and I have had the experience to prove it. But I still think it would be more dangerous to have a full primary failure at depth with no pony...... and most definitely the case if diving solo.

 
A pony can be used to safely extend a dive.

I use my pony bottle to extend my dive in that I leave a much smaller reserve in my main tank often surfacing with less than 250 psi. Or, I use it to extend an unusually interesting dive in which case I will leave the normal reserve in my main tank as backup to the pony.
 
A pony can be used to safely extend a dive.

I use my pony bottle to extend my dive in that I leave a much smaller reserve in my main tank often surfacing with less than 250 psi. Or, I use it to extend an unusually interesting dive in which case I will leave the normal reserve in my main tank as backup to the pony.
That’s a stage bottle….
 
A pony can be used to safely extend a dive.

I use my pony bottle to extend my dive in that I leave a much smaller reserve in my main tank often surfacing with less than 250 psi. Or, I use it to extend an unusually interesting dive in which case I will leave the normal reserve in my main tank as backup to the pony.
There’s different definitions of a PONY.

A Piss Off Not Yours is a tank that’s only available to the diver and would only be used in emergencies (and taking test breaths). The gas in that tank is not included in the planning calculations.

A bottom stage bottle is used to extend the bottom phase of a dive. This is most likely a slung tank of a reasonable volume, possibly even an ali80. The important thing here is the gas in the bottom stage is included in the gas planning.

A bottom stage can be used in emergencies as well as extending a dive. A PONY is only an emergency gas source and is often quite small, 3 litres/21cft
 
  • Are pony bottles dangerous?

Issues with PONY cylinders…
  • They’re frequently small cylinders with insufficient gas for the depth should things go really wrong
  • They’re often poorly configured to deploy, thus test on every dive.
  • Often there’s no visible SPG
  • When doing the gas volume calculations they have inadequate gas for the depths they’re used
Arguably they’re better than nothing, but the diver must be familiar with using one such that a "boom" on the primary gas would be a simple and calm switch to the well-practiced PONY with no panicking.
 

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