TESTCENTRE gently open the valve to allow gas to decant to the Spare Air . Once filled , turn to the ‘ open ’ position to vent it and remove .
The cylinder is supplied with its own highvisibility holster , which can be mounted wherever most convenient . I clipped it to the front of my BCD , where it was easily accessible to myself and my buddy . A leash is supplied to attach the cylinder to the diver ’ s person to avoid any mishaps .
Performance
While the specifications state a total of 57 breaths are available at the surface , I easily managed seventy , over a period of seven minutes . That , I must state was at rest , so how would it perform at depth and under activity ?
For my first dive I dropped down to 25 metres and finning along a wall to maintain depth , I switched from my primary supply to the Spare Air . Pulling open the holster , flipping off the mouthpiece cover and taking my first breath took seconds , which in an out-of-air situation is imperative .
While breathing resistance was a little more than my primary first stage , there was certainly no great effort involved . I had no difficulty in holding the cylinder in one hand or alternatively simply gripping the mouthpiece between my teeth to leave both hands free .
Coming up to my 25th breath ( total time 1.39 minutes ) I became aware of the cylinder ’ s capacity reaching exhaustion , so I switched back to my primary . That doesn ’ t sound a lot of time , but it ’ s surprising the distance I actually covered ; I believe it would certainly be enough to safely ascend from that depth .
My second outing was a 30m dive . Having deployed a shot-line I ascended at my normal rate , using the Spare Air to take me from the bottom to five metres under the surface . I then switched to my primary to complete a safety stop and back to the Spare Air again for the final ascent .
This went without a hitch and I still had sufficient air left to breathe it almost-dry at the surface while waiting to be picked up by the rib .
Conclusions
I do think it ’ s important to make it clear that the Spare Air is vastly different beast to a pony setup .
Indeed , the manufacturer pitches their product as ‘ the diver ’ s reserve parachute ’ and that essentially , is how it should be perceived . There ’ s no substitute for a pony or twinset when carrying out deep and / or decompression dives , but the Spare Air certainly has its place .
The real beauty of the system is its compact form and ease of use . It ’ s so small , lightweight and unobtrusive that it has no effect on buoyancy or balance and can be handed-off to a buddy in an instant .
Clipped in place on a diver ’ s harness
A further advantage is its portability . Once purged of gas , the demand valve can be unscrewed and dismantled allowing it to be taken on aircraft as hand luggage and then easily reassembled at your destination . Neil Hope
Spare Air and BSAC diving
While Neil has reviewed the Spare Air in light of his own diving experience , we also have a responsibility to consider it in relation to BSAC safety advice . First of all , Spare Air is not recommended for use below 10 º C , so there are parts of the year when it is not rated for use in UK waters . It should therefore be regarded as ‘ summer-only ’ for UK divers . Additionally , Spare Air has relatively shallow depth limits of 9m and 14m , depending on the model . The 300 model reviewed here is rated to 14m , according to specifications on the manufacturer ’ s website . Bear in mind that BSAC recommends auxiliary cylinders should have a capacity of no less than three litres , or they cannot be considered an adequate Alternate Source . On this basis , the Spare Air simply doesn ’ t have the depth rating or capacity to satisfy BSAC ’ s criteria . However , that isn ’ t to say that Spare Air cannot be used as a second level alternate source , for backup use , for example , in the event a traditional alternate source such as a pony cylinder should fail or free-flow . We are running this review for the sake of sharing real world experience with a piece of kit now being sold in the UK , but readers should note its limitations for application in club diving . Fundamentally , it should not be seen as a viable replacement for a 3-litre pony cylinder or similar . Simon Rogerson , SCUBA Editor
■ For more details on BSAC ’ s recommendations , go to bsac . com / safediving
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