KISS Air-powered Baby-booster

Steve Millard

One common problem to all rebreather divers is obtaining oxygen or helium at a sufficiently high pressure. Unless a cascade of several cylinders is used, the inevitable situation arises that the pressure in the supply cylinder drops below the required level and the rebreather oxygen or diluent cylinder cannot be completely filled. A practical solution to overcome this problem is to use a gas booster to increase the pressure of a gas from the supply cylinder to the required level. The technical diving community has pressed a variety of different gas boosters, air-powered, electric or manual into service. There are however some difficulties with acquiring a gas booster. Some come at a very high cost. Others can be very hard to find and may be of an antiquated design (e.g. using leather washers and seals). Some are very bulky and/or heavy and would be difficult to transport to the dive site.

A new air-powered gas booster development by Gordon Smith, Jetsam Technology Ltd (manufacturer of the KISS rebreather) in Vancouver now provides a practical solution, which should be of interest to all rebreather divers. Dubbed the "Baby -booster", due to its diminutive size and weight (under 3.5 kg!), this booster delivers an impressive performance at an affordable price. It is 1/10 of the weight and nearly 1/3 of the price of the existing electric KISS "Micro-booster". The basic "Baby -booster" is supplied without input and output filling hoses and is available for approximately $1000 US, plus carriage. A tough Pelican travel case is a sensible option for an additional 100 US dollars and will ensure that the booster arrives undamaged from Canada. A ready-to-use booster, complete with input and output filling hoses, pressure gauge, purge and control valves can be supplied in a Pelican case for around $1700 US. The ready-to-use price may come down little bit if future orders produce an economy of volume in sourcing hose components, but it may be even more economic to source the additional hose parts in the UK.

KISS3
Baby-booster supplied without hoses

KISS1
Baby-booster Ready for use

The booster is a very practical proposition and simple to use. Connect the input hose to the supply cylinder and the output hose to the rebreather cylinder. The booster is driven by a 10 bar supply of air simply by connecting to a standard stab jacket direct feed hose. Simply turn on the air cylinder and the booster begins immediately with a quiet repetitive "click-whoosh" sound. The (white) silencer ensures that the booster is quite enough to be used anywhere, even in a hotel room.

[KISS3]> BORDER=
Baby-booster in action

So ... how does it perform? I first tried the booster using a supply of helium gas at a meagre pressure of 10 bar. The booster is rated at a maximum boost ratio of 5:1 and it achieved an output of 50 bar quite comfortably. If you are willing to wait then an output pressure of 100 bar can actually be achieved, although at a boost ratio above 5:1 the output pressure rises very slowly and a lot of drive gas is consumed. I then used the booster with a more realistic supply of oxygen at 100 bar input pressure to fill a 1.0 litre rebreather cylinder to a final output pressure of 200 bar. It took just under 10 minutes to achieve this and consumed 40 bar of air from a 12 litre cylinder.

Two things to bear in mind when using the "Baby-booster":

  • The drive gas consumption is more related to the fill tank pressure than the supply pressure.
  • The supply pressure is the biggest factor determining the filling time.

However it is clear from the figures that the KISS "Baby-booster" is targeted at the rebreather market and is quite unsuitable for boosting gas into large open-circuit cylinders. Both the long filling time and the consumption of drive gas would be unacceptably high for anything other than the smaller one-litre to three-litre cylinders commonly used with rebreathers. However the slow boost rate has a safety bonus ... the oxygen is kept very cool, which minimises the chances of an oxygen explosion.

It has to be said that this equipment must be one of the coolest dive-toys of the year. It is superbly manufactured and a pleasure to use. Gordon Smith has made an initial batch of 50 units, but most of these have already been sold by word-of-mouth. No doubt additional batches will be made as the (inevitable) demand requires. For further information on the KISS "Baby-booster", the KISS electric "Micro-booster" and the KISS rebreather visit the web site: http://www.jetsam.ca/ or contact Gordon Smith at: Jetsam Technologies Ltd., 2817 Murray St., Port Moody, BC, V3H-1X3, Canada.

SG Millard 2/1/04

Ec96@liv.ac.uk