Bailout bottle Alternative air source




1 bailout bottle

1.1 bailout cylinders use surface supplied equipment
1.2 bailout cylinders use scuba

1.2.1 pony bottle
1.2.2 spare air







bailout bottle

the term bailout bottle, bailout cylinder or egs (military/professional - emergency gas supply) refers scuba cylinder carried underwater diver use emergency supply of breathing gas in event of primary gas supply failure. bailout cylinder may carried scuba diver in addition primary scuba set, or surface supplied diver using either free-flow or demand systems. bailout gas not intended use during dive except in emergency.


the term bailout bottle applied surface supplied divers scuba set carried alternative breathing gas supply in case of failure of surface supplied breathing gas. capacity of these back-mounted bailout cylinders must sufficient diver underwater worksite place of safety more breathing gas available, either surface, or diving bell or lockout submersible. , can small (7 l) or quite large (twin 12 l set), depending on depth , duration of dive.


scuba divers refer bailout bottle pony bottle, , mounted differently, main gas supply carried on back, , referred gas technical divers.


bailout cylinders use surface supplied equipment

surface supplied diver bailout cylinder


for commercial diving using surface supplied breathing gas, bailout cylinder in many cases required health , safety legislation , approved codes of practice obligatory component of diving system. in application intention bailout cylinder should hold sufficient breathing gas diver able reach place of safety more breathing gas available, such surface or diving bell. achieve cylinder must contain enough gas allow decompression if included in planned dive profile. cylinder volumes @ least 7 litres, , may in cases as twin 12 litre sets.


bailout cylinders use scuba

for scuba, bailout bottle , self-contained ascent bottle or emergency gas supply small diving cylinder meant used alternate air source allow controlled ascent required decompression, in place of controlled emergency swimming ascent, not allow required decompression. use of bailout bottle may required codes of practice or legislation in case of professional divers.


a pony bottle example of bailout cylinder has standard diving regulator first , second stages. there smaller cylinders have first stage — , in smallest models second stage — integrated cylinder valve itself. well-known example of class of bailout bottle spare air set, can supply few breaths allow diver ascend @ safe rate, not enough decompression stop. type of bailout bottle typically placed in holster attached diver.


a review carried out scuba diving magazine attempted give sense of depth bailout bottles of various capacities divers surface under maximum safe ascent rates, though review cautioned reviewers in controlled conditions , not replicate circumstances of actual panicked diver. review found 1.7-cubic-foot (0.24 l) bottle had sufficient air reviewing diver 45 feet (14 m) surface; 3-cubic-foot (0.4 l) bottle depth of 70 feet (21 m); , 6-cubic-foot (0.8 l) bottle maximum reviewed depth of 132 feet (40 m), maximum depth recommended recreational dives in parts of world.


pony bottle


a pony bottle (left) attached larger cylinder


a pony bottle small independently filled diving cylinder, of few litres capacity, forms part of extended scuba set , fitted own independent regulator. in emergency, such exhaustion of diver s main air supply, can used alternate air source in place of controlled emergency swimming ascent. key attribute of pony bottle provides totally independent , redundant source of breathing gas diver. pony bottle specific configuration of bailout cylinder.


configuration — in pony bottle system back-up regulator complete diving regulator (first , second stages, , submersible pressure gauge) on separate cylinder not intended use primary breathing gas during dive. provides totally redundant emergency air supply. size of pony bottle cylinder smaller of primary scuba cylinder. should provide enough breathing gas make totally controlled return surface, including required decompression stop or safety stop planned ascent. required pony cylinder capacity depend on profile safe ascent surface required particular dive plan. pony bottle used sport diving may 6, 13 or 19 cu ft in usa, while 2 litre , 3 litre common sizes in europe. deep, technical diving or wreck diving, 30 , 40 cu ft (4 litre , 5.5 litre) cylinders used. pony bottle minimum requirement doing solo diving, has no alternative source of air in form of buddy s available tank , octopus regulator if dive depth diver not able safe free ascent. in scientific diving operations, pony bottles can standard part of tethered scuba diving operations diver solo connected surface communications equipment.


there several options mounting of pony bottle. common way pony bottle carried fixing side of primary (back gas) scuba cylinder straps or clamps, may include quick-release system (as in above picture). common alternative slinging between 2 d-rings on diver s scuba harness or buoyancy compensator.


choice of pony bottle size — function of pony bottle provide source of breathing gas controlled , prudent ascent surface in emergency situation, volume must sufficient purpose. when doing no decompression diving, total reserves of breathing gas must still sufficient supply 3 phases of ascent:



at end of time pony bottle should still hold enough gas provide sufficient pressure smooth flow regulator first stage.



the table above constructed show gas consumed in such scenario – 2 minutes @ depth bailout , preparation ascend, safe rate of ascent 5 meters followed 3-minute safety stop. calculations based on heavy breathing rate of 30 litres per minute , initial tank pressure of 150 bar (2,200 psi). in particular scenario 3  litre pony sufficient diving @ 20 meters not 30 meters. these values may vary depending on diver , other circumstances. diver selecting pony bottle can such analysis his/her own breathing rates, cylinder pressure used, , required ascent profile, or take professional advice on selection. since monitoring of remaining air key safety issue during dive, submersible pressure gauge attached pony bottle regulator should readable @ time during dive.


spare air

charging spare air cylinder larger primary scuba cylinder


the smaller cylinders have combined first , second stage regulator directly mounted cylinder neck thread known spare air after commercially supplied unit of name. these can provide limited number of breaths out-of-air emergency , suitable relatively shallow dives without decompression. smaller 1.7 cu ft spare air provides approximately 30 breaths, , larger 3.0 cu ft approximately 60 breaths @ surface pressure. number of breaths provided in practice depend on diver s lung capacity, depth, exertion , state of mind. ascent 18 metres (60 ft) @ recommended rate of 9 metres per minute (30 ft/min) , typical residual minute volume of 15 litres per minute relaxed diver use approximately 60 litres of free air (volume @ surface pressure - approximately 2.1 cu ft.) dive profiles may adequate. manufacturers recommend these cylinders use within recreational diving limits , suggest little training required in use.


the small size , weight of these units makes them relatively convenient , easy carry, , more convenient travel larger cylinders. can handed off diver in need of air in emergency more conveniently larger cylinders. spare air unit commonly carried in small pouch can attached diver s harness or buoyancy compensator. unit may attached pouch safety leash if accidentally dropped underwater not lost.


recharging done through connector supplied unit purpose, , connects main cylinder valve decant air top-up. done diver before dive. button gauge provided allow diver check pressure.


since introduction in 1980s, spare air cylinders have been subject of debate within diving community. argument against them not have sufficient capacity diver in many emergency situations surface safely, , cause divers feel false sense of safety. arguments in favour spare air cylinders both less bulky , less complicated pony bottles, on , have no hoses or pressure gauges, , air better none in emergency.








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