Scott Safety offer either 200 or 300 bar steel cylinders, these can be provided with either 90 degree or straight flow valves, all valves have a safety locking handwheel.
Duration times for working are calculated at 40 litres per minute.
So a 6 litre 200 bar cylinder is, 6 times 200, which equals 1200 litres of air, 1200 divided by 40 (litres per minute used), gives a working time of 30 minutes. 15 minutes of the 30 should be adopted for escape.
When ordering please indicate whether you need a 90 degree or straight flow valve.