The Whitley Automatic Gas Change Over Unit offers complete peace of mind to owners and users of workstations by ensuring the gas supply is always maintained - even when a cylinder needs to be changed at night, at weekends or any other time the laboratory is unoccupied, such as public holidays.   Designed specifically to suit the operational requirements of all workstations in the Don Whitley Scientific range, the unit functions by using the gas pressure from the connected cylinders - and does not require an electrical supply.   Completely safe and reliable in operation, the unit switches automatically between two gas cylinders when pressure in the active cylinder drops below a pre-determined level. Clearly labelled gauges on the incoming and outgoing gas lines allow pressures to be checked easily and conveniently.   If you need to constantly maintain the correct internal atmospheric conditions in your workstation then this device provides the solution.