Pneumatics offer alternative to conventional PLCs

Paul Boughton
The latest range of air logic devices, developed and manufactured by Parker Hannifin, offer engineers an efficient and cost effective modular system that can improve productivity, reliability and profitability of pneumatic circuits in a wide range of applications. 

In particular, the latest air logic devices can be used as an alternative to conventional PLCs, for managing smaller or less complex pneumatic circuits, and in areas where there is no electrical supply or where compliance is required with ATEX directives.
Parker’s air logic system comprises a series of compact modules that operate in response to the condition of inlet and exhaust signals from connected upstream pneumatic devices, effectively replicating the operation of electrical switches and relays. They can thus be used individually or combined in series to create a range of simple or advanced functions.
For example, when used as individual in-line modules they can provide passive AND/OR functions. Alternatively, modules can be grouped together and mounted on standard rails, on sub-bases with a common air supply or in cabinets to provide active AND, OR, NOT, YES and MEMORY functions, with functionality being extended still further through user selectable cascade or common input modes. 
Modules are designed to plug together quickly and simply, with all inlet and exhaust connections being front mounted, and can easily be reconfigured if the requirements of the application change.  For rail or sub-base mounted systems this makes it possible to halve the amount of piping that would otherwise be needed.  Operating pressures can be between 3 and 8 bar, at temperatures from -40ºC to 60ºC, with modules typically having a response time under 3msecs and an operating life greater than 10million cycles at pressures of 6bar.
Parker’s latest air logic system is lubrication-free, incorporates pressure test points as standard, and is available with a range of accessories.  These include time delays, bleed sensors, solenoid actuators, pressure switch relays and modular sequencers. The latter are designed to provide an easy to use method of controlling machines that need to go through a defined set of cycles.
Application areas are where an electrical supply is unavailable or where ATEX controls apply; typically, these include the chemical, mining, transport and offshore sectors.

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