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An advanced Aerosol Function Testing Unit - developed and built by Sessions of York has been purchased by D H Industries Ltd to form a vital part of a major contract undertaken for a Canadian pharmaceutical house. The project, which involved supply of a complete aerosol production and assembly line, required an accurate and reliable means of testing aerosol containers for valve efficiency and dosage. The Aerosol Function Testing Unit was selected initially on the strength of Sessions' track record within the industry.

D H Industries Ltd is a specialist engineering company serving the aerosol, coating, sealant and pharmaceutical industries. The company's core activity is the manufacture of aerosol filling machines and it installs aerosol product processing lines throughout the world. The recently completed Canadian project was to build and install a line for assembling and filling a newly developed aerosol metered dose inhaler.

Sessions' Aerosol Function Testing Unit is designed to automate and combine testing and labelling of medical aerosol spray containers under accurately synchronised and fully controlled conditions. It provides all the necessary elements of a sophisticated quality control system within a single pass of the product but is constructed on a modular principle to enable tests to be included or omitted according to customers' needs.

This degree of flexibility is possible because the units' electronic sub-assemblies are plug-in modules and the computer software is individually tailored to each system's final format.

A typical configuration might begin with a rotary infeed table, which turns the aerosol containers from vertical to horizontal, and a unique synchronised moving beam system which separately conveys each container forward from one vee-shaped slot to another. This system allows a pause between each progression for the specified tests to be carried out. A product is tested in one vee and is then carried forward to the next vee to be accepted or rejected.

Automatic valve testing checks that a measured dose of drug is delivered within a specified length of time. On the standard machine valves are primed three times and then metered at the fourth operation. The result is compared electronically with pre-entered parameters for each type of product.

A checkweigh station that can utilise a variety of proprietary weighing units is built into the transporter. To ensure product security, a bar code reader checks the codes printed on the containers against a pre-set code in the computer's memory. The machines can also include a labelling unit, a hot foil printer and an ultraviolet sensor to monitor labelling.

In addition, operator information concerning the state of the unit can be read using the machine's touch screen control. Should the machine stop, fault location is immediately pinpointed to enable rapid clearing. Product changeover is made straightforward by the software, with no need for engineering staff intervention in most cases.