Control system maintains medical product quality

By commissioning a sophisticated batch control system for production of its medical adhesive Indermil, Loctite (Ireland) has ensured that exceptional product quality is maintained.

By commissioning a sophisticated batch control system for production of its medical adhesive Indermil, Loctite (Ireland) has ensured that exceptional product quality is maintained, with high standards of monitoring and management information.

The new system is based on Eurotherm's powerful EurothermSuite family of integrated control hardware and software solutions.

The system was selected only after a comprehensive vendor and product audit to ensure that the proposed system complied with relevant medical industry standards.

Indermil is Loctite's recently developed medical glue which is used for sealing small to medium sized open wounds up to 8cm in length.

Production of Indermil takes place at Loctite's facility at Whitestown, Dublin, the batch process consisting essentially of a steam heated distillation vessel and a cooled receiver for the distilled product.

Vacuum and glycol cooling services are required for the two-stage process.

Owing to the medical use of the product, prior to confirming the contract the proposed system had to be validated to US FDA and GAMP (Good Automated Manufacturing Practice) standards.

Loctite Ireland and its project management consultant carried out a successful audit of the Eurotherm quality management system against these standards.

The control system hardware for the process consists of two Eurotherm Type T103 distributed control units, connected via a proprietary Arcnet local instrument network (ALIN) to a single EurothermSuite server system.

A EurothemSuite client is attached to the server via an Ethernet communications link.

The two T103s, which are each capable of handling up to 128 I/O points, support 151 I/O points within this system, controlling five motors, 30 valves and three simple PID loops.

Two sequences provide modular operation of the vacuum and glycol services, whilst a single main sequence provides overall batch control.

The use of Wonderware InTouch as the standard graphics tool allowed the creation of a clear and unambiguous control interface to inform the operator of required actions during batch sequences.

The sequences themselves contain comprehensive fault diagnosis routines, alerting the operator of any hardware or process problems as they arise.

Built-in sequence prompts also provide the operator with a graphical step-by-step progress interface during sequences.

The LIN databases and sequences required for the processes were configured using Eurotherm's latest Windows based LINTools 2000 toolset, allowing graphical system configuration and on line monitoring via PC during set up.

This offered a significant saving in sequence development time over earlier DOS-based configuration tools.

A very effective hold/restart batch mechanism was also designed for the process.

This important facility can often be complicated to implement and can easily be overlooked during the design of such processes.

This provides a means of putting the plant into a safe condition upon receipt of a significant fault signal, whilst allowing the process to recover back to its previous state when safe to do so.

Because of its total flexibility and common architecture, EurothermSuite has the capability of handling the localised control needs of small production units and batch processing plants, as well as the more global information needs of enterprise management.

It can provide an almost infinite variety of totally integrated systems that grow with plant needs and investment programmes.

Within its integrated development environment (IDE), powerful developer tools provide a significant improvement over previously available tool sets.

The server configuration is easy to setup and only needs to be done from the configuration PC - the client does not require any setup until the last minute.

Once the system has been defined, automatic configuration is achieved by a single right click in the project environment, and although there are only two instruments in the Loctite system, this would equally apply to any number of instruments.

Alarm configuration was achieved quickly at Loctite using simple drag and drop software features and automatic online configuration of graphics.

In this way structured alarm groups needed only to be setup in one place.

All alarms generated by the server are stored in a relational database that can either reside on the local server or alternatively on a customer's own remote SQL server.

Each server/client connects to the SQL server to retrieve historical alarm information, and a built in alarm buffer provides data backup should the SQL server go offline.

An alarm printout facility is provided as standard, which allows the filtering out of spurious alarms and events before printing.

System security is a key strength, so that if unauthorised access is sought to the server even from a remote client, it is subject to blocking security filters and fully logged by the server.

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