The challenge of implementing process control in sterile environments

Based in the Melbourne suburb of Thornbury, A.E. Atherton & Sons manufactures a range of medium to large stainless steel infection control equipment including Tangent series sterilizers for use in hospitals and laboratories.

The company, which employs some 120 people and has branches in Brisbane, Sydney, Adelaide and Perth, is also developing export markets in a number of countries including New Zealand, Malaysia, Indonesia, Thailand, Brunei and the Philippines.

Atherton places a high priority on quality with both manufacturing and suppliers controlled by its quality management system which has been certified to both AS/NZS ISO 9001:2008 and AS ISO 13485:2003.

According to the company’s design engineer, Scott Lipman, the Tangent series, which includes the Gorilla, Tiger, Mongoose and Cobra, takes sterilizing technology to a new level. "A full colour touch screen operator interface guides you through selecting a cycle from a range of pre-vacuum and general purpose gravity cycles," he told PACE.

"The operator can just touch on an icon to select a cycle, and saved cycles are protected by a PIN to ensure process integrity. Specific levels of security can be set-up by the user to guard against access by people who do not have the necessary training or authority.

"PC and modem interface are standard, and Tangent series sterilizers can be supplied with their own built-in or free-standing generator."

Atherton sterilizing machinery utilises EXTER T100, T70 and T40 units supplied by Global Automation to provide a state-of-the-art operator/ machine interface, together with PLC equipment from Omron.

Lipman says hospitals and laboratories have many strict and variable sterilization setting requirements which can involve pre-vacuum, vacuum, pulsing steam, holding time and drying time.

"PLC software to control the sterilizer is constantly being developed and refined at Atherton utilising an in-house test unit to test the effectiveness of communications between the user and the sterilizer, and to ensure user friendliness.

"We operate in a highly competitive market, so it is important to stay on the front foot through a strong focus on R&D, especially in relation to the constant evolution of software.

Increased automation

"Because sterilization is a critical function in hospital operations a central aim is to make the process as automatic as possible so that when a cycle starts it will automatically go through all stages.

Automation takes control of the system out of the user’s hands, which helps to ensure the integrity of the system and enhances the protection of both patients and staff from infection.

"Automatic leak tests can be carried out to ensure that there is a complete vacuum and no leaks under pressure. In addition, usage reports can be provided to show, for example, how many cycles have been completed over a specified period of time.

"Various ways of record keeping are available including printouts, and email reports on operation of the system can be generated andsent back to our factory for system monitoring purposes.

"Cycle data can also be recorded on an SD card for future reference, and the control system is fully web enabled so that an iPhone can be used to remotely see how the system is operating.

"An automatic sterilizer warm-up function has also been developed through a PLC integration wherebythe user can set the sterilizer to be ready for the start of work next day. We are constantly looking to make systems easier and quicker because time is money."

An innovative touch screen operator interface guides the user through selecting a cycle from a range of pre-vacuum and general purpose gravity cycles.A power loading system is available for ease of loading and unloading the sterilizers. Built-in push button controls combined with a belt drive system power the loading car movement.

Tangent models come with a fully automatic sliding door to the sterilizer chamber, which is operated by tapping the door icon on the touch screen. If anything gets in the way as the door slides across the chamber opening, the door immediately reverses and glides back.

Lipman says that further developments in sterilizer technology include automated safety. "Currently there is a sensor plate with a micro-switch system on top of the doors to guard against any obstruction, but we are now investigating the use of light curtains as a potential safety measure.

"Sterilizer equipment must be compliant with the requirements of the Therapeutic Goods Association and safety considerations will be a major ongoing focus of technological development," said Lipman.

Intelligent terminals

Global Automation’s John Thomson explains that the intelligence behind the EXTER operator terminals is a high performance Intel XScale PXA270 RISC CPU processor with a Windows CE.NET operating system.

"Use of this operating platform provides the system with the flexibility for future development to keep pace with changing user demands," he said.

"A unique communications feature of EXTER operator terminals is their use of dual drivers with data exchange. This means that an operator terminal can be connected to two completely different devices (such as PLCs or inverters from different manufacturers) at the same time without any special configuration.

"An EXTER terminal can serve as a gateway for passing data from one connected terminal to another, and it is possible to exchange data between controllers connected to different terminals in a network.

"Also, remote network access to EXTER operator terminals can be maximised by use of the free Remote Access Viewer software package. This is useful not only for remote control, but also for remote customer support and troubleshooting."

Thomson points out that the remote user can access all of the operator terminal’s functions with Remote Access Viewer via a serial or network connection, so there is no need for Internet connectivity or software such as Windows Internet Explorer.

Laboratory applications

The Walter and Eliza Hall Institute of Medical Research in Melbourne operates laboratories where research is conducted in a range of areas including cancer, chronic inflammatory diseases andinfectious diseases.

The Institute’s Graham Pratt says the organisation has a range of Atherton sterilizing machines including a large Tangent Gorilla unit.

"These machines are utilised for a variety of laboratory requirements including sterilization of boxes for breeding animals, laboratory clothing, and laboratory hard goods," he said.

"Different sterilizer cycles are computer programmed and by simply touching a screen the operator can select the appropriate function required. All cycle parameters will come up on the screen and the sterilizer will automatically move through the specific cycle selected.

"This cuts the chance of human error, such as selecting the wrong cycle or the wrong temperature, for example."

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