Overview

Printers for bar code and batch number labels are found in many industrial locations. If the printer is to be located in a hazardous area, then a certified solution is required to ensure safe operation. Due to operational requirement & constraints, many of the possible Ex protection concepts are not suitable. Ex p (Purge & Pressurization) provides the most flexible and cost-effective solution. Expo has worked with Zebra Technologies, a leading manufacturer of industrial label printers to develop a standard certified solution based around their popular ZT400 series.

What is Exp? A two-step process that is required prior to energizing electrical equipment inside a suitable leak-tight enclosure. Using instrument quality air, the enclosure is first purged for a set time. This time is calculated based on the enclosure dimensions and the number of volume changes required by the certificate. After successful completion of the purge sequence, the enclosure is maintained at a set over-pressure (typically 5 mbarg) and the electrical equipment can be energised. This process must be controlled and monitored by a certified purge & pressurization system that can energise/deenergise the system as required.

The printer is installed inside a robust stainless steel enclosure. The system is fitted with a purge system to control and monitor the purge & pressurization process, and an isolation unit to provide power and ethernet control. While the overall system is standard, the internal mounting arrangements are adaptable to house either Zebra printer model. Expo’s design incorporates several unique features:

• Through-the-enclosure-wall pushbuttons to actuate the printer membrane switches for label feed control
• Clear window to view the printer display screen
• A low leakage, anti-static label slot to permit label exit while maintaining positive pressure inside the enclosure.
• The printer sits on an adjustable, sliding internal tray allowing accurate alignment for the label feed and pushbuttons. A side access door is provided for print media roll change.
• The system has three mounting configurations: table top; wall-mount or plinth-mount.