Enclosure purging systems eliminate the possibility of combustible gases within sealed, pressurized enclosures in hazardous areas by ensuring that their atmosphere is essentially nothing but the purge gas, typically nitrogen. Flow and pressure measurements are used to determine when the atmosphere is suitably purged, typically clearing an interlock that allows power to the enclosure.
"Our customers like the X-Purge control we designed 15 years ago," says Mike Hadaway, general manager, Daisy Data Displays. "We incorporated their comments when we decided to redesign it using new tools and techniques, and to improve it based on what we've learned from them since then. The new version works on multiple cabinets and complex cabinets. It's smaller, modular and easier to install, and can directly replace the original version using adaptors on the original cutouts."
The 9216 consists of inlet and exhaust modules. The redesign shifts the purge gas pressure and flow control from the inlet module to the exhaust module, essentially managing the flow rate inside the enclosure. Controlling on the basis of exhaust rather than inlet flow and pressure, "We can detect and measure any leaks, and meet requirements for IEC, Ex and Atex, as well as NEC and NFPA," Hadaway says.
The new version allows multiple exit modules—initially up to four—to be paired with a single inlet module. With multiple exhaust modules, a single inlet module—using multiple inlets—can control the atmosphere of multiple and complex cabinets.
"Very large enclosures with odd shapes and cavities may have pockets where the atmosphere is stagnant," says David "Avi" Shefet, president, Daisy Data. "Using multiple exhaust modules with a single supply module reduces purge time and the complexity of the purge system."
Daisy's modular design allows the system configurator to add more exhaust and inlet modules to increase airflow, reducing internal pressure and purge time. "The 9216 X-purge controls are fully automated and require no human intervention to purge a system," says Ray Ravida, R&D engineer, Daisy Data. "Most applications realize a substantial cost benefit as a result of being able to monitor multiple enclosures with one purge control, while automating the monitoring process."
Purging is demand-based. After the cabinet is completely purged, the exhaust modules shut off to maintain gas pressure where the original system would continue to demand gas. If leaks are not excessive, this conserves gas; and if the leakage rate is high, the system lets you know.
The new version also provides more frequent and detailed purge-cycle and data reporting, allowing users to monitor and manage system performance better, and to diagnose issues if and when they occur. Even in configurations with multiple enclosures, all inlet and outlet modules communicate back through one centralized reporting process to identify the pressure in each of the multiple units.
The redesign replaced buttons and LEDs with a keypad and LCD readout. A two-line by 20-character display provides information about the status of the purge control, including time to complete the purge cycle, pressure flow, enclosure size, historical data, failure mode and more. "Pressure, flow and temperature data is collected, and you can see it at any time, as well as any problems," says Shefet. "All data is accessible through USB, as well as by network connections." Interlock relays are provided for AC power and 12 data points.
The 9216 Series X-purge control meets aseptic regulations for pharmaceutical and food processing applications, and is certified for a variety of environments from non-hazardous process control manufacturing environments to Class I, II, III, Division 1.
"This 9216 Series X-purge control is a great example of how Daisy develops products in direct response to end-user needs and preferences," Shefet adds. "As applications become more demanding, environments more challenging, data needs become more complex, customers want industrial computing solutions that that can flex to meet their needs. The 9216 X-purge control is the ultimate in flexibility."
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