Emerson Exchange 365

Eastman Chemical Company has a long history of developing solutions. But according to the results of a project to be presented at the 2014 Emerson Global Users Exchange in Orlando, Florida, network upgrades also can be solved with the right blend of elements.

Andy Liptock, principal analyst at Eastman in West Elizabeth, Pennsylvania, will explain on Tuesday how his team completed a mission-critical network cutover and achieved redundancy, with no system outage or data loss, in less than 30 minutes.

“Our site along the Monongahela River is divided by a set of railroad tracks,” says Liptock. “This creates two long parcels of buildings and infrastructure, each with a separate WirelessHART gateway network.” Each network handles environmental measurements, subject to regulatory oversight and a monetary penalty for any lost data. The loss of a gateway also could expose Eastman to potential fines due to data loss.

“To increase network reliability and reduce risk,” Liptock continues, “we decided to replace each gateway with a redundant pair.” But with fines assessed on any lost data, Eastman had no tolerance for a network outage. Further complicating matters, the two networks were stretched by site topology. Network reformation would take too long in the event of an outage, increasing the likelihood of fines for data lost in the cutover process.

With a clear objective to attain network redundancy without any data loss, Liptock and Russ Muller, diagnostics and communications specialist at Emerson, implemented their cutover plan. The engineers reinforced existing networks by installing temporary repeaters using WirelessHART. The system backup for each gateway bolstered reliability, signal strength and path stability values during cutover. Stationed at each measurement, Eastman personnel manually recorded data until each point had rejoined the network. Liptock and Muller monitored system performance as temporary repeaters were removed.

“After determining the effective range for each network based on infrastructure density, antenna ranges and line of sight,” says Muller, “we scoped each network to a single process. For ideal mesh formation, we positioned a minimum of five wireless devices within effective gateway range. We also placed at least 25 percent of all wireless devices within range to reduce network ‘hops.’ Each wireless device had a minimum of three neighbors.”

As with many upgrades, there were a couple of surprises. The original integral-antenna gateways had been replaced earlier by remote-antenna gateways. Also, existing line-of-sight devices spanned a distance of only 750 feet. Liptock added range devices extending the line of sight to one-half mile, acting as repeaters for devices placed more than 1,000 feet from the gateway. To balance the networks, he repositioned a few of the measurement devices in each network, on both sides of the railroad tracks.

Less than 30 minutes after cutover was initiated, the redundant pairs reformed their networks. There was no network outage, and no data were lost. With system integrity assured, the team reduced the number of repeaters within hours. Aided by a well-devised plan for network redundancy cutover, Eastman effected a long term solution in short order.