Smart wireless sensors improve control, save money

‘We hear comments like that from customers all the time,’ says Paul Richards, vice president
at Sensicast Systems, a manufacturer of wireless sensor networks for industry and commerce. ‘Customers install our sensors to gather critical information about what’s going on in
manufacturing, and their facilities. Using Sensicast’s SensiNet

Wireless Sensors: Available, Reliable
Wireless sensors communicate with each other through routers and a gateway to form a mesh network. All the devices relay signals for each other, so if a given sensor is out of range of the gateway, other members of the network carry data. Since interference patterns can change, the network will automatically adapt to keep all members communicating .
This self-healing capability keeps data flowing with 99.99% reliability.

Sensicast provides off-the-shelf sensors for temperature, humidity, and electric power consumption. These battery-powered sensors operate for years without maintenance or replacement. They can also interface with virtually any other type of instrument to communicate through the network. Routers are externally powered but can be placed in a convenient location near existing supplies. A single network can scale from a handful, to thousands of devices.

Smart temperature sensors can handle anything from a freezer to the enclosure of an arc furnace at a steel mill. Electrical sensors can measure power consumption of a single device, a distribution panel or entire building. Both types are inexpensive, simple to setup, and operate. The information they send back will give you the ability to cut waste, control costs, and streamline processes.

Sound too good to be true? Here are three very different applications that share common success stories.

Pharmaceutical companies have unique manufacturing processes to meet safety standards and to comply with FDA regulations for monitoring and documenting production. When a major St Louis-based pharmaceutical manufacturer wanted to deploy a new temperature monitoring network on existing production lines, it chose SensiNet wireless technology to simplify installation while reducing cost and downtime.

The subject manufacturing lines are spread out over three buildings on the plant campus. Compliance with U.S. FDA 21 CFR Part 11 regulations required placing sensors at 130 locations, so adding cabling to all those would have been a major undertaking. However, using SensiNet technology, the individual sensors were installed over a period of several days, and since no data wiring had to be added, the work was done without interrupting production .

SensiNet mesh technology provides a self-managing and self-healing network. Using a combination of sensors and routers extends the range of sensors and supports reliable communication with the gateway. Robust data connection and integrity is essential for pharmaceutical manufacturers. Once operating, SensiNet networks configure themselves for optimal performance with typical reliability of 99.9%.

The flexibility of using wireless sensors to sample data from previously difficult environments—HVAC, mobile racks, and sealed chambers—is an obvious advantage over a wired solution. In pharmaceutical facility deployment, the wireless network was installed within minutes, and using a performance utility provided by Sensicast, operators were able to create a completely stable RF system within a few hours. According to a company spokesperson: ‘ Typical stainless steel environments create black spots for RF , but Sensicast’s system has been performing for over six months without a glitch.’ An additional added benefit was a significant decrease in the amount of time required to conduct in-place calibrations. The prior process required fixed sensors to be calibrated in place. Using its new wireless sensor approach, the company can gather all the SensiNet Smart Sensors into one room while still collecting data and perform a mass calibration in a fraction of the time that was previously necessary.’

The system also meets the manufacturer’s requirements for FDA compliance. Data from sensor monitoring points now flows into the control and logging software where it can be fully validated and documented.

Temperature monitoring increases aluminum rolling production
A premier aluminum manufacturing facility in Kentucky produces 500,000 tons of rolled aluminum sheet metal each year. Ingots are first rolled in the hot mill and then to final thickness in the cold mill. Between those two stages, the coils have to cool because cold rolling requires the material to be at a specific temperature to obtain desired metallurgical qualities. Since individual coils are different sizes and temperatures, the cooling period can vary from 24 to 48 hours. Fulfilling critical customer orders makes it important to monitor cooling progress in order to maintain specific rolling schedules. At any given time there are around 100 coils cooling in an area of the plant about the size of a football field. One crane operator has the responsibility to monitor all the coils and make sure they are ready as the schedule calls for orders. In the past, that meant climbing down from the bridge crane regularly to take temperature readings. It was not an efficient process and slowed production throughput.

To solve the bottleneck, plant operators now place a SensiNet temperature sensor in each coil as it comes from the hot mill. The crane operator receives temperature data wirelessly in the crane cab and can check cooling of any coil on the floor without having to dismount. The wireless mesh networking permits reliable communication with every coil regardless of the crane’s location.

Keeping the cooling floor moving efficiently increased production by 3,000 tons per year without incurring the cost and hassles of additional capital equipment. The gain in production paid for the SensiNet system in just three months. Wireless process control from aluminum rolling to monitoring furnaces in steel plants , makes good business sense.

Hollingsworth & Vose Company operates a paper mill in Ayer, MA, to produce specialty materials for filtration applications. Their equipment consumed large and growing volumes of compressed air, which was an area of concern for them and for National Grid, their local electric power utility. Both companies were looking for ways to reduce electric consumption, and the compressed air system was an obvious place to begin.

The Department of Energy estimates that US companies spend $1.5 billion annually to compress air using equipment that is only 30 to 50% efficient. As the H&V legacy system initially operated with virtually no monitoring, it was impossible to tell where air was being lost to leaks, inefficient application, and distribution system degradation. After installing a combination of temperature, flow, pressure, and power consumption sensors, which connected wirelessly with SensiNet’s mesh networking, the company was able to locate and correct problems and innefficiencies throughout the plant.

The result was immediate . Taking new steps to improve compressor efficiency yielded savings of $26,000 in the first year. The SensiNet system cost only $10,500 to install, against estimates of $75,000 for an equivalent wired system. National Grid was so pleased with the drop in electrical consumption, they reimbursed Hollingsworth & Vose for the full cost of the SensiNet system.

How can you use and benefit from wireless sensor networks?
As seen in the three case studies above, wireless sensor networks deliver significant benefits for operators of control, instrumentation and automation systems. Not all solutions are created equal. Thus plant managers and control engineers must ensure that wireless sensor systems meet criteria essential for success.