Industrial Ethernet / Valves / Wireless

"Hands-Free" Valves

Protocols Such as Bluetooth Can Be Used As a Configuration Interface to Allow Maintenance Work on the Device Without Having to Remove it from Service

By Ian Verhappen

By some estimates, 60-80% of valves are used in open-loop control, which effectively means they're controlled manually. Of course, a number of these valves are strictly for isolation purposes, and therefore, have no reason to be controlled remotely, since they'll only be changed as a result of an associated manual procedure, such as maintenance work. However, this does leave a significant opportunity for some method of communicating with these valves, especially for those located in awkward locations.

"Close coupling" the control element (sensor and controller) can make this happen by enabling the valve to be mounted in the pipe rack rather than being brought to grade. Wireless is one way of making the connection from the control system to the control element.

One consideration for any change from the present operating status is the question of the risk or perceived risk of using a wireless signal for control. However, since the loops being discussed here are presently being controlled manually, having the ability to be able to confirm remotely the actual position of the control element can be considered an improvement.

The most significant consideration, however, is whether or not the infrastructure is in place to implement a wireless system. Infrastructure includes a motive supply—usually air, since a typical wireless transmitter and milliwatt power supply is insufficient to provide the required torque—and the necessary equipment to link the control element to the control system, such as gateways and repeaters.

See Also: Wireless May Make Valve Maintenance Easier

Depending on the nature of the infrastructure (IEEE 802.15.4 wireless sensor networks such as ISA100.11a, WirelessHART, ZigBee and IEEE 802.11 or Wi-Fi), it could be dual-purposed, not only to support the backhaul of the control network (IEEE 802.11), but also to provide data to the field operators or technicians to receive real-time information while they're in the field. For example, a maintenance technician could confirm that the valve is indeed in manual prior to isolating it and starting work. Then, as he is working on the valve, he could also access related manuals and documentation, or warehouse inventory of necessary parts, while performing the task, and consequently, be a more efficient and safer worker. This requires not only the necessary infrastructure, but also changes in work practices, which is a much more difficult process than adding equipment.

Integration of all this is also something that can't be done haphazardly, as it affects many systems across the organization, which means it must be planned and executed as a multidiscipline project with a strong corporate sponsor.

Wireless communication with valves has been in place for many years already. Several suppliers use protocols such as Bluetooth as a configuration interface to allow maintenance work on the device without having to remove it from service or open the enclosure to connect to the wires. Because Bluetooth has a very limited broadcast range, it's not practical for wireless sensor networks, though it does this particular application well. In fact, since most mobile devices include a Bluetooth radio, the potential (and associated cybersecurity risk) exists that these devices could be used for calibration. All that's required is the appropriate app.

Another alternative is ZigBee. It's being used in some applications, predominantly in the utility sector, where it's part of the SmartGrid suite of protocols, not only to communicate to the controller, but also as a local configuration option similar to Bluetooth.

Some applications are end-to-end wireless now, but since most control engineers seem to be from the "show-me state," the preference continues to be hardwiring  However, the beachhead has been established, so I'm sure that it's only a matter of time before we see more wireless final control elements, though they may not always be configured or necessarily installed like the traditional control valve used today.