In a field of their own

Asset Management, which can include many different requirements and terminologies, is being used to ensure plants run more efficiently and for longer periods between maintenance intervals.

In the past, plant shutdowns were planned for a certain period and time, irrespective of whether the field devices required replacing or overhauling. Nowadays, the use of intelligent instrumentation can make these shutdowns a thing of the past.

The plant operators can interrogate these devices to ascertain certain critical information, depending on the device being interrogated. The information available could possibly include tag number, date of installation, date of last service, number of operations, cycle count, cycle time, seat wear, torque, historical performance, travel time, breakaway time, among others.

Generally, intelligent field devices communicate on some of the many network protocols currently available, including HART, ProfiBus and Foundation Fieldbus. The devices deliver the advanced functionality locally at the device, or in the field, or remotely at the control room. In any case, the information is available in real time.

The intelligence within the devices helps to provide optimum performance; for example, inbuilt electronics help to present the most up-to-date diagnostic capabilities in a simple and easily recognisable format.

On initial installation, set-up and calibration, the engineer can run a hysteresis check, which provides a footprint, or valve signature, of the installed device and a record of its initial optimum performance.

Any time during the life span of the device the engineer can then run a further hysteresis check and compare the latest valve signature with the initial signature, thereby providing information on the current performance of the device. The engineer can decide whether the performance of the device is acceptable, or has deteriorated to the point that the device requires maintenance.

Another option for actuated valves is to measure the breakaway time from the seat and the total time from open to close. At the same time, the engineer would be able to set defined parameters so that if there was a significant change in the time of these two measurements then an alert would be raised.

These settings can be initially downloaded to the device, and these parameters can be interrogated further at any time during the life span of the device. If, for example, the breakaway time from the seat has decreased, this could indicate that there is some seat wear: the valve now 'comes out' of the seat faster.

On the other hand, if the breakaway time has increased, this could indicate that the actuator has a leak, that the air pressure to the actuator has decreased, or even that the valve seat has been damaged. This information can also be analysed in conjunction with the total time information to ascertain the overall performance of the valve.

In either scenario, the engineer has the information immediately to hand to undertake any remedial action that is necessary and to ensure the plant downtime is optimised.

All of the information from these devices can be saved within the associated software to provide an audit trail that engineers can use to determine the optimum device for their process and provide valuable information on how different processes can affect different devices. This will enable plant operators and manufacturers alike to understand better the intricacies of process conditions, ensuring ongoing developments for products and processes.

Tyco Valves and Controls has long recognized the importance of intelligent field devices and the use of network protocols. Most intelligent field devices for valves are of the pneumatic type, but as Tyco manufacture both pneumatic and electric actuators, it has developed intelligent interfaces for both types. At present Tyco products can communicate on HART, ProfiBus, Foundation Fieldbus, AS Interface, DeviceNet, Modbus and Lonworks.

The complete Tyco range of intelligent devices can be included with the pneumatic or in the electric actuators, which can then control any type of valve, whether this is ball, butterfly, rotary process, plug, gate or globe. This also ensures that any process industry has access to a complete intelligent valve package for their process from a single source.

A recent Tyco innovation, FDT/DTM (Field Device Tool/Device Type Manager) technology, provides intelligent asset management and integration for fieldbus devices. This makes the implementation of intelligent field devices faster, easier and more efficient.

Tyco is a member of the FDT-JIG (Joint Interest Group), and aims to provide certified DTMs for all of its network and intelligent field devices. Within the next few weeks, the company will have a fully certified DTM for its AVID intelligent SmartCal positioner, providing a product that can be used with many other intelligent field devices.

Tyco has already had requests for this type of solution from major steel and gas manufacturers, who have already recognized the benefits of this type of engineering solution.

Tony Stark is Marketing Manager, Actuation & Controls for Tyco Valves & Controls.