Wireless Valve Control
In industrial installations, particularly in the oil, gas and chemical sectors, fluid flow around the plant is controlled by servo-driven valves controlled from a central point. In many cases these valves have to be installed in parts of the plant that are remote from the control room and rely on cross-site and sometimes inter-site cables to carry commands to the valves and tell-back from valves to the control room.
The Problem:
All of this cabling is expensive and time consuming to install or re-configure in the event of modifications to the plant. If an engineer out on the plant needs a valve state changed they have to contact the control room to confirm it is safe to continue and ask the controller to operate the valve remotely or switch the valve from remote to local control. The engineer then has to carry out their task and remember to set it back to remote before leaving the site. Tell-back usually takes the form of a contact set operated by the valve drive shaft changing state when the desired position is reached; this condition is relayed back to the control room to change the state of an indicator related to that valve. This system doubles the amount of cabling needed and is prone to error in the event of a cable fault.
The Solution:
Using wireless radio acquisition modules from the T24 telemetry range for command and tell-back eliminates the need for control wiring. In addition, these modules can make use of data from transducers near the valve to relay fluid flow-rate or pressure, indicating actual plant conditions (process variables) rather than just confirming that a selected action has occurred. By use of a radio T24-HA handheld device displaying the data readings, an engineer can interrogate interlocks and plant conditions allowing him to make decisions and changes without having to contact the control room once authority has been given to carry out the work.
Products used in this application:
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