Intro
In industrial installations, particularly in the oil, gas and chemical sectors, servo-driven valves maintain fluid flow around the plant. These are usually controlled from a central point. For the most part, these valves are installed in areas of the plant that are remote from the control room. Due to this, they rely on cross-site or inter-site cables to carry commands to the valves. In addition, further cabling is required if tell-backs from valves to the control room are required.
This cabling is expensive and time consuming to install. In addition, during modifications to the plant the cabling may have to be re-configured. An engineer on site, needing a valve state changed, must contact the control room to confirm it is safe to continue. The controller must operate the valve remotely, or switch the valve from remote to local control. The engineer then has to carry out their task and set it back to remote before leaving the site.
Pressure valve tell-back refers to a position indicator or feedback mechanism that confirms the state of a control valve. This is activated by the valve drive shaft changing state (i.e. open or closed) when the desired position is reached. The tell-back is then relayed back to the control room to change the state of the valve indicator. This system doubles the amount of cabling needed and is prone to error in the event of a cable fault.
Using wireless radio acquisition modules from the T24 telemetry range 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. These values indicate actual plant conditions (process variables) rather than just confirming that an action has occurred. By use of a T24-HA handheld device displaying the data readings, an engineer can interrogate interlocks and plant conditions. Once authority has been given to carry out the work, the engineer can make decisions and changes without having to contact the control room.
If you have an application requirement in the Industrial processing industry we are here to help. Please contact us.
