Indicators

Not every measurement needs to travel to a control room, and not every control task needs a PLC. The indicators category covers the instruments that display and act on process signals locally: at the panel, at the equipment or at the tank.

Loop-powered indicators are wired in series in a 4–20 mA loop and take their power from it, so they can be added to any existing transmitter loop. The panel-mounted version gives a scaled LCD readout in a control cabinet; the field-mounted version brings the reading down to eye level in an IP66/IP67 housing, passes HART through to the transmitter and can retransmit the signal or drive a local alarm relay.

Controllers take the next step. The general-purpose controller accepts analogue and digital inputs and drives analogue outputs and relays through configurable function blocks for batching, totalising, on/off and PID valve control and pump station sequencing, all shown on a colour touchscreen in an IP67 field housing. The inventory controller polls up to eight HART transmitters, converts level to volume and mass with strapping tables, manages alarms across sixteen relays and gives a small tank farm the inventory overview and instrument diagnostics that would otherwise need a full tank-gauging system.

Metron MENA supplies indicators and controllers alongside the transmitters they connect to, for oil and gas, petrochemical, chemical, power, water and wastewater and general industry, from single loops on packaged equipment to complete local control of skids and tank farms.