Instrumentation is used to monitor and control the process plant in the oil, gas and petrochemical industries. Instrumentation ensures that the plant operates within defined parameters to produce materials of consistent quality and within the required specifications. It also ensures that the plant is operated safely and acts to correct out of tolerance operation and to automatically shut down the plant to prevent hazardous conditions from occurring. Instrumentation comprises sensor elements, signal transmitters, controllers, indicators and alarms, actuated valves, logic circuits and operator interfaces. An outline of key instrumentation is shown on Process Flow Diagrams (PFD) which indicate the principal equipment and the flow of fluids in the plant. Piping and Instrumentation Diagrams (P&ID) provide details of all the equipment (vessels, pumps, etc), piping and instrumentation on the plant in a symbolic and diagrammatic form.

The elements of instrumentation

Instrumentation includes sensing devices to measure process parameters such as pressure, temperature, liquid level, flow, velocity, composition, density, weight; and mechanical and electrical parameters such as vibration, position, power, current and voltage.

Temperature instrumentation

Oil, gas and petrochemical processes are undertaken at specific temperatures.

Pressure instrumentation

Oil, gas and petrochemical processes are undertaken at specific operating pressures.

Flow instrumentation

The throughput of a petrochemical plant is measured and controlled by flow instrumentation.

Level instrumentation

The level measurement of liquids in pressure vessels and tanks in the petrochemical industry is undertaken by differential pressure level meters, radar, magnetostrictive, nucleonic, magnetic float and pneumatic bubbler instruments.

Analyser instrumentation

A wide range of analysis instruments are used in the oil, gas and petrochemical industries. Most instruments function continuously and provide a log of data and trends. Some analyser instruments are configured to alarm (AAH) if a measurement reaches a critical level.

Other instrumentation