Do You Know These 12 Key Instrumentation Terms?

Let’s Talk About These 12 Key Instrumentation Terms.

1.The Direct Measurement Point

Refers to the specific location on a pipe or piece of equipment where an instrument directly contacts the process medium to take a measurement.

2.Primary Component

Refers to the instrument fitting installed at a primary point, such as a pressure tap nipple or a thermowell boss.

3.Primary Valve

Refers to the valve installed directly on a primary component, serving as the first valve in the process control and measurement system.

4.Primary Element

A sensing element installed in the field that is in direct contact with the process medium.

5.Local/Field Mounted Gauge

Refers to an instrument installed locally in the field that is in direct contact with the process medium, such as a bourdon tube pressure gauge or a bimetal thermometer.

6.Initial Calibration

Refers to the individual calibration of an instrument before installation. As required by standards, each instrument must undergo this process to verify key performance indicators like indication error and variation, ensuring compliance with design or manual specifications and laying the groundwork for subsequent commissioning.

7.Secondary Instrument

Refers to instruments whose display signals do not come from direct contact with the process medium. They typically receive standardized signals from transmitters, such as pneumatic signals or signals from electric unit combination instruments.

8.Field Instrument

A general term for all instruments installed on-site in an industrial process. This includes all primary instruments as well as any secondary instruments that are located in the field.

9.Loop/System Calibration

Refers to the comprehensive calibration of an entire measurement loop or control system, performed after field installation and wiring are complete. It is the final verification before the instruments are put into official operation.A standard signal is applied at the measurement point, and the responses of all instruments in the loop are observed to ensure they fall within the permissible error range. If any value deviates and the cause cannot be pinpointed, all instruments in the system must be recalibrated.

10.Instrument Fittings

Refers to all machined metal or plastic components used for instrument installation, which hold a particularly important role in the installation process.

11.Piping & Instrumentation Diagram (P&ID)

A diagram that uses standardized symbols for process measurement and control to describe production automation. It details instrument locations and serves as a key design document for defining primary points, embodying the control strategy, and guiding construction.

12.Standard Instrumentation & Control Symbols

Refers to universal design symbols governed by national standards (e.g., HG20505-92). For instance, a measurement point is typically the start of a connection line, instruments are connected with fine solid lines, and energy sources can be annotated when necessary (e.g., AS-0.14 for a 0.14 MPa air supply).