Variable

Common

ISA

Single Device

Combination

Backflow

Check valve

Flow Safety Valve

FSV

Level

High Level sensor

Level Safety high

LSH

LSHL

Level

Low Level Sensor

Level Safety Low

LSL

LSHL

Pressure

Low Pressure Sensor

Pressure Safety Low

PSL

PSHL

Pressure

High Pressure Sensor

Pressure Safety High

PSH

PSHL

Fire

Heat Detection

Temperature Safety High

TSH

Fire

Fusible Material

Temperature Safety Element

TSE

Combustible Gas Concentration

Combustible Gas Detector

Analyzer Safety High

ASH