Introducing LT11

If you work with P&IDs (piping and instrumentation diagrams), you’ve probably seen instrument bubbles marked PT, PIT, or PDT and wondered what they mean.  The important thing to know is this: on a P&ID, the “pressure transmitter symbol” usually does not show what the physical instrument looks like. Instead, it shows what the instrument does and how it fits into the process or control loop.  In this guide, we’ll explain what a pressure transmitter symbol represents, how to read tags like

A pressure transmitter works by converting the physical pressure of a gas or liquid into a standardized electrical signal (most commonly 4–20 mA, often with HART or MODBUS on top). In most industrial designs, the process pressure deflects a metal diaphragm, that force is transferred to a sensor element (often piezoresistive), and onboard electronics linearize, temperature-compensate, and scale the signal to the chosen output.   What a pressure transmitter is doing in one sentence  Pressure → diaphragm movement → sensor changes electrically → electronics correct + scale → output signal.  That’s the core principle whether you’re measuring gauge pressure,

A differential pressure (DP) level transmitter measures liquid level by sensing the pressure at the bottom of a vessel and subtracting the pressure at the