🔍 Key Concepts

• Pneumatic level measurement methods for tanks • Difference between mechanical (float/diaphragm) and air-operated systems • How head pressure in a liquid column** is transmitted or simulated

💭 Think About

• Which option specifically needs a continuous or controlled flow of compressed air to operate? • Which devices can work purely from the liquid’s pressure or motion without needing an external air supply? • Think about systems where air is bubbled into the liquid and the back pressure is measured—what is that called?

✅ Before You Answer

• Identify which choices are purely mechanical and do NOT inherently require compressed air • Check which device operates by forcing air through a tube until bubbling just begins at the bottom of the tank • Confirm which system measures liquid level by monitoring air back pressure proportional to liquid head