Brief description

A pump is a mechanical device designed to move fluids (liquids or gases) from one place to another, typically by raising them from a lower elevation to a higher one.

Use / Function

• Water Supply: Drawing water from wells for drinking or irrigation.
• Drainage: Removing water from flooded areas (mines, polders, ships).
• Firefighting: Projecting water to extinguish fires.
• Industrial: Moving liquids in processing (e.g., brine, oils).
• Scale: Domestic / Industrial.

Operating principle

Pumps typically use energy to create a pressure difference (suction or positive pressure).

1. Suction: Creating a partial vacuum so atmospheric pressure pushes the fluid into the chamber.
2. Displacement: Physically pushing the fluid out of the chamber.
3. Check Valves: Flaps that allow flow in only one direction, preventing backflow.

How to create it

Simple Piston Pump:

1. Cylinder: A hollow tube (wood or metal).
2. Piston: A plug that fits tightly inside the cylinder (often wrapped in leather for a seal).
3. Valves: Two one-way valves (leather flaps). One at the inlet (bottom) and one on the piston itself.
4. Mechanism: A handle or lever to move the piston up and down.
   • Upstroke: Inlet valve opens, water is sucked in. Piston valve closes.
   • Downstroke: Inlet valve closes, piston valve opens, allowing water to pass above the piston.
   • Next Upstroke: Lifts the water above the piston to the spout while sucking in new water below.

Materials needed

• Body: Hollowed log or cast metal pipe.
• Piston: Wood or metal plug.
• Seals: Leather or greasy rags to ensure an airtight fit.
• Valves: Leather flaps or simple ball valves (stone/metal ball).
• Lubricant: Animal fat to reduce friction and improve the seal.

Variants and improvements

• Archimedes’ Screw: A screw inside a pipe; excellent for lifting water short distances (e.g., irrigation) without complex valves. Can be driven by a windmill.
• Chain Pump: A continuous chain with buckets or discs pulling water up a tube.
• Force Pump: Uses a solid piston to push water out under pressure (good for firefighting).
• Gear Pump: Uses two rotating gears to displace viscous fluids like oils. See Gear Pump.
• Rope Pump: Simple low-tech version using a rope and washers.

Limits and risks

• Suction Limit: A suction pump can only lift water about 10 meters (33 feet) due to atmospheric pressure limits.
• Leakage: Poor seals reduce efficiency drastically.
• Priming: Often needs water poured in first to wet the seals and start the suction.
• Freezing: Water remaining in the pump can freeze and crack the body.