Section 04 · Understand
Anatomy of a ram pump
Nine parts, two of which move. Click any numbered hotspot — or a chip below — to learn what the part does and what it's typically made of.
What each part is made of
| Part | Commercial rams | DIY builds | Watch out for |
|---|---|---|---|
| Drive pipe | Galvanised or stainless steel | Steel preferred; heavy pressure-rated PVC accepted on short runs | Flexible hose kills the hammer; glued PVC joints can let air in under suction |
| Waste valve | Brass/bronze body, guided disc or poppet, calibrated weight or spring | Brass swing check valve with a bolt-on weight arm; rubber flap facing | Worn rubber = missed beats; weight must be adjustable |
| Delivery check valve | Brass or bronze swing/poppet NRV | Brass swing check valve (same part as the waste valve, unweighted) | Debris on the seat lets water fall back; must seal against full static head |
| Air chamber | Welded or cast steel pressure vessel | Steel pipe with cap, or pressure-rated pipe + rated cap; inner-tube trick | Never use thin DWV/waste PVC — it can burst; pressure rating must exceed max head with margin |
| Snifter | Machined snifting valve or calibrated orifice | ~1 mm drilled hole or a small Schrader + needle valve | Too large = wasted air & sputtering; too small = waterlogged chamber |
| Delivery pipe | Steel, or HDPE for long runs | HDPE or pressure-rated PVC | Must be rated for full static head plus pulses; protect from UV if exposed |
| Foundation | Cast pad, hold-down bolts, often a stone/brick pump house | Concrete block or poured pad, anchor straps | Waste water must be channelled away or it undermines the pad |
How the parts relate
- Drive pipe matches the ram's inlet size and is never reduced mid-run — a change of diameter changes the wave behaviour.
- Delivery pipe is typically about half the drive pipe's diameter, since it carries a much smaller steady flow.
- Air chamber volume is commonly sized at roughly 20–50 × the water delivered per beat — bigger simply means smoother.
- Waste valve weight is the tuning dial: it sets the velocity at which the valve slams, hence the beat rate and the spike strength.
Now that you know the parts, see how they're sized together on a real site in Design & Sizing — or trace their evolution since 1772 in History.