The Three Feed System Types
| Feed Method | Consistency | Ease of Setup | Best For |
|---|---|---|---|
| Pressurized Tank | Good | Moderate | Clean, consistent flow with regulated pressure |
| Pump (Diaphragm) | Excellent | Easy | Most applications — recommended |
| Gravity Feed | Fair (varies) | Simple | Low-volume, no-power situations |
Pressurized Tank Feed
Pressurized Tank Requirements
- Use a diaphragm-type pressure regulator — orifice regulators will over-pressurize the tank
- Recommended operating pressure: 20 PSI
- ONLY use ASME-rated pressure vessels — propane tanks, compressor tanks. Plastic drums may rupture.
- Any welding or cutting on the tank weakens it below nameplate rating
Pump Feed — Recommended
A small pneumatic diaphragm pump is the ideal centrifuge feed pump: fully adjustable flow, no bypass needed, no motor to burn out.
Diaphragm Pump Best Practices
- Flow adjustable by varying inlet air pressure
- Output can be shut off instantly without pump damage
- Gentle on oil — does not blend contaminants
- Nitrile/neoprene diaphragms for mineral oil; Viton for WVO and biodiesel
- Mount close to feed tank; use pressure side to push oil (vacuum limited to 14.7 PSI)
- Use 3/8" ID hose for pump connections
Gear pumps are the worst choice for centrifuge feeding. Cannot be throttled without a bypass or VFD, run hot at low speed, and blend contaminants into the oil.
Gravity Feed
No moving parts, but flow varies significantly as the tank empties:
| Tank Configuration | Flow Rate Variation |
|---|---|
| Full 55-gal drum, vertical | Baseline (then drops to 83% variation — unusable) |
| Horizontal drum, 5 ft elevated | ~26% variation (marginal) |
| Horizontal drum, 8 ft elevated | ~18% variation (acceptable) |
Use the largest practical hose for gravity feed — 1" ID minimum. Heat oil to 120–160°F to improve gravity flow.