Equipment
Pumps, and what a rough pump does to cider
What kind of pump should be used for cider, and can a pump damage it?
In short
Pumps divide into centrifugal types, which accelerate liquid with a spinning impeller, and positive-displacement types, which trap a volume and move it bodily. The two behave very differently on a liquid that carries dissolved gas, suspended solids and a finished aroma.
The damage a bad transfer does is mostly invisible at the time. Dissolved oxygen picked up during pumping shows itself as oxidation months later; carbon dioxide stripped out of a carbonated cider shows itself as a flat product at the point of sale.
Almost every problem with pumping cider comes from the same three causes: air drawn in on the suction side, excessive shear at the impeller, and a pump that cannot be cleaned properly.
The pump families
The practical division is between the centrifugal pump, which is cheap, high-flow and rough, and everything else. A centrifugal pump is entirely appropriate for moving juice to a settling tank or for circulating cleaning solution around a tank; it is the wrong tool for transferring a finished carbonated cider to a filler.
| Type | How it moves liquid | Gentleness | Self-priming | Cleanability |
|---|---|---|---|---|
| Centrifugal | Impeller accelerates liquid outward | Low — high shear, can strip CO₂ and aerate | No; needs a flooded suction | Good if hygienically designed |
| Flexible impeller | Rubber vanes flex past an eccentric cam | Moderate; degrades as the impeller wears | Yes | Moderate; the impeller is a consumable and a residue trap |
| Lobe or rotary piston | Two rotating lobes trap and carry volume | Good at low speed | Yes | Good; designed for clean-in-place in dairy work |
| Progressive cavity | A helical rotor in a stator moves sealed cavities along | Very good; handles solids and lees | Yes | Moderate; long path, stator is a consumable |
| Peristaltic | Rollers squeeze a flexible tube | Excellent; liquid touches only the tube | Yes | Excellent; the tube is the only wetted part |
| Diaphragm, air-operated | Compressed air flexes diaphragms alternately | Good, but pulsating | Yes; can run dry | Moderate; many internal surfaces |
Shear, cavitation and aeration
Shear is the mechanical working of the liquid as it passes through the pump. High shear breaks up lees particles into fragments too small to settle, which turns a cider that would have fallen bright into one that needs filtration. It also disrupts the colloidal structure of a cider matured on lees, changing mouthfeel.
Cavitation happens when the pressure on the suction side falls low enough for dissolved gas and vapour to come out of solution and form bubbles, which then collapse violently as pressure rises. It damages the pump, it makes a characteristic gravelly noise, and it aerates the cider thoroughly. The usual causes are a suction line that is too long, too narrow or partly blocked, a valve not fully open, or a pump running far faster than it needs to.
Air ingress is the quiet one. A loose fitting, a perished gasket or a hose clip that has relaxed will let air into a suction line without any visible leak, because the pressure there is below atmospheric. The cider picks up oxygen the whole time and nothing looks wrong. Suction-side joints are the ones to check obsessively.
For a carbonated cider there is a further effect: any drop in pressure or increase in turbulence causes dissolved carbon dioxide to break out, foaming the product and losing carbonation. Transfers of carbonated cider are made slowly, under counter-pressure, and with as few restrictions in the line as possible.
Running a transfer well
- Run the pump as slowly as the job allows. Nearly every problem in this list gets worse with speed.
- Keep suction lines short, straight and full-bore, and make sure every valve in them is fully open before starting.
- Discharge below the surface of the receiving liquid, or down the wall of the vessel, rather than letting cider fall through air.
- Purge the line with carbon dioxide or with a small volume of cider before a transfer that matters, so the first thing through is not a hose full of air.
- Check gaskets, clamps and hose ends before every transfer; they are consumables and they fail quietly.
- Never dry-run a pump that is not designed for it. A flexible impeller destroys itself in seconds and sheds rubber into the product.
The pump as a contamination source
Also answered on this page
Questions this page covers, so you can tell at a glance whether it is the one you want.
- What pump is best for cider?
- Can pumping oxidise cider?
- Why is my pump making a rattling noise?
Related
What people ask next
Questions readers ask about the things this page mentions. Each one goes to the section that answers it rather than to a page written to receive the question.
- Can you fix a cider that has gone vinegary — Not really. Volatile acidity cannot be removed at small scale, and blending it away only dilutes it. The realistic options are to accept it, to blend a lightly affected batch into a much larger sound one, or to let it finish becoming vinegar.
- How do i move cider off the lees without a pump, and what tubing is safe
- How do i sterilise cider bottles — Wash them clean first, then sanitise with a no-rinse sanitiser or a sulphite solution, and fill while still wet with it. Bottles that look clean but have dried deposits inside are the usual source of bottle spoilage.
- What is oxidation in cider
- What is racking in cider making — Racking is siphoning cider off the sediment it has thrown into a clean vessel, leaving the lees behind. It clarifies the cider and, in traditional practice, is also used to slow a ferment by removing yeast with the lees.
- Where does the fizz in cider come from — Either from fermentation trapped in a sealed container, or from carbon dioxide dissolved into the cider under pressure before filling. The French cider appellations permit only the first, and require at least 1.0 to 1.5 bar at 20 °C depending on the name.
Sources
What this page rests on. Where a source is marked as registered rather than read, CiderHQ is recording that the body is authoritative on the subject without claiming to have worked through the document itself. See our evidence policy for what each state means.
Cider and perry production technical training material
Peter Mitchell / Cider and Perry Academy · reference work · registered as competent for this subject
Searched again on 2026-08-25 and it remains the one printed source here that a bibliographic check cannot fix, because it is not a published work with an edition. It is course material issued to participants of a training programme, so there is no catalogue record to verify, no ISBN, and no lawful public copy. Its state stays `registered` for that reason rather than through inattention.
Hochschule Geisenheim University — beverage technology
Hochschule Geisenheim · university · retrieved 2026-08-24
German beverage-technology research covering apple wine and fruit juice processing, including the enzymology of clarification.
The New Cider Maker’s Handbook: A Comprehensive Guide for Craft Producers
Claude Jolicoeur, Chelsea Green Publishing, 2013. ISBN 9781603584739 · reference work · bibliographic record verified, not opened 2026-08-25
Bibliographic record verified on 2026-08-25 against the Open Library union catalogue: Chelsea Green Publishing, 2013, ISBN 9781603584739, one edition recorded. That establishes the citation points at a real book in a stated edition, which is what a citation needs and is all it establishes. No copy was opened and nothing is quoted from it. The book itself is in print and not digitised in any open collection; where CiderHQ needs a figure from this territory it uses an accessible research source instead and says so.
Where to go next
- Cider making equipment — The rest of the equipment material, grouped by what each piece is for.
- How cider is made — The methods this equipment exists to carry out.
- Troubleshooting — The faults that are traced back to equipment and to cleaning.