What a Separation Session Costs to Run: Power, Water and Time
Buyers ask what a machine costs to buy far more often than what it costs to run, and for a small dairy the running side is usually the smaller number - but only if the sessions are planned. This page sets out the arithmetic for the three inputs that matter, with the assumptions stated so you can replace them with your own.
Electricity: the only easy one to calculate
The motor rating is stated for each build, and both machines in the catalogue list the same rating. Energy is simply that rating multiplied by the hours the machine actually runs:
energy (kWh) = motor rating (kW) x running hours
A 200 W motor is 0.2 kW. Run it for four hours and you have used about 0.8 kWh. That figure is independent of the milk, which is why it is the least interesting of the three inputs - and also the one people fixate on.
Worked figures for a 200-litre batch
| Build | Rated throughput | Hours for 200 L | Energy at 0.2 kW | Energy per litre |
|---|---|---|---|---|
| AD-50 | 50 L/h | about 4.0 h | about 0.8 kWh | about 0.004 kWh |
| AD-90 | 90 L/h | about 2.2 h | about 0.44 kWh | about 0.0022 kWh |
The hours come from the rates the pages state; the energy is arithmetic on the stated motor rating. Two honest caveats sit under that table. A nameplate rating is not a measured draw - the motor may run below it for most of a session and above it briefly at start-up, which is why a meter reading beats this calculation. And the larger build uses less energy per litre only because it runs for less time, not because it is more efficient.
Water: measure it once, then you know
Cleaning water dominates most small dairies' consumption and almost nobody has a figure for it, because it is never metered separately. The measurement takes one session:
1. Count how many times you fill a known container during the rinse and wash, and write the number down.
2. Do it for two or three sessions at the same routine.
3. Multiply by the container volume.
What you get is your own number for your own practice. Published figures for separator cleaning vary so widely - by bowl size, by whether the discs are removed every time, by whether a pre-rinse is reused - that quoting one would tell you more about the source than about your dairy. The useful outcome of the measurement is not the total but the comparison: if removing the disc stack every time doubles the water, that is a decision you can now see the price of.
Time: usually the largest input
Operator time is the one people forget to count, and in a one- or two-person dairy it is normally the biggest of the three. A session is not just the run: it is filling, the run itself, emptying, dismantling, washing, reassembling and putting the machine away. Only the middle item is on the datasheet.
The point of writing it down is to see which part dominates. If the run is 4 hours and the wash is 40 minutes, a faster machine helps. If the run is 30 minutes and the wash is an hour, a faster machine changes almost nothing and the cleaning and reassembly checklist is the more useful page.
Putting the three together
You do not need a currency figure to make a decision. Compare two plans instead of two prices: Plan A runs four short sessions a week, Plan B runs two long ones. Count the hours of machine time and the hours of your own time for each, then look at which input grows faster. That comparison is stable across countries and tariffs in a way that a quoted running cost is not.
If you want to convert energy to money, multiply the kWh figures above by your own tariff - we do not publish a price, because a figure from one market is misleading in another.
Where this connects to the rest of the site
Energy per litre follows directly from the throughput arithmetic in the yield guide, and the hours in the table above assume the rated rate holds, which the real throughput guide explains it often will not. To compare the two builds on their stated figures rather than on a datasheet impression, the AD-50 and AD-90 pages carry their own specification tables.
What this page does not do
It does not tell you what electricity, water or labour cost where you are, and it does not estimate your wear-part consumption, which depends on how often you run and how the machine is cleaned. It is a framework for putting your own measurements in the right places, not a quotation.
Related maintenance resources
Use the ANDUUK replacement parts catalog to match seals, discs, outlets, motor components and cleaning tools to the correct machine assembly.
Browse replacement parts · Read the cleaning and reassembly checklist · Read separator FAQs