Dry-type or oil-lubricated pump: which to choose?

On mobile milking machines, the pump that creates the vacuum comes in two basic types: oil-lubricated (turbo) and dry-type. Both do the job; the difference shows up in maintenance, working conditions and daily routine. This article sets out the pros and cons of each as plainly as we can.

How the two pumps work

In an oil-lubricated pump, fibre vanes inside the spinning rotor are lubricated by a thin film of oil. The oil reduces friction and also helps seal the pump. In a dry-type pump the vanes are made of graphite (carbon) and run without oil; the vane material wears very slowly as it works and lubricates itself.

Oil-lubricated pump: pros and things to watch

• Thanks to the oil film, the vanes usually wear more slowly, which suits long, heavy daily use.
• It generally tends to run cooler and quieter, although this varies with the model and motor.
• It needs regular oil checks, topping up and oil changes. If these are neglected, the pump will be damaged.
• Some oil mist or drips can come from the exhaust, so the spot where the machine stands needs to be kept clean.
• Used oil has to be collected and disposed of properly.

Dry-type pump: pros and things to watch

• There is no oil to add, change or keep an eye on.
• No oil smell, no oil drips and no waste oil, which can matter where cleanliness is a priority.
• Graphite vanes wear over time and need replacing at intervals. The wear produces fine carbon dust.
• Water or milk getting into the pump can damage graphite vanes, so take care not to overfill the bucket and keep the vacuum line clean.
• Depending on the model and use, it may run hotter than an oil-lubricated pump.

Which suits which situation

There is no fixed rule, but these questions can help you decide:

• Will the machine run for long hours every day? For heavy use, an oil-lubricated pump is often a comfortable choice.
• Can you keep up with oil checks? If you are not sure, a dry-type pump needs less daily attention.
• Does having no oil or oil mist matter to you? Here the dry-type pump has the advantage.
• Can you get spare parts easily? Vanes are a wear part in both types, so keeping a spare set on hand saves trouble.

Noise is hard to generalise about: the motor, the housing and the surface the machine stands on matter as much as the pump type. If noise is important to you, ask us before you decide.

Maintenance and support

Whichever pump you choose, regular maintenance is what decides how long it lasts. Our videos show fibre vane and oil changes on the oil system, and graphite vane changes on the dry system, step by step. Check your machine's manual for vane change intervals. If you still cannot decide, call us and tell us how many animals you milk and how you use the machine, and we will work out the right machine together. Our machines carry a 2-year warranty.