When people compare compressors, they compare purchase prices. It's the number on the quote, so it feels like the decision. It's also the smallest part of what the machine will cost.
Over a working life, an industrial compressor's total cost behaves like an iceberg.
The visible tip — purchase price plus maintenance — is roughly a fifth to a quarter of the total. Everything below the waterline, the rest, is electricity. (For a 75 kW machine on heavy duty, the lifetime energy bill commonly runs to several times the purchase price; figures depend on tariff and running hours, but the proportion holds across the industry.)
Now layer the lifecycle curve on top. If the machine's efficiency declines a little every year because its seal is wearing, that decline acts on the biggest line in the whole calculation — the one below the waterline, getting larger. A few percent of efficiency drift sounds trivial against a purchase price.
Against the energy bill, compounded over a decade, it's the 870,000-kWh-a-year problem from the previous post, sitting unnoticed on someone's electricity account.
Buy on the tip of the iceberg and you optimise the cheapest fifth. The decision that matters is the four-fifths you can't see.
The full lifecycle-cost breakdown → https://www.linkedin.com/pulse/why-screw-compressor-efficiency-declines-over-time-rotary-contaldi-usqkf/
