Don’t come in from the cold.

THE ENGINEER’S VIEW

There was an item in the Sunday Times gossip column-cum-Diary on Sunday 6 February 2011 that caught the eye of The Lad. He cannot give you a hyperlink to it because the website of the newspaper seems to be subscription only. He does not subscribe and probably nor do you.

A man in the UK Lakeland was boasting that he had a refrigerator that was 55 years old and still going strong and he hoped to pass it on in his family. It crystallised a feature that, as an engineer, The Lad has often noted: the longevity, usually without any maintenance, of the domestic fridge.

In his view this is simply because most fridge’s components are lowly loaded and the loads and temperatures are almost constant. The electric motor and its pump are very quiet which indicates that they are not running highly loaded and at their limits. The rest of the components such as the radiator at the back and chilling coils inside pretty well stay warm and cool respectively throughout the day and, indeed, its life. High loads and big temperature swings are frequently the cause of failures in engineering.

Contrast this with the domestic washing machine and spin drier. The Lad makes the point that these machines tend to be less reliable than the fridge. This, he says, is due to the different duty imposed on their components. The washer drier does not operate, like the fridge, continuously. It is always being switched on and off. The drum and motors are frequently powered up and down and operate at quite high loads. The drum and the bearings are spun up and down to high speeds under high, frequently off balance, forces. The systems within the machine frequently see high temperature spikes due to the heating of the washing water which is rather corrosive due to the detergent loads. The rubbery seals are pushed to their limit during every wash cycle. On top of all this, every component of an increasingly complex machine design is packed tightly in a hot, vibrating environment.

Unless somebody out there can disagree with The Lad.

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