Kaiser wrote:

If it's used for work, I think the Pressure System Regulations
apply.

I don't know if there's any legal requirement to inspect & test DIY
compressors, like an MOT test.

It's a code of practice and the inspection carried out by the
Companys
Insurer.

Yes. I know.

So, if it's a compressor for DIY use, there is no company and no
company's insurer.

Anyone know of any relevant legislation?