D.I.Y fridge compressor as air assist

[Robertmr]

No, they can't be used for continuous use (they get quite hot). I used them to inflate bicycle-tires but even that was too much for them eventually.
A big aquariumcompressor (for bigger outside pools) can work for longer periods / contiuous and can produce quite an amount of air if you use wide tubes where possible.
they operate as quiet as refridgerator-compressors..

[Michaelea]

Yes and no, you can build silent compressors using fridge pumps but they give out quite dirty air and require a few of them to be daisy chained to get enough volume(and stay within the duty cycle). Pressure wise they can go to 600 - 700 psi so a good air receiver would be required.

The clarke series of Shhh compressors effectively use fridge pumps but are expensive to buy.

cheers

Dave