"The Medway Handyman" wrote in message
...
On 01/05/2011 19:39, Steve Walker wrote:
The KEW Hobby was one of the first on the market, IIRC it had a bypass
valve rather than a pressure switch which most modern machines use.




That would tie in with the in-use sound ..you can hear pump getting up to
pressure, and if you are 'jetting' it is one, sound, when you release the
trigger, sound changes as I presume it reaches peak pressure and 'by pass'
opens ... but certainly does not stop running.