Posted By Chris Pollington Hi Clive Having bought one for home use, I have noticed that it is stamped on the lance itself as a maximum safe pressure, This is much higher than the maximum working pressure of the washer unit. If you have bought it as a set the manufacturer should ensure that it is matched with the unit. If you are after information on the maximum legal pressure you can use through any lance system then I guess it is down to risk assessment and the maximum would be that which is safe under the circumstances. I hope this is of some use Chris.