A petrol machine exists for work with no mains supply, and once that is the reason for buying one, engine power is the figure that sizes it. The range runs 4hp at the light end through 5.5hp, 6.5hp, 7hp and 9hp to 13hp, and the engine has to carry the pump rather than the other way round.
Pressure follows the engine. Sealey run 150 bar at 4hp and 220 bar at 6.5hp, Draper reach 262 bar at 13hp, and the V-TUF DD and GB machines cover 200 bar at 9hp and 13hp. Honda GX and Kohler engines run through the SIP Tempest and PP ladders, and the engine make is stated per machine rather than left to the photograph.
Direct drive or gearbox driven is the durability decision. A direct drive pump turns at engine speed, which is simpler and lighter. A gearbox drops the pump speed, which means less wear and longer life on a machine running all day. The V-TUF GB110 carries a gearbox at 13hp where the DD machines are direct.
Water supply is the question a petrol machine raises that a mains machine does not, since the work is often nowhere near a tap. Self-priming machines draw from a tank or a stream, and barrow bowsers at 150 litres and a 500 litre highway trailer carry their own. Questions go over WhatsApp on 07754288583 with the site and the water source.