Combustion Pressure Washers

Professional petrol washers are built for continuous duty and take site conditions better than hobby equipment. The difference is the pump: industrial versions use a brass head with ceramic pistons and a reduction gearbox, running at around 1450 rpm instead of the 3400 rpm typical of pumps driven off the engine shaft. Lower speed means longer seal life — at roughly 200 bar and 900 l/h such a machine will handle many hours of work a day. Servicing means an oil change every 50–100 hours and a check of the water filter.

Petrol consumption follows engine power and pump load. A machine of around 7 hp burns roughly 1.5–2 l/h under load, a stronger unit of about 13 hp some 2.5–3.5 l/h. Tanks usually hold 3–6 litres, giving some 1.5–3 hours between refuelling stops. When planning a shift, count the actual cleaning time — an idling engine burns fuel too.

Running a petrol washer in an enclosed space is unacceptable because of carbon monoxide, which is odourless and lethal at concentrations as low as roughly 0.1% in the air. An open garage door comes nowhere near the air exchange a 5–15 hp engine needs, and the hazard builds up within minutes. In warehouses and workshops the standard choice is a cold-water electric washer. Where work is split between indoors and outdoors, two machines are the practical answer.

Pairing an electric washer with a generator pays off only when it also powers other tools. A three-phase washer of about 7.5 kW needs a set of at least 10–12 kVA, since inrush current runs several times higher than the rated value. Such a set weighs a few hundred kilograms and costs many times the gap between the washers. For field cleaning alone, a petrol drive is cheaper and quicker to set up.