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Turning up the heat on industrial pressure washers

02 June 2017

Recent independent cleaning tests conducted by the Wfk – Cleaning Technology Institute in Dusseldorf, Germany compared pressure washer cleaning efficiencies across four different applications. The tests were conducted at three temperature levels, cold, 60°C and 90°C. Matthew Rogers, product manager for Nilfisk UKI, examines the results. Does hot water win over cold every time in pressure washer applications and how hot is hot?

Customer demands for improved productivity with a lower overall cost of ownership are redefining hot water cleaning methods in the industrial pressure washer market as manufacturers develop technologies and solutions to lower the customer’s total cost of cleaning.

But what is the optimum temperature level when using an industrial pressure washer? Does it vary depending on the application and what are the implications on the cost of ownership?

Recent independent tests carried out by the Wfk – Cleaning Technology Institute located near Dusseldorf in Germany compared the cleaning efficiency of industrial pressure washers at different temperature levels for four applications. For all tests the bar pressure was set at 180 bar and the water flow rate at 810 litres per hour. Investigation WL 6203/12 refers as follows -

Applications tested were:

  • Oil and grease on metal work
  • Rim dirt on metal sheets
  • Traffic film on car bodywork
  • Grease and oil on truck bodywork

All tests were conducted with water at cold, 60oC and 90oC respectively.

The conclusion

The results were surprising and provide us with greater insights as we move forward into a more measured environment where customers are constantly looking for an excellent cleaning result at a lower cost achieved by reducing fuel and labour costs by increasing efficiency.

Yes, hot wins over cold overall as hot water was found to be much more efficient resulting in a dramatic reduction in cleaning time and therefore associated labour and water costs could be reduced significantly.

Most significantly when cleaning oil and grease from metallic surfaces with water at a temperature of 60oC as opposed to cold water, the cleaning time is reduced to 25%. A quarter therefore of the cleaning time required with cold water.

The overall increase in efficiency when cleaning at 60oC compared with 90oC degrees is low and the increased fuel costs do not result in a large enough reduction in cleaning time to warrant the increased cost. The only application where water at 90°C is beneficial in the test conditions is the removal of rim dirt on metal surfaces.

So what does this mean for the user when aiming for the optimum result in the least time and for the lowest cost?

It means that the majority of traditional hot water cleaning tasks can be completed using hot water at a lower temperature of 60oC with excellent results. Cleaning at 90oC whilst quicker does not offer substantial savings as the increase in fuel costs will outweigh the reduction in cleaning time.

EUnited approval scheme

Innovation across the industry has led to the development of improvements in boiler technology such as eco modes that heat water very economically to 90oC and provide significant savings when compared to running at full heat unnecessarily. The European Cleaning Machine Association (ECMA) rates and approves pressure washer boilers under their EUnited scheme. Buyers are therefore advised to seek out EUnited certified products to ensure low consumption. 

Some EUnited approved boilers are classed as >92% efficient and therefore provide big reductions in fuel consumption and cost. In some cases saving up to 15% when compared to similar machines in their class. This should be a prime consideration for the cost conscious purchaser to ensure the lowest costs of ownership can be achieved.