Failure of pressure washer

  • Safety Flash
  • Published on 27 October 2011
  • Generated on 28 July 2026
  • IMCA SF 11/11
  • 2 minute read

A Member has reported an incident in which a Karcher HDS1195 pressure washer failed when a technician was conducting a test run after maintenance. 

What happened?

The model involved was a portable unit designed for domestic and industrial use, and was three years old. A technician had completed the replacement of an electrical switch, and was checking that the switch was working correctly. On successful completion of the tests, the unit was powered up to ensure it was fully operational.

The technician saw water emerging from the nozzle of the cleaning gun, and proceeded to shut down power to the washer. As this was done, there was a loud bang and the hatch for the boiler was blown off into the air. The technician received two small cuts to the face and minor droplet burns to the right arm.

What were the causes?

Investigation revealed that:

  • A pressure relief valve, designed to prevent system overpressure, was corroded and unserviceable.

  • A switch, designed to regulate the boiler, was also defective.

    • As a result, overpressure within the system caused the heating coil to rupture, and the escaping water and steam blew the hatch off the boiler unit and into the air.

Recommendations

The following recommendations were made:

  • A thorough inspection of similar portable pressure washing devices, particularly those using a heating system, would be beneficial.

  • Portable pressure washing devices should be part of the planned maintenance schedule.
pressure washer with boiler hatch missing

pressure washer with boiler hatch missing

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