Protection class IP69K was developed for high-pressure jet cleaning at high temperatures. The code number “6” stands for protection against the ingress of dust, while the number “9” stands for protection during high-pressure cleaning at low distances. IP69K was first introduced in 1993 and is based on the DIN40050-9 standard, originally developed for motor vehicles to protect against the ingress of foreign bodies such as dust, dirt, and hot water jets. In the latest version of the IEC60529 standard, only IP69 is referred to (IP69K = IP69).