The principal hazard to personnel when using a diesel engine fuel nozzle tester is ______.

The principal hazard to personnel when using a diesel engine fuel nozzle tester is related to blood poisoning, which can occur due to exposure to specific chemicals involved in the testing process. Diesel fuel and additives, if improperly handled, can lead to exposure through skin contact or inhalation.

In the context of these operations, fuel nozzle testers frequently come into contact with high-pressure fuel systems that may dispense tiny droplets or mist of fuel. If any of this fuel enters the bloodstream through cuts or abrasions, it can potentially cause serious health risks, including blood poisoning.

Taking appropriate safety measures, such as wearing gloves and ensuring the work area is well-ventilated, can help mitigate these risks. Understanding the chemistry and handling procedures of diesel fuel is crucial for ensuring the safety of personnel involved in inspecting and testing these components.