When might a regulator need special preparation?

A regulator requires special preparation primarily when the mixture being used contains more than 40 percent oxygen. This is because higher concentrations of oxygen can lead to the risk of oxygen toxicity when diving at depths or under certain conditions. Gases that are rich in oxygen, such as Nitrox blends, can increase the chance of dangerous partial pressures if not managed properly.

Regulators used for high-oxygen blends must be serviced and prepared to prevent combustion and ensure safe functioning. This preparation might include using certain materials that can withstand the effects of higher oxygen content, as some materials may degrade or fail under these conditions. Proper preparation is crucial for maintaining the integrity of the regulator and ensuring diver safety.

In this scenario, the focus is on the necessity of special preparation specifically in relation to the oxygen percentage in the breathing gas. Therefore, it’s important to recognize the specific situations involving high-oxygen environments where such precautions are vital.