What characteristic must regulators have to ensure their functionality?

Regulators play a critical role in the safe and efficient operation of compressed natural gas (CNG) systems. For regulators to function effectively, they must be designed to withstand various environmental conditions without compromising their performance. The characteristic that they must not be affected by external factors such as freezing rain, sleet, snow, ice, mud, or debris is essential. This property ensures that the regulators can operate reliably in diverse weather conditions and remain free from contamination that could alter their operation.

If a regulator is impacted by such environmental elements, it could lead to malfunction or failure in regulating gas pressure, which poses safety risks. Thus, their proper functionality is critically linked to their durability against these adverse weather conditions, making this characteristic vital for safe operations in the field.