What auxiliary equipment is required to prevent water from entering LP Gas systems?

The use of rain caps is essential for protecting LP Gas systems from water intrusion. Rain caps are designed to be installed on vent pipes or the openings of outdoor equipment. They serve as a barrier against rain and other forms of moisture, preventing them from entering and potentially contaminating the gas system. Moisture can lead to issues such as rust, corrosion, or reduced system efficiency, and in extreme cases, can result in operational failures or dangerous situations.

While other equipment like filters plays an important role in maintaining the quality of the gas by trapping impurities, they do not specifically address the issue of water intrusion. Flame arresters are used for safety purposes to prevent flames from passing back into a gas system, and grates may be utilized in various contexts but do not directly relate to preventing water from entering LP Gas systems. Thus, the primary function of rain caps makes them the correct choice for this scenario.