Automatic drain valves on air tanks:
a.Must be manually operated every day
b.Automatically expel water and oil that accumulate in the tanks
c.Regulate the air pressure in the system
d.Are only found on trailer air tanks
Explanation
Automatic drain valves are installed on air tanks to automatically expel accumulated water, oil, and other contaminants. Even with automatic valves, it is good practice to manually drain the tanks periodically to ensure they are working properly.