20-DC Series automatic differential condensate controllers in cast iron are designed to function on applications where condensate must be lifted from a drain point or in gravity drainage applications where increased velocity will aid in condensate drainage.

When lifting from the drain point, often referred to as siphon drainage, the reduction in pressure that occurs when the condensate is elevated causes a portion of it to flash back into steam.

Ordinary steam traps, unable to differentiate between flash steam and live steam, close and impede drainage. Increased velocity with gravity drainage will aid in drawing the condensate and air to the DC.

This increased velocity is caused by an internal bypass, controlled by a manual metering valve, so the condensate controller will automatically vent the bypass or secondary steam. This steam is then directed to the condensate return line or collected for use in other heat exchangers.