This distillation head features automatic reflux control via a solenoid valve arrangement

Vapors pass for the most part around the outside of the plunger housing to reach the condenser. The condensate is directed to the interior of the housing and returns to the column via holes in the housing at the valve seat. A drip below the plunger seat directs the reflux to the center of the packing. The design is such that viscous liquids like glycerin cause no difficulty. Temperature measurement is by means of a thermocouple or thermometer; a [ST] 10/30 side port for 40mm immersion is located in the vapor stream. Vapor velocity prevents reflux from running down the well.

Hold-up: Static — 0.2 mL for liquids such as toluene or ethanol; Dynamic — 0.4 mL toluene at 4.5 mL/min. Distance from column to takeoff arm is approximately 75 mm. Fabricated from borosilicate glass.

Reflux control is effected by an adjustable time switch and solenoid takeoff valve. Reflux ratio is thus a time function, and is hence independent of throughput except when a single drop is a significant part of the condensate. Even then, drops can be split by shortening takeoff time and adjusting plunger travel by means of the brass washers provided