Condensate Drain

a device for automatic removal of condensate from steam-consuming apparatus and steam pipelines. To reduce steam consumption and avoid water hammer in pipes, the condensate must be removed without allowing steam to escape. Condensate drains may be classified by their principle of operation as float, nozzle, and thermostatic types.

The difference in density between the steam and the condensate is used in the operation of float drains, which may have a float that is open at the top or bottom. In such a device, the condensate is forced out of the float by the entering steam. The float then rises and closes the discharge opening by means of a rod. In this case the discharge of condensate is periodic. Float drains with hermetically sealed spherical floats are equipped with slide or gate valves, and removal of the condensate is continuous.

In nozzle drains the size of the opening is calculated according to the condensate flow. The difference in the specific volumes of the steam and condensate is used in the operation of this type of drain. The removal of condensate is continuous.

Thermostatic drains incorporate a hermetically sealed elastic container filled with a liquid having a relatively high vapor pressure (for example, toluene). As the drain fills with steam, whose temperature is higher than that of the condensate, the liquid in the container evaporates. As a result, the container is deformed and a valve is displaced, thus blocking the opening. In this design condensate removal is periodic.