Abstract: A thermostatic steam trap having a balanced pressure thermostatic element (2,2A,2B) operated by volatile fluid (15) is disclosed in which an internal void (10) of the element is open to steam/condensate within the trap, and in which the volatile fluid fills a housing (6) outside the element when the trap is fully open thereby to support the element against high pressure within the element. In the trap fully-closed condition the element adopts a nearly nesting condition so that if the element is then subjected to higher pressure externally it adopts a fully nesting condition in which it can withstand great external pressure.

Abstract: A float actuated valve mechanism for automatically removing a predetermined amount of accumulated liquid condensate from a sump area of a gas pressurized drain trap or the like so as to regulate the level of liquid in such a sump area. A four-bar linkage between a float and a valve plug provides a non-linearly varying mechanical advantage throughout the movement of the float. In a closed position the valve plug mates with a rigid seating surface and an elastomeric seating surface to provide a wear-resistant seal.

Abstract: Temperature dependent actuating mechanism comprising a temperature responsive sensor including a variable volume chamber in fluid communication with a chamber in an actuator containing a variable volume member connected with an operating member; the sensor further including temperature responsive means change in volume of which brought about by a rise in temperature increases the interior volume of said variable volume chamber to permit fluid to flow out of said actuator chamber and the volume of said variable volume member to increase with resultant movement of the operating member.