Abstract: A tube-type heat exchanger has the tube ends substantially flush with the upper tube sheet and liquid is distributed to the tubes through distributor heads which are sealed and therefore provide gas cushions absorbing volume changes in the tubes.

Abstract: A system for maintaining a predetermined average liquid level in a pool comprises a pilot valve responsive to a float in the pool and a main valve controlled by the pilot valve to unblock a normally blocked supply conduit when the liquid in the pool drops below that level. The pilot valve, when opened by the float, lets incoming liquid under pressure--branched off the supply conduit at a point upstream of the main valve--enter a compartment under a membrane in the body of the main valve, that membrane carrying a control rod connected with a movable plate which coacts with a stationary plate obstructing the supply conduit inside the valve body; the two plates have apertures which are normally offset from each other but register upon pressurization of the membrane to give passage to the incoming liquid.

Abstract: A flow-regulating valve, with a body forming a flow channel between an entrance port and an exit port, has a shutter in the form of an apertured backing plate and an apertured slide which adjoin each other along a plane inclined or parallel to the axis of at least one of these ports so as to be accessible, for inspection or repair, through a neck with an opening offset from both ports but normally closed by a cover. The ports can therefore be formed by nipples rigid with the valve body, e.g. welded thereto, not requiring disconnection from their conduits. The slide is shiftable by a rod extending parallel to the aforementioned plane, specifically horizontally when the valve is controlled by a float in an adjoining tank. In order to isolate the interior of the tank from the flow channel during repairs, a thruster in the tank can be manually operated from the outside to move the rod into a limiting position in which the passage traversed by that rod is plugged.