Pressure controlled liq. metering unit - is esp. for adding liquids to flowing water with metering tank filled from top-up tank during flow pauses

摘要

Pressure-controlled liquid metering unit meters a first liquid into a flow of a second liquid with the first liquid in a tank connected by a pressure-controlled valve to the flow passage. A second tank with larger volume is connected to the first tank by a top-up valve controlled by the liquid level in the first tank and the pressure in the flow passage. The top-up valve has upper and lower valve seats and heads (27a, 27b) spaced apart on a single stem. Inside the first tank the stem carries a float (31), and in the flow passage (4) or an intermediate chamber (9) connected to it the stem carries a pressure-sensitive element (32) connected to the stem by a push-rod (34) with axial movement by an amount less than the spacing between the valve heads.