The Architectural Drawing Is of Hydraulic Balance of Water Cooling Air Conditioner. By changing the open space through which the water flows within the valve, the flow rate can be adjusted and set. The pressure across the seat of the PICV is held constant by the differential pressure controller. Whilst setting, the open area around the disk will change resulting in a change to the flow rate. Pressure independent control valves will often be abbreviated to the letters PICV. This is a type of valve found in Hydronic systems, meaning water based, which provide heating and cooling in buildings. The diaphragm reacts to the system and regulates the pressure differential across the actuated control valve orifice to maintain its flow rate. On a PICV (see graphic below), when pre-setting the maximum flow rate, the inlet orifice changes in size, which does not interfere with the length of the stroke. For more details and information download the drawing file.