Fluidic time delay system

Abstract

A variable fluidic time delay system for operating a plurality of pressure sensitive control switches to effect sequential operations at different pressure settings or for different components in response to the fluid pressure at a predetermined location in a refrigeration system, the time delay system including a fluid flow restrictor and unidirectional flow control in parallel by-pass relation with each other and connecting the control switches to the predetermined location of the refrigeration system for restricting pressurized fluid flow with a concomitant time delay in one direction and providing unrestricted fluid pressure equalization in the other direction, respectively. The time delay system controls the operation of pressure responsive switches to sequentially and cyclically operate multiple parallel compressors at preselected upper and lower refrigerant suction pressures to maintain evaporator suction pressures within preselected ranges or to sequentially and cyclically operate multiple condenser fans at preselected refrigerant head pressures to effect zoned condenser cooling for adjusting effective condenser capacity and maintain low head pressures.