The flow controllers RP 32 have been designed to hold constant set point of the flow capacity of a medium without respect to any change of pressure conditions on inlet side or outlet side of the flow controller. The usual working medium is refined crude oil containing up to 25 % of water, hydrogen monosulphide up to 0.01 gm/L and solids, particle size of which is up to 25 mm, temperature of this medium being from +5 °C to 60 °C.