... Oil Flow Switch FSF series : 1) Connection: 3/4"ODF 2) Medium: R134a, R22, R407C, R404A/507, Water and oil 3) Material: Brass Oil ... Flow Switch FSF series :FSF20W- 3/4 Magnetic flow ... R134a, R22, R407C, R404A/R507, oil and mixture of oil and refrigerant. Type data ModelConnection size(inch) ... /4” ODF148FSF25W-9/81” ODF194 Oil Flow Switch FSF series