... Oil Flow Switch : 1) Connection: 3/4"ODF 2) Medium: R134a, R22, R407C, R404A/507, Water and oil 3) Material: Brass FSF series Oil ... Flow Switch :FSF20W- 3/4 Magnetic flow switch ... R134a, R22, R407C, R404A/R507, oil and mixture of oil and refrigerant. Type data ModelConnection size ... 4G3/450FSF20W-3/43/4” ODF148FSF25W-9/81” ODF194 FSF series Oil Flow Switch