A sensor (10) is disclosed for sensing the entrainmentof a fluid of low specific gravity in a fluid of higher specificgravity, particularly the entrainment of refrigerant gas inrefrigerant liquid. The sensor (10) is typically installed into ahigher pressure liquid supply line (24) of a refrigerationsystem (26). The sensor (10) has a differential float (16)including a float member (54) pivoted about a pivot (56) in achamber (14) coupled to the supply line (24). The float member(54) has a specific gravity greater than the specific gravity ofboth of the fluids in which it operates, however, the locationof the pivot (56) intermediate of the length of the floatmember (54) gives a nett specific gravity for the differential float(16) which is less than the specific gravity of one of the fluids.Hence, the differential float (16) can withstand a highpressure operation, say 2MPa, and can operate as a float fordetecting the presence or absence of the fluid of lower specificgravity in the fluid of high specific gravity. The differentialfloat (16) can also be used as a gauge snubber (20) or toreplace refrigerant capillary control tubes.
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