Abstract: A protection system for a compressor. The system comprises a compressor having a discharge and including at least one rotor and at least one bearing; a lubrication system including at least one oil recovery device for recovering oil from the compressor, and further including bearing conduit connecting the oil recovery device to the compressor bearing and including rotor conduit for connecting the oil recovery device to the compressor rotors; and an oil protection system. The oil protection system includes a compressor discharge temperature sensor located in the discharge for sensing the temperature of a lubricant/refrigerant mixture discharged by the compressor, a differential pressure sensor located in the bearing conduit for measuring a differential pressure in the bearing conduit, and an oil detector located in the rotor conduit for detecting the presence of oil in the rotor conduit.

Abstract: Apparatus are disclosed for sensing the velocity of a fluid stream, as may be flowing in a duct, pipe, or the like, which fluid stream exhibits variations in its temperature under different operating conditions. The apparatus includes a first probe which is exposed to the fluid stream and includes first temperature sensing means for sensing the temperature of the fluid stream. A second probe is provided which is disposed within the fluid stream and includes at least a portion constructed of a thermally conductive material. Heater means are disposed in thermally conductive relationship with said thermally conductive portion, and second temperature indicative of the temperature of said heater means. Third temperature sensing means are provided for sensing the temperature of the thermally conductive portion of the second probe at a point removed from the heater means, which temperature is a function of the heater means temperature, the fluid temperature, and the velocity of the fluid flowing thereover.