Fan air flow measurement system
View Patent ↗A fan air flow measurement sensor comprising a housing having a sensor cap, a thermistor pair disposed within the housing, each thermistor projecting through the sensor cap a predetermined distance above the sensor cap, a flange extending normally from the housing, the flange engagable with a mounting surface, a sensor circuit comprising a multiplexer for controlling each thermistor, and for measuring a condition of each thermistor, and for receiving and transmitting signals, and a cable for connecting the sensor to a multiplexing circuit.
1. A fan air flow sensor comprising:
a housing having a sensor cap;
a thermistor pair disposed within the housing and in housing potting to prevent movement of the thermistor pair in the housing, each thermistor projecting through the sensor cap a predetermined distance above the sensor cap up to approximately 0.03 inches, the sensor cap disposed to protect the thermistor pair from airborne particulate;
a flange extending normally from the housing, the flange for flush mounting the housing on a mounting surface;
a sensor circuit comprising a multiplexer for controlling each thermistor, and for measuring a condition of each thermistor, and for receiving and transmitting signals, and a microprocessor to calculate air velocity and temperature;
a control transmitter connected to the multiplexer for displaying the air velocity and temperature; and
a cable for connecting the sensor to a multiplexing circuit.
2. The fan mass air flow measurement sensor as in claim 1 , wherein the sensor cap comprises stainless steel.
3. The fan mass air flow sensor as in claim 1 , wherein the flange further comprises a notch for receiving the cable.
4. The fan mass air flow sensor as in claim 1 , wherein the flange receives fasteners for attaching the flange to a mounting surface.
5. A fan air flow measurement system comprising:
a fan having an inlet;
a sensor having a substantially flush mounting to a surface of the inlet;
the sensor comprising a housing having a sensor cap;
a thermistor pair disposed within the housing and in housing potting to prevent movement of the thermistor pair in the housing, each thermistor projecting through the sensor cap a predetermined distance above the sensor cap up to approximately 0.03 inches, the sensor cap disposed to protect the thermistor pair from airborne particulate;
a flange extending normally from the housing, the flange engagable with a mounting surface;
a sensor circuit comprising a multiplexer for controlling each thermistor, and for measuring a condition of each thermistor, and for receiving and transmitting signals;
a cable for connecting the sensor to a multiplexer circuit;
the multiplexer circuit connected to a transmitter circuit.
6. The fan air flow measurement system as in claim 5 further comprising a plurality of sensors, each having a substantially flush mounting to the fan inlet.
7. The fan air flow measurement system as in claim 5 , wherein the fan comprises a centrifugal fan.
8. The fan air flow measurement system as in claim 6 , wherein:
the fan inlet comprises an inlet bell and the sensors are mounted at the narrowest portion (D) of the inlet bell; and
each sensor is connected to the multiplexer circuit.
9. The fan air flow measurement system as in claim 5 , wherein each thermistor pair further comprises a microprocessor for storing calibration date for the thermistor pair.