HVAC/R Sensors

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Building Automation Products, Inc.,
Tel: +1-608-735-4800
Fax: +1-608-735-4804

Copyright © 2007 BAPI

The focal of any sensor is the sensing element itself, and BAPI has gone to great lengths to produce one of the best sensors on the market today. The heart of every BAPI unit is a micro-machined, single-crystal silicon, piezoresistive pressure sensor that changes resistance as a function of applied pressure. Each sensor is fabricated using the same integrated circuit technology used to make millions of cell phones, game machines and personal computers. To control and maintain the quality of these sensors, BAPI is involved in all phases of production from design to use.
The diaphragm at the core of BAPI’s pressure sensor is made of silicon with strain gauges diffused into the substrate to form a one-piece crystalline structure. Since silicon strain gauges have high output levels in relation to the pressure applied, the pressure levels in the BAPI diaphragm can be lower than in other non-silicon strain gauges. This means a more accurate measurement of lower pressure levels.
Silicon does bring with it one undesired trait—thermal sensitivity. The traditional method of compensating for this thermal sensitivity is an external circuit with discreet resistors, some of which have their own temperature dependencies, introducing more error. BAPI uses a different, unique approach. We employ a custom compensation ASIC (Application Specific Integrated Circuit) that uses digital compensation while maintaining an analog signal path, producing a sensor that is precise and interchangeable. The result is a pressure sensor that offers the ultimate in high accuracy, while preserving the fast response and smooth output inherent to silicon sensors.
Because of the innovative sensor and digital temperature compensation circuit, we are able to produce a highly accurate and stable product. This accuracy is verified during final calibration at our factory using a pressure-controlled source accurate to 0.001 inch of water and traceable to NIST standards.

Pressure Sensor Specifications

Output Ranges: 4 to 20 mA, 0 to 5 V or 0 to 10V

Supply Voltage:
10 to 30 VDC (current or voltage output)
18 to 30 VAC (voltage output only)

Ranges Inches W.C.
Unidirectional
0-0.1", 0-0.25", 0-1.0", 0-2.5", 0-5.0"
Bi-directional
±0.1", ±0.25", ±1.0", ±2.5", ±5.0"

Bi-directional Pressure: Zero pressure at mid-span

Accuracy:
±1% on 0-0.1 and ±0.1 ranges
±0.5% all other ranges

Temperature Limits:
Storage: -25° to 80°C (-13° to 176°F)
Operational: -25° to 80°C (-13° to 176°F)
Compensated: 0° to 60°C (32° to 140°F)

Operating RH Range: 0 to 95% non-condensing

Media: Non-Ionic, Non-Corrosive, Clean, Dry Gasses