Foxboro 871A-2F-1 871A Series pH/ORP Electrochemical Sensor
Manufacturer: Foxboro
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Part Number: 871A-2F-1
Condition：New with Original Package
Product Type: pH/ORP Sensors
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Country of Origin: USA
Payment:T/T, Western Union
Shipping port: Xiamen
Warranty: 12 months
Foxboro 871A-2F-1 871A Series pH/ORP Electrochemical Sensor
The Foxboro 871A-2F-1, also cataloged as the 871A pH/ORP Electrochemical Sensor, operates as a dedicated hardware component for continuous process fluid hydrogen ion activity and oxidation-reduction potential measurement within industrial analytical monitoring systems. The unit utilizes a flat glass measuring electrode alongside a double-junction gel-filled reference cell to deliver raw millivolt potential changes to an integral preamplifier.
Hardware Specifications
| Parameter | Specification |
|---|---|
| Model | 871A-2F-1 |
| Brand | Foxboro |
| Origin | USA |
| Weight | Not specified |
| Dimensions | Standard 871A body dimensions (1 in NPT fitting) |
| Operating Temp | -5 to +105 deg C |
| Power Consumption | Powered by transmitter loop via signal leads |
| Measuring Range (pH) | 0 to 14 pH |
| Measuring Range (ORP) | -2000 to +2000 mV |
| Measuring Electrode | Flat glass pH electrode |
| Reference Electrode | Double-junction, gel-filled |
| Signal Output | Analog via integral preamplifier |
| Accuracy | +/-0.1 pH units typical |
| Maximum Pressure | 100 psig (690 kPa) |
| Process Connection | 1 in NPT thread |
| Electrical Connection | No. 6 spade lugs |
| Body Materials | Chemical-resistant industrial housing |
| Compliance | CE marked |
Cold Junction Compensation and 4-20 mA HART Loop Protocol Integration
The 871A-2F-1 interfaces directly with Foxboro 870ITPH or 875PH analyzers, routing millivolt signals through its integral preamplifier to eliminate high-impedance signal degradation over long field runs. When connected to digital process transmitters, the temperature component of the sensor stream enables automatic Nernst slope compensation. The transmitter subsequently conditions this analytical data into a calibrated 4-20 mA HART loop protocol signal, maintaining channel-to-channel isolation back to central DCS controller racks.
Frequently Asked Questions
Q: How does the integral preamplifier function within the sensor housing?
A: The internal preamplifier converts high-impedance millivolt signals generated by the glass electrode into a low-impedance analog output, preventing signal noise and voltage drop across long wiring distances.
Q: What physical connections are used for process insertion and wiring?
A: Mechanical mounting relies on standard 1 in NPT male threads for inline or submersion installation, while electrical field wiring terminates at No. 6 spade lugs.
Q: What are the maximum operating limits for temperature and pressure?
A: The sensor functions across a process temperature range of -5 to +105 deg C and withstands operational line pressures up to 100 psig (690 kPa).
Field Installation Guidelines
Mount the 871A-2F-1 into a standard 1 in NPT process tee or insertion assembly. Ensure a minimum of 5 full turns of thread engagement, applying PTFE tape exclusively to male NPT threads to seal against process fluid leakage. Position the sensor at least 15 deg above horizontal to keep the internal gel electrolyte in contact with the glass bulb.
Terminate field cable leads using the No. 6 spade lugs, connecting signal positive, reference ground, and shield drain wires to dedicated analyzer terminals. Route low-voltage analytical cables through dedicated grounded metal conduit, keeping them separate from high-voltage AC power lines to avoid electromagnetic interference.