METTLER TOLEDO InPro3250 / InPro3250SG / InPro3250i Online pH Electrode System
| Brand | METTLER TOLEDO |
|---|---|
| Origin | Switzerland |
| Model | InPro3250 / InPro3250SG / InPro3250i |
| pH Range | 0–14 (InPro3250), 0–12 (InPro3253) |
| Temperature Range | 0–140 °C (32–284 °F) |
| Max. Process Pressure | 4 bar (58 psi) |
| Reference System | Ceramic junction, Ag/AgCl |
| Optional Features | Silver-ion trap (SG models), Solution Grounding (SG), ISM digital interface, ATEX certification (II 1/2G EEx ia IIC T6/T5/T4/T3), FM/CSA Class I Div 1, IP68 |
Overview
The METTLER TOLEDO InPro3250 series represents a class of factory-prepressurized, low-maintenance online pH electrodes engineered for continuous, high-integrity measurement in demanding industrial process environments. Designed around the principle of controlled electrolyte outflow via internal overpressure, these electrodes eliminate reliance on manual refilling and significantly reduce fouling risk at the liquid junction—particularly critical in biopharmaceutical fermentation, sterile API synthesis, and aggressive chemical processing. The core sensing architecture employs a glass membrane electrode paired with a robust ceramic-junction reference system and silver/silver chloride (Ag/AgCl) internal element. Models InPro3250SG and InPro3250i integrate an integrated silver-ion trap to prevent sulfide-induced clogging of the junction—a known failure mode in protein-rich or sulfur-containing media. All variants comply with intrinsic safety requirements for hazardous locations and support hygienic installation per ASME BPE and EHEDG standards.
Key Features
- Factory-prepressurized design ensures stable, drift-free electrolyte flow without operator intervention
- Patented silver-ion trap (SG models) mitigates junction blockage in sulfide- or protein-laden streams
- Digital ISM (Intelligent Sensor Management) interface enables plug-and-play commissioning, real-time diagnostics, and predictive maintenance alerts
- ATEX-certified (II 1/2G EEx ia IIC T6/T5/T4/T3) and FM/CSA Class I Division 1 rated for Zone 0/1 and Class I, Div 1 hazardous areas
- Wide operational range: pH 0–14 (InPro3250), 0–12 (InPro3253); temperature up to 140 °C; pressure tolerance up to 4 bar (58 psi)
- Solution Grounding (SG) option provides galvanic isolation and eliminates ground-loop interference in conductive or grounded vessels
- Optional ORP functionality enabled via platinum auxiliary electrode in SG configurations
Sample Compatibility & Compliance
The InPro3250 series is validated for use across GMP-regulated bioprocesses—including mammalian cell culture, microbial fermentation, and downstream purification—where pH stability directly impacts yield, product quality, and regulatory compliance. Electrodes meet USP , , and EU Annex 1 requirements for sensor qualification and traceability. Certifications include EHEDG EP-004 (hygienic design), ASME BPE 2023 (surface finish Ra ≤ 0.4 µm), and FDA 21 CFR Part 11–compliant data integrity when integrated with METTLER TOLEDO’s LabX or iC software platforms. All units undergo full functional testing per ISO 17025-accredited procedures prior to shipment. Biocompatibility is confirmed per ISO 10993-5 (cytotoxicity) and ISO 10993-10 (irritation/sensitization) for direct-contact applications.
Software & Data Management
ISM technology embeds non-volatile memory within the electrode housing, storing calibration history, lifetime metrics (e.g., junction resistance, asymmetry potential), and installation timestamps. When connected to METTLER TOLEDO’s M300 or EasyClean transmitter platforms—or integrated into DCS/SCADA systems via HART, Profibus PA, or FOUNDATION Fieldbus—the system delivers audit-trail-ready diagnostics compliant with FDA 21 CFR Part 11 and EU Annex 11. Calibration events are digitally signed and time-stamped; sensor replacement triggers automatic configuration transfer, eliminating manual parameter re-entry. Firmware updates are performed remotely via secure HTTPS, supporting lifecycle management across large-scale multi-site deployments.
Applications
- Real-time pH monitoring in stainless-steel bioreactors (up to 20,000 L) during fed-batch and perfusion cultures
- In-line control of neutralization steps in fine chemical synthesis and catalyst recovery loops
- Continuous pH assurance in clean-in-place (CIP) and sterilize-in-place (SIP) validation protocols
- Regulatory-compliant monitoring of buffer preparation tanks under GMP conditions
- High-temperature pH measurement in steam-jacketed reactors and distillation columns
- Redox-coupled process control using SG-configured units in electrochemical synthesis
FAQ
What distinguishes the InPro3250SG from the standard InPro3250?
The InPro3250SG includes an integrated silver-ion trap and solution grounding capability—critical for minimizing drift in sulfur-containing media and eliminating ground-loop errors in electrically noisy plant environments.
Can the InPro3250 be autoclaved?
Yes—models rated for SIP/CIP cycles withstand repeated exposure to 121 °C saturated steam for up to 60 minutes per cycle, provided mechanical stress (e.g., thermal shock) is minimized per ASME BPE guidelines.
Is ISM data compatible with third-party DCS systems?
ISM metadata is accessible via standardized HART 7 or Modbus TCP; full diagnostic interpretation requires METTLER TOLEDO’s iSense software or certified integration partners.
How often does the electrode require recalibration in continuous operation?
Under stable process conditions, recalibration intervals may extend to 7–14 days; ISM diagnostics recommend recalibration only when asymmetry potential exceeds ±30 mV or junction resistance rises above 200 kΩ.
Does the InPro3250 series support FDA 21 CFR Part 11 compliance?
Yes—when deployed with METTLER TOLEDO’s validated transmitter firmware and iC software, full electronic signature, audit trail, and role-based access control are enforced per Part 11 Subpart B requirements.
