Hach SC200 Universal Water Quality Controller

Overview

The Hach SC200 Universal Water Quality Controller is an industrial-grade, field-deployable platform engineered for continuous, multi-parameter monitoring of critical water quality indicators in municipal, industrial, and wastewater treatment applications. Designed as a direct successor to the legacy SC100 digital and GLI 53 analog controllers, the SC200 integrates both digital and analog sensor interfacing within a single, unified architecture—eliminating the need for application-specific controllers. Its core functionality relies on standardized digital communication protocols (Hach Digital Sensor Protocol) for plug-and-play integration with Hach’s full suite of 23 digital sensors, while simultaneously supporting legacy analog sensors—including pH, conductivity, dissolved oxygen, turbidity, and flow transmitters—from both Hach and GLI product lines. This dual-input capability enables flexible system expansion, allowing users to deploy single- or dual-sensor configurations without hardware replacement. The controller operates under rigorous environmental conditions (–20 to 60 °C, IP66-rated enclosure), making it suitable for outdoor mounting, process skids, and harsh utility environments where long-term stability and operational continuity are essential.

Key Features

• True universal input architecture: configurable for two digital inputs, two analog (4–20 mA) inputs, or mixed-mode operation (e.g., one digital + one analog channel)
• Two independent 4–20 mA current outputs—each programmable to transmit primary or auxiliary measurements (e.g., pH + temperature compensation value)
• Graphical LCD display (240 × 160 pixels) with intuitive menu navigation, step-by-step calibration prompts, and visual alarm indicators to minimize operator error
• Secure data handling via password-protected SD card slot for audit-compliant data export and firmware updates
• Four SPDT relays (5 A, 250 VAC, 1200 W) for local control actions—pump activation, valve sequencing, or alarm signaling—fully configurable via onboard logic
• Robust mechanical construction: polycarbonate front bezel, powder-coated aluminum housing, stainless steel mounting hardware
• Comprehensive electromagnetic compatibility: certified to EN 50081-2 (emissions) and EN 61000-6-2 (immunity), ensuring reliable operation in electrically noisy plant environments

Sample Compatibility & Compliance

The SC200 is compatible with all Hach digital sensors utilizing the proprietary Hach Digital Sensor Protocol—including but not limited to the HQd series, CL17sc chlorine analyzers, and TU5 turbidity sensors—as well as analog sensors compliant with standard 4–20 mA output specifications (e.g., GLI pH/ORP, conductivity, DO, and flow transmitters). It supports simultaneous measurement of up to two parameters per unit, enabling co-monitoring of interdependent variables (e.g., pH and ORP; conductivity and salinity; DO and temperature). From a regulatory standpoint, the SC200 meets requirements for continuous emission monitoring support (CEMS) and process water quality assurance under ISO 5667 (water sampling), ASTM D1129 (terminology relating to water), and US EPA Method 1600-series guidelines for online instrumentation validation. Its password-protected configuration interface and SD-card-based data logging facilitate adherence to GLP and GMP documentation practices, particularly when paired with time-stamped calibration records and event logs.

Software & Data Management

While the SC200 operates autonomously without external software, its configuration, calibration, and diagnostics are managed locally via the integrated LCD interface. All settings—including sensor assignment, alarm thresholds, relay logic, and output scaling—are stored in non-volatile flash memory, preserving integrity during power loss. The SD card reader enables secure, offline transfer of historical measurement data (time-stamped at 1-second to 1-hour intervals), calibration logs, and system events—supporting traceability for internal QA audits or regulatory submissions. Optional integration with Hach’s PlantVue™ or third-party SCADA systems is achieved via MODBUS RTU (RS485) or Profibus DPV1 (with optional module), enabling real-time telemetry and centralized supervisory control. HART communication capability allows for remote diagnostics and sensor health monitoring without interrupting process operation.

Applications

The SC200 serves as a foundational control node across diverse water infrastructure segments: intake monitoring for drinking water plants (turbidity surge detection, pH stabilization), biological nutrient removal (BNR) basins (DO and ORP profiling), disinfection control (chlorine residual + pH feedback), industrial cooling tower management (conductivity + pH), and wastewater effluent compliance monitoring (DO, turbidity, flow). Its modular design supports phased deployment—starting with a single parameter (e.g., pH) and upgrading to dual-parameter control (e.g., pH + conductivity for acid/base dosing) without controller replacement. Municipal utilities leverage its NEMA 4X rating for unsheltered installation at lift stations and remote pumping sites, while food & beverage processors use its dual 4–20 mA outputs to feed both PLCs and local HMIs simultaneously.

FAQ

Can the SC200 controller operate with both digital and analog sensors simultaneously?
Yes—the SC200 supports hybrid configurations, such as one digital sensor (e.g., Hach HQ40d pH probe) and one analog sensor (e.g., GLI conductivity transmitter), provided the correct model variant (e.g., LXV404.99.00512) is selected.
Does the SC200 support FDA 21 CFR Part 11 compliance?
The SC200 itself does not provide electronic signature or audit-trail features required for full Part 11 compliance; however, its password-protected configuration, timestamped SD card logs, and deterministic relay behavior support alignment with Part 11 Annex 11 principles when deployed within validated systems.
What is the maximum cable length supported for digital sensor connections?
Hach specifies a maximum of 300 meters (984 ft) for digital sensor cables using shielded twisted-pair cabling meeting RS-485 electrical standards.
Is firmware update capability available through the SD card interface?
Yes—Hach releases firmware updates via downloadable .bin files; users can install them directly using the password-protected SD card slot without requiring a PC connection.
Can the SC200 be mounted in hazardous locations?
No—the SC200 is rated for general-purpose use only (NEMA 4X/IP66) and is not certified for Class I, Division 1 or ATEX Zone 0/1 environments.