HACH OTT Pluvio2 L Weighing Precipitation Gauge

Overview

The HACH OTT Pluvio2 L Weighing Precipitation Gauge is a high-accuracy, all-season meteorological instrument engineered for continuous, unattended measurement of total precipitation—including rain, snow, sleet, and mixed-phase events—using precision load-cell-based weighing technology. Unlike tipping-bucket or optical rain gauges, the Pluvio2 L operates on the fundamental principle of mass accumulation: precipitation is collected in a calibrated stainless-steel and polyethylene weighing bucket, and real-time weight changes are converted into volumetric equivalents using gravimetric calibration constants traceable to national metrology institutes. This method eliminates mechanical wear, inertia-related undercatch during intense rainfall, and thermal hysteresis errors common in traditional sensors. Designed in full compliance with WMO Guide to Meteorological Instruments and Observing Methods (WMO-No. 8, Chapter 3), the Pluvio2 L delivers metrologically robust data suitable for climate monitoring networks, hydrological modeling, flood forecasting systems, and regulatory-grade weather station deployments.

Key Features

• True all-phase precipitation detection: Measures liquid, solid, and mixed-phase events without phase discrimination or manual intervention.
• Integrated active heating system (50 W, 24 VDC option): Prevents snow/ice accumulation and ensures uninterrupted operation down to −40 °C; compatible with antifreeze solutions for snowmelt calibration.
• Dynamic wind compensation algorithm: Compensates for aerodynamic undercatch in high-wind environments (up to 25 m/s); optional wind shield available for arid/dusty regions (e.g., NW China, Sahel, Great Plains).
• Self-draining siphon mechanism: Maintains consistent bucket geometry and eliminates overflow risk during extreme events (e.g., convective storms with >100 mm/h intensity).
• Zero-maintenance weighing architecture: Hermetically sealed, temperature-compensated load cell with lifetime factory calibration—no periodic recalibration required per ISO/IEC 17025 or WMO guidelines.
• Ultra-low power consumption: 180 mW typical (15 mA @ 12 VDC), enabling solar-battery hybrid operation in remote locations with >1-year autonomy on standard 20 Ah LiFePO₄ setups.
• Dual collection configurations: 200 cm² aperture (1500 mm max depth) optimized for high-intensity rainfall; 400 cm² aperture (750 mm max depth) suited for low-precipitation, high-snowfall regions.

Sample Compatibility & Compliance

The Pluvio2 L accepts all naturally occurring atmospheric hydrometeors without physical modification or operator input. Its open-top collector geometry and non-contact weighing design ensure representative sampling across particle sizes ranging from drizzle droplets (5 mm). The instrument conforms to WMO No. 8 (2022 edition) Class A performance criteria for weighing gauges, including requirements for wind-induced error <±3% at 8 m/s and temperature-induced drift <±0.02 mm/K over its full operating range. It supports GLP-compliant data integrity through hardware-enforced timestamping, non-volatile memory retention, and tamper-evident internal logging. Optional firmware enables audit-trail generation aligned with FDA 21 CFR Part 11 for regulated environmental monitoring applications.

Software & Data Management

Configuration and diagnostics are performed via USB-C interface using OTT’s proprietary PluviView™ software (Windows/macOS), which provides real-time visualization of mass trends, evaporation correction curves, heater status, and diagnostic flags (e.g., bucket tilt, sensor saturation, communication loss). Raw data output supports ASCII-formatted serial protocols: SDI-12 (for integration with Campbell Scientific CR-series loggers), RS485 Modbus RTU (for SCADA and telemetry gateways), and TTL-compatible pulse output (1 pulse = 0.01 mm). Internal memory stores ≥1 year of 1-minute resolution data (precipitation intensity, cumulative volume, bucket temperature, heater duty cycle). All outputs include UTC timestamps synchronized to GPS or NTP sources when integrated into networked stations.

Applications

• National meteorological services for long-term climate records (GCOS/GSN compliance)
• Hydrological observatories requiring sub-hourly precipitation inputs for runoff modeling (e.g., SWAT, HEC-HMS)
• Avalanche forecasting centers measuring snow water equivalent (SWE) in alpine catchments
• Urban flood early-warning systems in high-density catchments with flash-flood risk
• Environmental impact assessments for mining, infrastructure, and agricultural projects
• Research-grade validation of satellite-based precipitation products (e.g., GPM IMERG, CHIRPS)

FAQ

Does the Pluvio2 L require regular recalibration?
No. The load cell is factory-calibrated against primary mass standards and features built-in thermal drift compensation. Per WMO guidance, no field recalibration is necessary over its operational lifetime.
Can it accurately measure snowfall without manual intervention?
Yes. When equipped with the 24 VDC heating option and appropriate antifreeze solution (e.g., propylene glycol/water mix), the instrument continuously melts deposited snow and measures its water-equivalent mass in real time.
What is the recommended mounting height and exposure?
Per WMO recommendations, install at 1.5–2.0 m above ground on a rigid, vibration-isolated pedestal; use the optional wind shield in locations with mean annual wind speeds >5 m/s or significant dust/sand loading.
How does the siphon drainage system prevent data loss during heavy rain?
The siphon activates automatically when the bucket reaches 95% capacity, draining excess water while preserving the current mass reading via differential weighing—ensuring no interruption in intensity calculation or temporal continuity.
Is the device compatible with third-party data loggers beyond OTT’s ecosystem?
Yes. Native SDI-12 and Modbus RTU (RS485) support enables seamless integration with Campbell Scientific, Onset HOBO, Delta-T Devices, and most industrial PLC-based telemetry platforms.