Solinst Model 104 Ultrasonic Water Level Meter

Overview

The Solinst Model 104 Ultrasonic Water Level Meter is a field-portable, non-invasive acoustic instrument engineered for precise, rapid measurement of static water level depth in boreholes, piezometers, standpipes, and sealed vertical conduits. Unlike submersible pressure transducers or tape-based methods, the Model 104 operates on the principle of time-of-flight ultrasonics: the probe emits a short-duration acoustic pulse downward into the air column above the water surface; the reflected echo is detected, and the distance to the water interface is calculated using the known speed of sound in air—dynamically corrected in real time via an integrated NTC temperature sensor. This contactless methodology eliminates physical intrusion, thereby preventing cross-contamination of aquifer samples, avoiding well-screen fouling, and eliminating pre-measurement decontamination protocols. Its robust design supports deployment in confined, obstructed, or tortuous casings—including elbows and offset sections—where traditional sounding devices fail. With a certified operational range from 3 to 600 meters (9–2000 ft), it serves hydrogeological, environmental monitoring, and regulatory compliance applications requiring traceable, repeatable, and operator-independent water level data.

Key Features

• Non-contact ultrasonic measurement—no probe immersion, zero risk of chemical or biological contamination
• Real-time temperature compensation using onboard NTC thermistor for consistent accuracy across ambient conditions (−20 to +45 °C)
• Configurable measurement parameters including pipe diameter, offset height, and user-defined upper/lower bounds to suppress spurious reflections from well features (e.g., couplings, sediment layers, or debris)
• Dual-unit display (metric/imperial) with 1 cm (0.05 ft) resolution and ±3 cm (±0.1 ft) stated accuracy
• Power-optimized architecture: up to 500 hours of continuous operation on standard AA alkaline cells; power-saving mode extends standby life to 21 days
• Ergonomic handheld control unit with backlit LCD, tactile keypad, and intuitive menu navigation—designed for single-operator use in low-light or adverse weather
• Included accessories: universal plastic well cover disk (for large-diameter openings), rugged field carry case, and compatibility with Solinst’s 2-inch locking well caps and vent-hole adapters

Sample Compatibility & Compliance

The Model 104 is validated for use in PVC, steel, concrete, and fiberglass casings ranging from 2 inches to >36 inches in diameter. It accommodates both straight and bent conduit configurations without signal degradation, provided the internal path remains acoustically unobstructed. The instrument meets functional requirements outlined in ASTM D4044 (Standard Test Method for Determining the Integrity of Well Casings) and supports data integrity practices aligned with ISO/IEC 17025 and EPA Method 9020B. While not a certified Class I Div 1 device, its intrinsically safe electronics (no high-voltage components, no spark-prone circuitry) make it suitable for use in non-hazardous environmental monitoring zones. All firmware operations log timestamped events, supporting audit-ready GLP documentation when paired with Solinst’s optional data export utilities.

Software & Data Management

The Model 104 operates as a standalone field instrument with no mandatory software dependency. However, ASCII-formatted measurement logs—including date/time stamp, depth value, temperature reading, and user-configured metadata—can be exported via optional USB-to-serial adapter to compatible desktop applications (e.g., Excel, GIS platforms, or LIMS). Firmware supports customizable auto-shutdown intervals, unit preference persistence, and factory-reset capability. No cloud connectivity or remote telemetry is embedded; all data remain under direct user control—critical for projects governed by data sovereignty regulations (e.g., GDPR, provincial groundwater acts). Audit trails are maintained locally on-device for up to 1,000 readings, with overwrite protection enabled only upon explicit user confirmation.

Applications

• Long-term groundwater level monitoring in municipal, agricultural, and industrial well networks
• Verification of piezometer integrity and hydraulic head stability during geotechnical site investigations
• Regulatory reporting for environmental agencies requiring ASTM- or ISO-aligned water level records
• Rapid assessment of water table fluctuations following precipitation events or pumping tests
• Baseline surveys prior to remediation activities where sample purity must be preserved
• Academic hydrology fieldwork in remote or logistically constrained locations

FAQ

Does the Model 104 require calibration before each use?
No. Factory calibration is stable over the instrument’s service life. Field verification may be performed using a known reference depth (e.g., marked tape or verified casing length); deviation beyond ±3 cm warrants service review.
Can it measure in partially flooded or gas-filled wells?
It measures only the air–water interface. Presence of vapor, light mist, or non-condensing gases does not impair performance. Heavy condensation, standing water above the water table, or dense foam layers may attenuate signal return and should be noted in field logs.
Is the probe rated for submersion or outdoor weather exposure?
The probe is IP65-rated for dust and water jet resistance but is not submersible. Prolonged exposure to direct UV or freezing condensate is discouraged; storage in the supplied field case is recommended between uses.
How does it handle multi-level wells with multiple screens or packers?
It reports the shallowest detectable water surface. For nested or multi-zone installations, sequential measurements with temporary sealing of upper ports are required to isolate individual intervals.
What warranty and support does Solinst provide?
The Model 104 carries a full three-year limited warranty covering materials and workmanship. Solinst Technical Support offers firmware updates, application guidance, and authorized repair services through global distributor partners.