1. Overview

The HQP-80 bubble water level gauge is suitable for environments requiring continuous and precise water level measurement. As it does not require the construction of a water level well, it is an ideal instrument for monitoring water levels at hydrological stations, reservoirs, dam piezometric tubes, and upstream/downstream water levels. It features convenient installation and maintenance, flexible operation, stable and reliable performance, and high accuracy.

The water level gauge uses a core unit as a high-precision pressure detection component. With a pressure measurement accuracy of 0.05%, it offers advantages such as low power consumption, corrosion resistance, radiation resistance, interference immunity, and the ability to withstand long-term pressurization.

2. Working Principle of the Bubble Water Level Gauge

When measurement is required, the air pump operates to generate compressed air. This air enters the buffer chamber inside the water level gauge, flows through a dedicated airflow pipeline, and enters the underwater air chamber. When the air pressure exceeds the water pressure, air escapes from the underwater chamber, achieving a balance between air pressure and water pressure. The air pump then stops, and once the pressure stabilizes, the air pressure at the core unit inside the water level gauge equals the water pressure. This pressure is converted into water level height based on the liquid density.

3. Product Features of the Bubble Water Level Gauge

◆ Lightning protection for power, communication, and other ports

◆ No need to construct a measuring well; uses barbed fittings for air tubing connections, ensuring convenience, reliability, and ease of installation, use, and maintenance

◆ Dual-stage one-way air valve for automatic pressure stabilization

◆ Two-stage air chamber buffering: one inside the water level gauge and one at the end of the underwater air tube to buffer instantaneous pressure

◆ Automatic fault detection for core unit failure, tube blockage, air leakage, overpressure timeout, high/low water levels, low power supply voltage, etc., with upload capability

◆ High-precision core unit sensor

◆ Ultra-low power consumption: static current less than 3.2mA

◆ Wide voltage range: 10VDC~14VDC. Customizable 8-30V input available

◆ Wide measurement range: 0-20m, 0-40m (customizable for 40-50m, 50-60m, 60-70m)

◆ Multiple communication methods: standard digital output: RS485 (MODBUS_RTU protocol); optional analog output: 4~20mA

◆ Multiple operating modes: Mode 0 for timed collection, enabling ultra-low power consumption by setting air pump intervals and operation time to ensure real-time data while minimizing power usage; Mode 2 for manual or host command collection, facilitating on-site debugging

◆ Built-in clock module

◆ 2.5MB solid-state storage capable of storing 20,480 timestamped data points. If stored twice daily, data can be retained for 28 years with cyclic storage

◆ Dual configuration methods (software and buttons): parameters such as operating mode, liquid density, collection timing, trigger interval, air pump timeout, stabilization time, monitoring timeout, monitoring range, and RS485 address can be set via software or buttons. Button operation is disabled during data collection.

◆ Chinese LCD display: automatically lights up during collection; press any key to turn on/off display; automatically turns off after 5 seconds of inactivity; exits settings after 1 second of inactivity during button configuration, and screen turns off

4. Main Technical Specifications

Range: 0-20m, 0-40m (customizable for 40-50m, 50-60m, 60-70m)

Accuracy: ±0.05% FS

Resolution: 1mm or 0.1mm (standard 1mm)

Output interface: standard RS485 (MODBUS-RTU), optional 4~20mA

Power supply: standard DC12V, customizable DC8-30V

2.5MB solid-state storage (detailed in section 5.3 of the protocol)

Air tube diameter: outer φ8, inner φ5

Integrated purification function

Operating temperature: -20～70°C; storage temperature: -40～80°C

Relative humidity: 95%RH

Air source: air

Pressure regulation: 2-stage one-way valve automatic pressure stabilization

Collection timing (1～65535 minutes): In Mode "0", a collection starts after this delay following the previous collection

Liquid density: 01000 to 65000 (corresponding to density 0.1000～6.5000), typically set to 1.0000

Monitoring timeout (1～1440 minutes) and monitoring range variation (0.1～10 meters): After collection, if the water level changes beyond the "monitoring range variation" after this delay, a new collection is triggered. Monitoring timeout must be less than collection timing.

Air pump operation timeout: continuous operation time of the air pump. 0～255 seconds, typically set to 30 seconds

Pressure stabilization timeout: maximum wait time for pressure stabilization. 0～255 seconds, typically set to 20 seconds

Core unit overload: 1.5 times

Service life: over 1 million cycles

Mounting method: wall-mounted with four ф6 holes