Hydrology

Bubbler Water Level Measurement

Measuring Principle:

Bubbler Systems measure water level based on the amount of pressure it takes to push an air bubble out of an orifice line (plastic tubing) and into the water body. This pressure, often referred to as the “line pressure”, requires changes with the elevation of the water. As the water elevation rises and falls, so does the line pressure needed to discharge bubbles. The line pressure value, measured in psi, is then converted into the desired units of measurement to represent water level from the point of discharge to the water’s surface.

The Bubbler Water Level Sensor is preferable for measurement of Level of big span turbulent Indian Rivers where others sensor cannot be installed and not fit to get reliable data. The Bubbler need proper lay down of the orifice line and suitable termination device at River Bed. Most suitable is to terminate near to existing SG Line, where we have a cross section of the channel.

Advantages of Pressure Sensors in Water Level Measurements:

• The benefits of the bubbler are response and accuracy. When stage (water level) increases, the Bubbler senses this change, and within 30 seconds adjusts the tank pressure to keep the line pressure continually following the current water level.

• Because only the orifice line touches the water, it is an ideal instrument for measurement in areas where large amounts of debris are common, waters are turbulent, or long-term deployment of submersed instrument is hazardous.

• High Accuracy and Stability

• Unaffected by Foam and Vapors

• Quickest Response to Change in Water Levels

• Temperature & Pressure in One Measurement

• Satellite Telemetry option available

• Excellent for Hazardous, High-Temperature, corrosive or wastewater management

• NEMA 4X Enclosures Available

Applications:

• Stream Gauging Station

• Lake Level Monitoring Station

• Portable Flood Warning Station

• Wastewater Lift Station Monitoring

• Ground Water Monitoring

Pressure Water Level Sensor

Measuring Principle:

Pressure sensor delivers accurate results while still remaining very affordable for a wide range of level measurement applications.High impact, corrosion-resistant PVC Type II housing and potted electronics make the pressure gauge extremely durable for most water and hostile fluid environments. The pressure gauge is also an excellent choice for level measurement application that may put more expensive sensors at risk for damage.

The Pressure gauge comes equipped with user specified vented cable lengths. The vent provides an atmospheric reference for the sensor, which is necessary for ensuring the highest possible accuracy when making a level measurement.

Advantages of Pressure Sensors in water level measurements:

• Output can be analog or digital depending on model

• Smaller diameter stilling well or pipe can be used for installation.

• A low profile installation site can be achieved using pressure sensors with internal data logging.

• Easy to install, maintain and calibrate.

Applications:

• Ground water level monitoring

• Ground water slug testing

Shaft Encoder

Measuring Principle:

A shaft encoder is an electro-mechanical device used to convert the angular position of a shaft or axle to an analog or digital electrical signal. These devices are used in many applications including liquid level measurement. Part of the mechanical aspect of this device for level measurement utilizes a float and counter-weight attached to a line or tape placed around a pulley attached to the encoder’s shaft.

As the level changes, the float moves up and down and, thereby, rotating the pulley and the attached shaft – generating an electronic wave form for both rotating direction and amount. By converting shaft rotation into electronic signals, encoders are used to electronically monitor the position of a rotating shaft..

Advantages of Float-operated Sensors for Water Level Measurements:

• Since many older sites were designed for mechanical float operated measurement, encoders are easily adapted to existing float gear and gaging system.

• Float-operated systems are easy to understand and troubleshoot.

• Most encoders offer good temperature stability.

• Float is protected in a stilling well and sensor is not in direct contact with the water. Therefore the risk of damage is low from debris flow or fouling.

• Highly accurate with large sized floats.

Surface Velocity

Simple, non-contact, compact surface water velocity radar sensor. Designed for measuring flow in open channels and rivers where reliable velocity data is required continuously, during floods or periods of high concentrations of suspended sediments.

The sensor is mounted above the water surface, away from floating debris using a flexible bracket for vertical or horizontal installation. Velocity measurements and sensor status information from the integrated vibration and tilt sensor is available via SDI-12 over RS-485 and Modbus.

Side Looking Doppler Sensor

SLD is a measurement system for continuous measurement of water velocity and level in streams, rivers, and canals. The sensor employs the acoustic Doppler principle to reliably measure flow velocity in a variety of naturally occurring conditions, including during most flood events.

Mini Current meter for discharge measurements

Small current meter for discharge measurements for shallow waters in small rivers, channels, laboratories and river models. Proven a thousand times to measure reliably flow velocities from 0.025 up to 5 m/s.