MEASUREMENTS TO MIND (M2M) is a growing suite of Stevens products that embraces cloud-computing with an all-inclusive vision of shortening the communication path from the sensors to data on-line. That is, what the sensors MEASURE the MIND sees.
Stevens is the original water level measurement instrumentation company with the introduction of the widely known chart recorders introduced in 1911. Today, Stevens offers a wide selection of water level measurement sensors including robust ceramic pressure sensors, shaft encoders, acoustical sensors, and visual reference staff gages. Stevens still offers the low-powered, mechanical chart recorders for long-term uninterrupted, real-time chart of water level.
Pressure sensors like Smart PT perform liquid level measurement by having the sensor submerged at a fixed level under the water surface. The pressure sensor measures the equivalent hydrostatic pressure of the water above the sensor diaphragm, using this to calculate the total liquid depth. This function of a pressure sensor can be compared to “weighing the water”. Pressure sensors are ideal for ground and surface water level applications.
Cost-effective and reliable, compact groundwater logging sensors like the Van Essen TD-Diver provide accurate and reliable long-term measurements of water levels, temperature, and conductivity—essential data needed for effective water resource management, environmental remediation, mine dewatering, and slope stability.
All Diver sensors have a 3 year warranty, up to 10 years battery life, and can be used from 300 m below to 5000 m above sea level.
We offer additional Diver sensors and other logging sensors.
Both ultrasonic and sonic level instruments operate on the basic principle of using sound waves to determine fluid level. The frequency range for ultrasonic methods is ~20-200 kHz, and sonic types use a frequency of 10 kHz. A transducer directs sound waves downward in bursts onto the surface of the water. Echoes of these waves return to the transducer, which performs calculations to convert the distance of wave travel into a measure of height, and therefore water level.
A shaft encoder like the Stevens PAT is an electro-mechanical device used to convert the angular position of a shaft or axle to an analog or digital electrical signal. 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. There are two main types of encoders for liquid level measurements: absolute and incremental.
Absolute encoders provide a binary “word” for each position. Each bit requires a separate optical channel. The resolution is equal to the number of output bits. Absolute encoders constantly retain the correct position for one revolution. Therefore, the main advantage is that the output signal is not affected by a power shut-off. When power returns the encoder recognizes what position it is in based on the voltage measurement reference. Whereas incremental measurements rely on a referenced position pointer. Therefore, if power is shut off to an incremental encoder, the reference is lost and incremental pointer resets to zero.
Incremental (relative) encoders provide a contact or pulse for each increment of shaft movement. Usually this consists of two optical quadrature channels to enable the determination of the direction of rotation. The incremental encoder has a lower cost than the absolute encoder due to the limited number of channels, and the encoded position is not limited in revolutions.
Staff gages provides a quick and easy visual indicator of water level. Made with a durable baked-on porcelain enamel finish on a metal plate. Stevens was the company who originally designed and introduced the staff gage measurement styles used by the water resource market.
Stevens is one of the leading designers and providers of custom staff gages. Custom staff gages are for non-standard sizes, slopes or flow measurements or for other unique mounting angles that a site may require for a easy visual measurement.
Our contact meter is an ideal device for quick, portable measurement of bore holes, wells, reservoirs, and other applications where liquid level depth is needed. The probe is simply fed down and when it reaches liquid the light on the front of the unit illuminates. Depth can then be read from the easy-to-read white tape.
Stevens offers a range of multi-parameter sensors that provide a choice of water quality parameters to meet your unique monitoring needs.
Total dissolved gas
Ion-Selective Electrodes (Ammonia/Ammonium, Nitrate, Chloride)
eTracker is a cellular modem and "virtual" cloud-based data logger in one (meaning you don't need to install a separate data logger). Simply connect your sensor and a power source to eTracker and you're done. Configure (or reconfigure) anytime from any Internet-connected device, and use Stevens-Connect to retrieve your data, or forward it to your favorite software system.