pressure data-logger - ONSET - (Version JPG) - PDF Catalogue | Technical Documentation



Inside this package: • HOBO U20 Water Level Logger • Calibration Certificate	Onset Computer Corporation Models
		The Water Level logger is available in the following models: • U20-001-01 (30 foot depth) and U20-001-01-Ti (30 foot depth/Titanium) • U20-001-02 (100 foot depth) • U20-001-03 (250 foot depth) • U20-001-04 (13 foot depth) and U20-001-04-Ti (13 foot depth/Titanium) Required/Recommended Accessories • Cable (CABLE-1-300 or CABLE-1-50) and Cable Crimp (CABLE- 1-CRIMP) • Replacement Coupler (Coupler2-B) Barometric Compensation The HOBO Water Level Logger records absolute pressure, which is later converted to water level readings by the software. In this application, absolute pressure includes atmospheric pressure and water head. Atmospheric pressure is nominally 100 kPa (14.5 psi) at sea level, but changes with weather and altitude. Left uncompensated, barometric variations could result in errors of 0.6 m (2 ft) or more. To compensate for barometric pressure changes, you can use the HOBO U20 Water Level Logger as a barometric reference. The barometric reference is typically deployed in the same well or at the same location as the water level of interest, but rather than being placed in the water column, it is deployed above the water in air. Barometric pressure readings are consistent across a region (except during fast-moving weather events), so you can generally use barometric pressure readings that are taken within 15 km (10 miles) of the logger or more, without significantly degrading the accuracy of the compensation. Therefore, one U20 or weather station (HOBO U30 or H21-001 recommended) can be used to compensate all of the water level loggers in an area. The 0-9m (0-30 ft) HOBO Water Level Logger (U20-001-01) is a good barometric reference due to its smaller range, temperature-compensated accuracy, and rugged stainless steel case. HOBOware Pro includes a Barometric Compensation Assistant for easy and accurate barometric compensation.
Doc #12315-C, MAN-U20 © 2008 Onset Computer Corporation. All rights reserved. Patent #: 6,826,664 Onset, HOBO, and HOBOware are registered trademarks of Onset Computer Corporation. Viton is a registered trademark of DuPont. Other products and brand names may be trademarks or registered trademarks of their respective owners. The HOBO U20 Water Level Logger is used for monitoring changing water levels in a wide range of applications including streams, lakes, wetlands, tidal areas and groundwater. The loggers are typically deployed in existing wells or stilling wells installed specifically for deploying the loggers. This logger features high accuracy at a great price and HOBO ease-of-use, with no cumbersome vent tubes or desiccants to maintain. The logger uses a maintenance-free absolute pressure sensor and features a durable stainless steel or titanium housing (depending on model) and ceramic pressure sensor. The HOBO Water Level Titanium is recommended for saltwater deployment for recording water levels and temperatures in wetlands and tidal areas. The logger uses precision electronics to measure pressure and temperature and has enough memory to record over 21,700 combined pressure and temperature measurements. Software HOBOware Pro^® software is required for logger operation. Using a reference water level, HOBOware Pro automatically converts the pressure readings into water level readings. HOBOware Pro also supports compensation for temperature, fluid density, and barometric pressure. Communication For launching and reading out the Water Level logger in the field, you can use a laptop computer with HOBOware Pro and an Onset Optic USB Base Station (BASE-U-4), with a coupler (COUPLER2-B) or the HOBO Waterproof Shuttle (U-DTW-1) with a coupler (COUPLER2-B). The optical interface allows the logger to be offloaded without breaking the integrity of the seals. The USB compatibility allows for easy setup and fast downloads.

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pressure data-logger - ONSET - #1

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