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Vol. 9  No. 12

LEVELOGGERS

&
BAROLOGGERS

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Leveloggers and Barologgers

In our last newsletter we discussed three different slug test methods as examples of how slug test are conducted and analysed. In this newsletter we will describe how some of the equipment available, leveloggers and barologgers, that can be used to simplify performed slug tests.

LEVELOGGERS

A Levelogger is installed below the water level to record the pressure at the datum position (as inscribed) on the Levelogger. The pressure measured is the total of the weight of the water and the atmospheric pressure. Unless the measurement period is over a short time with stable barometric conditions, the fluctuations in barometric pressure should be measured for compensation. This can be done using a Barologger.

Selecting the Right Levelogger

Leveloggers are rated for use at certain depths.  It is important to know, before purchasing a Levelogger, what conditions the Levelogger will be used in. The Leveloggers are rated from 5 meters (M5) to 300 meters (M300). Exceeding the depth rating of the Levelogger may yield inaccurate data.  In addition, exceeding the rating by over 150% may permanently damage the Levelogger.

Programming the Levelogger

The Levelogger has three programming options:

  • Linear sampling - sampling every 0.5 seconds to 99 hours.

  • Event-based - the readings are checked at the selected time interval (0.5 seconds to 99 hours) and if the levels have changed over the selected amount of 0.1% to 25% of the full range of the Levelogger the readings will be stored, otherwise they are discarded.

  • User-selectable

Each Levelogger can handle up to 30 different schedule items, each with their own sampling rates and durations.

Setting up the Levelogger

Before you install the Levelogger, there are a few measurements that should be taken:

  • The distance on the suspension cable from the top of the casing to the datum on the levelogger (for the installation depth) to check for cable stretching over time.

  • Depth to the water level to ensure the Levelogger will be fully submerged at the planned installation depth

  • Total borehole depth

When installing the Levelogger, lower it slowly into the borehole to prevent damage. The cable used to lower the Levelogger should be made of a material that will not easily stretch, such as stainless steel. Ensure that the Levelogger is positioned so that it will be submerged at all times, and that the maximum submergence depth is within the range of the Levelogger you are using.

Take a manual measurement after the installation has stabilized, preferably at the same time as a scheduled Levelogger reading for a baseline measurement. It is recommended that you take manual measurements whenever possible as a quality control check.

Getting your Levelogger Data

There are two methods of getting your Levelogger data: with or without the communication package.

    Without the Communication Package

Data can be downloaded by connecting the Levelogger to a laptop using the optical reader, with a click of a screen icon using the Levelogger software. The level data that is downloaded is automatically corrected for temperature and altitude, and the temperature data is also recorded for future reference. Barometric pressure compensation of the Levelogger data can be performed by the Wizard within the Levelogger software.

    With the Communication Package

The communication package uses a direct read cable which allows you to get real-time data, and communicate with the Levelogger without removing it from the borehole. The lower end of the direct read cable has a miniaturized infrared optical reader, and the top cap of the Levelogger is removed to allow the cable to thread into it's place. The upper end of the cable can be attached to a laptop or a Leveloader (an data transfer unit designed to store and rapidly transfer Levelogger data) using a USB or R232 PC Interface to upload the data.

BAROLOGGER

The Barologger is a Levelogger with a small range of approximately 1.5 m, which is adequate for measuring the barometric pressure. These readings are used to compensate the Levelogger readings. Typical readings range from 1 to 3.3 ft when the Barologger is programmed with its operating altitude; failure to input correct altitude results in incorrect readings. The Barologger should never be submerged, but should be installed in a well, below the frost line and deep enough to avoid temperature fluctuations. The general rule of thumb is that one barologger can be used to compensate for all Leveloggers in a 20 mile radius.

It is also possible to manually compensate for barometric readings. Converting typical barometric data involves converting the units (usually atm, mm Hg, psi, mb or kPa) to feet or meters of water. The converted barometric values are then subtracted from the Levelogger readings to get the proper water pressure values. A converter for barometric pressure is given below:

Barometric Pressure Converter

Input: Units:

Output: Units:

For more info or to purchase a Levelogger and/or a Barologger click here: Levelogger & Barologger



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