WL650 Sonic Water Level Meter
Global Water's WL650 Sonic Water Level Meter is a self-contained, battery-operated meter that uses sound waves to measure well water level. Fast, accurate measurements are possible in the field or anywhere without the use of down-hole water level meters. The Sonic Water Level Meters are lightweight, compact, versatile, and easy to operate.
The water level meter allows you to measure crooked wells, wells with cascading water, partially cased rock wells, wells with submersible pumps, capped or uncapped wells, wells with pipes and wires inside, in fact, you can even measure the length of coiled pipe with the water level meter. As long as the obstructions take up no more than half of the bore area the meter will not suffer any loss of accuracy. The sonic water level meter should only be used on wells under 10 inches in diameter as the accuracy decreases with larger diameter wells.
Sonic Water Level Meter Operation
The WL650 Sonic Water Level Meter is simple to operate. Select either the NORMAL (10-500 feet) or DEEP (200 to 1,200 feet) setting on the DEPTH switch. Then, to measure a capped well, simply insert the duct into the 5/8 inch wide access port and push the power-on switch. In a few seconds, the water level will appear on the water level meter's digital display. In the NORMAL setting, the sonic water level meter stays activated for 5 seconds or 5 pings. Using the DEEP mode, the water level meter emits 4 pings in 16 seconds. For more measuring time, hold the sonic water level meter's switch down as long as necessary.
Ignore distance feature
The factory distance default values for the sonic water level meter are 10 ft ( 3 meters) in Normal mode and 200 ft (60 meters) in Deep mode. If problems occur due to reflections from liners that don't come all the way to the top of the casing or unwanted signal returns from such things as pitless adaptors and such that interfere with getting a proper reading the water level meter's default values can be increased so that returns within that distance are ignored. Also, if you are making draw-down measurements that require the use of the sonic water level meter's deep mode but you wish to be able to measure to less than 200 ft (60 meters) you can reduce the minimum distance accordingly so that you don't have to switch modes during the test.
For uncapped wells, use the provided cover plate, which slips onto the measuring duct and provides a seal for up to 6-inch diameter casings. Cover plates for larger diameters can be easily fabricated from plastic or metal sheet.
Gain/Sensitivity - ''Which Gain Setting to Use, Fixed or Variable?''
The Variable gain mode provides, in effect, a rising gain or sensitivity with time. This method gives greater weight to return signals that occur later in the measurement cycle and is beneficial on deeper wells where the return signal is more attenuated. This also makes the units less susceptible to unwanted returns from various surfaces in the well casing that might interfere with proper measurement.
The Variable gain mode is somewhat more susceptible to interference from pump noise or other sources of high ambient noise. Also, in some specific configurations, it is possible for the unit to favor a secondary return over the primary one and give a reading that is twice the actual water level.
The Fixed mode is less susceptible to interference from ambient noise and the secondary return problem. This mode can be used to advantage in such cases. Some sensitivity is sacrificed so the unit might not read the deepest water levels in this mode.
Obtaining an accurate measurement with the sonic water level meter requires that the temperature setting on the meter be equal to the average air temperature inside the well casing. The temperature setting corrects for the variation of the velocity of sound with the air temperature in the wellbore. The sonic water level meter's temperature toggle switch adjusts the temperature setting for the variation of sound velocity in the well casing. The value set shows on the display and is retained until changed.
The correct temperature setting can be determined by using the TEMPERATURE MAP TABLE provided with the water level meter for the state where the meter will be used (temperature settings are provided for all states in the United States). Alternatively, the reverse side of the map table has a LOOK-UP TABLE giving the setting if the well water and average monthly surface temperatures are known.
Please note: The outside or ambient air temperature does not affect the water level meter operation, provided the meter and its components remain within the operating temperature range.
Sonic Water Level Meter Specifications
Measurement range: Normal 10-500 ft (3-152 m), Deep 200-1200 ft (61-366 m)
Display resolution: 0.1 ft