Xylem H-312-22 - Manual (Page 10)

2-2 Installation
H-312
2.2 Water Depth
The following chart shows the maximum depth to which the H-312 is factory calibrated. The
sensor can survive temporary operation up to twice the maximum rated depth for you model’s
range. However, any pressure measurements made beyond the rated depth will be inaccurate.
The H-312 will be damaged if it is placed deeper than twice the maximum rated depth.
Model Pressure Range Depth Range * Accuracy
H-312-15 0 to 15 psi 0 to 34.60 ft. +0.017 ft
H-312-30 0 to 30 psi 0 to 69.20 ft. +0.035 ft.
* NOTE: Depth calculations are derived from the standard equation that one PSI is generated by
a column of water 27.680 inches deep at 39.4 F.
2.3 General Installation Recommendations
The sensor must be located where there is no velocity flow. Changes in water flow cause pressure
changes. Thus, if the sensor is subjected to open flow there is a good chance your water level
measurements will be inconsistent. To obtain accurate and reliable data, use stilling wells, sand
points, or other "no flow" installation techniques.
The H-312 submersible pressure transducer is not recommended for use in applications where silt
and mud are problematic. In addition, if the sensor is used in a shallow water application and
happens to dry out with mud coating the sensor diaphragm, the diaphragm compliance will be
altered and the factory calibration spoiled.
The H-312 sensor will be permanently damaged if it is frozen. Transducers which are installed in
geographical areas with harsh winters should be removed for the winter unless they are installed
deep enough in the water that there is no danger of freezing. Ice may form around the sensor
cable without causing damage or performance degradation. However, the cable should be
protected so as to minimize the possibility of it being damaged as the ice shifts or breaks up
during times of thawing.
The polyurethane drop cable is suitable for immersion, direct burial and is somewhat ultraviolet
(UV) resistant. Whenever possible, precautions should be taken to protect the cable from direct
sunlight, rodents and mechanical damage.
Experience has shown that if a portion of the H-312 housing or the sensor cable is installed above
the water and exposed to sunlight (e.g. installed in shallow water), a temperature gradient can
occur inside the enclosure and vent tube. As the air temperature changes the air density changes.
A change in the air density inside the sensor or vent tube column causes a partial pressure on the
reference side of the sensor which will raise or lower the H-312's pressure reading. This is a "law
of physics" problem not unique to W
ATER LOG ® Series transducers. It can be avoided by
installing the transducer horizontal so that the entire enclosure is covered by water. Cover or