Xylem H-312-22 - Manual (Page 16)

2-8 Installation
H-312
2.12 Testing
Before installing the H-312 in your field location, you may wish to first test the sensor and data
logger in your shop or lab. This allows you to become familiar with H-312 and the data logger in
a controlled environment. The H-312 can be tested in a bucket of water. However, for this test to
work correctly, you must run a wire from inside the bucket that comes in contact with the water
back to the chassis ground of the data recorder. The wire establishes a ground connection
between the water and the data logger. Water and other conductive objects isolated by a plastic
bucket or table surface pick up AC noise from nearby lighting and power lines. The AC noise is
coupled by the water to the stainless diaphragm in the submerged pressure sensor. Because the
H-312 has a non-conductive housing it is electrically isolated from the surrounding water. The AC
noise may affect the pressure measurement due to large voltages between the water media and the
sensor (data logger) ground. This precaution is not necessary for field installations because
surface water and ground water are not isolated from earth ground.