Xylem H-310 - Manual (Page 11)

Chapter 2
Installation
H-310
Installation 2-1
2.1 Installing the W ATER LOG ® H-310 and the H-305
To install the W ATER LOG ® H-310 sensor and the H-305 dry air system, simply deploy the H-310
at the desired location and connect the hook-up cable from the H-305 junction box to your data
logger.
2.1.1 Sensor Deployment
There are as many ways to deploy the H-310 as there are customers. However, as versatile as the
H-310 is, there are some site preparations and maintenance that must be considered.
1. If the sensor is to be clamped or tied down at a fixed location, the sensor must be where there
is no velocity flow. The W ATER LOG ® H-310 is a pressure sensor and changes in flow
correlate to changes in pressure. Thus, if the sensor is subjected to open flow, there is a good
chance your readings will be inconsistent. Key point: Use stilling wells, sand points, or
other "no flow" installation techniques. The result will be very accurate, reliable data.
2. The H-310 can be hung in well bores and float type stilling wells or conduits. If this is the
type of installation that is being done, the H-310 should be installed by suspending the sensor
not by its polyethylene vent cable, but by using a stainless steel drop cable and by using a
weighted ballast or sinker, such as the one that has been provided. The ballast will cause the
sensor to sink to the desired depth and will help the sensor to hang straight down. The
stainless cable and the miscellaneous hardware can be purchased from Design Analysis
Associates, or from a number of other sources.
The polyethylene vent cable has an extremely large thermal coefficient of expansion. This
coupled with the fact that the polyethylene tubing will stretch with applied weight, make the use
of the stainless steel drop cable a must. Use of the stainless steel drop cable will insure long
term stability. THIS IS A MUST!!!
One end of the stainless steel tube is attached to the support bail on the sensor and the other end
is fastened to a fixed reference point at the surface. The ballast is attached to the ballast hook of
the sensor, as shown in Figure 2-1.