10
Density and Compressibility
Density is defined as the mass per unit volume, and it depends upon the temperature
and pressure intensity. The density of pure water is given in Figure 4 below.
Figure 4. Density p of pure water as a function of temperature and pressure
intensity. By permission from Fluid Mechanics for Hydraulic Engineers, by
Hunter Rouse, copyright 1938, McGraw-Hill Book Company, Inc.
5. Maintenance ______________________________________________________
5.1 Moisture Trap
The vibrating wire sensor has a vent tube to prevent loading on the sensor due to
changes in atmosphere pressure, and the moisture trap on the vent line requires
periodic changing of the desiccant capsules. The frequency of this is dependent on
weather conditions, but three to six months is a normal period.
5.2 Weight Maintenance
Since the weight is assumed to be of constant mass, it is important that it be kept
clean and free of encrustation, algal growth, etc. Periodic observation should be made
and this can coincide with the moisture trap maintenance.
