Emerson 2468CD Manuel D’Utilisation

Hydrastep 2468CB and 2468CD Manual 

Introduction to the Hydrastep 2468 Electronic Gauging System 

The Hydrastep 2468 Electronic Gauging System is designed as an electronic alternative to 
water level gauges on boilers, giving a more reliable and safer water level indication than 
conventional visual gauges.  It uses the significant difference in resistivities of water and 
steam in temperatures up to 370

C (698F) to determine the water level. 

 

 

 
 
 
A vertical row of electrodes is installed in the water level column attached to boiler and 
typically aligned so that half the electrodes are above and half below the normal water level 
(see Figure 1.2).  The resistance measurement is made between the insulated tip of each 
electrode and the wall of the column. 
 
The “cell constant” defining the actual resistance measured is determined by the length and 
diameter of the electrode tip and the column bore.  In practice, the cell constant is chosen so 
that the resistance in water is less than 100k ohms and the steam resistance is greater than 
10M ohms.  Since the resistivities of water and steam are substantially different, the system 
is simple and requires no setting up adjustments.  It is not susceptible to power supply 
variations, ambient temperature changes, etc., resulting in a highly reliable system. 
 
A general overview showing how a typical Hydrastep 2468 System is installed is illustrated 
in Figure 1.3.