The measuring technique with the SMS 2500S electronic pressure meter consists in piercing through a silicon bung closing a tensiometer, by means of a hypodermic needle, itself connected to a pressure transducer (or vacuumeter). This type of measure, both very precise and very economical (a unique appliance can be used on a great number of tensiometers) is particularly practical for all users of tensiometric technics in general. This appliance is easily transportable in its small bag and will allow the user to envisage all field experimentations outside of the laboratory. It is obvious to use such a system in agronomy or agriculture for managing water use : determination of irrigation conditions, of the amount of water needed and of the best moment to irrigate. The knowledge of water potentials is also very important when a control of groundwater ressources must be done.

The measuring principle of this system is both simple and gives very accurate readings. It consists in measuring the vacuum created in an airtight system filled with water which equilibrates with the soil through the porous ceramic.

The porous ceramic cup is glued to the bottom of a hollow PVC tube which will be set into the soil to measure its water potential. The water saturated ceramic will be linked to the plastic tube full of water (sort of water container) which is also linked by a capillary to a mercury reservoir.

Key Advantages
ACCURATE
EASY TO USE
ECONOMIC (one sensor can be used on a great number of SMS tensiometers)

Disadvantages
No monitoring

Measured value : pressure
Technology : electronic, digital
Applications : industrial, water
Configuration : portable