The SMS series tensiometric tubes are designed to be used with the electronic hand held meter, ref. SMS 2500S. SDEC France's tensiometer tubes are also compatible with all other tensimeters on the market (compatible outer diameter).
The functioning principle of the SMS tensiometer tubes is based on the use of a hypodermic needle to measure the suction in the tube through a special septum type stopper. To make the measurement, the meter is set on the top of the tensiometric tube. A special silicon stopper is used to close the tube. It is filled with a synthetic compound with self-sealing properties. The meter uses the needle to pierce the stopper at the top of the tube, and measures the vacuum (suction) inside. Due to its special design, the stopper remains airtight (it can stand up to 500 piercings without leaking). The porous ceramic SDEC 2150 used on the SMS series tensiometric tubes enables it to make measurements over -850 mbar. No air will be able to enter in this range of vacuum, thanks to the excellent porousness characteristics of SDEC ceramics.
The main interest, therefore, of this technique, lies in the multiplication of the tensiometric measurements at a low cost, since only one electronic meter is needed for many tubes. This technique is well adapted to agricultural research, and soil science in particular.
EASY TO USE
Tensiometer tube : U.V resistant transparent P.V.C.
Tube dimensions : inside Ø = 15,4 mm. outside Ø = 21,5 mm.
Weight : 150 to 550 grams (depending on the length of the tube).
Porous ceramic cup : SDEC 2150
Air entry value : 1,5 Bar.
Hydraulic conductivity : 5,5 . 10-7cm.s-1.
Connection ceramic/tube : with special glue under vacuum.
Stopper : silicone with special stuffing (TECSIL 2034).
Life time of stopper : More than 500 punctures.