Tensior T8 - Eijkelkamp Agrisearch Equipment

Also, for quality assurance, the status of the signal can be logged for later
evaluation of the readings.
4.3 The ceramic cup
Avoid to touch the cup with your fingers. The ceramic should not have
contact with grease or soap as this will influence the hydrophilic
performance.
To transfer the soil water tension as a negative pressure into the Tensiometer,
a semi-permeable diaphragm is required. This must have good mechanical
stability and water-permeability, but also have gas impermeability.
The T8 cup consists of ceramic Al2O3 sinter material. The special
manufacturing process guarantees homogeneous porosity with good water
conductivity and very high firmness. Compared to conventional porous ceramic
the cup is much more durable.
The bubble point is higher than 6000 hPa. If the soil is dryer than 6000 hPa the
negative pressure inside the cup decreases and the readings go down to 0 hPa.
With these characteristics this material has outstanding suitability to work as
the semi permeable diaphragm for Tensiometers.
4.4 Reference air pressure
The reference atmospheric air pressure is conducted to the pressure
transducer via the air permeable (white) Teflon membrane and through the
cable. The membrane does not absorb water. Water will not pass through the
membrane into the cable, but condensed water inside the cable will leave the
cable through the membrane.
The white membrane on the cable must always have contact to air and
should never be submersed into water.
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