T8 Manual - UMS
T8 Manual - UMS
T8 Manual - UMS
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Service and maintenance<br />
If the soil dries out more than -1500 kPa (-15 bar), the negative<br />
pressure will drop much faster as air will enter the cup.<br />
5.1.2 Refilling in the lab<br />
To reach the optimal measuring range of -90 kPa Tensiometers<br />
should be refilled in the laboratory using the refill kit.<br />
1. Set up the refilling kit and connect the vacuum pump as shown in<br />
the photo. The pump should achieve at least 0,8 kPa against<br />
vacuum. Use distilled or de-ionized water which necessarily does<br />
not have to be degassed when a pump is used.<br />
2. Unscrew the cup in clockwise direction and empty it.<br />
Do not touch the ceramic cup with your fingers. Wrap a clean<br />
towel around the cup!<br />
The pressure sensor diaphragm is inside the small hole on the<br />
pressure sensor body. It is very sensitive and may never be<br />
touched! It can be destroyed even by slightest contact!<br />
No contamination should get on the sealing and gasket.<br />
3. If the cup is dry it should be placed in a beaker filled with distilled<br />
water for several hours or overnight. Initially there should be no<br />
water inside the cup! Place the empty cup into the beaker in an<br />
upright position, with the external water level reaching no higher<br />
than 2/3 of the cup.<br />
If the cup is filled with water and water intrudes from both inside<br />
and outside cavities of air will be enclosed inside the ceramic.<br />
Adaptor for<br />
sensor body<br />
Vacuum gauge<br />
Adaptor for<br />
ceramic cup<br />
Fig. 5.1: <strong>UMS</strong> laboratory refill kit BKT468<br />
Connection to vacuum<br />
pump<br />
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