Porous Ceramics
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Porous Ceramics are an integral part of many soil-monitoring and sampling instruments. The ceramic matrix serves as the interface between the soil matrix and the instrument. The ceramic material is porous, and allows water to pass into and out of the instrument. A pressure gradient across the ceramic wall will cause water to flow through the ceramic. The pressure gradient may be due to a pressure being applied, as occurs when using a ceramic pressure plate in a pressure chamber. The gradient may be due to a tension being applied, as occurs when using a tensiometer in the soil. The gradient may be due to a vacuum being applied
Ceramics are available in a variety of shapes and sizes for use in replacing damaged components on existing instruments or for constructing new ones.
Mini-Tensiometers
Mini-Tensiometers are used under conditions in which a tensiometer with a full-size ceramic cup cannot be used. These conditions might include: in a greenhouse environment to monitor plants growing in small containers; in laboratory column studies; or outside under turf, for measurements very near the surface.
The mini-tensiometers are constructed with a length of flexible tubing which allows the ceramic sensing cup to be placed exactly where it is needed. Several different ceramic cup sizes and shapes are available, ranging in size from 2 mm to 13 mm in diameter. The larger water reservoir tube is then placed in a more convenient location.
The silicon-rubber endcap allows periodic measurements to be made with a septum-and-needle-type portable electronic transducer, or a dial gauge can be attached. Continuous measurements can be made by attaching an electronic transducer and wiring the transducer to an electronic datalogger.
Features:
- variety of small ceramic cup sizes and shapes
- 22-mm (0.87-in) diameter PVC water reservoir/body tube
- silicon-rubber endcap
| Part Number | Ceramic Cup | Cup length |
| SMS2030S0 | 13 mm (0.5 in) diameter
flat-bottom cup |
32 mm (1.24 in) |
| SMS2030S1 | 6 mm (0.24 in) diameter
round-bottom cup |
35mm (1.38 in) |
| SMS2030S2 | 2 mm (0.09 in) diameter
needle-type cup |
25mm (0.98 in) |
| SMS2030S3 | 12 mm (0.47 in) diameter
round-bottom cup |
20mm (0.79 in) |
Model Ten Dial-Gauge Tensiometers
The Model Ten tensiometer offers versatility as well as reliability. The dial gauge and ceramic cup are easily replaceable, and threaded connections allow easy attachment of accessories.
The construction of the Model Ten make it a rugged and versatile instrument. The porous ceramic cup is attached to the body tube with a threaded connection, and is easily replaced in case of damage. The large inner-diameter body tube forms a large water reservoir, resulting in longer intervals between refilling.
The attachment point for the dial gauge is angled, making it easier for the user to read the gauge. The Bourdon-tube dial gauge is designed for prolonged outdoor use, and is recalibratable. The user can easily adjust the gauge to account for the effect of the water-column and any slight gauge offset, and obtain more accurate readings.
A plastic endcap screws into a threaded fitting at the top and seals the tensiometer. The 1/4-NPT threaded fitting can also be used to attach accessories, such as an electronic pressure transducer or a vacuum switch.
Features:
- 22-mm (0.87-in) diameter ceramic cup and body tube
- replaceable ceramic cup
- clear, large-diameter water reservoir/body tube
- recalibratable Bourdon-tube dial-gauge
- angled dial-gauge placement for easy gauge reading
- threaded fitting for easy attachment of accessories, such as electronic pressure transducers
| Part Number | Installed Depth |
| Ten15 | 15cm (6in) |
| Ten30 | 30cm (12in) |
| Ten45 | 45cm (18in) |
| Ten60 | 60cm (24in) |
| Ten90 | 90cm (36in) |