Model "TG" 18" Soil Water Tension Meter, AC Switch Open Past Setting
The IRROMETER was first developed in 1951 to help growers improve irrigation efficiency. It provides the user with accurate information on soil moisture status regardless of soil type. The instrument measures in centibars (cb) or kilopascals (kPa) of soil water tension. This value represents the energy a plant's root system uses to draw water from the soil. Understanding soil moisture activity helps the user make informed irrigation scheduling decisions resulting in improved yield and quality while reducing water, fertilizer, labor and energy costs. The IRROMETER Model TG is best suited for turf and shallow rooting areas such as turf grass or seed beds or anywhere installation requires horizontal placement.
- Cap section
- Body tube and tip and hermetically sealed IRROMETER vacuum gauge with dual scale of centibars (cb) and kilopascals (kPa)
- AC Switch Open Past Setting
- 0-100 cb (kPa) range gauge
- Fixed ceramic tip (white)
- Air-free gauge gives accurate readings
- Hermetically sealed gauge designed for harsh environments
The IRROMETER operates on the tensiometer principle, which is entirely different from other systems which measure percent of moisture. The IRROMETER consists of a sealed water filled tube equipped with a special vacuum gauge and a porous tip that is installed in the ground at desired root zone depths. In dry soil, water is drawn out of the instrument, reducing the water volume in the instrument, thus creating a partial vacuum which is registered on the gauge. The drier the soil, the higher the reading. A rainfall event or irrigation application reverses this action. The vacuum created by dry soil draws water back into the instrument from the soil, which in turn results in a lower gauge reading. The instrument is in effect a “dummy root” equipped with a gauge that continuously registers “how hard the roots are working”. A gauge reading of 50 indicates that the roots are extracting the same amount of moisture whether the crop is planted in sandy soil or clay soil. Due to the IRROMETER’s unique principle of operation, no calibrations are necessary, under normal operating conditions, for different soil types.
The irrigation system shall incorporate soil moisture indicators to aid in making irrigation scheduling decisions. The soil moisture indicator shall operate on the tensiometer principle and display soil water tension in units of centibars or kilopascals. It shall have a hermetically sealed gauge. Tube shall be constructed of durable plastic, that is impervious to attack by soil chemicals, with a ceramic sensing tip. It shall be designed for near horizontal installation to adequately represent soil moisture for very shallow rooted plant material. All ceramic to plastic connections shall be guaranteed leak proof. The soil moisture indicator shall be an Irrometer Model TG as manufactured by the IRROMETER Company, Inc. of Riverside, California.
The Model TG Automatic Switching Gauge option is compatible with AC irrigation control systems, when combined with the proper selection of automatic gauge assembly. Automatic gauge assemblies are available in the following configurations:
- AAR for 24 volt AC valve circuits with switch closed when wet
Option "A" - Automatic Gauge - provides direct switching capabilities in addition to indicating available soil moisture. Soil water tension readings above the moisture setting can activate an irrigation valve solenoid, time clock or warning device. A switch mechanism (AC Switch Open Past Setting) is mounted on the gauge and can be rotated to desired setting. The gauge reads in centibars (cb) and kilopascals (kPa) of soil water tension.