SU1411644A1 - Strain-measuring device - Google Patents

Abstract

The invention relates to moisture devices, can be used to monitor the soil moisture content and its regulation in control devices using chemical means and improves reliability. The tensio.meter contains a sealed vessel filled with water, fitted in the upper part with a choke valve, a semi-permeable ceramic probe mounted on the lower end of the vessel, and a float with rigid walls and a semi-permeable membrane at the base located inside the vessel. 1 il.

Description

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The invention relates to moisture facilities and can be used to control soil moisture and its regulation in reclamation control devices.

The aim of the invention is to increase reliability.

The drawing shows the tensiometer, a General view in section.

The tensiometer contains a sealed vessel 1, the lower part of which is equipped with a semi-permeable ceramic probe 2. Inside the vessel 1 there is a float 3 of rigid construction, the base of which is equipped with a semi-permeable membrane 4. The upper part of the vessel 1 is equipped with a fitting with a shut-off valve 5.

The tensiometer works as follows.

In the assembled M. tensiometer, the probe 2 of which is pre-moistened, a certain negative pressure is set from the operating range of the device (for example, 0.2 kgf / cm) by communicating a hermetic vessel 1 with a vacuum source through a fitting with a stop valve 5. When this is the same pressure in the float 3 as in the vessel 1, so the air exits through the membrane 4.

Then the probe 2 of the tensiometer is immersed in water, which begins to flow into the co-ud 1 under the influence of a predetermined pressure. When the water in the vessel 1 is semiprocled, the membrane 4 is wetted and the volume of air remaining in the float 3 is closed at the bottom. The float 3 remains afloat. The tensiometer is then completely filled with water, after which the Stop Valve of fitting 5 seals the Vessel 1 and the vacuum supply source. After removing the vacuum pressure 1 the vessel 1 is equalized with the atmospheric pressure of the probe 2 immersed in water. Water through- |) without the membrane 4 enters the float 3, the air in which is reduced, and the Fn is lowered into the lower part of the vessel 1.

Since the float of 3 tons is made with zero buoyancy, i.e. it has some reserve of buoyancy, the float later on with decreasing pressure 1 vessel 1 emerges not at a negative pressure value that was set before, g | at some new (value) negative pressure. The difference between these pressures of the scientific research institute is specified when the device is filled with water and the response pressure is set

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The device operates at a constant pressure for a particular camera. After determining the aforementioned correction, the device can be set to act at any desired negative pressure over the entire range of the tensiometer, setting its pressure equal to the required one given the specified correction.

When the probe is introduced into the soil under the action of the potential difference of water in vessel 1 from soil moisture, water moves through the walls of the probe from vessel 1 to the soil until equilibrium of pressure in vessel 1 and the suction pressure of soil moisture functionally associated with soil attenuation is established.

As a result of soil drying, the soil moisture suction pressure increases, the vacuum in vessel I also increases, and when the suction pressure reaches the tensiometer response value, the float 3 pops up, signaling the need to start watering.

The tensiometer can be easily adjusted to the required response pressure (the required humidity with regard to a particular soil type) by filling it with water while maintaining the required pressure in a sealed vessel with a correction that has a constant value for the given measuring chamber. The need for such an improvement is due to the fact that different agricultural crops require different optimal values of the suction pressure of the soil moisture (different soil moisture).

Thus, the proposed tensiometer can be successfully used to signal the need for irrigation of various agricultural crops without any design changes or replacement of the measuring chamber.

Claims (1)

Invention Formula A tensiometer containing a sealed vessel filled with water, a semi-permeable ceramic probe mounted on the lower end of the vessel and a float with rigid walls located inside the vessel, characterized in that, in order to increase reliability, the float is provided with a semi-permeable membrane at the base P X