Air mercury tensiometer with adjustable built-in U-type tube

Abstract

The invention provides an adjustable inside U-type pipe air mercury draft gauge in the field of soil moisture measuring device. It comprises a transparent pipe, a U-type pipe, a mercury column, a water column, a gas column, a graduated plate, a gas valve, a gas column valve, a pressure capsule, a sealed cover and an argil pipe and so on. The draft gauge cuts down the height of the normal U-type mercury pipe to a half inside the main pipe of the draft gauge; it uses gas column valve to control the air column inside the U-type pipe to accommodate the soil lower water potential negative pressure area and higher negative pressure area water potential measurement.

Description

technical field [0001] The invention belongs to the field of soil moisture measurement equipment, in particular to an adjustable built-in U-shaped tube air mercury tensiometer device for soil moisture measurement. Background technique [0002] Mercury tensiometer is a commonly used instrument in the research and measurement of soil irrigation moisture. As long as the soil negative pressure value is measured, the soil moisture content can be converted through the "soil moisture characteristic curve". It is easy to make, easy to assemble and accurate to measure. Etc. However, the conventional mercury tensiometer is an external U-tube mercury tensiometer, that is, the U-shaped mercury column tube is separated from the main tube of the tensiometer, and the two are only connected by a connecting hose; The U-shaped glass tube is longer, greater than 76 centimeters, so it is inconvenient to carry and bury in the field; in addition, the U-shaped thin glass tube is exposed to the ou...

AI Technical Summary

Problems solved by technology

However, the conventional mercury tensiometer is an external U-tube mercury tensiometer, that is, the U-shaped mercury column tube is separated from the main tube of the tensiometer, and the two are only connected by a connecting hose; The U-shaped glass tube is longer, greater than 76 cm, so it is inconvenient to carry and bury it in the field; in addition, the U-shaped thin glass tube is exposed to the outside, and it is easy to collide and break, and mercury leaks, which is very unsafe

Although there is a pre-sealed built-in non-adjustable U-tube air mercury tensiometer [Xu Fuan. Development and application of mercury contact soil moisture sensor. Soil, 1987, 19 (2): 91-96], but its U-shaped The top of the upper air column on one side of the glass tube is pre-sealed and not adjustable. Since the accuracy of measuring the negative pressure value of the soil is proportional to the length of the air column, in the case that the air column is pre-sealed and not adjustable, in order to achieve shortening The purpose of the U-shaped glass tube can only be at the cost of reducing the measurement accuracy, especially at the low suction end. It can be seen from Table 1 that the suction measurement accuracy of 0-190mm Hg under the state of 19 cm of air sealing is only the original 34-43% of

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