CN100451606C - Air mercury tensiometer with adjustable built-in U-type tube - Google Patents
Air mercury tensiometer with adjustable built-in U-type tube Download PDFInfo
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- CN100451606C CN100451606C CNB2005100609932A CN200510060993A CN100451606C CN 100451606 C CN100451606 C CN 100451606C CN B2005100609932 A CNB2005100609932 A CN B2005100609932A CN 200510060993 A CN200510060993 A CN 200510060993A CN 100451606 C CN100451606 C CN 100451606C
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Abstract
The present invention provides an air mercury tensiometer with an adjustable built-in U-shaped tube, which belongs to the field of soil moisture measuring instrument equipment. The present invention comprises a transparent tube, a U-shaped tube, a mercury column, a water column, a gas column, a scale plate, a gas stopping valve, a gas column valve, a pressure guide bag, a sealing cover, a clay tube and other components. The tensiometer shortens the height of a normal U-shaped mercury tube by half and assembles the normal U-shaped mercury tube in a main tube of the tensiometer; the opening and closing of an air column in the U-shaped tube is adjusted and controlled by the gas column valve in order to be respectively suitable for water-potential measurement in a negative-pressure region with lower soil water potential and water-potential measurement in a negative-pressure region with higher soil water potential. In such a way, the present invention has the advantages that the U-shaped mercury tube is not easily broken and shivered; the use is safe; larger convenience is provided for burial use in a field and the carrying of the tensiometer; high measurement precision is maintained.
Description
Technical field
The invention belongs to soil nmoisture content analyser device apparatus field, especially belong to a kind of air mercury tensiometer with adjustable built-in U-type tube device of determining soil moisture.
Background technology
Mercury tensiometer is an instrument and equipment commonly used during present soil irrigation moisture is studied and measured, as long as measure the soil negative pressure value, just can converse the water cut of soil by " characteristic curve of soil moisture ", has and makes advantages such as simple, easy to assembly, that measurement is accurate.But conventional mercury tensiometer is a kind of external U type pipe mercury tensiometer, and promptly U type mercury column jecket is what to separate between being responsible for tensiometer, only is communicated with flexible pipe by one between the two and is connected; Simultaneously its U type glass tube is longer, greater than 76 centimetres, so in carrying the way and the equal inconvenience when burying underground of field; In addition, outside U type thin glass tube was exposed to, easy collision caused broken, and mercury leaks, and is very dangerous.Though the built-in non-adjustable U type pipe air mercury tensiometer of existing existing pre-envelope [Xu Fuan. the development and the application of mercury-wetted contact formula soil moisture sensor. soil, 1987,19 (2): 91-96], but its U type glass tube one upper lateral part air column top is a pre-envelope and nonadjustable, because the degree of accuracy of measured soil negative pressure value is directly proportional with the length of gas column, so at air column is pre-envelope and under the nonadjustable situation, in order to reach the purpose that shortens U type glass tube, can only be to reduce measuring accuracy, particularly reducing bargain-hunting power end measuring accuracy significantly is cost, as shown in Table 1, the 0-190mm mercury column suction measuring accuracy under 19 centimetres of states of envelope gas has only original 34-43%.
Summary of the invention
The present invention seeks to overcome the deficiency that above-mentioned two kinds of existing devices exist, propose a kind of U type mercury tube to be assembled in tensiometer is responsible for, and make U type glass tube foreshorten to reasonable length by combining, so that carry, bury underground conveniently, and be difficult for broken, safe in utilization, with low cost and under＜190mm mercury column soil negative pressure, do not influence a kind of air mercury tensiometer with adjustable built-in U-type tube device of measuring accuracy with the adjustable air post.
The present invention is achieved through the following technical solutions:
A kind of air mercury tensiometer with adjustable built-in U-type tube comprises transparent tube, U type pipe, mercury slug, scaleplate, pilot capsule, gland bonnet (comprising rubber stopper), air-stopping valve, vitrified-clay pipe; Wherein gland bonnet is fixed on the transparent tube upper port, the two ends mouth of pipe that is assemblied in the equal U-shaped pipe of the interior both sides height that includes mercury slug of transparent tube from bottom to top passes from set two holes of gland bonnet, establish air-stopping valve at one side pipe mouth, below this side U-shaped seal of tube lid, be provided with the pilot capsule that is connected with the U-shaped pipe, the U-shaped pipe is fixed with scaleplate behind, the lower port of transparent tube is connected with vitrified-clay pipe, and fills with air free water in transparent tube and vitrified-clay pipe; Both sides zero-bit to the height of mercury slug bottom is 19 centimetres in the described U type pipe, the maximum pressure differential that both sides can form in the U-shaped pipe is 38 cm Hgs, contour water column all is set in the square tube on the zero-bit of both sides, opposite side port equal-height position at U type pipe air-stopping valve is provided with the gas column valve, this gas column valve is to being gas column between water column top, below, and it highly is 19 centimetres.
Described scaleplate is for beginning to have up and down respectively the highly panel of mark from zero-bit, the highest scale is 19 centimetres, and minimum scale is-19 centimetres, and minimum scale is 1 millimeter.When in measurement＜190mm mercury column soil negative pressure, the gas column valve is opened, the mercury slug discrepancy in elevation of being read is exactly the soil negative pressure, when measurement＞190mm mercury column soil negative pressure, the gas column valve cuts out, the mercury slug discrepancy in elevation of being read during measurement can be converted into soil negative pressure value (because the represented negative pressure value of mercury slug liquid level reading this moment by lookup table 1, the discrepancy in elevation that should comprise mercury slug is elongated the negative pressure value that the back is reduced with the gas column that seal, so must be by the flow of water negative pressure value of the calculating or the 1 acquisition soil of tabling look-up).
Table 1 " air mercury tensiometer with adjustable built-in U-type tube soil negative pressure measured value and degree of accuracy ratio lookup table " is soil negative pressure value and the two survey measurements degree of accuracy ratio that the mercury slug liquid level records under the pairing gas column valve opening and closing of the position on scaleplate state.First (first and second hurdle) rests on diverse location on the scaleplate for the mercury slug liquid level in the table, gas column valve one side mercury moves down from zero-bit during measurement, the value that reads is a negative value, air-stopping valve one side moves up from zero-bit, the value that reads on the occasion of, both add up to the generation liquid level discrepancy in elevation, list in third column.Under the state that the gas column valve is opened, the value of third column is the soil negative pressure value, under gas column valve closed condition, finds corresponding soil negative pressure value (be all measured values under standard state of temperature and air pressure strictly speaking, see embodiment 2 for details) by the 4th hurdle.The 5th hurdle value is got divided by the 4th hurdle by third column, reading degree of accuracy ratio under the state that reading degree of accuracy and gas column valve are opened under the expression gas column valve closed condition.
Described water colunm height is the distance of pilot capsule bottom to air-stopping valve bottom;
When described water colunm height is made as 6 centimetres, the length of gas column is 19 centimetres in the U-shaped glass tube, the height of both sides mercury slug also respectively is 19 centimetres, it highly is 44 centimetres that mercury slug, water column, air column three add up to, the height that adds air-stopping valve or gas column valve and tube head (referring to that U-shaped glass tube two ends must be unnecessary after air-stopping valve or gas column valve are installed) part is made as 2 centimetres, and then the overall height of U-shaped pipe is 46 centimetres.
Described pilot capsule is waterproof a, gas, and the membrane vesicle with retractility is shrivelled state when soil does not have pressure reduction, can expand when pressure reduction is arranged and transmits negative pressure;
Described its max cap. of pilot capsule is to hold the whole air of discharging in this side U type pipe and the water of water column.
Air mercury tensiometer with adjustable built-in U-type tube by above technical scheme formation, when the soil negative pressure of measurement＜190mm mercury column (the pairing soil negative pressure value of soil moisture of the growths such as most of vegetables that for example suit all belongs in this scope), can open the gas column valve measures, air mercury tensiometer with adjustable built-in U-type tube and the conventional mercury tensiometer of this moment are just the same, and measuring accuracy does not reduce yet.When the soil negative pressure of measured value possibility＞190mm mercury column (under the arid situation of soil), need close the gas column valve measures, the maximum pressure differential that this moment, mercury slug can form also has only the 380mm mercury column, compare with conventional mercury tensiometer, this moment, the survey measurements precision of air mercury tensiometer with adjustable built-in U-type tube was reduced to original 43%-50% (table 1).But according to Li Yu fine jade research (Li Yuqi. depressimeter is measured the applied analysis of soil moisture. the Chinese countryside water conservancy and hydropower, 1999 (3): 18-19), soil moisture content that tensiometer is surveyed and soil negative pressure are following exponential relationship:
Q＝A+Bln(10s+1).....................(1)
Q is soil weight water percentage (%), and A is the value of symbol saturated aqueous rate, and B is a parameter, and s is holard tension force (Kpa).By formula (1) as can be known, under the bigger situation of negative pressure, negative pressure variation causes that the variation of soil moisture content is less, and therefore, the column valve of holding one's breath in the bigger situation ShiShimonoseki of negative pressure is measured the measurement result influence of soil moisture content also less.
Beneficial effect of the present invention, the one, the present invention combines with air column by mercury slug, make at least 76 centimetre 46 centimetres of foreshortening to embodiment 1 of the U type glass tube length of tensiometer by routine, therefore shortened the total length of air mercury tensiometer with adjustable built-in U-type tube greatly, burying underground to use for carrying of tensiometer and field provides bigger convenience.Because during the measured soil negative pressure, the peak suction value that pot clay end can be responded to is 1 atmospheric pressure under standard state, the maximum injection rate IR of conventional mercury depressimeter mercury (is equivalent to 1 atmospheric pressure for the discrepancy in elevation that can form 76 centimetres.Its monolateral mercury slug length is 38 centimetres, starts at from zero-bit, and the maximum height that the mercury face rises also is 38 centimetres, and the mercury discrepancy in elevation is the twice of lifting height, down with), therefore, require the U type length of tube must be more than 76 centimetres.The present invention is by calculating and verifying clear and definite, if the gas column at conventional mercury tensiometer U type our beginning of pipe is sealed (having 38 centimetres of mercury slug and gas column height respectively), under standard state during the measured soil negative pressure, the mercury slug maximum height that can rise only is 23.49 centimetres, while is along with the shortening of the gas column that seals in the U type pipe, the maximum height that the mercury face can rise also shortens thereupon, but as can be seen from Figure 2, when gas column height drops to 19 centimetres just and 19 centimetres of (see figure 2)s that coincide of mercury slug rising maximum height, after this shorten U type pipe (both sides are contour) if continue with the length that reduces gas column, then mercury rising maximum height reduces the degree that degree has reduced less than gas column, be mercury when hit the ceiling, will overflow U type glass tube.Therefore think, 19 centimetres of gas columns are that (we opens the U type glass tube mouth of pipe, both sides mercury slug liquid level is equated at zero-bit envelope gas, all be in the zero graduation position, close the envelope gas that the gas column valve carries out then, be called zero-bit envelope gas) realize the optimal length of shortization of pipe range under the situation.At this moment when the soil negative pressure is reduced to 1 atmospheric pressure, the zero-bit distance that mercury slug rises is 19 centimetres also, pilot capsule bottom to the water colunm height of air-stopping valve bottom is 6 centimetres, the U type glass tube height of tensiometer is 44 centimetres, add 2 centimetres of air valve and tube head part height, the overall height of U-shaped pipe is 46 centimetres, and the common U type glass tube of this aspect ratio reduces 30 centimetres for 76 centimetres, operates thereby greatly facilitate to carry with the field; Another advantage of the present invention is that this makes U type mercury tube be difficult for fragmentation, use is safer because U type mercury tube is assemblied in the tensiometer person in charge; Though being its length, an advantage more of the present invention shortens, but adopt worn-out mouthful to measure during the determining soil moisture of right＜190mm mercury column negative pressure, so still kept the same precision (seeing Table 1) of conventional mercury tensiometer, and＜soil moisture of the negative pressure of 190mm mercury column is the normal moisture condition of most of plant growth; Seal measurement when need adopt during to the determining soil moisture of soil negative pressure＞190mm mercury column negative pressure, measuring accuracy reduces less.
Description of drawings
Fig. 1 air mercury tensiometer with adjustable built-in U-type tube structural representation of the present invention.
Fig. 2 gas column length and mercury slug rising maximum height concern synoptic diagram.
Embodiment
In conjunction with the accompanying drawings the present invention is described in further detail by the following examples.
Embodiment 1:
Referring to shown in Figure 1, the present invention is a kind of air mercury tensiometer with adjustable built-in U-type tube, comprises that transparent tube 1 made by simple glass pipe or plexi-glass tubular, makes the threaded lucite pipe of a processing that connects of body of the simple glass pipe and does tube head; Make the directly machining screw pipe of body with plexi-glass tubular and make tube head, adopt 3/4 inch caliber body, body length is by buried depth and adjustable built-in U type length of tube decision; U type glass tube 2 is formed by the glass capillary bending, and its both sides height is 46 centimetres; The formation of the following injection of zero-bit mercury highly is 19 centimetres mercury slug 3 in the U type glass tube 2; Length respectively be set be 6 centimetres water column 11 more than the mercury slug 3 both sides zero-bits; Scaleplate 4 the highest scales are 19 centimetres, and minimum scale is-19 centimetres, and minimum scale is 1 millimeter; Air free water 5 is cold boiling water or distilled water; Pilot capsule 6 is waterproof a, gas and can expands and transmit the membrane vesicle of suction function, utricule requires existing retractility, the material that is difficult for breaking is again made (as rubber film), do not have at U type pipe two ends that it keeps shrivelled state under the situation of pressure reduction, its max cap. is to hold the whole air of discharging in this side U type pipe and the water of water column; Gland bonnet 7 is made up of threaded cap and rubber plug; Air-stopping valve 8; Gas column valve 9; Gas column 10 fingers are 19 centimetres air cavity by the length that forms between gas column valve 9 and water column 11 upper surfaces; Vitrified-clay pipe 12 is soil water potential inductive means, has permeable air-locked function, in the process that soil becomes dry gradually, the moisture filled in pot clay end 12 and the transparent tube 1 is produced negative pressure by sucking-off progressively, pulling mercury slug 3 and gas column 10 motions, realize measurement function, it is the pot clay end of 20mm that present embodiment adopts diameter for matching with transparent caliber; The up and down free height of U type glass tube 2 both sides mercury slug of tensiometer of the present invention is 38 centimetres, comprising 19 centimetres of the height of gas column 10, add that pilot capsule 6 bottoms to air-stopping valve 8 distances from bottom are 6 centimetres of water column 11 height, add 2 centimetres of air valve and tube head part height, only be 46 centimetres altogether.
Embodiment 2:
The using method of air mercury tensiometer with adjustable built-in U-type tube is:
1, different soils suction section adopts distinct methods to measure to guarantee precision: according to the Changing Pattern of soil water potential, when soil moisture content changes identical numerical value, the negative pressure variation that higher soil moisture content state produces down is littler than the negative pressure variation that produces under the low state of soil moisture content, therefore, at the bargain-hunting power section, take worn-out format invention tensiometer gas column valve to measure its soil negative pressure value when being soil negative pressure value＜190mm mercury column, and read the mercury slug difference from scaleplate, make it with common tension force in respect of same measuring accuracy; When measuring high suction section soil negative pressure value, when being soil negative pressure value possibility＞190mm mercury column, open air-stopping valve, mercury slug returns zero, inhale flat pilot capsule with ear washing bulb, close the gentle column valve of air-stopping valve and measure, read the mercury slug difference after, check in the soil negative pressure value by table 1, survey calibration in case of necessity.According to above-mentioned gained soil negative pressure value, can obtain the soil water-containing numerical quantity in conjunction with " soil moisture curve table ".
2, zeroing: air-stopping valve is normally closed, and having gas leakage or mercury slug can not return under the situation that will forward the measurement of envelope gas in zero or the measuring process from the opening measurement to slightly, opens the air-stopping valve zeroing, can close after the zeroing.
3, buried depth: the following pipe range of the buried depth position line is the degree of depth of placing into the soil, and can make the tensiometer of different buried depth as required.Air mercury tensiometer with adjustable built-in U-type tube of the present invention is incorporate, the following pipe range of buried depth line need be determined according to the depth capacity that will measure when tensiometer is made, therefore, buried depth position during measurement had better not be on pile things on line as shown in Figure 1, otherwise brings inconvenience for the tensiometer reading.
4, close the calculating and the correction of gas column valve measured value when measuring: tensiometer is that the displacement with mercury slug shows the soil water potential negative pressure, for common tensiometer, the displacement of mercury slug and the soil water potential negative pressure value relation of being in line, can directly represent the soil water potential negative pressure value with the displacement discrepancy in elevation of mercury slug, but for air mercury tensiometer when measuring (promptly close gas column valve), the displacement of mercury slug becomes the non-rectilinear relation with the soil water potential negative pressure value, for (1 atmospheric pressure under standard conditions, 20 ℃) carry out zero-bit envelope gas tensiometer, the computing formula of soil water potential value is:
In the formula (1):
P---soil water potential value (negative atmospheric pressure number);
P
0---the standard atmospheric pressure value;
h
0---air column length (cms) during encapsulation;
h
1---a certain moment air column height (cms);
The column valve of holding one's breath in standard state ShiShimonoseki is measured and the pairing soil negative pressure value of different mercury slug displacements that produces has been listed in the table 1 by calculating, can conveniently check in.
For data measured under non-standard condition, need carry out the actual measurement of temperature and air pressure change and proofread and correct.But according to Xu Fuan research (Xu Fuan. the development and the application of mercury-wetted contact formula soil moisture sensor. soil, 1987,19 (2): 91-96), differ in environment temperature and standard temperature be no more than ± 10 ℃ the time, its measuring error is just less than ± 1.7%, therefore, measure at normal temperatures, measuring error generally can not surpass 5%; Usually, sea level elevation is below 500 meters, and the air pressure change value can be got the listed approximate value of table 1 also below 5%.Under, the situation that measuring accuracy is had relatively high expectations big, can relatively proofread and correct by actual measurement in changes in environmental conditions.
Claims (6)
1, a kind of air mercury tensiometer with adjustable built-in U-type tube, comprise transparent tube (1), U type pipe (2), mercury slug (3), scaleplate (4), pilot capsule (6), gland bonnet (7), air-stopping valve (8), vitrified-clay pipe (12), wherein gland bonnet (7) is fixed on transparent tube (1) upper port, the two ends that are assemblied in the equal U type pipe (2) of the interior both sides height that includes mercury slug (3) of transparent tube (1) from bottom to top pass from set two holes of gland bonnet (7), establish air-stopping valve (8) at one side pipe mouth, be provided with the pilot capsule (6) that is connected with U type pipe (2) in the below of this side U type pipe (2) gland bonnet (7), U type pipe (2) is fixed with scaleplate (4) behind, the lower port of transparent tube (1) is connected with vitrified-clay pipe (12), and in transparent tube (1) and vitrified-clay pipe (12), fill with air free water (5), it is characterized in that the interior both sides of described U type pipe (2) zero-bit to the height of bottom mercury slug (3) is 19 centimetres, contour water column (11) all is set in the square tube on the zero-bit of both sides, opposite side port equal-height position at U type pipe (2) air-stopping valve (8) is provided with gas column valve (9), this gas column valve (9) is to being gas column (10) between below water column (11) top, and it highly is 19 centimetres.
2, according to the described tensiometer of claim 1, it is characterized in that described scaleplate (4) for begin to have up and down respectively the highly panel of mark from zero-bit, the highest scale is 19 centimetres, minimum scale is-19 centimetres.
3,, it is characterized in that described water column (11) highly is the distance of pilot capsule (6) bottom to air-stopping valve (8) bottom according to the described tensiometer of claim 1.
4,, it is characterized in that described water column (11) highly is 6 centimetres according to claim 1 or 3 described tensiometers.
5, according to the described tensiometer of claim 1, it is characterized in that described pilot capsule (6) is a membrane vesicle waterproof, that gas has retractility, when not having pressure reduction, soil is shrivelled state, and can expand when pressure reduction is arranged and transmit negative pressure.
6,, it is characterized in that its max cap. of described pilot capsule (6) is to hold the whole air of discharging in this side U type pipe and the water of water column (11) according to claim 1 or 5 described tensiometers.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005100609932A CN100451606C (en) | 2005-10-01 | 2005-10-01 | Air mercury tensiometer with adjustable built-in U-type tube |
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| CNB2005100609932A CN100451606C (en) | 2005-10-01 | 2005-10-01 | Air mercury tensiometer with adjustable built-in U-type tube |
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| CN100451606C true CN100451606C (en) | 2009-01-14 |
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| CN102147355B (en) * | 2011-01-08 | 2012-10-03 | 安徽农业大学 | Determination device for water absorption of drought resisting compound fertilizer and method |
| CN106885764B (en) * | 2015-12-16 | 2019-08-27 | 北京银河巴马生物技术股份有限公司 | A kind of biomembrane anti-permeability detection device and application |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06160378A (en) * | 1992-11-24 | 1994-06-07 | Sankei Rika Kk | Moisture measuring instrument for soil and the like |
| CN2585222Y (en) * | 2002-12-19 | 2003-11-05 | 中国科学院南京土壤研究所 | Switching soil moisture sensor |
-
2005
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH06160378A (en) * | 1992-11-24 | 1994-06-07 | Sankei Rika Kk | Moisture measuring instrument for soil and the like |
| CN2585222Y (en) * | 2002-12-19 | 2003-11-05 | 中国科学院南京土壤研究所 | Switching soil moisture sensor |
Non-Patent Citations (1)
| Title |
|---|
| 气传感土壤水分负压计. 姜祖骞，周正度.土壤，第2期. 1979 * |
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