CN1932452A - Method for detecting flow parameter - Google Patents

Abstract

The invention relates to a test method of the flow metering, especially for the glass rotameter and the metallic conduit rotameter. The method needs to get the output pressure of the floating flowmeter and the flow coefficient k according to the K=Q/P; it sets the K value and the other parameter in the flow integrating instrument to display the instantaneous delivery and the accumulative flux. The method can improve the measurement accuracy and the measurement efficient, so the precision can reach the 0.5-1.5 grade. The method can be proper for the flowmeter of different caliber, so it can be used in the calibration of the floater flowmeter and the industry production widely.

Description

A kind of method that is used to detect flow parameter

Technical field

The present invention relates to a kind of detection method of flow metering, particularly a kind of glass rotameter and metal-tube rotameter of being applicable to is used to detect the method for flow parameter.

Technical background

At present, glass rotameter of producing both at home and abroad or metal-tube rotameter realize that teletransmission, accumulative total, communication are interlock or magnetic coupling mode that the magnetic float is taked the magnetic conduction.It generally is several tongue tubes to be arranged form that homemade glass rotameter is measured flow, because the magnetic switch performance of tongue tube itself directly influences measuring accuracy, and must strict screening tongue tube.Become changes in resistance, can detect the variation of flow like this because the position of the magnetic float that changes with flow opens or closes the tongue tube that is in this position.The glass rotameter of import also is that the magnetic float takes magnetic conduction interlock mode that the slide block of the potentiometer of precision linear is moved up and down, and draws the resistance value that changes with fluctuations in discharge, because the friction force of this linear potentiometer must be very little, so cost is very high.Metal-tube rotameter is that the taper float moves up and down with fluctuations in discharge in the metal tube of perforated plate, the position of float is to pass to indicator in magnetic-coupled mode, make pointer by lobe plate or other mechanism, indicate the size of its flow value, and drawing changes in resistance by the precision resistor of rotation, the current signal that converts standard then to shows, teletransmission, accumulative total, communication.But because the displacement of taper float is little, its measuring accuracy is low, error is big.

The bore of spinner-type flowmeter that more than can realize teletransmission, accumulative total, communication is all more than DN10, and the spinner-type flowmeter of the following low discharge of DN10 also can't be made.Therefore, can realize teletransmission, accumulative total, the communication problem that need undergo technological transformation, must exploration a kind of method of new detection flow for solving the glass rotameter that generally uses and metal tube rotor flow.

Summary of the invention

In sum, for improving measuring accuracy, stop the error of magnetic force coupling and the error of mechanical friction, widen measurement range, solve the suspended body flowmeter that generally uses and realize the technological transformation problem of teletransmission, accumulative total, communication, improve industrialized level, the spy provides a kind of method that is used to detect flow parameter.

The present invention is used to detect the method for flow parameter, comprises the steps:

One, get the suspended body flowmeter that is provided with reference point of a demarcation, or get the common suspended body flowmeter of a demarcation, at first check the flow range of suspended body flowmeter, the medium classification, inside nominal diameter, working pressure and precision, then it is installed on the pipeline, the import connection traffic variable valve of suspended body flowmeter, its outlet connects pressure unit and pressure-regulating valve by threeway, perhaps do not connect pressure-regulating valve, the output connection traffic integrating instrument of pressure unit, perhaps flow control valve is connected the outlet of suspended body flowmeter, flow control valve connects pressure unit and pressure-regulating valve by threeway, does not perhaps connect pressure-regulating valve, the output connection traffic integrating instrument of pressure unit, install, the medium classification of pressing in the suspended body flowmeter feeds medium, simultaneously energized;

Two, the suspended body flowmeter reference point flow value of at first determine demarcating is alternately regulated pressure-regulating valve and flow control valve, does not have pressure-regulating valve, only regulates flow control valve, make float be stabilized in reference point in limit the quantity of on the Cheng Kedu, the output valve of pressure transmission device exists

In the scope; At this moment, the output valve of suspended body flowmeter reference point range value and pressure unit is noted, then the fixation pressure variable valve; Perhaps at first determine the upper limit, middle limit and three flow values of lower limit of the suspended body flowmeter of demarcation, alternately regulate pressure-regulating valve and flow control valve then, do not connect pressure-regulating valve, only regulate flow control valve, float is stabilized on the higher limit scale, and the output valve of pressure unit exists

In the scope, note the range higher limit of suspended body flowmeter and the output valve of pressure unit this moment, then the fixation pressure variable valve; Regulate flow control valve again, float is stabilized on the middle limit value scale, at this moment, the pressure unit output valve is noted; And then the adjusting flow control valve, float is stabilized on the lower limit scale, at this moment, the pressure unit output valve is noted;

Three, with reference point flow value Q and corresponding pressure unit output valve P substitution relationship in the suspended body flowmeter of the demarcation noted in the step 2: $K=\frac{Q}{\sqrt{P}},$ Solve its flow coefficient k value;

Perhaps be Q1, Q2, Q3 and corresponding pressure unit output valve P1, P2, P3 substitution relationship respectively with the upper limit, middle limit, lower limit flow value in the common suspended body flowmeter of the demarcation noted in the step 2: $K=\frac{Q}{\sqrt{P}},$ Solve its flow coefficient k 1, K2, K3 respectively, obtain average flow coefficient K then;

Four, the suspended body flowmeter flow coefficient k value of reference point will be provided with in the step 3, or the common suspended body flowmeter average flow coefficient K value of adopt demarcating and flow integrator desired other about parameter setting in flow integrator, can come into operation;

Five, regulate flow control valve again according to technological requirement, both can show actual instantaneous delivery and integrated flow.

Through repeatedly calculating and the analog detection discovery, glass rotameter and the metal-tube rotameter flow and the mathematical model of top hole pressure (pressure unit output valve and pressure unit output area lower limit poor) in measurement range is as follows:

Under the constant situation of equipment, the evolution value of its flowmeter top hole pressure is directly proportional with flow, and this ratio is that coefficient of flow is represented with K:

$K=\frac{Q}{\sqrt{P}}$ $Q=K\sqrt{P}$

In the formula: Q---flow (range) unit: m ³/ h

P---top hole pressure unit: Pa (pressure unit output valve and pressure unit output area lower limit poor)

K---coefficient of flow

From the above-mentioned relation formula as can be seen: flow Q promptly is the volumetric flow rate of flowmeter, it is known parameter, if ask the flow coefficient k value, must measure the top hole pressure P of flowmeter, the flow coefficient k value is the parameter of the required setting of flow integrator, it is known that other has related parameter to be, having only the K value is a unknown number, therefore, as long as obtain the K value, and with the relevant parameter setting of K value and other in flow integrator, flow integrator will demonstrate instantaneous delivery and integrated flow.Therefore the establishment of above-mentioned relation formula is the key of this method.

When the top hole pressure of the suspended body flowmeter of detect demarcating that is provided with reference point, during top hole pressure when perhaps the float in detecting the common suspended body flowmeter of demarcating is stabilized in the range higher limit, the output valve scope of its pressure unit also is a basis $K=\frac{Q}{\sqrt{P}}$ Relational expression derives out, and through repeatedly calculating its accuracy of checking.Wherein be provided with the output valve scope of pressure unit of the suspended body flowmeter of reference point:

The output valve scope of the pressure unit of common suspended body flowmeter:

In the formula: Q _Benchmark---suspended body flowmeter reference point flow scale value P _{Higher limit}---pressure unit output area higher limit

Q _Detect---suspended body flowmeter arbitrfary point flow scale value

Q _{Higher limit}---suspended body flowmeter flow upper limit scale value P _{Lower limit}---pressure unit output area lower limit

For selecting coefficient

When the output valve of pressure unit does not meet above-mentioned output area, can reselect the measurement range of pressure unit, changing that its measurement range of pressure unit selects should be according to following formula:

In the formula: P _{In the survey}---the measurement range upper limit of the pressure unit that is replaced

P _Measure---the output valve of the pressure unit that is replaced

Q _Detect---suspended body flowmeter arbitrfary point flow scale value

Adopt the principle of this method measurement flow parameter as follows:

When fluid flowing through during Taper Pipe from bottom to top, owing to be subjected to the impact of fluid, float will move upward, float and taper circulation area increase, flow velocity lowers, and balances each other up to the weight and the power that acts on the float of fluid of float in fluid, and float rests on a certain height and keeps balance.At this moment, has certain pressure by fluid, this pressure can detect by the pressure unit that is connected the suspended body flowmeter outlet, be the top hole pressure of flowmeter, through change give, integrating can obtain instantaneous delivery and integrated flow, when fluctuations in discharge, float will move on to new position and reach new balance, the top hole pressure of flowmeter will change, with the force value that changes through change give, integrating, can obtain new instantaneous delivery and integrated flow.

The beneficial effect that the present invention produces is: improved measuring accuracy and efficiency of measurement, its degree of accuracy can reach 0.5～1.5 grade, widened measurement range, solved the suspended body flowmeter that generally uses and realized the technological transformation problem of teletransmission, accumulative total, communication, thereby improved industrialized level.

Description of drawings

Fig. 1 implements pick-up unit of the present invention (regulating before the flowmeter) connection diagram and as Figure of abstract;

Fig. 2 is the synoptic diagram that does not connect pressure-regulating valve among Fig. 1;

Fig. 3 implements pick-up unit of the present invention (regulating behind the flowmeter) connection diagram;

Fig. 4 is the synoptic diagram that does not connect pressure-regulating valve among Fig. 3.

The difference of pick-up unit connected mode is to require to be provided with according to the difference of using among the above-mentioned figure, no matter is anyly can both use this method.

Embodiment

Embodiment one, get the common suspended body flowmeter of a demarcation, range is 0.25～2.5m ³/ h, the medium classification is an air, and inside nominal diameter is DN15mm, and working pressure is 0.4Mpa, and precision is 1.5 grades.Then it is installed on the pipeline, the import connection traffic variable valve of suspended body flowmeter, its outlet connects pressure unit and pressure-regulating valve by threeway, or do not connect pressure-regulating valve, the output connection traffic integrating instrument of pressure unit, perhaps flow control valve is connected the outlet of suspended body flowmeter, flow control valve connects pressure unit and pressure-regulating valve by threeway, or do not connect pressure-regulating valve, the output connection traffic integrating instrument of pressure unit, install, press the medium classification bubbling air in the suspended body flowmeter, simultaneously energized.Wherein pressure unit current value output area is 4～20mA, and pressure measurement range 0～20kpa, flow integrator then select for use and have flow formula and have $Q=K{(P\×P)}^{\frac{1}{2}}$ Integrating instrument.

At first determine three flow values on the flowmeter: on be limited to 2.5m ³/ h, in be limited to 1.5m ³/ h, be limited to 0.5m down ³/ h alternately regulates pressure-regulating valve and flow control valve then, when not having pressure-regulating valve, only regulates flow control valve, makes the float in the flowmeter be stabilized in 2.5m ³On/h the range scale, the output current value of pressure unit is 19mA, and note this current value this moment, then the fixation pressure variable valve; Regulate flow control valve again, make float be stabilized in 1.5m ³On/h the range scale, the output current value of pressure unit is 9.53mA, and note this current value this moment; And then the adjusting flow control valve, make float be stabilized in 0.5m ³On/h the range scale, the output current value of pressure unit is 4.62mA, and note this current value this moment.With above-mentioned numerical value difference substitution relationship $K=\frac{Q}{\sqrt{P}}$ After, obtain coefficient of flow respectively:

$K_1=\frac{Q_1}{\sqrt{P_1}}=\frac{2.5}{\sqrt{19-4}}=0.6455$

$K_2=\frac{Q_2}{\sqrt{P_2}}=\frac{1.5}{\sqrt{9.53-4}}=0.6378$

$K_3=\frac{Q_3}{\sqrt{P_3}}=\frac{0.5}{\sqrt{4.62-4}}=0.6350$

Other that the average flow coefficient K=0.6394 that obtains and integrating instrument are required to set have related parameter as: pressure transmitter measurement upper limit 20kpa, lower limit 0, pressure unit type are that III type, density p value are 1, are set in the flow integrator and come into operation.Regulate flow control valve again according to technological requirement, make the float of suspended body flowmeter be stabilized in 2m ³On/h the scale value, this moment, the flow integrator instantaneous delivery was shown as: 2m ³/ h, error ± 0.0375m ³/ h, behind 0.5h (h be hour), integrated flow shows 1m ³, error ± 0.018m ³

Embodiment two, in order to improve measuring accuracy and to improve efficiency of measurement, should be provided with datum mark (can section out as the calibration point of measuring) reference point at flowmeter on scale and should be located in the range on the limit value, make its measuring accuracy reach 0.5 grade.Therefore, get the suspended body flowmeter that is provided with reference point of a demarcation, range is 0.25～2.5m ³/ h, the medium classification: water, inside nominal diameter are DN40mm, and working pressure is 0.4Mpa, and precision is 0.5 grade, then it is installed on the pipeline import connection traffic variable valve of suspended body flowmeter; Its outlet connects pressure unit with pressure-regulating valve or be not connected pressure-regulating valve by threeway; The output connection traffic integrating instrument of pressure unit; Perhaps flow control valve is connected the outlet of suspended body flowmeter, flow control valve connects pressure unit with pressure-regulating valve or be not connected pressure-regulating valve by threeway, the output connection traffic integrating instrument of pressure unit, install, the medium classification of pressing in the suspended body flowmeter feeds water, simultaneously energized.Pressure unit current value output area is 4～20mA, and the measurement range of pressure unit is 0～100kpa, and precision is 0.25 grade, and flow integrator is then selected for use and had flow formula and have $Q=K{(P\×P)}^{\frac{1}{2}}$ Integrating instrument.

Determine that at first the datum mark on the flowmeter is 1.2m ³/ h alternately regulates pressure-regulating valve and flow control valve then, only regulates flow control valve when not having pressure-regulating valve, makes the float in the flowmeter be stabilized in 1.2m ³On/h the scale, the output valve of pressure unit is 5.25mA, the scope of obtaining according to the output area formula of pressure unit, this output valve do not meet＞5.84mA and＜requirement of 7.68mA, the measurement range of pressure unit is excessive, need to change the measurement range of pressure unit, according to the selection formula of changing the pressure transmitter measurement scope

Obtain the measurement range upper limit≤67.9kpa of pressure unit, and 〉=33.9kpa, therefore, the measurement range of changing pressure unit is 0～50kpa, and it is output as 4～20mA, and precision is 0.25 pressure unit.

After changing pressure unit, determine that at first the datum mark on the flowmeter is 1.2m ³/ h, alternately regulate pressure-regulating valve and flow control valve then, when not having pressure-regulating valve, only regulate flow control valve, float in the flowmeter is stabilized on the 1.2m3/h scale, the output current value of pressure unit is 6.5mA, meet 5.84mA＜6.5mA＜7.68mA requirement, this current value is noted, then the fixation pressure variable valve.With above-mentioned numerical value substitution relationship $K=\frac{Q}{\sqrt{P}}$ After, obtain K=0.7589.

Other that the flow coefficient k value obtained and integrating instrument are required to set has related parameter as pressure transmitter measurement upper limit 50kpa, lower limit 0, pressure unit type-iii type, the density p value is 1, be set in the flow integrator, can come into operation, can also be used to demarcate the scale value of other flow of suspended body flowmeter, regulate flow control valve according to technological requirement again, when the suspended body flowmeter float is stabilized in 1.5m ³/ h, the flow integrator instantaneous delivery is shown as 1.5m ³/ h, error is ± 0.0125m ³/ h behind 10min, checks that integrated flow is shown as 0.25m ³, error amount ± 0.0021m ³/ h.

From above-mentioned two embodiment as can be seen: this method both had been applicable to the detection of common suspended body flowmeter to flow, also be applicable to of the detection of high-precision suspended body flowmeter to flow, because this method is suitable for the flowmeter of different bores, and enlarged measurement range, therefore can be widely applied in the demarcation and suitability for industrialized production of suspended body flowmeter.

Claims (1)

1. a method that is used to detect flow parameter is characterized in that, comprises the steps:

One, get the suspended body flowmeter that is provided with reference point of a demarcation, or get the common suspended body flowmeter of a demarcation, at first check the flow range of suspended body flowmeter, the medium classification, inside nominal diameter, working pressure and precision, then it is installed on the pipeline, the import connection traffic variable valve of suspended body flowmeter, its outlet connects pressure unit and pressure-regulating valve by threeway, perhaps do not connect pressure-regulating valve, the output connection traffic integrating instrument of pressure unit, perhaps flow control valve is connected the outlet of suspended body flowmeter, flow control valve connects pressure unit and pressure-regulating valve by threeway, does not perhaps connect pressure-regulating valve, the output connection traffic integrating instrument of pressure unit, install, the medium classification of pressing in the suspended body flowmeter feeds medium, simultaneously energized;

Two, the suspended body flowmeter reference point flow value of at first determine demarcating is alternately regulated pressure-regulating valve and flow control valve, does not have pressure-regulating valve, only regulates flow control valve, make float be stabilized in reference point in limit the quantity of on the Cheng Kedu, the output valve of pressure transmission device exists

In the scope; At this moment, the output valve of suspended body flowmeter reference point range value and pressure unit is noted, then the fixation pressure variable valve; Perhaps at first determine the upper limit of the suspended body flowmeter of demarcation, three flow values of the sharp lower limit of middle limit, alternately regulate pressure-regulating valve and flow control valve then, do not connect pressure-regulating valve, only regulate flow control valve, float is stabilized on the higher limit scale, and the output valve of pressure unit exists

And

In the scope, note the range higher limit of suspended body flowmeter and the output valve of pressure unit this moment, then the fixation pressure variable valve; Regulate flow control valve again, float is stabilized on the middle limit value scale, at this moment, the pressure unit output valve is noted; And then the adjusting flow control valve, float is stabilized on the lower limit scale, at this moment, the pressure unit output valve is noted;

Three, with reference point flow value Q and corresponding pressure unit output valve P substitution relationship in the suspended body flowmeter of the demarcation noted in the step 2: $K=\frac{Q}{\sqrt{P}},$ Solve its flow coefficient k value;

Perhaps be Q1, Q2, Q3 and corresponding pressure unit output valve P1, P2, P3 substitution relationship respectively with the upper limit, middle limit, lower limit flow value in the common suspended body flowmeter of the demarcation noted in the step 2: $K=\frac{Q}{\sqrt{P}},$ Solve its flow coefficient k 1, K2, K3 respectively, obtain average flow coefficient K then;

Four, will be provided with the suspended body flowmeter flow coefficient k value of reference point in the step 3, or the common suspended body flowmeter average flow coefficient K value of adopt demarcating and flow integrator desired other about parameter setting in flow integrator, can come into operation;

Five, regulate flow control valve again according to technological requirement, both can show actual instantaneous delivery and integrated flow.

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