CN202057396U - Standard liquid flow calibration device - Google Patents

Abstract

The utility model discloses a standard liquid flow calibration device. The standard liquid flow calibration device adopts an overflow structure in a closed container to obtain stable liquid level; and stable high air pressure is acted on the stable liquid level, so that a fluid source of the device has the advantages of flow stability of the water tower method and high reynolds number of the container pressure-stabilizing method, and the cost and the floor area are smaller than those of the water tower method. The standard liquid flow calibration device needs no converter so as to avoid the error caused by asymmetry during the bidirectional switching process of the converter; the opening and the closing of a valve are not taken as a timing start point and a timing end point in the calibration process; the liquid stably flows in the whole time period; and the calibration error mainly depends on the measurement error of liquid volume or weight in the standard weighing container. Therefore, compared with the liquid flow calibration device with the conserver, the standard liquid flow calibration device has higher calibration precision.

Description

Fluid flow useful test device

One, technical field

The present invention relates to a kind of useful test device in flow metering standard technique field.

Two, background technology

In the national economy every profession and trade, use a large amount of various forms of flow-meters.In order to guarantee data that these flowmeters are surveyed accurately and reliably, must on the flow standard calibrating installation, carry out periodic verification to these flowmeters.Flow standard calibrating installation kind is a lot, but because in the verification process of flowmeter, the discharge stability of fluid sources requires very high, so the good Static Volumetric Method flow standard calibrating installation of discharge stability has obtained being extensive use of.In Static Volumetric Method flow standard calibrating installation, water pump is delivered to the head-tank of water tower with the water of low pool, and in whole verification process, head-tank is in overflow situation, thereby has produced the constant voltage water source of a constant water level.Constant current scale to be checked is installed on the test section, during the calibrating beginning, arrives commutator behind the current overtesting pipeline section in the head-tank, and this moment, commutator was connected to bypass line; Treat water flow in stable condition after, commutator starts current is switched to etalon by bypass line, etalon is a kind of standard weighing container.When commutator starts, start the output signal value of timer and record constant current scale to be checked, after arriving the predetermined water yield or timing time, timing stops, and commutator moves once more, and current are switched back bypass line.The volume or weight of water just obtains the volumetric flow rate or the weight flow of standard divided by timing time in the etalon, and treats the output signal value of examining and determine flowmeter with this standard volume and examine and determine.The shortcoming of Static Volumetric Method flow standard calibrating installation is because the existence of water tower and commutator makes that the required investment of flow standard calibrating installation of construction is many, take up space and ground is big, water tower height (being pressure) positive and negative progressive error restricted, that commutator has makes whole device measuring accuracy be difficult to further raising again.

Three, summary of the invention

Consider that the pond that is in overflow situation in the water tower can obtain stable water level (pressure), but limitation in height makes it be difficult to allow the calibrating medium obtain than high reynolds number, and gases at high pressure are easy to make the calibrating medium to reach very high Reynolds number, and therefore the fluid source of the flow standard calibrating installation of development should adopt the container of overflow structure and fill the scheme that combines with gases at high pressure in this container; Twice handoff procedure considering commutator again all caused the instability of examining and determine fluid flow state, and this instability state that flows is present in the initiating terminal in timing time interval and finishes end, therefore the flow standard calibrating installation of development should abandon using commutator, and will examine and determine the timing period and be chosen in and examine and determine the interval that fluid is in steady flow condition.

Shown in Figure 1 in the technical solution adopted in the present invention such as the Figure of description: the flow standard calibrating installation of development is a kind of fluid flow useful test device, by the upper overflow vessel of high pressure, the next overflow vessel of normal pressure, the test section at constant flow meter to be checked place, do not need the standard weighing container of commutator, the measuring instrument of liquid level or weight in can high-acruracy survey standard weighing container, the high pressure hopper, the normal pressure hopper, supercharge pump, ebullator, operating valve, calibrating valve and corresponding pipeline are formed, the upper overflow vessel of high pressure is to adopt the overflow structure to obtain to stablize the closed container of liquid level, liquid in the high pressure hopper injects the upper overflow vessel of high pressure by ebullator through circulation pipe, these the test sections that to be checked constant flow meter be installed of a part through being connected to the upper overflow vessel fluid space of high pressure that inject liquid are flowed directly to the fluid space of the next overflow vessel of normal pressure, the overflow that another part becomes the upper overflow vessel of high pressure is flowed back to the high pressure hopper through run-down pipe again, the next overflow vessel of normal pressure has the overflow structure identical with the upper overflow vessel of high pressure, but act on atmospheric pressure on its liquid level, so need not to be closed container, the high pressure hopper is a closed container, all act on onesize air pressure on its liquid level with on the liquid level of the upper overflow vessel of high pressure from same high-pressure air source, liquid from test section becomes overflow in the next overflow vessel of normal pressure, this overflow flows to does not need the standard of commutator weighing container, the liquid that flows to the standard weighing container flow to the normal pressure hopper according to the keying of calibrating valve or builds up in the standard weighing container, the standard weighing container be furnished with can high-acruracy survey standard weighing container in the measuring instrument of liquid level or weight, liquid in the normal pressure hopper pumps into the high pressure hopper by supercharge pump through non-return valve, operating valve can be manual shut-off valve with the calibrating valve, also can be electronic shut-off valve or pneumatic shut-off valve, in fluid flow useful test device, also can cancel the next overflow vessel of normal pressure, and allow the liquid that flows out from test section directly flow to the standard weighing container.In Fig. 1, for the ultimate principle that makes this fluid flow useful test device seems clearer, some and ultimate principle relation is little, device commonly used again in existing flow standard calibrating installation is (as flexible meter-clamping apparatus, sinker) all do not draw in the drawings, the test section of different tube diameters has also only been drawn one.The course of work of this fluid flow useful test device is as follows: open operating valve and calibrating valve, start cycles pump and supercharge pump, flow regulator (not drawing among the figure) is a set-point with predetermined calibrating flow point, by regulating with the fluid flow in the flowmeter measured test pipeline section, flow regulator is controlled computing according to the deviation between measured value and the set-point, go to regulate the variable valve valve opening with the regulator output signal relevant, the stability of flow in the test section is being examined and determine on the flow point with the control operation result.When flow after stable on this calibrating flow point, close the calibrating valve, the liquid level rising in the standard weighing container, when liquid level rose to timing and begins the liquid level place, timing began; When the accumulation liquid weight after liquid level continues to rise to timing and stops liquid level place or timing and begin reached predetermined value, timing stopped.Consider that volumetric flow rate formula and weight flow formula are:

$q_V=\frac{\mathrm{\ΔV}}{\mathrm{\Δt}}$

$q_W=\frac{\mathrm{\ΔW}}{\mathrm{\Δt}}$

Q in the formula _VBe volumetric flow rate, q _WBe weight flow, Δ t is a timing time, Δ V is the volume semi-invariant of liquid in the Δ t timing time internal standard weighing container, Δ W is the weight build-up amount of liquid in the Δ t timing time internal standard weighing container, therefore, if behind the calibrating valve breakdown in whole timing time Δ t the leakage rate of valve be zero maybe can ignore, by Δ t and Δ V or the Δ W that above-mentioned verification process obtains, can obtain the volumetric flow rate q of standard _VOr weight flow q _W, and remove to compare the corresponding output signal value of constant flow to be checked on the test section in this normal flow, so just finished calibration operation of examining and determine flow point of constant flow meter to be checked.

The invention has the beneficial effects as follows; because the overflow structure that the next overflow vessel of upper overflow vessel of high pressure and normal pressure adopts can obtain stable liquid level difference; and upper overflow vessel of closed container high pressure and high pressure hopper do not consume gas in verification process; be communicated with these two closed container headrooms and give its air feed gas-holder supporting air compressor in verification process, can shut down; to guarantee the stable and consistent of gas-holder and two closed container internal gas pressures; therefore; this fluid flow useful test device can have the discharge stability that is equivalent to water tower voltage stabilizing fluid source, has avoided water tower voltage stabilizing investment many simultaneously again; take up space and ground big; the water tower limitation in height is difficult to reach the defective of high reynolds number.When fluid flow useful test device used pneumatic meter-clamping apparatus, air operated controller and pneumatic shut-off valve etc. to consume gas type device, these devices should use another gas-holder air feed, to avoid influencing the stable of closed container internal gas pressure.This device does not use commutator, has avoided the asymmetric error that causes of the two-way handoff procedure of commutator.In the verification process of this device, liquid flow all is in steady state (SS) in the whole timing time section, the gauging error of device depends primarily on the measuring error of interior liquid volume of standard weighing container or weight, and this measuring error can be done smallerly, therefore, from the principle, than the flow standard calibrating installation that uses commutator, the calibration accuracy of this fluid flow useful test device is higher.

Four, description of drawings

Fig. 1 is a structural representation of the present invention.

Wherein: 1. the upper overflow vessel of high pressure, 2. operating valve, 3. variable valve, 4. regulate and use flowmeter, constant flow meter 5. to be checked, 6. test section, 7. the next overflow vessel of normal pressure, 8. standard weighing container, 9. master gauge, 10. calibrating valve, 11. normal pressure hoppers, 12. supercharge pumps, 13. non-return valve, 14. high pressure hoppers, 15. ebullators, 16. run-down pipe, 17. high-pressure air pipes, 18. circulation pipes.

Five, embodiment

Following content is 1 to provide embodiment technical scheme of the present invention is described further in conjunction with the accompanying drawings.

(embodiment 1, liquid level gauge detecting pattern)

In Fig. 1, operating valve 2 all adopts pneumatic shut-off valve with calibrating valve 10, a master gauge 9 has been installed on standard weighing container 8 lower pipeline, when the calibrating valve cuts out, when the liquid level in the standard weighing container rises gradually, the pressure size that the variation of liquid level and master gauge are experienced is one to one, and master gauge is measuring liquid level in view of the above.

The course of work of this embodiment: after several calibrating flow points of constant flow meter 5 to be checked are input to industrial computer in advance, whole verification process just will carry out under the control of industrial computer automatically.Industrial computer is at first opened pneumatic operating valve and pneumatic calibrating valve on certain calibrating flow point, start cycles pump 15 and supercharge pump 12 are regulated variable valve 3 apertures according to regulating with flowmeter 4 measured discharge values, make stability of flow at last on the calibrating flow point that requires.Behind stability of flow, industrial computer is controlled pneumatic calibrating valve and is closed, liquid level in the standard weighing container rises, avoiding pneumatic calibrating valve closes initial stage pressure and changes the unsettled period, two liquid levels in the stable liquid level change interval of rising of selection pressure begin liquid level as timing and timing finishes liquid level, thereby obtain and these two timing times that liquid level is corresponding.Because the liquid volume between these two liquid levels is known in advance in the standard weighing container, so after obtaining timing time by timing, just can be regarded as to such an extent that this calibrating flow is put flow value accurately, and remove to compare the output signal value of constant flow correspondence to be checked in this value.Finish constant flow meter to be checked on request after the calibration operation of this calibrating flow point, industrial computer just turns to the calibration operation of the next calibrating of this constant flow meter to be checked flow point automatically, and its course of work is the same.

(embodiment 2, electronic scales detecting pattern)

Do standard weighing container, calibrating valve and connecting pipe as a whole, and this whole weight is acted on the electronic scales, after the calibrating valve cuts out, electronic scales carries out weighing to the variation of weight, when reaching the timing minimum weight, weight picks up counting, when reaching, weight finishes timing when timing finishes weight, the timing time that obtains according to the weight difference on two time points and timing, promptly can be regarded as this calibrating flow point delicate flow, and remove to compare the corresponding output signal value of constant flow to be checked in this exact value.The advantage of this embodiment be to the metering of weight to compare usually volume accurate measurement some.

Claims (2)

1. fluid flow useful test device, it is characterized in that: the upper overflow vessel of high pressure (1) is to adopt the overflow structure to obtain to stablize the closed container of liquid level, liquid in the high pressure hopper (14) injects the upper overflow vessel of high pressure by ebullator (15) through circulation pipe (18), these test sections (6) of a part through being connected to being equipped with of the upper overflow vessel fluid space of high pressure constant flow meter to be checked (5) that inject liquid are flowed directly to the fluid space of the next overflow vessel of normal pressure (7), the overflow that another part becomes the upper overflow vessel of high pressure is flowed back to the high pressure hopper through run-down pipe (16) again, the next overflow vessel of normal pressure has the overflow structure identical with the upper overflow vessel of high pressure, act on atmospheric pressure on its liquid level, the high pressure hopper is a closed container, all act on onesize air pressure on its liquid level with on the liquid level of the upper overflow vessel of high pressure from same high-pressure air source, liquid from test section becomes overflow in the next overflow vessel of normal pressure, this overflow flows to standard weighing container (8), the liquid that flows to the standard weighing container flow to normal pressure hopper (11) according to the keying of calibrating valve (10) or builds up in the standard weighing container, the standard weighing container be furnished with can high-acruracy survey standard weighing container in the measuring instrument (9) of liquid level or weight, the liquid in the normal pressure hopper pumps into the high pressure hopper by supercharge pump (12) through non-return valve (13).

2. fluid flow useful test device according to claim 1 is characterized in that: operating valve can be manual shut-off valve with the calibrating valve, also can be electronic shut-off valve or pneumatic shut-off valve.

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