阅读说明：本技术 差压变送器静压特性测试及活塞压力计有效面积检定方法 (Static pressure characteristic test and effective area verification method for piston pressure gauge of differential pressure transmitter ) 是由 甘蓉 罗凡 尹保来 王彭 于 2021-05-29 设计创作，主要内容包括：本申请公开了一种差压变送器静压特性测试及活塞压力计传递方法,将差压变送器连接到压力源和压力调节装置；将压力测量仪并联至所述差压变送器的高压端和低压端；控制所述压力源使压力升至测量点,记录所述差压变送器示值和所述压力测量仪的示值Pl；断开所述差压变送器高压端和所述压力测量仪之间的连接；控制所述压力调节装置使差压变送器低压端的压力降低或升高,同时获取所述压力测量仪的示值变化量,当该变化量达到预定的上行程差压点或下行程差压点时,记录压力测量仪的示值Ph,差压变送器的示值ΔP-(1)；通过Ph和Pl之间的差值得到实际差压值ΔP-(2)。解决了相关技术中对差压变送器的静压特性测量过程较为复杂,效率较低,耗费时间较长的问题。(The application discloses a static pressure characteristic test and piston pressure gauge transmission method for a differential pressure transmitter, wherein the differential pressure transmitter is connected to a pressure source and a pressure adjusting device; connecting a pressure measuring instrument to a high-pressure end and a low-pressure end of the differential pressure transmitter in parallel; controlling the pressure source to increase the pressure to a measuring point, and recording the indication value of the differential pressure transmitter and the indication value Pl of the pressure measuring instrument; disconnecting the high-pressure end of the differential pressure transmitter from the pressure measuring instrument; controlling the pressure regulating device to reduce or increase the pressure at the low-pressure end of the differential pressure transmitter, simultaneously acquiring the indication value variation of the pressure measuring instrument, and recording the indication value Ph of the pressure measuring instrument and the indication value delta P of the differential pressure transmitter when the variation reaches a preset upper stroke differential pressure point or a preset lower stroke differential pressure point 1 (ii) a Obtaining the actual differential pressure value delta P by the difference between Ph and Pl 2 . The problems that the static pressure characteristic measuring process of the differential pressure transmitter is complex, the efficiency is low and the time consumption is long in the related technology are solved.)

1. A static pressure characteristic test method of a differential pressure transmitter is characterized by comprising the following steps:

connecting a differential pressure transmitter to a pressure source and a pressure regulating device;

connecting a pressure measuring instrument to a high-pressure end and a low-pressure end of the differential pressure transmitter in parallel;

maintaining the communication between the high pressure end and the low pressure end of the differential pressure transmitter, controlling the pressure source to raise the pressure to a measuring point, and recording the indication value of the differential pressure transmitter and the indication value Pl of the pressure measuring instrument;

disconnecting the high-pressure end of the differential pressure transmitter from the pressure measuring instrument and keeping the indication value of the differential pressure transmitter unchanged;

controlling the pressure regulating device to reduce or increase the pressure at the low-pressure end of the differential pressure transmitter, simultaneously acquiring the indication value variation of the pressure measuring instrument, and recording the indication value Ph of the pressure measuring instrument and the indication value delta P of the differential pressure transmitter when the variation reaches a preset upper stroke differential pressure point or a preset lower stroke differential pressure point₁；

Obtaining the actual differential pressure value delta P by the difference between Ph and Pl₂By Δ P₂And Δ P₁Obtaining the error value of the differential pressure transmitter under the current upper stroke differential pressure point or the lower stroke differential pressure point by the difference value;

and evaluating the error value of the differential pressure transmitter and judging whether the differential pressure transmitter meets the requirement.

2. The differential pressure transmitter static pressure characteristic testing method of claim 1, further comprising, prior to evaluating an error value of the differential pressure transmitter:

sequentially acquiring error values of the differential pressure transmitter under other upper stroke differential pressure points and lower stroke differential pressure points;

and sequentially acquiring error values of the differential pressure transmitter at each upper stroke differential pressure point and each lower stroke differential pressure point under other measurement points.

3. The differential pressure transmitter static pressure characteristic testing method of claim 2, wherein the connecting the differential pressure transmitter to the pressure source and the pressure regulating device is specifically:

and connecting the low-pressure end of the differential pressure transmitter to a pressure source, and respectively connecting a second pressure regulator and a first pressure regulator to the high-pressure end and the low-pressure end of the differential pressure transmitter.

4. The differential pressure transmitter static pressure characteristic testing method according to claim 3, wherein the pressure gauge is in communication and closed with a high pressure end of the differential pressure transmitter through a valve.

5. The differential pressure transmitter static pressure characteristic testing method according to claim 4, wherein the controlling the pressure adjusting device to reduce or increase the pressure at the low pressure end of the differential pressure transmitter is specifically:

the pressure at the low pressure end of the differential pressure transmitter is reduced by controlling the first pressure regulator or increased by controlling the first pressure regulator.

6. The differential pressure transmitter static pressure characteristic testing method of claim 2, wherein the connecting the differential pressure transmitter to the pressure source and the pressure regulating device is specifically:

connecting the high-pressure end of the differential pressure transmitter to a piston type pressure gauge, and connecting a third pressure regulator at the low-pressure end of the differential pressure transmitter;

the step of controlling the pressure regulating device to reduce or raise the pressure at the low-pressure end of the differential pressure transmitter specifically comprises the following steps:

the pressure at the low pressure end of the differential pressure transmitter is reduced or increased by controlling the third pressure regulator.

7. A method for calibrating the effective area of a piston pressure gauge, which is a satisfactory differential pressure transmitter obtained by using the test method in any one of claims 1 to 6, is characterized in that the piston pressure gauge to be tested is measured by a standard piston pressure gauge, and comprises a measuring step and a calculating step,

the measuring steps are as follows:

connecting the standard piston pressure gauge and the detected piston pressure gauge to the differential pressure transmitter and a pressure source respectively;

the mass of the standard piston pressure gauge is m₁The weight of (1) is m on the detected piston pressure gauge₂The weight of (2);

working stateThen, the differential pressure between the standard piston pressure gauge and the detected piston pressure gauge is measured by the standard differential pressure transmitter to be delta P₃；

The calculation steps are as follows:

under the working state:

m₁g/A₀＝m₂g/A_i+ΔP₃

therefore, the method comprises the following steps:

Ai＝m₂g/(m₁g-ΔP₃A₀)A₀

in the formula: g-gravitational acceleration;

A₀-the effective area of a standard pressure gauge;

ai is the effective area of the pressure gauge to be tested;

m₁and m₂-special weight masses applied to both pressure gauges.

8. The method of calibrating the effective area of a piston pressure gauge according to claim 7, wherein the following calibration apparatus is used:

a differential pressure detection device is connected between the standard piston pressure gauge and the detected piston pressure gauge, and comprises a first differential pressure detection system and a second differential pressure detection system which are connected in parallel;

the first differential pressure detection system comprises a stop valve V3, a differential pressure transmitter P2 and a stop valve V4 which are connected in series, and a balance valve V2 which is connected in parallel at two ends of the differential pressure transmitter P2 and is positioned between the stop valve V3 and the stop valve V4; the second differential pressure detection system includes a differential pressure transmitter P1 and a balancing valve V1 connected in parallel across the differential pressure transmitter P1.

9. The method for calibrating the effective area of a piston pressure gauge according to claim 8, wherein the measuring step is specifically as follows:

opening balance valves V1 and V2 in the verification process, observing whether zero points of a differential pressure transmitter P1 and a differential pressure transmitter P2 drift or not, and carrying out zero clearing operation if the zero points drift;

closing the cut-off valves V3 and V4, and selecting the range of the standard piston pressure gaugeThe pressure point limited to 10-20% is used as the starting point, and the standard piston pressure gauge and the piston pressure gauge to be detected are respectively placed with mass m₁And m₂The weight of (2);

controlling the pressure source to make the standard piston pressure gauge and the detected piston pressure gauge rise to working positions, and obtaining the indication value P2 of the differential pressure transmitter P2₀；

Closing the balance valve V1, and controlling the pressure source to stabilize the standard piston pressure gauge and the detected piston pressure gauge at the working positions;

observing whether the indication value of the differential pressure transmitter P1 is within a set range, if not, placing a small weight on the standard piston pressure gauge or the detected piston pressure gauge, adjusting the pressure source again, and lifting the standard piston pressure gauge and the detected piston pressure gauge to working positions until the indication value of the differential pressure transmitter P1 is within the set range;

opening the stop valve V3 and the stop valve V4, closing the balance valve V2, and adjusting the pressure source to stabilize the standard piston pressure gauge and the detected piston pressure gauge at the working positions;

recording the mass m of weights placed on the standard piston pressure gauge and the detected piston pressure gauge₁And m₂Differential pressure transmitter P2 has an indication of P_i，P_i-P₀To obtain delta P₃。

10. The method for calibrating the effective area of a piston pressure gauge according to claim 9, wherein the measuring of other calibration points is performed according to the measuring step and the calculating step, and the calibration points are uniformly distributed;

after each point is verified, re-testing the initial point again, wherein the pressure difference of the initial balance point before and after verification does not exceed 10% of the maximum allowable error, otherwise, re-verification is required;

and after the effective area value of the piston of each pressure point is obtained through the calculating step, the average value of the effective areas of the pistons is calculated.

Technical Field

The application relates to the field of pressure measurement, in particular to a method for testing static pressure characteristics of a differential pressure transmitter and calibrating the effective area of a piston pressure gauge.

Background

The piston type pressure gauge is a standard pressure gauge with high accuracy, high reproducibility and high reliability, which works based on the Pascal law and the hydrostatic balance principle, and is mainly used as a pressure reference device or a standard device in a measuring room, a laboratory and a production or scientific experiment link. Two certification methods are provided in piston manometer certification protocols jjjg 59-2007 and JJG 1086-2013: direct equilibrium and initial equilibrium. The two methods are also accepted piston pressure measurement transmission methods in the field of pressure measurement, wherein the initial balance method is more widely applied because the calculation formula is simple, and the operation process is simpler and more convenient than that of the direct balance method. Even with the easier initial equilibrium method, the assay process is quite cumbersome, the requirements on the operating experience and skill of the assay personnel are quite high, and the whole assay process takes a long time.

The pressure difference transmitter meeting the requirements is required to be used in the measurement process of the piston type pressure gauge, so the static pressure characteristic of the pressure difference transmitter is required to be measured, the static pressure characteristic evaluation method of the pressure difference transmitter in the related technology is carried out by using a standard piston pressure gauge, the judgment of a piston balance point is required to be carried out by naked eyes, and the problems of complex operation, high operation requirement and low measurement efficiency exist.

Disclosure of Invention

The application mainly aims to provide a static pressure characteristic testing method of a differential pressure transmitter and an effective area calibrating method of a piston pressure gauge, so as to solve the problems that the static pressure characteristic measuring process is complex, the efficiency is low and the time consumption is long in the related technology.

In order to achieve the above object, the present application provides a method for testing static pressure characteristics of a differential pressure transmitter, the method comprising the steps of:

connecting a differential pressure transmitter to a pressure source and a pressure regulating device;

connecting a pressure measuring instrument to a high-pressure end and a low-pressure end of the differential pressure transmitter in parallel;

maintaining the communication between the high pressure end and the low pressure end of the differential pressure transmitter, controlling the pressure source to raise the pressure to a measuring point, and recording the indication value of the differential pressure transmitter and the indication value Pl of the pressure measuring instrument;

disconnecting the high-pressure end of the differential pressure transmitter from the pressure measuring instrument and keeping the indication value of the differential pressure transmitter unchanged;

controlling the pressure regulating device to reduce or increase the pressure at the low-pressure end of the differential pressure transmitter, simultaneously acquiring the indication value variation of the pressure measuring instrument, and recording the indication value Ph of the pressure measuring instrument and the indication value delta P of the differential pressure transmitter when the variation reaches a preset upper stroke differential pressure point or a preset lower stroke differential pressure point₁；

Obtaining the actual differential pressure value delta P by the difference between Ph and Pl₂By Δ P₂And Δ P₁Obtaining the error value of the differential pressure transmitter under the current upper stroke differential pressure point or the lower stroke differential pressure point by the difference value;

and evaluating the error value of the differential pressure transmitter and judging whether the differential pressure transmitter meets the requirement.

Further, before evaluating the error value of the differential pressure transmitter, the method further comprises:

sequentially acquiring error values of the differential pressure transmitter under other upper stroke differential pressure points and lower stroke differential pressure points;

and sequentially acquiring error values of the differential pressure transmitter at each upper stroke differential pressure point and each lower stroke differential pressure point under other measurement points.

Further, connecting the differential pressure transmitter to a pressure source and a pressure regulating device is embodied as follows:

and connecting the low-pressure end of the differential pressure transmitter to a pressure source, and respectively connecting a second pressure regulator and a first pressure regulator to the high-pressure end and the low-pressure end of the differential pressure transmitter. Furthermore, the pressure measuring instrument is communicated with and closed by a valve at the high-pressure end of the differential pressure transmitter.

Further, controlling the pressure adjusting device to reduce or increase the pressure at the low-pressure end of the differential pressure transmitter specifically comprises:

the pressure at the low pressure end of the differential pressure transmitter is reduced by controlling the first pressure regulator or increased by controlling the first pressure regulator.

Connecting a differential pressure transmitter to a pressure source and a pressure regulating device is embodied as follows:

connecting the high-pressure end of the differential pressure transmitter to a piston type pressure gauge, and connecting a third pressure regulator at the low-pressure end of the differential pressure transmitter;

the step of controlling the pressure regulating device to reduce or raise the pressure at the low-pressure end of the differential pressure transmitter specifically comprises the following steps:

the pressure at the low pressure end of the differential pressure transmitter is reduced or increased by controlling the third pressure regulator.

According to another aspect of the present application, there is provided a method for calibrating the effective area of a piston pressure gauge, which measures a piston pressure gauge to be tested by a standard piston pressure gauge using the standard differential pressure transmitter evaluated as described above, comprising a measuring step and a calculating step,

the measuring steps are as follows:

connecting the standard piston pressure gauge and the detected piston pressure gauge to the differential pressure transmitter and a pressure source respectively;

the mass of the standard piston pressure gauge is m₁The weight of (1) is m on the detected piston pressure gauge₂The weight of (2);

under the working state, the differential pressure between the standard piston pressure gauge and the detected piston pressure gauge is measured to be delta P by the standard differential pressure transmitter₃；

The calculation steps are as follows:

under the working state:

m₁g/A₀＝m₂g/A_i+ΔP₃

therefore, the method comprises the following steps:

Ai＝m₂g/(m₁g-ΔP₃A₀)A₀

in the formula: g-gravitational acceleration;

A₀-the effective area of a standard pressure gauge;

ai is the effective area of the pressure gauge to be tested;

m₁and m₂-special weight masses applied to both pressure gauges.

Further, the method uses the following assay device:

a differential pressure detection device is connected between the standard piston pressure gauge and the detected piston pressure gauge, and comprises a first differential pressure detection system and a second differential pressure detection system which are connected in parallel;

the first differential pressure detection system comprises a stop valve V3, a differential pressure transmitter P2 and a stop valve V4 which are connected in series, and a balance valve V2 which is connected in parallel at two ends of the differential pressure transmitter P2 and is positioned between the stop valve V3 and the stop valve V4; the second differential pressure detection system includes a differential pressure transmitter P1 and a balancing valve V1 connected in parallel across the differential pressure transmitter P1.

Further, the measuring steps are specifically as follows:

opening balance valves V1 and V2 in the verification process, observing whether zero points of a differential pressure transmitter P1 and a differential pressure transmitter P2 drift or not, and carrying out zero clearing operation if the zero points drift;

closing the stop valve V3 and the stop valve V4, selecting a pressure point with 10% -20% of the range upper limit of the standard piston pressure gauge as a starting point, and respectively placing a piston pressure gauge with mass m and a piston pressure gauge to be detected on the standard piston pressure gauge and the piston pressure gauge to be detected₁And m₂The weight of (2);

controlling the pressure source to make the standard piston pressure gauge and the detected piston pressure gauge rise to working positions, and obtaining the indication value P2 of the differential pressure transmitter P2₀；

Closing the balance valve V1, and controlling the pressure source to stabilize the standard piston pressure gauge and the detected piston pressure gauge at the working positions;

observing whether the indication value of the differential pressure transmitter P1 is within a set range, if not, placing a small weight on the standard piston pressure gauge or the detected piston pressure gauge, adjusting the pressure source again, and lifting the standard piston pressure gauge and the detected piston pressure gauge to working positions until the indication value of the differential pressure transmitter P1 is within the set range;

opening the stop valve V3 and the stop valve V4, closing the balance valve V2, and adjusting the pressure source to stabilize the standard piston pressure gauge and the detected piston pressure gauge at the working positions;

recording the mass m of weights placed on the standard piston pressure gauge and the detected piston pressure gauge₁And m₂Differential pressure transmitter P2 has an indication of P_i，P_i-P₀To obtain delta P₃。

Further, the measurement of other verification points is completed according to the measurement step and the calculation step, and the verification points are uniformly distributed;

after each point is verified, re-testing the initial point again, wherein the pressure difference of the initial balance point before and after verification does not exceed 10% of the maximum allowable error, otherwise, re-verification is required;

and after the effective area value of the piston of each pressure point is obtained through the calculating step, the average value of the effective areas of the pistons is calculated.

Further, the span of differential pressure transmitter P1 is 2500KPa, and the span of differential pressure transmitter P2 is 60 KPa.

In the present embodiment, the differential pressure transmitter is connected to a pressure source and a pressure regulating device; connecting a pressure measuring instrument to a high-pressure end and a low-pressure end of the differential pressure transmitter in parallel; maintaining the communication between the high pressure end and the low pressure end of the differential pressure transmitter, controlling the pressure source to raise the pressure to a measuring point, and recording the indication value of the differential pressure transmitter and the indication value Pl of the pressure measuring instrument; disconnecting the high-pressure end of the differential pressure transmitter from the pressure measuring instrument and keeping the indication value of the differential pressure transmitter unchanged; controlling the pressure regulating device to reduce or raise the pressure at the low pressure end of the differential pressure transmitter, acquiring the indication value variation of the pressure measuring instrument, and when the variation reaches a preset upper stroke differential pressure point or a preset lower stroke differential pressure pointRecording indication Ph of pressure measuring instrument and indication delta P of differential pressure transmitter₁(ii) a Obtaining the actual differential pressure value delta P by the difference between Ph and Pl₂By Δ P₂And Δ P₁Obtaining the error value of the differential pressure transmitter under the current upper stroke differential pressure point or the lower stroke differential pressure point by the difference value; and evaluating the error value of the differential pressure transmitter, and judging whether the differential pressure transmitter meets the requirements, so that the aim of quickly, simply and accurately measuring and evaluating the static pressure characteristic of the differential pressure transmitter is fulfilled, and the problems of complex measurement process, low efficiency and long time consumption of the static pressure characteristic of the differential pressure transmitter in the related technology are solved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this application, serve to provide a further understanding of the application and to enable other features, objects, and advantages of the application to be more apparent. The drawings and their description illustrate the embodiments of the invention and do not limit it. In the drawings:

FIG. 1 is a schematic structural diagram of a static pressure characteristic testing device of a pressure transmitter according to an embodiment of the present application;

FIG. 2 is a schematic structural view of another pressure transmitter static pressure characteristic testing apparatus according to an embodiment of the present application;

FIG. 3 is a schematic diagram of a configuration for delivering a test for a piston manometer in accordance with an embodiment of the present application;

the pressure measuring device comprises a standard piston pressure gauge 1, a differential pressure transmitter 2, a detected piston pressure gauge 3, a second pressure regulator 4, a pressure source 5, a pressure measuring instrument 6, a valve 7 and a first pressure regulator 8.

Detailed Description

In order to make the technical solutions in the embodiments of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below, and it is obvious that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

It is noted that the terms first, second and the like in the description and in the claims of the present application are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It should be understood that the data so used may be interchanged under appropriate circumstances such that embodiments of the application described herein may be used.

Moreover, some of the above terms may be used to indicate other meanings besides the orientation or positional relationship, for example, the term "on" may also be used to indicate some kind of attachment or connection relationship in some cases. The specific meaning of these terms in this application will be understood by those of ordinary skill in the art as appropriate.

Furthermore, the terms "disposed," "provided," "connected," "secured," and the like are to be construed broadly. For example, "connected" may be a fixed connection, a detachable connection, or a unitary construction; can be a mechanical connection, or an electrical connection; may be directly connected, or indirectly connected through intervening media, or may be in internal communication between two devices, elements or components. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art as appropriate.

In addition, the term "plurality" shall mean two as well as more than two.

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail with reference to examples.

Before differential pressure transmitter 2 is used, it is necessary to evaluate its error under different static pressure conditions to determine whether differential pressure transmitter 2 meets the use requirements. Judging whether the differential pressure transmitter 2 meets the use requirement or not means whether the error of the differential pressure transmitter 2 meets the precision requirement of indicating value error under the requirement of metering performance in national measurement and verification regulations of the people's republic of China (JJJG 882-2019). Need use standard piston pressure gauge among the traditional measurement process, because the piston shape size among the standard piston pressure gauge 1 is fixed, therefore the pressure point of piston is fixed for it is accurate inadequately to differential pressure transmitter 2's measurement, and measurement process needs the manual work to judge whether balanced piston pressure gauge, and the judgement error is big, and the operation requirement is high, and whole test procedure is complicated, and efficiency is lower. The present embodiment thus provides a method of testing the static pressure characteristics of differential pressure transmitter 2 by which the performance of differential pressure transmitter 2 is more accurately demonstrated.

As shown in FIG. 1, the testing method takes the high-pressure end of a differential pressure transmitter as a static pressure condition for measurement, and comprises the following steps:

connecting a differential pressure transmitter 2 to a pressure source 5 and a pressure adjusting device, wherein the pressure adjusting device can adjust the pressure of a high-pressure end and a low-pressure end of the differential pressure transmitter 2, and the volume of a pipeline is changed through rotation, so that the system pressure is finely adjusted;

connecting a pressure measuring instrument 6 to a high-pressure end and a low-pressure end of the differential pressure transmitter 2 in parallel, wherein the pressure measuring instrument 6 can be a digital pressure measuring instrument or a pressure sensor and has the characteristic of high-precision measurement;

the communication between the high-pressure end and the low-pressure end of the differential pressure transmitter 2 is kept, the pressure source 5 is controlled to raise the pressure to a measuring point, the indication value of the differential pressure transmitter 2 and the indication value Pl of the pressure measuring instrument 6 are recorded, the pressure values of the high-pressure end and the low-pressure end of the differential pressure transmitter 2 are the same at the moment, the pressure of the whole measuring system is balanced, and the pressure Pl of the low-pressure end and the high-pressure end of the differential pressure transmitter 2 is accurately obtained through the pressure measuring instrument 6;

disconnecting the high-pressure end of the differential pressure transmitter 2 from the pressure measuring instrument 6, and keeping the indication value of the differential pressure transmitter 2 unchanged; the high-pressure end of the differential pressure transmitter 2 is originally communicated with the pressure measuring instrument 6, the volume of a pipeline is changed after the differential pressure transmitter 2 is disconnected, so that the indication value of the differential pressure transmitter 2 can possibly change, and in order to ensure the accuracy of a measuring result, a pressure adjusting device positioned at the high-pressure end of the differential pressure transmitter 2 needs to be adjusted, so that the indication value of the differential pressure transmitter 2 is kept unchanged; the disconnection and the communication between the high-pressure end of the differential pressure transmitter 2 and the pressure measuring instrument 6 can be realized through a valve 7, and the valve 7 can be a stop valve;

the pressure at the low-pressure end of the differential pressure transmitter 2 is reduced or increased by controlling the pressure adjusting device, the indication value variation of the pressure measuring instrument 6 is obtained, when the variation reaches a preset upper stroke differential pressure point or a preset lower stroke differential pressure point, the indication value Ph of the pressure measuring instrument 6 and the indication value delta P of the differential pressure transmitter 2 are recorded₁；

At the moment, the high-pressure end of the differential pressure transmitter 2 is disconnected with the pressure source 5, namely the pressure of the high-pressure end of the differential pressure transmitter 2 is kept unchanged, the pressure of the low-pressure end of the differential pressure transmitter 2 is reduced through the pressure source 5, when the pressure of the low-pressure end is reduced to a set upper stroke differential pressure point, the pressure measuring instrument 6 obtains the actual pressure Ph of the system, and the differential pressure delta P displayed on the high-pressure end and the low-pressure end of the differential pressure transmitter 2 is obtained₁And obtaining the actual differential pressure delta P at the upper stroke differential pressure point through the actual system pressure Ph-Pl₂By Δ P₂And Δ P₁Obtaining the error value of the differential pressure transmitter 2 under the current upper stroke differential pressure point or the lower stroke differential pressure point, so as to finish the measurement of one upper stroke differential pressure point, repeating the operation until the measurement of other upper stroke differential pressure points is finished, then raising the pressure of the low pressure end of the differential pressure transmitter 2 through the pressure source 5, and finishing the measurement of other lower stroke differential pressure points in the same way, thereby obtaining the error values of a plurality of upper stroke differential pressure points and lower stroke differential pressure points of the differential pressure transmitter 2 under the static pressure condition;

in order to obtain the error values of the differential pressure transmitter 2 under the upper stroke differential pressure point and the lower stroke differential pressure point under other static pressure conditions, after the measurement under one static pressure condition is finished, the pressure measuring instrument 6 is communicated with the low pressure end of the differential pressure transmitter 2, the system pressure is increased to other pressure points through the pressure source 5, and the steps are repeated to finish the error value measurement under the upper stroke differential pressure point and the lower stroke differential pressure point.

And evaluating all error values of the obtained differential pressure transmitter 2 under different static pressure conditions, different upper stroke differential pressure points and lower stroke differential pressure points, and judging whether the error value of the differential pressure transmitter 2 meets the requirement or not.

Further, connecting the differential pressure transmitter 2 to the pressure source 5 and the pressure regulating device is embodied as:

the low pressure end of the differential pressure transmitter 2 is connected to a pressure source 5, the high pressure end and the low pressure end of the differential pressure transmitter 2 are respectively connected to a second pressure regulator 4 and a first pressure regulator 8, and the pressure source 5 is set as a pressure checker.

Further, controlling the pressure regulating device to reduce or raise the pressure at the low-pressure end of the differential pressure transmitter 2 specifically comprises:

the pressure at the low pressure side of differential pressure transmitter 2 is reduced by controlling first pressure regulator 8 or the pressure at the low pressure side of differential pressure transmitter 2 is increased by controlling first pressure regulator 8.

On the other hand, the present embodiment provides another embodiment of connecting differential pressure transmitter 2 to pressure source 5 and pressure regulating means, specifically, connecting the high pressure end of differential pressure transmitter 2 to piston pressure gauge 10, and connecting third pressure regulator 9 at the low pressure end of differential pressure transmitter 2; the step of controlling the pressure regulating device to reduce or raise the pressure at the low-pressure end of the differential pressure transmitter specifically comprises the following steps: the pressure at the low pressure side of the differential pressure transmitter 2 is reduced or increased by controlling the third pressure regulator 9. The use of the regulated piston pressure gauge 10 raises the system pressure to the point of measurement and maintains the piston of the piston pressure gauge 10 in the operating position.

The piston type pressure gauge is greatly applied to metering mechanisms and professional laboratories due to unique superiority, the quantity tracing requirement of the piston type pressure gauge is increased day by day, the traditional quantity transmission mode of the piston type pressure gauge cannot meet the increased verification requirement, a stable, feasible and efficient quantity transmission mode of the piston type pressure gauge is urgently needed to be researched, and according to long-term accumulated pressure professional knowledge and experience, the embodiment provides a new quantity transmission method for applying a high-precision differential pressure transmitter to the verification process of the piston type pressure gauge. The high-precision differential pressure transmitter is the differential pressure transmitter 2 which meets the requirements and is obtained by the method for testing the static pressure characteristics of the differential pressure transmitter.

Firstly, in the GB/T30432-2013 liquid piston type pressure gauge, the nominal effective areas of pistons of the piston type pressure gauge in different measuring range ranges are required, and the effective area of the piston with each nominal area is required to be in a specified range. The effective areas of the standard piston and the detected piston with the same nominal area always have certain difference, and the limit deviation can reach 2%. Special weights with the same mass are added on the two sets of pistons, and differential pressure exists between the two sets of balance systems. The requirement of the detection point in JJG59-2007 is that no less than 5 points are selected in the detection range and distributed as uniformly as possible, and the first point is 10% -20% of the upper limit of the measurement. Weights with the same mass are added and released on the two sets of piston systems under different verification pressure points, different limit pressure differences can be generated, and the closer the effective areas of the two sets of pistons are, the smaller the differential pressure under each verification pressure point is.

Because the piston is verified, a plurality of pressure points need to be tested, and the allowable error of each pressure point is different. In order to ensure accuracy, a differential pressure sensor with a small range needs to be used, but if the differential pressure between the standard piston and the detected piston exceeds the range of the small-range differential pressure transmitter 2 during initial measurement, irreversible damage can be caused to the differential pressure transmitter 2. Therefore, the differential pressure transmitter 2 with two different ranges is used, the large range is used for rough adjustment, and accurate measurement is carried out when the differential pressure between the standard piston and the detected piston is within the measurement range of the differential pressure transmitter 2 with the small range. Therefore, in order to reduce the uncertainty component of the maximum allowable error of the differential pressure transmitter 2 introduced in the piston measurement process as much as possible in the embodiment, two differential pressure transmitters 2 with full ranges of 2500kPa and 60kPa are adopted, wherein the measurement result of the differential pressure transmitter 2P1 with the full range of 2500kPa is used as the basis for adjusting the differential pressure of two balance systems, and the measurement result of the differential pressure transmitter 2P2 with the full range of 60kPa is used as the calculation parameter of the effective area of the piston.

The method for calibrating the effective area of the piston pressure gauge provided by the embodiment measures the piston pressure gauge 3 to be tested through the standard piston pressure gauge 1, comprises a measuring step and a calculating step,

the measuring steps are as follows:

respectively connecting a standard piston pressure gauge 1 and a detected piston pressure gauge 3 to a differential pressure transmitter 2 and a pressure source 5;

the mass of the standard piston pressure gauge 1 is m₁The weight of (3) is m₂The weight of (2);

under the working state, the differential pressure transmitter measures the differential pressure between the standard piston pressure gauge 1 and the detected piston pressure gauge 3 to be delta P₃；

The calculation steps are as follows:

under the working state:

m₁g/A₀＝m₂g/A_i+ΔP₃

therefore, the method comprises the following steps:

Ai＝m₂g/(m₁g-ΔP₃A₀)A₀

in the formula: g-gravitational acceleration;

A₀-the effective area of a standard piston manometer;

ai is the effective area of the checked piston pressure gauge;

m₁and m₂-special weight masses applied to both pressure gauges.

Further, the method uses the following assay device:

a differential pressure detection device is connected between the standard piston pressure gauge 1 and the detected piston pressure gauge 3, and comprises a first differential pressure detection system and a second differential pressure detection system which are connected in parallel;

the first differential pressure detection system comprises a stop valve V3, a differential pressure transmitter P2 and a stop valve V4 which are connected in series, and a balance valve V2 which is connected in parallel at two ends of the differential pressure transmitter P2 and is positioned between the stop valve V3 and the stop valve V4; the second differential pressure detection system includes a differential pressure transmitter P1 and a balancing valve V1 connected in parallel across the differential pressure transmitter P1.

Further, the measuring steps are specifically as follows:

opening balance valves V1 and V2 in the verification process, observing whether zero points of a differential pressure transmitter P1 and a differential pressure transmitter P2 drift or not, if so, carrying out zero clearing operation, wherein the zero points refer to indicating values presented by the differential pressure transmitter 2 when pressures at two ends are absolutely equal, and if actual pressures are unequal or the design and manufacturing defects of a product per se exist, zero point drift occurs, so that the zero clearing operation needs to be carried out manually;

closing the stop valve V3 and the stop valve V4, selecting a pressure point with 10% -20% of the range upper limit of the standard piston pressure gauge 1 as a starting point, and respectively placing a piston pressure gauge 3 to be detected and the standard piston pressure gauge 1 with a mass m_aAnd m_bThe weight of (2);

controlling the pressure source to enable the standard piston pressure gauge 1 and the detected piston pressure gauge 3 to rise to working positions, namely the positions where weights on the standard piston pressure gauge 1 and the detected piston pressure gauge 3 are jacked up and suspended, and acquiring the indicating value of the differential pressure transmitter 2P2 as P0; the standard piston pressure gauge 1 and the detected piston pressure gauge 3 are connected to one pressure source, respectively, and since the balance valve V1 is in an open state at this time, the standard piston pressure gauge 1 and the detected piston pressure gauge 3 are in communication, and therefore the pressure source of either pressure gauge can be selected to adjust so as to raise the system pressure. In actual operation, the piston of the standard piston pressure gauge 1 may be lifted first, and at this time, a small weight needs to be added on the standard piston pressure gauge 1 to lift the piston pressure gauge 3 to be detected;

closing the balance valve V1, wherein the system pressure may change due to the change of the volume of the pipeline, and at the moment, the pressure source needs to be controlled to stabilize the standard piston pressure gauge 1 and the detected piston pressure gauge 3 at the working positions, and if the pressure source is used, the difficulty in control is high, a pressure adjusting device which can be finely adjusted can be connected to the standard piston pressure gauge 1 and the detected piston pressure;

observing whether the indication value of the differential pressure transmitter P1 is within a set range, wherein the set range is 20KPa to 50KPa, if not, placing a small weight on the standard piston pressure gauge 1 or the detected piston pressure gauge 3, adjusting the pressure source 5 again, and lifting the standard piston pressure gauge 1 and the detected piston pressure gauge 3 to working positions until the indication value of the differential pressure transmitter P1 is within the set range;

opening the stop valve V3 and the stop valve V4, closing the balance valve V2, and adjusting the pressure source 5 to stabilize the standard piston pressure gauge 1 and the detected piston pressure gauge 3 at the working positions;

recording the mass m1 and m of the weights placed on the standard piston pressure gauge 1 and the piston pressure gauge 3 to be detected₂Differential pressure transmitter P2 has an indication of P_i，P_i-P₀To obtain delta P₃。

This time, Δ P is obtained by this measurement step₃，m₁The weight m initially placed on the standard piston pressure gauge 1_aAdding small weights m added in the subsequent process₂The weight m initially placed on the standard piston pressure gauge 1_bAnd adding small weights added in the subsequent process.

Further, the measurement of other verification points is completed according to the measurement step and the calculation step, and the verification points are uniformly distributed;

after each point is verified, re-testing the initial point again, wherein the pressure difference of the initial balance point before and after verification does not exceed 10% of the maximum allowable error, otherwise, re-verification is required;

and after the effective area value of the piston of each pressure point is obtained through the calculating step, the average value of the effective areas of the pistons is calculated.

As shown in fig. 1, according to another aspect of the present application, there is provided a static pressure characteristic testing apparatus for a differential pressure transmitter, which includes a differential pressure transmitter 2 to be tested, a high pressure end and a low pressure end of the differential pressure transmitter 2 are respectively connected to a second pressure regulator 4 and a first pressure regulator 8, and a pressure source 5 is further connected to the high pressure end of the differential pressure transmitter 2, and is a pressure checker; the testing device further comprises a pressure measuring instrument 6, two ends of the pressure measuring instrument 6 are connected in parallel to the high-pressure end and the low-pressure end of the differential pressure transmitter 2 through pipelines, a valve 7 is arranged on the pipeline connecting the pressure measuring instrument 6 and the low-pressure end of the differential pressure transmitter 2, and the valve 7 is preferably a stop valve.

As shown in fig. 2, in another aspect, the present embodiment provides another testing apparatus, which includes a differential pressure transmitter 2 to be tested, a high pressure end of the differential pressure transmitter 2 is connected to a pressure regulator 9, a low pressure end is connected to a piston type pressure gauge 10, the piston type pressure gauge 10 is connected to a pressure source, where the piston type pressure gauge 10 is used as a first pressure regulator 8 in the above apparatus; the testing device further comprises a pressure measuring instrument 6, two ends of the pressure measuring instrument 6 are connected in parallel to the high-pressure end and the low-pressure end of the differential pressure transmitter 2 through pipelines, a valve 7 is arranged on the pipeline connecting the pressure measuring instrument 6 and the low-pressure end of the differential pressure transmitter 2, and the valve 7 is preferably a stop valve.

As shown in fig. 3, according to another aspect of the present application, there is provided a device for testing the transmission of a piston pressure gauge, which includes a standard piston pressure gauge 1, a detected piston pressure gauge 3, and pressure sources respectively connected to the standard piston pressure gauge and the detected piston pressure gauge 3, wherein a differential pressure detection device is disposed between the standard piston pressure gauge 1 and the detected piston pressure gauge 3, and includes a first detection pipeline and a second detection pipeline connected in parallel;

a stop valve V3, a differential pressure transmitter P2 and a stop valve V4 are connected in series on the first detection pipeline, a balance valve V2 is connected in parallel on the first detection pipeline, and two ends of the balance valve V2 are respectively connected with the high-pressure end and the low-pressure end of the differential pressure transmitter P2 and are positioned between the stop valve V2 and the stop valve V4;

the second detection pipeline is provided with a differential pressure transmitter P1 and a balance valve V1 connected in parallel at the high-pressure end and the low-pressure end of the differential pressure transmitter P1.

The differential pressure transmitter P1 and the differential pressure transmitter P2 are labeled differential pressure transmitters obtained by the differential pressure transmitter static pressure characteristic test method.

The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.