A method of measuring the accuracy of a control valve

Abstract

The application discloses a kind of methods for measuring regulating valve precision, wherein the method for measuring regulating valve precision includes the following steps: measuring the distance between the free end of the rotating transmission rod and the base, and the distance between the valve core and the outlet before rotating;Rotating the transmission nut N circle in positive direction;Rotating the transmission nut N circle in reverse direction;Measure the distance between the free end of the transmission rod and the base after rotating and the distance between the valve core and the outlet after rotating;The precision of regulating valve is obtained by the distance between the free end of the transmission rod and the base before rotating, the distance between the valve core and the outlet before rotating, the distance between the free end of the transmission rod and the base after rotating and the distance between the valve core and the outlet after rotating.The method for measuring regulating valve precision in the application has the advantages of convenient measurement, simple and fast method, and further enables personnel to adjust regulating valve in time according to the precision of regulating valve, to improve the reliability and stability of regulating valve.

Description

Technical Field

[0001] This invention relates to the field of regulating equipment technology, and further to a method for measuring the accuracy of a regulating valve. Background Technology

[0002] Control valves are widely used flow regulation components in industrial process control in petroleum, chemical, power, metallurgical and other industrial enterprises. The drive component connected to the valve core of the control valve together serves as the actuator of the control system. The control system controls the movement of the drive component to change the flow area of ​​the control valve, thereby achieving the purpose of flow regulation.

[0003] Control accuracy is a crucial performance characteristic of control valves. According to mechanical standards (JB / T 7387), the technical indicators related to accuracy include basic error, hysteresis, and dead zone. While basic error, hysteresis, and dead zone reflect the overall accuracy of the control valve, they do not reflect the degree to which individual components of the control valve affect the accuracy. Furthermore, the overall measurement method is complex, making it impossible to quickly measure and calculate the accuracy of the control valve. Summary of the Invention

[0004] In view of the above-mentioned technical problems, the purpose of this invention is to provide a method for measuring the accuracy of a regulating valve, which can solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides a method for measuring the accuracy of a regulating valve, comprising:

[0006] The regulating valve includes a valve body, an actuator connected to the valve body, and a flow channel inside the valve body. A valve core is disposed within the flow channel, and an outlet is provided at one end of the flow channel. A transmission rod is drivenly connected to the valve core. A base is provided on the side of the actuator near the valve body. A transmission nut is sleeved on the transmission rod through the base. When the transmission nut is rotated, the transmission rod can move closer to or further away from the flow channel, so that the valve core can move along the flow channel.

[0007] The method for measuring the accuracy of the regulating valve includes the following steps:

[0008] Measure the distance between the free end of the transmission rod and the base before rotation, and the distance between the valve core and the outlet before rotation;

[0009] Rotate the transmission nut N turns in the forward direction;

[0010] Rotate the transmission nut in the opposite direction N turns;

[0011] Measure the distance between the free end of the transmission rod and the base after rotation, and the distance between the valve core and the outlet after rotation;

[0012] The accuracy of the regulating valve is determined by the distance between the free end of the transmission rod and the base before rotation, the distance between the valve core and the outlet before rotation, the distance between the free end of the transmission rod and the base after rotation, and the distance between the valve core and the outlet after rotation.

[0013] The accuracy of the regulating valve is determined by measuring the distance between the free end of the transmission rod and the base before rotation, the distance between the valve core and the outlet before rotation, the distance between the free end of the transmission rod and the base after rotation, and the distance between the valve core and the outlet after rotation. This method is convenient, simple, and quick, enabling personnel to fine-tune the regulating valve in a timely manner based on its accuracy, thereby improving the reliability and stability of the regulating valve.

[0014] In some embodiments, the accuracy of the regulating valve is determined using the following formula:

[0015]

[0016] Wherein, L1 is the distance between the free end of the transmission rod and the base before rotation, L2 is the distance between the valve core and the outlet before rotation, L3 is the distance between the free end of the transmission rod and the base after rotation, L4 is the distance between the valve core and the outlet after rotation, and L is the rated stroke of the regulating valve.

[0017] In some embodiments, the steps of measuring the distance between the free end of the transmission rod and the base before rotation and the distance between the valve core and the outlet before rotation are further included: removing the actuator while retaining the base.

[0018] By removing the actuator and retaining the base, the transmission nut is exposed to the external environment, making it easier for personnel to rotate it with tools. This also allows for real-time observation during the rotation of the transmission nut, thus providing the necessary guarantee for the accuracy and precision of the operation.

[0019] In some embodiments, between the steps of removing the actuator and retaining the base and measuring the distance between the free end of the transmission rod and the base before rotation, and the distance between the valve core and the outlet before rotation, the step of rotating the transmission nut in the forward direction is further included: stopping the rotation of the transmission nut when the valve core begins to move.

[0020] By rotating the transmission nut forward before measuring the distance between the free end of the transmission rod and the base, and the distance between the valve core and the outlet before rotation, and stopping the rotation of the transmission nut when the valve core begins to move, excessive invalid rotation during subsequent rotation of the transmission nut can be effectively avoided, thus preventing errors in the measurement results and further optimizing the speed and convenience of the measurement method.

[0021] In some embodiments, the steps of measuring the distance between the free end of the transmission rod and the base before rotation, the distance between the valve core and the outlet before rotation, and the step of rotating the transmission nut forward N turns further include the step of setting an aligned set of marks on the transmission nut and the base.

[0022] By setting aligned markings on the transmission nut and the base, a reference is provided for rotating the transmission nut, which effectively ensures the precision and accuracy of rotating the transmission nut. This provides a valid prerequisite for subsequent steps and effectively avoids possible errors in the method of measuring the accuracy of the regulating valve.

[0023] In some embodiments, the marking group includes a first marking line and a second marking line, which are respectively disposed on the transmission nut and the base, and correspond to each other on the same straight line.

[0024] By marking the first and second graduations on the transmission nut and the base, it is easy for personnel to observe whether the first and second graduations can be connected to form a complete line after rotating the transmission nut N times, so as to determine whether the transmission nut has rotated a full circle. This effectively ensures the accuracy of the operation steps and provides a strong guarantee for the method of measuring the accuracy of the regulating valve.

[0025] In some embodiments, if the valve core does not shift after rotating the transmission nut N turns in the reverse direction, then the following steps are performed: rotate the transmission nut 2N turns in the forward direction and then rotate the transmission nut 2N turns in the reverse direction.

[0026] By increasing the number of turns of the transmission nut to cause displacement of the valve core, effective data can be obtained through measurement, ensuring the proper use of the method for determining the accuracy of the control valve.

[0027] In some embodiments, the method for measuring the accuracy of a regulating valve provided by the present invention further includes:

[0028] The accuracy of the base is determined using the following formula:

[0029]

[0030] Where A represents the precision of the base.

[0031] By measuring the accuracy of the base, it is determined whether the accuracy of the base meets the standard. Then, the base is adjusted according to the actual situation to improve the accuracy of the regulating valve, thereby effectively optimizing the reliability of the regulating valve.

[0032] In some embodiments, the method for measuring the accuracy of a regulating valve provided by the present invention further includes:

[0033] The common accuracy of the valve body and the base is calculated using the following formula:

[0034]

[0035] Wherein, B represents the combined precision of the valve body and the base.

[0036] By measuring the combined accuracy of the control valve and its base, it is determined whether the accuracy of the valve core inside the control valve meets the standard. Then, based on the actual situation, the components of the control valve are adjusted to improve accuracy, thereby further optimizing the reliability of the control valve.

[0037] In some implementations, when A, B, and C are all less than the basic error value, it is determined that the accuracy of the regulating valve meets the accuracy standard; when any one of A, B, and C is not less than the basic error value, it is determined that the accuracy of the regulating valve does not meet the accuracy standard.

[0038] Compared with the prior art, the method for measuring the accuracy of a regulating valve provided by the present invention has the following advantages:

[0039] 1. The method for measuring the accuracy of a regulating valve provided by the present invention measures the distance between the free end of the transmission rod and the base before rotation, the distance between the valve core and the outlet before rotation, the distance between the free end of the transmission rod and the base after rotation, and the distance between the valve core and the outlet after rotation, in order to determine the accuracy of the regulating valve. It has the advantages of convenient measurement and simple and quick method, thereby enabling personnel to fine-tune the regulating valve in a timely manner according to the accuracy of the regulating valve, so as to improve the reliability and stability of the regulating valve.

[0040] 2. The method for measuring the accuracy of a regulating valve provided by the present invention provides a reference for rotating the regulating nut by setting an aligned set of marks on the transmission nut and the base, which effectively ensures the accuracy and precision of rotating the transmission nut, and thus provides an effective prerequisite for subsequent steps, effectively avoiding possible errors in the method for measuring the accuracy of the regulating valve. Attached Figure Description

[0041] The preferred embodiments will now be described in a clear and easy-to-understand manner, in conjunction with the accompanying drawings, to further explain the above-mentioned characteristics, technical features, advantages, and implementation methods of the present invention.

[0042] Figure 1 This is a flowchart illustrating the steps of a preferred embodiment of the method for measuring the accuracy of a regulating valve according to the present invention.

[0043] Figure 2 This is a front view schematic diagram of the regulating valve in the method for measuring the accuracy of the regulating valve according to a preferred embodiment of the present invention;

[0044] Figure 3 This is a top view of the control valve in a method for measuring the accuracy of a control valve according to a preferred embodiment of the present invention.

[0045] Explanation of icon numbers:

[0046] Valve body 10, base 20, second graduation line 21, transmission nut 30, first graduation line 31, transmission rod 40, valve core 50. Detailed Implementation

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings and other implementation methods can be obtained based on these drawings without any creative effort.

[0048] To keep the drawings concise, each figure only schematically shows the parts relevant to the invention, and these do not represent the actual structure of the product. Furthermore, to facilitate understanding, in some figures, only one of components with the same structure or function is schematically depicted, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one."

[0049] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or welded connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0050] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0051] In one embodiment, refer to the appendix to the specification. Figure 1 , Figure 2 and Figure 3The present invention provides a method for measuring the accuracy of a regulating valve, wherein the regulating valve includes a valve body 10, an actuator is connected to the valve body 10, and a flow channel is provided inside the valve body 10. A valve core 50 is disposed in the flow channel, and an outlet is provided at one end of the flow channel. The valve core 50 is driven by a transmission rod 40. A base 20 is provided on the side of the actuator near the valve body 10. The transmission rod 40 passes through the base 20 and is fitted with a transmission nut 30. When the transmission rod 40 rotates the transmission nut 30, it can move closer to or further away from the flow channel, so that the valve core 50 can move along the flow channel. The method for measuring the accuracy of the regulating valve includes the following steps: Step S1: Measure the transmission before rotation. Step S2: Rotate the transmission nut 30N turns in the forward direction; Step S3: Rotate the transmission nut 30N turns in the reverse direction; Step S4: Measure the distance between the free end of the transmission rod 40 and the base 20 after rotation, and the distance between the valve core 50 and the outlet after rotation; Step S5: Determine the accuracy of the regulating valve by measuring the distance between the free end of the transmission rod 40 and the base 20 before rotation, the distance between the valve core 50 and the outlet before rotation, the distance between the free end of the transmission rod 40 and the base 20 after rotation, and the distance between the valve core 50 and the outlet after rotation.

[0052] Specifically, a flow channel is provided through the valve body 10, with the two ends of the flow channel being the inlet and outlet, respectively. The actuator is generally located on the valve body 10 between the outlet and inlet of the flow channel. The actuator is generally connected to the valve core 50 in the flow channel via a transmission rod 40. Personnel can observe the state of the valve core 50 from one end of the valve body 10. A transmission nut 30 is fitted on the transmission rod 40 to adjust the transmission rod 40. Personnel can rotate the transmission nut 30 to move the position of the valve body 10 in the flow channel, thereby controlling the flow rate of the medium flowing through the flow channel.

[0053] To obtain the necessary data for determining the accuracy of the control valve, a depth gauge is used to measure the distance between the free end of the transmission rod 40 and the base 20 before rotation, and the distance between the valve core 50 and the outlet before rotation. The corresponding data are recorded. Then, a tool is used to rotate the transmission nut 30, making it rotate N turns in the forward direction and then N turns in the reverse direction. The depth gauge is used again to measure the distance between the free end of the transmission rod 40 and the base 20 after rotation, and the distance between the valve core 50 and the outlet after rotation. The corresponding data are recorded again. By substituting the four types of data into the corresponding formulas, the accuracy of the control valve can be determined.

[0054] In some implementations, based on the above embodiments, refer to the appendix to the specification. Figure 1 and Figure 3 The accuracy of the control valve is determined using the following formula:

[0055]

[0056] Wherein, L1 is the distance between the free end of the transmission rod 40 and the base 20 before rotation, L2 is the distance between the valve core 50 and the outlet before rotation, L3 is the distance between the free end of the transmission rod 40 and the base 20 after rotation, L4 is the distance between the valve core 50 and the outlet after rotation, and L is the rated stroke of the regulating valve.

[0057] Specifically, due to the gaps between the parts in the control valve, when the valve's direction of movement changes, the driving component must travel a certain distance before all parts come into contact, and then the driven component will move. This distance is called the idle stroke. According to the measured data, the idle stroke of the base 20 is |L1-L3|, the idle stroke of the base 20 and the valve body together is |L2-L4|, and the idle stroke of the valve body is |L2-L4|-|L1-L3|. Generally, the transmission ratio between the transmission rod 40 and the valve core 50 is 1:1. The accuracy of the control valve can be obtained by calculating the ratio of the idle stroke of the valve body to the rated stroke of the control valve.

[0058] In one embodiment, based on the above embodiments, refer to the appendix to the specification. Figure 1 and Figure 3 Before step S1, which measures the distance between the free end of the front drive rod 40 and the base 20 and the distance between the front valve core 50 and the outlet, step S0 is included: removing the actuator while retaining the base 20.

[0059] Specifically, the actuator is removed while the base 20 is retained, so that the transmission nut 30 is exposed to the external environment. This allows personnel to rotate the nut using tools and also facilitates real-time observation during the rotation of the transmission nut 30, thus providing the necessary guarantee for the accuracy and precision of the operation.

[0060] In one embodiment, based on the above embodiments, refer to the appendix to the specification. Figure 1 and Figure 2 Between the steps of removing the actuator and retaining the base 20 (S0) and measuring the distance between the free end of the transmission rod 40 and the base 20 and the distance between the valve core 50 and the outlet (S1), there is also step S01: rotating the transmission nut 30 in the forward direction, and stopping the rotation of the transmission nut 30 when the valve core 50 starts to move.

[0061] Specifically, before measuring the distance between the free end of the transmission rod 40 and the base 20, and the distance between the valve core 50 and the outlet, the transmission nut 30 is rotated in the forward direction. When the valve core 50 starts to move, the rotation of the transmission nut 30 is stopped to avoid excessive invalid rotation when the transmission nut 30 is rotated later, which would cause errors in the measurement results.

[0062] In one embodiment, refer to the appendix to the specification. Figure 1 , Figure 2 and Figure 3 Between step S1, which measures the distance between the free end of the transmission rod 40 and the base 20 before rotation, and the distance between the valve core 50 and the outlet before rotation, and step S01, which rotates the transmission nut 30 N turns in the forward direction, step S11 is also included: setting an aligned set of marks on the transmission nut 30 and the base 20.

[0063] Specifically, since there are generally no obvious markings on the transmission nut 30 and the base 20, the accuracy of rotating the transmission nut 30 is poor. Therefore, an aligned set of markings is set on the transmission nut 30 and the base 20, so that the rotation of the transmission nut 30 can be judged by using the set of markings as a reference, thereby effectively improving the accuracy of the rotation of the transmission nut 30 and thus ensuring the reliability of the method for measuring the accuracy of the regulating valve.

[0064] In one embodiment, based on the above embodiments, refer to the appendix to the specification. Figure 2 and Figure 3 The marking group includes a first marking line 31 and a second marking line 21. The first marking line 31 and the second marking line 21 are respectively set on the transmission nut 30 and the base 20, and are on the same straight line.

[0065] Specifically, a first graduation line 31 and a second graduation line 21 are drawn on the transmission nut 30 and the base 20 respectively using a marker pen, and the first graduation line 31 and the second graduation line 21 are connected to form a complete line so that the transmission nut 30 has a reference object for rotation. After the transmission nut 30 rotates an integer number of times, the first graduation line 31 and the second graduation line 21 can still be connected to form a complete line. By observing that the first graduation line 31 and the second graduation line 21 can be connected to form a complete line, it can be determined whether the transmission nut 30 has rotated a complete circle, thus providing a strong guarantee for the method of measuring the accuracy of the regulating valve.

[0066] In one embodiment, based on the above embodiments, refer to the appendix to the specification. Figure 1 and Figure 3 If the valve core 50 does not shift after rotating the transmission nut 30N turns in the reverse direction, then perform the following steps: rotate the transmission nut 30 2N turns in the forward direction, and then rotate the transmission nut 30 2N turns in the reverse direction.

[0067] Specifically, when N is not large enough, the displacement of the valve core is too small to be measured using a depth gauge. Therefore, in order to ensure the validity and usability of the data, the transmission nut 30 is first rotated 2N turns in the forward direction, and then rotated 2N turns in the reverse direction to allow the transmission nut to move, so as to provide effective data for the calculation of the control valve accuracy.

[0068] In one embodiment, based on the above embodiments, refer to the appendix to the specification. Figure 1 and Figure 3 The method for measuring the accuracy of the regulating valve provided by this invention also includes the accuracy of the base 20. The accuracy of the base 20 is obtained using the following formula:

[0069]

[0070] Where A represents the precision of base 20.

[0071] Specifically, by measuring the accuracy of the base 20, it is determined whether the accuracy of the base 20 meets the standard. Then, the base 20 is adjusted according to the actual situation to improve the accuracy of the regulating valve, thereby effectively optimizing the reliability of the regulating valve.

[0072] In one embodiment, based on the above embodiments, refer to the appendix to the specification. Figure 1 , Figure 2 and Figure 3 The method for measuring the accuracy of a regulating valve provided by this invention also includes the common accuracy of the valve body 10 and the base 20. The common accuracy of the valve body 10 and the base 20 is obtained by the following formula:

[0073]

[0074] Wherein, B represents the common precision of valve body 10 and base 20.

[0075] Specifically, by measuring the combined accuracy of the valve body 10 and the base 20, it is determined whether the accuracy of the valve core 50 inside the regulating valve meets the standard. Then, based on the actual situation, the components inside the valve body 10 are adjusted to improve the accuracy, effectively optimizing the reliability of the regulating valve.

[0076] In one embodiment, refer to the appendix to the specification. Figure 3 If A, B, and C are all less than the basic error value, the valve's accuracy is deemed to meet the accuracy standard. If any one of A, B, or C is not less than the basic error value, the valve's accuracy is deemed to not meet the accuracy standard.

[0077] Specifically, a set of experimental data was obtained: the regulating valve stroke was 90mm, and the depth gauges measured L1 = 32.60mm, L2 = 113.50mm, L3 = 33.12mm, and L4 = 114.43mm respectively.

[0078] Then, according to the calculation formula, we know that:

[0079] The free travel of base 20 is 33.12mm - 32.60mm = 0.52mm;

[0080] The common free travel of the base 20 and the valve body is 114.43mm - 113.50mm = 0.93mm;

[0081] The valve body's idle stroke c = 0.93mm - 0.52mm = 0.41mm;

[0082] The accuracy of base 20 is B = 0.52 / 90 × 100% = 0.58%.

[0083] The combined accuracy A of the base 20 and the valve body is 0.93 / 90 × 100% = 1.03%.

[0084] The valve body's precision C = 0.41 / 90 × 100% = 0.46%

[0085] The data above shows that the biggest factor affecting the accuracy of the control valve is the base 20. The method to improve accuracy is to adjust the base 20. Furthermore, according to the mechanical standard "Electric Control Valves for Industrial Process Control" (JB / T7387-2014), the combined accuracy of the valve body 10 and base 20 (1.03%) exceeds the 1.0 grade standard by 1%. Therefore, it can be basically determined that this control valve as a whole is unlikely to meet the requirements of grade 1.0 for basic error, hysteresis, and dead zone.

[0086] It should be noted that the above embodiments can be freely combined as needed. The above are merely preferred embodiments of the present invention. It should be pointed out that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for measuring the accuracy of a regulating valve, characterized in that, The regulating valve includes a valve body, an actuator connected to the valve body, and a flow channel inside the valve body. A valve core is disposed within the flow channel, and an outlet is provided at one end of the flow channel. A transmission rod is drivenly connected to the valve core. A base is provided on the side of the actuator near the valve body. A transmission nut is sleeved on the transmission rod through the base. When the transmission nut is rotated, the transmission rod can move closer to or further away from the flow channel, so that the valve core can move along the flow channel. The method for measuring the accuracy of the regulating valve includes the following steps: Measure the distance between the free end of the transmission rod and the base before rotation, and the distance between the valve core and the outlet before rotation; Rotate the transmission nut N turns in the forward direction; Rotate the transmission nut in the opposite direction N turns; Measure the distance between the free end of the transmission rod and the base after rotation, and the distance between the valve core and the outlet after rotation; The accuracy of the regulating valve is determined by the distance between the free end of the transmission rod and the base before rotation, the distance between the valve core and the outlet before rotation, the distance between the free end of the transmission rod and the base after rotation, and the distance between the valve core and the outlet after rotation.

2. The method for measuring the accuracy of a regulating valve according to claim 1, characterized in that, The accuracy of the regulating valve is determined using the following formula: Wherein, L1 is the distance between the free end of the transmission rod and the base before rotation, L2 is the distance between the valve core and the outlet before rotation, L3 is the distance between the free end of the transmission rod and the base after rotation, L4 is the distance between the valve core and the outlet after rotation, and L is the rated stroke of the regulating valve.

3. The method for measuring the accuracy of a regulating valve according to claim 2, characterized in that, Before measuring the distance between the free end of the transmission rod and the base before rotation, and the distance between the valve core and the outlet before rotation, the procedure further includes the step of removing the actuator while retaining the base.

4. The method for measuring the accuracy of a regulating valve according to claim 3, characterized in that, Between the steps of removing the actuator and retaining the base, and measuring the distance between the free end of the transmission rod and the base before rotation, and the distance between the valve core and the outlet before rotation, the following step is also included: rotating the transmission nut in the forward direction, and stopping the rotation of the transmission nut when the valve core begins to move.

5. The method for measuring the accuracy of a regulating valve according to claim 4, characterized in that, Between the steps of measuring the distance between the free end of the transmission rod and the base before rotation, and the distance between the valve core and the outlet before rotation, and the step of rotating the transmission nut N turns in the forward direction, there is also a step of setting an aligned mark group on the transmission nut and the base.

6. The method for measuring the accuracy of a regulating valve according to claim 5, characterized in that, The marking group includes a first marking line and a second marking line, which are respectively disposed on the transmission nut and the base, and correspond to each other on the same straight line.

7. The method for measuring the accuracy of a regulating valve according to any one of claims 1-6, characterized in that, If the valve core does not shift after rotating the transmission nut N turns in the opposite direction, then proceed with the following steps: rotate the transmission nut 2N turns in the forward direction and then rotate the transmission nut 2N turns in the reverse direction.

8. The method for measuring the accuracy of a regulating valve according to claim 7, characterized in that, Also includes: The accuracy of the base is determined using the following formula: Where A represents the precision of the base.

9. The method for measuring the accuracy of a regulating valve according to claim 8, characterized in that, Also includes: The common accuracy of the valve body and the base is calculated using the following formula: Wherein, B represents the combined precision of the valve body and the base.

10. The method for measuring the accuracy of a regulating valve according to claim 8 or 9, characterized in that, If A, B, and C are all less than the basic error value, the accuracy of the regulating valve is determined to meet the accuracy standard. If any one of A, B, or C is not less than the basic error value, the accuracy of the regulating valve is determined to not meet the accuracy standard.

Images