JPS6086419A - Apparatus for measuring flow rate of fluid - Google Patents
Apparatus for measuring flow rate of fluidInfo
- Publication number
- JPS6086419A JPS6086419A JP19344683A JP19344683A JPS6086419A JP S6086419 A JPS6086419 A JP S6086419A JP 19344683 A JP19344683 A JP 19344683A JP 19344683 A JP19344683 A JP 19344683A JP S6086419 A JPS6086419 A JP S6086419A
- Authority
- JP
- Japan
- Prior art keywords
- deviation
- flow rate
- measured value
- differential pressure
- low flow
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
- G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
- G01F1/363—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction with electrical or electro-mechanical indication
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Volume Flow (AREA)
Abstract
Description
【発明の詳細な説明】
〔発明の技術分野〕
本発明はオリフィス、ノズル等の絞シ機構を用いた流体
の流量測定装ｆｌＫ関する。DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a fluid flow rate measuring device flK using a throttling mechanism such as an orifice or a nozzle.
流体の流量測定方法としてオリフィス、ノズル等の絞り
機構を流体の通過する導管内に設置し、絞り機構の上流
側の圧力上下流側の圧力との差（差圧）から流体の流量
を測定する方法が一般に行なわれている。そして測定値
がプロセス制御等に用いられる場合等特に信頼度を要求
される場合、測定値の妥当性を判断するために１つの絞
り機構に複数の差圧検出器を設け、そのうちの２つの測
定値の偏差の大小によって２つの測定値の妥当性全判断
している。すなわち、偏差があらかじめ決められた許容
偏差を越えた場合に、入力不良として警報を発したり、
測定を中止したり、この測定値を用いている制御を中止
し７Ｉｊｖすることが行なわれる。To measure fluid flow rate, a restriction mechanism such as an orifice or nozzle is installed in a conduit through which the fluid passes, and the fluid flow rate is measured from the difference (differential pressure) between the pressure on the upstream side of the restriction mechanism and the pressure on the downstream side. The method is commonly used. When reliability is particularly required, such as when measured values are used for process control, etc., multiple differential pressure detectors are installed in one throttle mechanism to determine the validity of the measured values, and two of them are used to measure The validity of two measured values is determined based on the magnitude of the deviation of the values. In other words, if the deviation exceeds a predetermined tolerance, an alarm will be issued as an input failure, or
Measurement is stopped or control using this measured value is stopped and 7Ijv is performed.
しかしながら、絞り機構ケ用いた流量計測方法では低流
量域での流量測定誤差が大きく、従来許容偏差が全流量
域で一足であったために、低流量時に人力した差圧のわ
ずかな誤差によって偏差が許容偏差を逸脱して頻繁に警
報が発生したり、流量がＯから徐々に増加している迷中
の低流量域で、偏差大となって、この測定値を用いてい
る制御を中止されるといった不具合が発生していた。However, the flow rate measurement method using a throttling mechanism has a large flow rate measurement error in the low flow rate range, and conventionally the allowable deviation was one foot over the entire flow rate range, so a slight error in the manually applied differential pressure at low flow rates can cause deviations. If the tolerance deviation is exceeded and alarms are generated frequently, or in a low flow area where the flow rate is gradually increasing from O, the deviation becomes large and the control using this measured value is stopped. Problems such as this were occurring.
以下に低流量時の流量測距誤差について説明する。流量
を絞り機構の上流側、下流側の圧力の差（差圧）からめ
る場合、流量は差圧の平方根に比例し、低流量時には差
圧の誤差に対する流量変化が大きく誤差が大きくなる。The flow rate measurement error at low flow rates will be explained below. When the flow rate is calculated from the difference in pressure between the upstream side and the downstream side of the throttle mechanism (differential pressure), the flow rate is proportional to the square root of the differential pressure, and at low flow rates, the flow rate change with respect to the error in the differential pressure is large, and the error becomes large.
第１図は差圧Ｐと流量Ｑとの関係を表わした図であり、
横軸が差圧Ｐ、縦軸が流量Ｑであり、流量Ｑは差圧Ｐの
平方根に比例する。胃流量時は差圧の変化△Ｐ２に対す
る流量の変化△Ｑ２は小さいが、低流量時の差圧の変化
ΔＰ４に対する流量の変化ΔＱ４はこれに比べ大きくな
る。したがって低流“量時すなわち低差圧時の計測した
差圧の誤差は流量に変換するときわめて大きな誤差とな
る。FIG. 1 is a diagram showing the relationship between differential pressure P and flow rate Q.
The horizontal axis is the differential pressure P, the vertical axis is the flow rate Q, and the flow rate Q is proportional to the square root of the differential pressure P. At the time of gastric flow, the change in flow rate ΔQ2 with respect to the change in differential pressure ΔP2 is small, but the change in flow rate ΔQ4 with respect to the change in differential pressure ΔP4 at the time of low flow rate is larger than this. Therefore, the error in the differential pressure measured when the flow rate is low, that is, when the differential pressure is low, becomes an extremely large error when converted to a flow rate.
本発明の目的は測定値の誤差が大きくなる低流量時に発
生する測定値の偏差大によって、頻繁に警報が発生した
り、測定値の用いられている制御が中止されたりするこ
とを防止することにある。 −〔発明の概要〕
本発明は絞り機構と差圧検出器を用いた流体の流量計測
装置に関して差圧検出器を複数台設け、複数の測定値を
得て、これらを相互に比較し、その偏差の大小で測定値
の妥当性を判断し、その結果から複数の測定値から妥当
な測定値を決定する流量の計測装置であり、測定誤差の
大きい低流量時には許容偏差を大きくすることによって
、低流量時の頻繁な偏差大警報の発生計測中止等を防止
することを特徴とする。The purpose of the present invention is to prevent frequent alarms from being generated or control using measured values to be stopped due to large deviations in measured values that occur at low flow rates when the errors in measured values become large. It is in. - [Summary of the Invention] The present invention relates to a fluid flow rate measuring device using a throttle mechanism and a differential pressure detector. This is a flow rate measuring device that determines the validity of a measured value based on the magnitude of the deviation, and then determines a valid measured value from multiple measured values.By increasing the allowable deviation at low flow rates with large measurement errors, It is characterized by preventing frequent occurrence of large deviation alarms and suspension of measurement during low flow rates.
以下本発明の一実施例を第２図および第３図を参照して
説明する。第２図は本発明の実施例を示す流量計測装置
の全体構成図である。２１は流体の流れる導管、２２は
導管内に設けられた絞り機構の一種でおるオリアイス２
３．２４はオリフィスの上流側と下流側の差圧を検出し
これを電気信号に変換する差圧検出器、２５はこの電気
信号を入力する入力装置、２６は入力装置より２つの差
圧信号を入力しこれらを流量に変換する入力処理手段、
２７は変換された２つの流量の偏差人を検出する偏差大
検用手段、２８は偏差太検出手段に許容偏差を指示する
許容偏差選択手段、２９は２つの流量から妥当な測定値
を決定する妥当測定値決定手段であり、３０は偏差大検
出時にしかるべき処理を行なう偏差入処理手段である。An embodiment of the present invention will be described below with reference to FIGS. 2 and 3. FIG. 2 is an overall configuration diagram of a flow rate measuring device showing an embodiment of the present invention. Reference numeral 21 indicates a conduit through which fluid flows, and 22 indicates an oriice 2, which is a type of throttling mechanism provided within the conduit.
3.24 is a differential pressure detector that detects the differential pressure between the upstream and downstream sides of the orifice and converts it into an electrical signal, 25 is an input device that inputs this electrical signal, and 26 is a differential pressure signal that receives two differential pressure signals from the input device. input processing means that inputs and converts these into flow rates;
27 is a large deviation detection means for detecting the deviation of the two converted flow rates; 28 is an allowable deviation selection means for instructing the deviation detection means to an allowable deviation; and 29 is for determining an appropriate measured value from the two flow rates. It is a valid measured value determining means, and 30 is a deviation input processing means that performs appropriate processing when a large deviation is detected.
第３図は第２図における入力処理手段２６、偏差大検用
手段２７、許容偏差選択手段２８、妥当測定値決定手段
２９、偏差入処理手段３０の動作全示すフローチャート
である。３１．３２は入力処理手段２６で行なわれ、３
１は入力装置を用いて差圧検出器よりの電気信号を入力
し、これ以降の処理に適し比信号に変換する処理であり
、３２は２つの差圧検出器の測定した差圧Ｄ１．Ｄｔ’
ｒそれぞれ流量ｆ、、ｆ、に変換する処理である。ｆ、
、ｆ、は第２図に示すように、偏差大検用手段２７．許
容偏差選択手段２８、妥当測定値決定手段２９へ送られ
る。FIG. 3 is a flowchart showing all the operations of the input processing means 26, the large deviation inspection means 27, the allowable deviation selection means 28, the appropriate measured value determination means 29, and the deviation input processing means 30 in FIG. 31 and 32 are performed by the input processing means 26, and 3
1 is a process of inputting an electrical signal from a differential pressure detector using an input device and converting it into a ratio signal suitable for subsequent processing, and 32 is a process of inputting an electrical signal from a differential pressure detector using an input device, and 32 is a process of inputting an electrical signal from a differential pressure detector using an input device, and 32 is a process of inputting an electrical signal from a differential pressure detector using an input device, and converting it into a ratio signal suitable for subsequent processing. Dt'
This process converts r into flow rates f, , f, respectively. f,
, f, as shown in FIG. It is sent to the allowable deviation selection means 28 and the appropriate measured value determination means 29.
３５は許容備差選択手段２８にて行なわれ、計測した流
：１１ｔ ｆ１＋ ｆｔの大小によって２つの測定値の
許容偏差として厳しい値ｆＬ１と緩い値ｆｒ、ｔのどち
らを選択するかを判断する処理であり、２つの測定され
た流量ｆ、とｆ２の算術平均があらかじめ決められた許
容偏差切換値ｆｏｅ：ｖ大きいかどうかでｆＬｌまたは
ｆＩ、ｔが選択される。許容偏差ｆＬ１ 、ｆＬｌ及び
許容偏差切換値ｆＤは流量計測範囲、差圧検出器の精度
、要求されている計測精度等を勘案して決定されるがた
とえば次の様な基準で決定できる。35 is carried out by the tolerance selection means 28, and is a process of determining which of the strict value fL1 and the relaxed value fr, t should be selected as the tolerance deviation between the two measured values, depending on the magnitude of the measured flow: 11t f1 + ft. fLl or fI,t is selected depending on whether the arithmetic mean of the two measured flow rates f and f2 is greater than a predetermined tolerance deviation switching value foe:v. The allowable deviations fL1, fLl and the allowable deviation switching value fD are determined by taking into account the flow rate measurement range, the accuracy of the differential pressure detector, the required measurement accuracy, etc., and can be determined based on, for example, the following criteria.
差圧検出器のもつ誤差を流量に換′Ｎすると、流量の誤
差は低流量になる程大きくなる７、この誤差が要求精度
をみたすための許容誤差ｆｍを越える点を許容偏差切換
値ｆＤとし、この値以上では許容偏差ｆＬ１を許容誤差
ｆＩ１１＆シこれ以下では偏差大が頻繁に発生しない程
度の値にすることにより許容偏差切換値ｆＤ以上の流量
計測時は要求精度を保つよう偏差太監視を行ない、ｆＤ
以下の流量計測時は頻繁に偏差大とならない様調整でき
る。When the error of the differential pressure detector is converted into a flow rate, the error in the flow rate becomes larger as the flow rate becomes lower7.The point at which this error exceeds the tolerance fm to satisfy the required accuracy is defined as the tolerance switching value fD. , above this value, the allowable deviation fL1 is set to a value that does not cause large deviations frequently, and below this value, the deviation is monitored to maintain the required accuracy when measuring the flow rate above the allowable deviation switching value fD. conduct, fD
Adjustments can be made to prevent frequent deviations when measuring the following flow rates.
３６．３７は偏差大検用手段２７で行なわれ３５で選択
され次許容偏差ｆＬ１またはｆＬｇｔ’２つの測足流ｉ
ｔ： ｆ＋ 、 ｈ間の偏差が越えているかどうかの判
断を行なう処理であり、許容偏差として厳しい値ｆＬｌ
が選択されていれば３６の処理が行なわれ、緩い値ｆＬ
２が選択されていれば３７の処理が行なわれる。３６
、３７の処理では、２つの測定値の偏差が選択されてい
る許容偏差より大のときは偏差入処理手段３０にて３８
の偏差犬侍の処理が行なわれ警報の出力や、この測’？
Ｌ （ｔｉ、 ｆ：用いている制御の中止等の処理全行
ない、許容偏差以下であれば、測定値は妥当な値である
として、妥当測定値状足手段２９によりたとえば両者の
平均値金とって測定値とする３９の処理が行なわれる。36.37 is carried out by the large deviation checking means 27, and the next allowable deviation fL1 or fLgt' selected in 35 is the two measurement flows i.
t: This is a process to judge whether the deviation between f+ and h exceeds the strict value fLl as an allowable deviation.
is selected, 36 processes are performed and a loose value fL
If 2 is selected, processing 37 is performed. 36
, 37, when the deviation between the two measured values is larger than the selected tolerance deviation, the deviation input processing means 30
The deviation of Inu Samurai is processed and the alarm output or this measurement'?
L (ti, f: If all processes such as stopping the control being used have been carried out and the measured value is below the allowable deviation, the measured value is considered to be a valid value, and the valid measured value footing means 29 calculates, for example, the average value of both. 39 processes are performed to obtain a measured value.
以上の処理によって低流量時には２つの測定値の許容偏
差を中高流量時より大とすることができる。By the above processing, the allowable deviation between the two measured values can be made larger at low flow rates than at medium and high flow rates.
以上の説明のように絞り機構と多重化された差圧検出器
上用いた流量計測装置に関して、多重化された差圧検出
器の複数の測定値の偏差の大小によって測定値の妥当性
を判断し、その結果によつ測定誤差の大きくなる低流量
時に頻繁に偏差大となって入力不良として警報が発生し
たり、測定値を用いて行なわれている制御を中止したり
することが抑制でき、かつ本来偏差大全検出すべき中高
流量域では従来の偏差大監視を行なうことが可能である
。As explained above, regarding the flow rate measuring device used on the throttle mechanism and the multiplexed differential pressure detector, the validity of the measured value is determined based on the magnitude of the deviation of multiple measured values of the multiplexed differential pressure detector. As a result, it is possible to prevent deviations from frequently occurring at low flow rates, where measurement errors become large, resulting in alarms due to input failures, or from stopping control that is being performed using measured values. , and it is possible to carry out conventional large deviation monitoring in medium and high flow rate ranges where all deviations should be detected.
第１図は絞り機構を用いた流体の流量測定において、計
測した差圧と流量との関係を示す特性図、第２図は本発
明の実施例を示す流量計測装置の全体構成図、第３図は
本発明の流量計測装置の動作を示すフローチャートであ
る。
２１・・・導管 ２２・・・オリフィス２３ 、２４・
・・差圧検出器 ２５・・・入力装置２６・・・入力処
理手段 ２７・・・偏差大検山手段２８・・・許容偏差
検出手段
２９・・・妥当測定値状足手段
３０・・・偏差入処理手段Fig. 1 is a characteristic diagram showing the relationship between the measured differential pressure and the flow rate in fluid flow rate measurement using a throttle mechanism, Fig. 2 is an overall configuration diagram of a flow rate measuring device showing an embodiment of the present invention, and Fig. 3 The figure is a flowchart showing the operation of the flow rate measuring device of the present invention. 21... Conduit 22... Orifice 23, 24.
... Differential pressure detector 25 ... Input device 26 ... Input processing means 27 ... Large deviation detection means 28 ... Allowable deviation detection means 29 ... Valid measurement value foot means 30 ... Deviation input processing means
Claims (1)
上流側と下流側の圧力差を検出する複数の差圧検出器と
、これら検出器からの信号を入力装置を介して読込む入
力処理手段と、複数の検出器からの測定値の偏差を検出
する偏差検出手段と、測定誤差の大きい低流量時には大
きい許容偏差を選択し測定誤差の小さい高流量時には小
さい許容偏差を選択する許容備差選択手段と、前記偏差
検出手段で検出された測定値の偏差が前記許容偏差より
大のときは警報を出力しそれ以外のときは妥当な測定値
全算出する偏差検出手段とからなる流体の流量測定装置
。A throttling mechanism installed in a conduit through which fluid flows, multiple differential pressure detectors that detect the pressure difference between the upstream and downstream sides of the throttling mechanism, and input processing that reads signals from these detectors via an input device. a deviation detection means for detecting the deviation of measured values from multiple detectors; and a tolerance detection means for selecting a large tolerance deviation at low flow rates with a large measurement error and selecting a small tolerance deviation at high flow rates with a small measurement error. A fluid flow rate comprising a selection means and a deviation detection means that outputs an alarm when the deviation of the measured value detected by the deviation detection means is larger than the permissible deviation, and otherwise calculates all reasonable measured values. measuring device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19344683A JPS6086419A (en) | 1983-10-18 | 1983-10-18 | Apparatus for measuring flow rate of fluid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19344683A JPS6086419A (en) | 1983-10-18 | 1983-10-18 | Apparatus for measuring flow rate of fluid |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS6086419A true JPS6086419A (en) | 1985-05-16 |
Family
ID=16308124
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19344683A Pending JPS6086419A (en) | 1983-10-18 | 1983-10-18 | Apparatus for measuring flow rate of fluid |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6086419A (en) |
-
1983
- 1983-10-18 JP JP19344683A patent/JPS6086419A/en active Pending
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