JP5357478B2 - Differential pressure type flow measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a differential pressure flow measuring apparatus which can measure a plurality of fluid flows with different measurement ranges even by a single apparatus, without affecting the cleanliness of a fluid, or an object under measurement, and easily. <P>SOLUTION: The differential pressure flow measuring apparatus 10A arranges a first pressure detection section 20 and a second pressure detection section 25 for detecting the fluid pressure of the fluid under measurement through a pressure loss section 30. The apparatus includes a connecting flow channel 40 which connects the first pressure detection section 20 and the second pressure detection section 25 through a single flow channel, an on-off valve 60A which is arranged in the connecting flow channel 40 and has a poppet valve member 65A through which a through hole 66 is formed, and an arithmetic section 80 for controlling the opening/closing operation of the on-off valve 60A. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a differential pressure type flow rate measuring device in which a first pressure detection unit and a second pressure detection unit that detect a fluid pressure of a fluid to be measured are arranged via a pressure loss unit.

  There are various flow sensors such as a rotary flow sensor, a float flow sensor, an ultrasonic flow sensor, a Karman vortex flow sensor, and the like as flow sensors for measuring the flow rate of fluid. The rotary flow sensor and the float type flow sensor have a problem that particles (fine dust) are generated in the flow path when the impeller and the float move in the flow path. Ultrasonic flow rate sensors and Karman vortex flow rate sensors are vulnerable to bubbles generated during the flow of fluid (liquid) and have problems such as variations in accuracy due to fluid disturbance. In particular, it has been difficult to use in environments where high cleanliness is required, such as semiconductor manufacturing and medical sites, and sites where foaming fluid is used.

  A differential pressure type flow sensor is known as a flow sensor that solves the above problems. In the conventional differential pressure type flow sensor, two pressure detection parts (pressure sensors) are arranged in a fluid flow path with a pressure loss part (orifice) sandwiched between them, and a differential pressure is generated before and after the orifice. The flow rate is measured based on the detected pressure difference between the fluid pressures (see, for example, Patent Documents 1, 2, and 3).

  Currently, when the flow rate is measured using the differential pressure type flow rate sensor, a differential pressure type flow rate sensor corresponding to an assumed flow rate measurement range is arranged in the distribution line. When changing the measured flow rate outside the flow measurement range of the flow sensor currently in use, an unexpected pressure fluctuation occurs, so the flow measurement range of the flow sensor must be changed to correspond to the fluctuating pressure. Goodbye. When changing the flow rate measurement range, the measurement range that can be measured by a single orifice is limited, so the orifice arranged in the flow path can be replaced with an orifice corresponding to another measurement range, or a difference can be made. It was necessary to replace the pressure type flow rate sensor itself with a flow rate sensor having a different measurement range.

  However, when exchanging the orifice or the flow sensor itself, the flow of the fluid must be temporarily stopped to remove or install the orifice or the flow sensor. Such replacement work is laborious, and since a plurality of flow sensors must be arranged at all times, the cost of the equipment is also increased. In particular, when exchanging the orifice, there is a possibility of contamination such as dust mixing into the flow path during the exchanging operation, which may adversely affect the fluid to be circulated and the cleanliness of the usage environment. Concerned. For this reason, there is a demand for a differential pressure type flow rate sensor having a large range ability that can maintain optimum measurement accuracy corresponding to various flow rate regions.

Thus, in one apparatus, a differential pressure type flow measuring device that can easily measure different fluid flow rates in a plurality of measurement ranges (measurement ranges) without affecting the cleanliness of the fluid to be measured has been required. .
JP 2007-78383 A JP 2006-153677 A JP 2006-250955 A

  The present invention has been made in view of the above points, and can easily measure different fluid flow rates in a plurality of measurement ranges without affecting the cleanliness of the fluid to be measured while being a single device. The present invention provides a differential pressure type flow rate measuring apparatus capable of achieving the above.

In other words, the first aspect of the present invention is the differential pressure type flow rate measuring device in which the first pressure detection unit and the second pressure detection unit that detect the fluid pressure of the fluid to be measured are arranged via the pressure loss unit . The pressure detection unit and the second pressure detection unit are arranged with respect to the fluid to be measured via a protective film made of a diaphragm, and a single space is provided between the first pressure detection unit and the second pressure detection unit. And a poppet valve body that is disposed in the connection flow path portion, is formed integrally with the diaphragm portion and has a through-hole, and the poppet valve body is in the valve chamber. Is controlled to open and close with respect to the outlet having the pressure loss portion, and when the outlet is closed, the inlet side flow path to the valve chamber and the outlet side from the valve chamber through the through hole The fluid to be measured flows through the through hole in communication with the flow path. Differential pressure, wherein the on-off valve unit to generate a differential pressure, that an arithmetic unit for controlling the opening and closing operation of the movable valve between said inlet-side flow path and the outlet side flow passage when The present invention relates to a flow measurement device.

According to a second aspect of the present invention, in the differential pressure type flow rate measuring device in which the first pressure detection unit and the second pressure detection unit that detect the fluid pressure of the fluid to be measured are arranged via the pressure loss unit, the first pressure detection And the second pressure detection unit are arranged with respect to the fluid to be measured via a protective film made of a diaphragm, and a single flow is provided between the first pressure detection unit and the second pressure detection unit. A connection flow path portion connected by a passage, and a needle valve body that is disposed in the connection flow path section, is formed integrally with the diaphragm section and is formed in a multistage shape, and the needle valve body is formed in the valve chamber Opening and closing of the outlet having the pressure loss portion is controlled to open and close, and the opening amount of the outlet is varied in accordance with the insertion state of the needle valve body with respect to the outlet, so that the fluid to be measured flows to the outlet. Inflow side flow into the valve chamber when flowing through the outlet Differential pressure type flow measuring device comprising a movable valve that causes a pressure differential, that an arithmetic unit for controlling the opening and closing operation of the movable valve between the outlet side flow path from the valve chamber and Concerning.

According to a third aspect of the present invention, all of the first pressure detection unit, the second pressure detection unit, the connection flow path unit, and the on-off valve unit are arranged in a single body block. It concerns on the differential pressure type flow measurement apparatus of any one of claim | item 1 or 2 .

The differential pressure type flow rate measuring apparatus according to claim 1 is a differential pressure type flow rate measuring apparatus in which a first pressure detecting unit and a second pressure detecting unit for detecting a fluid pressure of a fluid to be measured are arranged via a pressure loss unit. The first pressure detection unit and the second pressure detection unit are disposed via a protective film made of a diaphragm with respect to the fluid to be measured, and the first pressure detection unit and the second pressure detection unit And a poppet valve body that is disposed in the connection flow path portion, is formed integrally with the diaphragm portion and has a through-hole formed therein. The valve body is controlled to be opened and closed with respect to the outlet having the pressure loss portion in the valve chamber, and the inlet side flow path to the valve chamber and the valve via the through hole when the outlet is closed. The fluid to be measured is communicated with the outflow side flow path from the chamber. Because having a movable valve to cause pressure differential between said inlet-side flow path and the outlet side flow passage when flowing through the through hole, and a computing unit for controlling the opening and closing operation of the on-off valve unit, one In this apparatus, it is possible to easily measure different fluid flow rates in a plurality of measurement ranges without affecting the cleanliness of the fluid to be measured.

The differential pressure type flow rate measuring device according to the invention of claim 2 is a differential pressure type flow rate measuring device in which a first pressure detecting unit and a second pressure detecting unit for detecting a fluid pressure of a fluid to be measured are arranged via a pressure loss unit. The first pressure detection unit and the second pressure detection unit are disposed via a protective film made of a diaphragm with respect to the fluid to be measured, and the first pressure detection unit and the second pressure detection unit A connection flow path portion that connects the two with a single flow path, and a needle valve body that is disposed in the connection flow path portion, is formed integrally with the diaphragm portion, and is formed in a multistage shape. The valve body is controlled to open and close with respect to the outlet having the pressure loss portion in the valve chamber, and the opening amount of the outlet is varied according to the insertion state of the needle valve body with respect to the outlet. The fluid to be measured flows through the outlet. An opening and closing valve portion to cause a pressure differential between the outflow side flow path from the valve chamber and the inflow side flow path to the valve chamber, because of an arithmetic unit for controlling the opening and closing operation of the movable valve In addition to being less susceptible to thermal deformation , the valve body portion can easily measure different fluid flow rates in a plurality of measurement ranges without affecting the cleanliness of the fluid to be measured even though it is a single device. .

A third aspect of the present invention is the main body block according to the first or second aspect , wherein the first pressure detection unit, the second pressure detection unit, the connection flow path unit, and the on-off valve unit are all a single body block. Therefore, it is possible to reduce the number of parts and the like, thereby realizing simplification and miniaturization of the apparatus, and easy management of maintenance and the like.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
1 is a longitudinal sectional view of a differential pressure type flow rate measuring apparatus according to a first embodiment of the present invention, FIG. 2 is a longitudinal sectional view of an on-off valve portion having a poppet valve body, and FIG. 3 is a differential pressure type flow rate according to a second embodiment. FIG. 4 is a longitudinal sectional view of a measuring device, FIG. 4 is a longitudinal sectional view of an on-off valve portion having a needle valve body, and FIG. 5 is a sectional view of a main part of a needle valve body formed in a multistage shape.

  In the differential pressure type flow rate measuring apparatus 10A according to the first embodiment of the present invention shown in FIG. 1, the first pressure detecting unit 20 and the second pressure detecting unit 25 for detecting the fluid pressure of the fluid to be measured are used as the pressure loss unit 30. And a connection flow path portion 40 that connects the first pressure detection section 20 and the second pressure detection section 25 with a single flow path, and an on-off valve section 50 disposed in the connection flow path section 40. And a calculation unit 80 for controlling the opening / closing operation of the opening / closing valve unit 50. In FIG. 1, reference numeral 12 denotes an inflow channel for a fluid to be measured, 13 denotes an outflow channel for the fluid to be measured, 15 denotes an electropneumatic regulator, 41 denotes an inflow side channel of the connection channel unit 40, and 42 denotes a connection channel unit. 40 outflow channels are shown.

  In this differential pressure type flow rate measuring apparatus 10A, as shown in the figure, all of the first pressure detection unit 20, the second pressure detection unit 25, the connection flow path unit 40, and the on-off valve unit 50 are a single body block. 11 is configured to be disposed in the inside. The single main body block 11 includes a first block 11a and a second block 11b, and is integrally formed by a bolt or the like (not shown).

  In addition, the member in contact with the fluid to be measured in the main body block 11, the pressure detection parts 20 and 25, the pressure loss part 30, the connection flow path part 40, the on-off valve part 50, etc. Formed from. The fluororesin that is the material of the member is PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxyalkane), FEP (perfluoroethylene propene copolymer), PVDF (polyvinylidene fluoride), or the like. These fluororesins are selected in consideration of the properties of the flowing fluid, ease of processing, and the like. Thereby, it is suppressed that the cleanliness is influenced at the time of measurement of the fluid to be measured.

  The first and second pressure detectors 20 and 25 are arranged via a protective film (not shown) such as a diaphragm with respect to the fluid to be measured, and the load from the protective film pressed by the pressure of the fluid to be measured A known pressure sensor for detecting the pressure is used. As shown in FIG. 1, the first pressure detection unit 20 is arranged on the inflow channel 12 side (upstream primary side) of the main body block 11, and the second pressure detection unit 25 is on the outflow channel 13 side of the main body block 11. (Secondary side downstream). In this figure, reference numeral 21 denotes a signal line for transmitting a pressure signal detected by the first pressure detection unit 20 to the calculation unit 80 described later, and 26 denotes a pressure signal detected by the second pressure detection unit 25 to the calculation unit 80. This is a signal line for transmission.

  The pressure loss unit 30 is configured to generate a predetermined differential pressure between the fluid pressure detected by the first pressure detection unit 20 and the fluid pressure detected by the second pressure detection unit 25 by narrowing the flow path area. The The pressure loss part 30 of an Example is comprised as the well-known orifice part 31 which can be attached or detached.

  As shown in FIGS. 1 and 2, the on-off valve portion 50 is configured as a poppet valve device 60A having a poppet valve body 65A in which a through hole 66 is formed. In FIGS. 1 and 2, reference numeral 62 denotes a valve chamber formed in the connection flow path section 40, 63 denotes an inlet through which the fluid to be measured flows into the valve chamber 62 from the inflow side flow path 41, and 64 denotes a valve for the fluid to be measured Outlet that flows out from the chamber 62 to the outflow side passage 42, 67 is a diaphragm part integrally formed with the poppet valve body 65A, 70 is an operating mechanism (cylinder device) of the poppet valve body 65A, 71 is its cylinder chamber, 72 is a partition block that divides the cylinder chamber 71 and the valve chamber 62, 73 is a piston member connected to the poppet valve body 65A, 74 and 75 are inflow / outflow portions of the working fluid for moving the piston member 73 forward and backward, and 76 is an air vent portion , 77 is an attachment member for the poppet valve body 65A, and 78 is an elastic member made of a spring that biases the poppet valve body 65A in the forward direction.

  In this poppet valve device 60A, the orifice portion 31 is disposed at the outflow port 64, and the poppet valve body 65A is advanced and retracted with respect to the outflow port 64 in the valve chamber 62 so as to be opened and closed. In the embodiment, the electropneumatic regulator 15 supplies and stops air (working fluid) for moving the poppet valve body 65A forward and backward based on a signal from the calculation unit 80 described later. Thereby, the flow of the fluid flowing out from the outlet 64 is controlled.

  Further, since the through-hole 66 is formed in the poppet valve body 65A, the inflow side channel 41 and the outflow side channel 42 are communicated with each other through the through hole 66 when the outflow port 64 is closed. When the fluid to be measured flows, a pressure difference is generated between the inflow side flow channel 41 and the outflow side flow channel 42 because the flow channel area is narrowed by the through hole 66. Therefore, the through hole 66 acts as a pressure loss part 30 different from the orifice part 31 arranged at the outlet 64.

  The calculation unit 80 includes a known calculation means such as a PLC. The calculation unit 80 corresponds to the value of the differential pressure corresponding to the flow area of the orifice 31, the flow rate value determined based on the differential pressure, or their broken line approximation, and the flow area of the through hole 66. The differential pressure value to be measured, the flow value determined based on the differential pressure, or their broken line approximation is stored in advance, and the optimum flow measurement range is set for each stored flow value in consideration of measurement error etc. Is done. In the calculation unit 80 of the embodiment, the differential pressure is calculated based on the pressure value detected by the first pressure detection unit 20 and the pressure value detected by the second pressure detection unit 25, and the differential pressure and flow rate value stored in advance are calculated. The flow rate is measured from the line approximation of the relationship.

  In the differential pressure type flow rate measuring device 10A, when the poppet valve device 60A is in an open state, the fluid to be measured flows in the single connection flow path portion 40 from the inflow side flow path 41 through the orifice section 31 to the outflow side flow path. 42. Therefore, when the poppet valve device 60A is opened, the flow rate is measured based on the differential pressure generated by the orifice portion 31.

  When the poppet valve device 60A is in the closed state, the fluid to be measured flows from the inflow side channel 41 to the outflow side channel 42 through the through hole 66 of the poppet valve body 65A in the single connection channel portion 40. Circulate. Therefore, when the poppet valve device 60A is closed, the flow rate is measured based on the differential pressure generated by the through hole 66.

  Therefore, the operation of the differential pressure type flow measuring device 10A will be described assuming that the flow rate measurable by the orifice 31 is 20 to 100 mL / min and the flow rate measurable by the through hole 66 is 5 to 20 mL / min.

  First, when the fluid to be measured of 100 mL / min is circulated, the poppet valve body 65A of the poppet valve device 60A is operated in an open state based on the operation of the calculation unit 80. At that time, a polyline approximation of the differential pressure value and the flow rate value based on the orifice portion 31 is selected, and a corresponding flow rate measurement range is set.

  Further, when the fluid to be measured of 20 mL / min is circulated, the poppet valve body 65A of the poppet valve device 60A is operated in a closed state based on the operation of the calculation unit 80. At that time, a polyline approximation of the differential pressure value and the flow rate value based on the through hole 66 is selected, and a corresponding flow rate measurement range is set.

  Therefore, in the differential pressure type flow rate measuring device 10A of the present invention, even when the fluid to be measured having different flow rates is switched and circulated, a measurement range corresponding to each target flow rate can be obtained even though it is a single device. It can be set easily.

  The differential pressure type flow rate measuring device 10B according to the second embodiment of the present invention shown in FIG. 3 is an example using a needle valve device 60B having a needle valve body 65B as the on-off valve portion 50. In the following embodiments, the same reference numerals as those in the first embodiment denote the same components, and the description thereof is omitted.

  As shown in FIGS. 3 and 4, the needle valve device 60 </ b> B is controlled to open and close as the needle valve body 65 </ b> B advances and retreats with respect to the outlet 64 in the valve chamber 62. In the embodiment, the electropneumatic regulator 15 supplies and stops air (working fluid) for moving the needle valve body 65B forward and backward based on a signal from the calculation unit 80 described later. Thereby, the flow of the fluid flowing out from the outlet 64 is controlled. At that time, since the opening amount of the outflow port 64 is finely adjusted according to the advance / retreat position of the needle valve body 65B, the outflow port 64 has a differential pressure between the inflow side channel 41 and the outflow side channel 42. It acts as a pressure loss part 30 consisting of the variable orifice part 32 to be generated.

  The calculation unit 80 of the differential pressure type flow rate measuring apparatus 10B stores in advance a differential pressure value corresponding to the flow path area of the variable orifice unit 32, a flow rate value determined based on the differential pressure, or a polygonal line approximation thereof. The optimum flow rate measurement range is set for each flow rate value stored in consideration of measurement errors and the like. In the calculation unit 80 of the embodiment, the differential pressure is calculated based on the pressure value detected by the first pressure detection unit 20 and the pressure value detected by the second pressure detection unit 25, and the differential pressure and flow rate value stored in advance are calculated. The flow rate is measured from the line approximation of the relationship. Note that the flow area of the variable orifice portion 32 is set to an arbitrary value in a stepwise manner within a range from closing to opening (full opening).

  Therefore, regarding the operation of the differential pressure type flow rate measuring device 10B, it is assumed that the flow rate measurable by the variable orifice portion 32 is in an open state (needle valve body 65B is in a retracted position) in a range from an open (fully open) state to a closed state. The description will be made assuming that the setting is made in three stages of 50 to 100 mL / min, 20 to 50 mL / min in the intermediate state (needle valve body 65B is in the intermediate position), and 5 to 20 mL / min in the minimum state (needle valve body 65B is the forward position). .

  First, when a fluid to be measured of 100 mL / min is circulated, the needle valve body 65B of the needle valve device 60B is operated to the open (fully open) position based on the operation of the calculation unit 80. At that time, a polyline approximation of the differential pressure value and the flow rate value based on the open state of the variable orifice portion 32 is selected, and a corresponding flow rate measurement range is set.

  Further, when the fluid to be measured of 50 mL / min is circulated, the needle valve body 65B of the needle valve device 60B is operated to the intermediate position based on the operation of the calculation unit 80. At that time, a polyline approximation of the differential pressure value and the flow rate value based on the intermediate state of the variable orifice portion 32 is selected, and the corresponding flow rate measurement range is set.

  Further, when the fluid to be measured of 20 mL / min is circulated, the needle valve body 65B of the needle valve device 60B is actuated to the advance position based on the operation of the calculation unit 80. At that time, a polyline approximation of the differential pressure value and the flow rate value based on the minimum state of the variable orifice portion 32 is selected, and a corresponding flow rate measurement range is set.

  Therefore, in the differential pressure type flow rate measuring device 10B of the present invention, even if the fluid to be measured having different flow rates is switched and circulated, a measurement range corresponding to each target flow rate can be obtained even though it is a single device. It can be set easily.

  In the differential pressure type flow rate measuring device 10B, the needle valve body 65C formed in a multistage shape shown in FIG. 5 can be used in the needle valve device 60B. Since the needle valve body 65C has a multistage shape, there is an advantage that the valve body 65C portion is less susceptible to thermal deformation.

  The needle valve body 65C of the embodiment is formed in a first valve main body 68a formed in a smaller diameter cylindrical shape of the outflow port 64, and in a further smaller diameter cylindrical shape provided on the forward side of the first valve main body 68a. The second valve body 68b has a multi-stage shape. In the needle valve body 65C, the opening amount of the outflow port 64 can be easily varied according to the insertion state of the valve bodies 68a and 68b with respect to the outflow port 64. That is, when the needle valve body 65C is not inserted into the outflow port 64 (not shown), the opening amount of the outflow port 64 is fully opened (opened). As shown to Fig.5 (a), in the state in which the 2nd valve main body 68b was inserted, the opening amount of the outflow port 64 will be in a state (intermediate state) smaller than a full open state. As shown in FIG. 5B, in the state where the first valve body 68a is inserted, the opening amount of the outlet 64 is smaller than the state where the second valve body 68b is inserted (minimum state).

Above illustrated as described, the differential pressure type flow measuring device 10A of the present invention, the 10B, both without affecting cleanliness of the fluid to be measured, yet one device, conveniently a plurality of measurement range Different fluid flow rates can be measured. Therefore, for example, in the field of semiconductor manufacturing, there is no need to use different flow rate measuring devices with different measurement ranges for each required process, and the equipment burden can be reduced.

  Also, in medical equipment, if the differential pressure type flow rate measuring device is built into an artificial dialysis machine, etc., the patient undergoing dialysis may have different blood volume permeating through the dialysis machine due to differences in the size of infants, children, adults, etc. However, it is not necessary to use a different dialysis machine for each patient, and the work efficiency and equipment burden can be greatly improved.

  Furthermore, by controlling the opening / closing operation of the opening / closing valve section by the calculation section, the switching operation of the pressure loss section can be automatically performed, and the setting of the flow rate measurement range corresponding to the flow rate to be measured is performed easily and efficiently. be able to.

  The differential pressure type flow rate measuring device of the present invention is not limited to the above-described embodiments, and can be implemented by appropriately changing a part of the configuration without departing from the spirit of the invention. For example, a removable orifice part was used as the pressure loss part, but the pressure loss part may have any configuration as long as it can generate a differential pressure by reducing the channel area. For example, an appropriate configuration such as a known venturi tube structure can be adopted.

1 is a longitudinal sectional view of a differential pressure type flow rate measuring apparatus according to a first embodiment of the present invention. It is a longitudinal cross-sectional view of the on-off valve part which has a poppet valve body. It is a longitudinal cross-sectional view of the differential pressure type flow measuring device concerning a 2nd example. It is a longitudinal cross-sectional view of the on-off valve part which has a needle valve body. It is principal part sectional drawing of the needle valve body formed in the multistage shape.

10A, 10 B difference pressure type flow measuring device 20 first pressure sensing portion 25 and the second pressure sensing portion 30 the pressure loss portion 40 connecting flow path 50 on-off valve unit

Claims (3)

In the differential pressure type flow rate measuring device in which the first pressure detection unit and the second pressure detection unit that detect the fluid pressure of the fluid to be measured are arranged via the pressure loss unit,
The first pressure detection unit and the second pressure detection unit are arranged via a protective film made of a diaphragm with respect to the fluid to be measured,
A connection flow path section that connects the first pressure detection section and the second pressure detection section with a single flow path;
The poppet valve body is disposed in the connection flow path portion, is formed integrally with the diaphragm portion and has a through hole formed therein, and the poppet valve body has a pressure loss portion in the valve chamber. The fluid to be measured is controlled by opening and closing and opening and closing, and communicating the inflow side flow path to the valve chamber and the outflow side flow path from the valve chamber through the through-hole when the outflow port is closed. An on- off valve portion for generating a differential pressure between the inflow side flow path and the outflow side flow path when flowing through the through hole ;
A differential pressure type flow rate measuring apparatus comprising: an arithmetic unit that controls an opening / closing operation of the on-off valve unit. In the differential pressure type flow rate measuring device in which the first pressure detection unit and the second pressure detection unit that detect the fluid pressure of the fluid to be measured are arranged via the pressure loss unit,
The first pressure detection unit and the second pressure detection unit are arranged via a protective film made of a diaphragm with respect to the fluid to be measured,
A connection flow path section that connects the first pressure detection section and the second pressure detection section with a single flow path;
A needle valve body that is disposed in the connection flow path portion, is formed integrally with the diaphragm portion and is formed in a multistage shape, and the needle valve body has a pressure loss portion in the valve chamber. The opening and closing of the needle valve body is controlled to advance and retreat, and the opening amount of the outlet is varied according to the insertion state of the needle valve body with respect to the outlet, so that the fluid to be measured flows to the valve chamber when flowing through the outlet. An on- off valve portion that generates a differential pressure between the inflow side flow path of the gas flow and the outflow side flow path from the valve chamber ;
A differential pressure type flow rate measuring apparatus comprising: an arithmetic unit that controls an opening / closing operation of the on-off valve unit. Said first pressure sensing portion, and the second pressure detecting portion, and the connecting flow path, either one of claims 1 or 2 are arranged in a single body block of the on-off valve unit 2. The differential pressure type flow rate measuring device according to item 1.

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