JPS6130716A - Apparatus for measuring flow amount of gas - Google Patents

Abstract

PURPOSE:To miniaturize the titled apparatus and to measure a flow amount without performing correction operation, by providing pressure taking-out holes respectively opened to two chambers formed by partitioning an apparatus main body and a coil shaped fine tube received in one chamber and opened to the other chamber. CONSTITUTION:Pressure taking-out holes 16, 17, which are respectively opened to the inlet side chamber 11 and an outlet side chamber 12 formed by partitioning the inner bore 2 of an apparatus main body 1 by a fine tube mount base 10, are provided to the wall of the main body 1. A stainless fine tube 18, for example, having a coil shape with an inner diameter of 0.58mm., a length of 2,000mm. and a wound-up diameter of 16mm. is received in the inlet side chamber 11 and attached thereto so that one end part thereof is pierced through the fine tube mount base 10 to be opened to a protector 15. Then, a flow amount is calculated on the basis of the pressure difference between gases taken out from both pressure taking-out holes 16, 17 proportional to the flow amount in the fine tube 18 according to an simple operation formula. By this method, the apparatus can be miniaturized and piping work is dispensed with to enable easy repairing work.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a gas flow rate measuring device that measures the flow rate of gas using the pressure difference between two points in the axial direction of a pipe.

[Prior art]

Generally, a laminar flow meter is known as a flow rate measuring device that utilizes pressure drop due to viscous resistance of fluid flowing in a pipe.

Conventionally, this type of flow rate measuring device has been equipped with a thin tube as a viscous resistance tube installed in the middle of the pipeline and a differential pressure detector that measures the pressure difference between the inlet and outlet of this thin tube. has been done.

However, in the case of a fluid that can obtain a laminar flow, that is, a fluid that is incompressible, conventional flow rate measurement devices can measure the flow rate using a simple proportional calculation formula, but if the fluid is compressible like a gas, Calculation correction was required when measuring the flow rate of a fluid, which must take into account the effects of

Furthermore, when the thin tube becomes longer, the distance between the pressure detection parts increases, making it impossible to directly install the differential pressure detector on the main body of the measurement apparatus, resulting in an increase in the size of the apparatus as a whole.

[Summary of the invention]

The present invention has been made in view of the above circumstances, and includes pressure extraction holes that open into two chambers defined by a partition member within the cylindrical measuring device main body, which are provided in the wall of the measuring device main body. With an extremely simple configuration in which the formed thin tube is stored in one chamber and one end of this thin tube is passed through a partition member and opened into the other chamber, correction calculations can be made for gas flow rate measurement using a differential pressure detector. The object of the present invention is to provide a gas flow rate measuring device that not only can be used to measure the amount of gas without having to do so, but also can reduce the size of the entire device. Hereinafter, the configuration and the like will be explained in detail with reference to embodiments shown in the drawings.

〔Example〕

FIG. 1 is a sectional view showing a gas flow rate measuring device according to the present invention;
FIG. 2 is a partially sectional view showing the state of use of the gas flow rate measuring device. In the figure, the reference numeral 1 indicates a cylindrical measuring device main body, with threaded portions 2a near both open ends.
, 2b, and is held between connecting pipes 4 by a through bolt 3. This measuring device body 1
A connecting flange 5 is provided at the open end on the inlet side, and a connecting flange 7 having a through hole 6 is attached to the open end on the outlet side with bolts 8 and gaskets 9 interposed therebetween. lO is the inner hole 2 with the entrance side chamber 11° and the exit side chamber 12
Hole 1 is a thin tube mounting base that serves as a partition member that defines a chamber.
3a and L3b and screwed onto the threaded portion 2a, the seal 1 is pressed onto the stepped portion 2c of the inner hole 2.
Fixed via 4. A hole 15a located inside the holding member 13 is located at the center of the outlet side of the thin tube mounting base 10.
A cylindrical protector 15 is provided. 16
and 17 are the inlet side chamber 11 and the outlet side chamber 12, respectively.
This is a pressure extraction hole that opens inward and is provided in the wall 1a of the measuring device main body l. Reference numeral 18 denotes a thin tube made of a material such as stainless steel, which is housed in the inlet side chamber 11 and fixed to the thin tube attachment heath 10 by soldering. This thin tube 18 has an inner diameter of 0.581 nm, a length of jooom, and is formed into a coil shape with a winding diameter of 160 mm, and one end thereof passes through the thin tube mounting base 10 and opens into the protector 15. . 19 is a cylindrical guide tube having a hole 19a opening into the inlet side chamber 11, and one end thereof is connected to the thin tube 1.
8 and the other end thereof is screwed into the threaded portion 2b. Reference numeral 20 denotes a differential pressure detector incorporating a pressure sensor (not shown), which has a high-pressure side diaphragm 21 and a low-pressure side diaphragm 22, and is installed on the measuring device main body 1.

This differential pressure detector 20 has both diaphragms 21°2
Apply each measured pressure to 2, and the pressure transmission liquid 2 due to these pressures
The pressure sensor is configured to extract the movement of 3 as an electrical output. Further, 24 and 25 are respectively attached to the measuring device main body 1 and are attached to the entrance side chamber 11.
This is a drain drain for draining the drain inside the outlet side chamber 12.

In the gas flow rate measuring device configured in this way, the gas to be measured is introduced from the inlet side of the measuring device body 1 through the guide tube 19. It passes through the entrance side chamber ll and enters into i from one end of the thin tube 18. Then, the gas to be measured becomes a laminar flow or a nearly muddy flow within the thin and long tube, loses to the other end of the thin tube 18, and is ejected into the protector 15, that is, into the outlet side chamber 12 of the measuring device main body 1. At this time, pressures PI and P are taken out from the pressure extraction holes 16 and 17, respectively, and the high pressure side diaphragm 21. It is applied to the low pressure side diaphragm 22. Here, a pressure difference is generated between the pressures P and P2 due to the viscous resistance of the gas to be measured due to the flow inside the thin tube 18. Then, the pressure sensor detects the difference in the amount of movement of the pressure transmission liquid 23 caused by the depression of each diaphragm 21 and 22, and transmits this as an electric signal, thereby measuring the pressure difference and determining the flow rate of the gas to be measured. I can do it. in this case,
Plotting the pressure differences P and -Pg for each flow rate shows that the linearity characteristics are very similar to those obtained when using a laminar flowmeter, and the reproducibility is also good. It will be done.

In the present invention, as shown in FIG. 3(a), a guide tube 26 and a liner 27 having a small diameter inner hole 26a are used, and as shown in FIG. By using the spacer 28, the volume inside the inlet side chamber 11 can be reduced, and response delay during flow rate measurement can be improved.

〔Effect of the invention〕

As explained above, according to the present invention, the measuring device main body is divided into two chambers by a partition member, a thin tube formed in a coil shape is stored in one chamber, and one end of this thin tube is separated from the partition member. Since it is passed through and opened into the other chamber, the gas to be measured flowing inside the tube becomes a laminar flow due to the boundary effect of the tube wall, and the pressure difference between the gas to be measured taken out from both pressure extraction holes is proportional to the flow rate. Flow rate measurement using a differential pressure detector can be performed using an extremely simple calculation formula. In addition, since both pressure extraction holes are provided on the wall of the measuring device, the differential pressure detector can be installed directly on the measuring device, regardless of the length of the thin tube, making it possible to downsize the entire device. In addition, the piping work required to connect the differential pressure detector and the measuring device main body, which was required in the past, is no longer necessary.Furthermore, the thin tube can be fixed to the partition member, and this partition member can be freely attached and removed within the measuring device main body. If installed in the system, the only part that generates differential pressure due to the flow of the fluid to be measured is the thin tube, so when repairing the device, all you have to do is remove the thin tube along with the partition member and replace it, eliminating the need for a special calibration plate on site. Therefore, repair work can be carried out extremely easily.Another advantage is that the diameter and length of the capillary can be freely changed depending on the fluid to be measured.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a gas flow rate measuring device according to the present invention;
FIG. 2 is a partial cross-sectional view showing how the gas flow rate measuring device is used, and FIGS. 3 and 3 are cross-sectional views showing application examples of the gas flow rate measuring device. , 1a... Measurement device main body wall, 10... Capillary tube attachment heath, 11... Inlet side chamber, 12... Outlet side chamber, 16° 17... Pressure extraction hole, 18... ...tubule.

Claims (2)

[Claims] (1) The cylindrical measuring device main body is divided into two chambers by a partition member, pressure extraction holes opening into both chambers are provided in the wall of the measuring device main body, and a thin tube formed in a coil shape is inserted into one of the two chambers. 1. A gas flow rate measuring device, characterized in that the thin tube is housed in a chamber, and one end of the thin tube passes through the partition member and opens into the other chamber. (2) The gas flow rate measuring device according to claim 1, wherein both pressure extraction holes are located at positions where differential pressure detection means can be installed.