JPH0953965A - Differential pressure flowmeter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a differential pressure flowmeter in which the condensate can be discharged constantly from a detection tube without having any effect on the pressure in a pressure conduction tube and erroneous detection of differential pressure due to stagnation of condensate can be prevented and the need of periodic overhaul and cleaning work can be eliminated. SOLUTION: The differential pressure flowmeter comprises a first drain pipe 31 communicating with a first pressure conduction tube 21 for introducing the pressure from the upstream side from a detection tube 10, and a drain pot 35 containing a liquid L into which the open end of first drain pipe 31 is immersed and sustaining the pressure in the drain pipe 31 at the same level as the first pressure conduction tube 21. Condensate in the first pressure conduction tube 21 can be discharged constantly through the drain pipe 31. Furthermore, a second drain pipe 32 communicating with a second pressure conduction tube 22 for introducing the pressure from the downstream side from detection tube 10 is provided and the open end 32b of drain pipe 32 is preferably immersed into the liquid L in drain pot 35.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure type flow meter for measuring the flow rate of a fluid flowing in a large-diameter pipe, and more particularly to a differential pressure type flow meter having an installation structure in which a detection pipe is inserted in a direction orthogonal to the pipe.

[0002]

2. Description of the Related Art Conventionally, as a differential pressure type flow meter, one using an orifice, a Venturi tube, a flow nozzle, etc. has been known. However, when a gas flows through a large diameter pipe, these flow meters are In many cases, it is not possible to measure, or it is not preferable in terms of installation cost and maintenance. Therefore, conventionally, a detection pipe of a predetermined diameter is inserted in a large-diameter pipe in the orthogonal direction to generate a differential pressure between the upstream side and the downstream side, and the upstream side and the multiple pressure detection holes formed in the detection pipe. There is a method in which the pressure on the downstream side is extracted to the outside, the differential pressure is detected, and the flow rate is calculated based on the differential pressure value.

As a differential pressure type flow meter of this type, for example, one shown in FIG. 3 is known. In the figure, 1 is a process pipe which is a large-diameter pipe, and 2 is this process pipe 1.
The detection pipes of the differential pressure type flow meter attached to the, 3 and 4 are the detection holes on the high pressure side and the low pressure side of the differential pressure type flow meter 3, respectively. A predetermined gas flows in the process pipe 1 in the direction of the arrow, and at the upstream surface of the detection pipe 2 where the upstream detection holes 3 are formed, the pipe wall of the pipe 1 is zero depending on the flow velocity distribution of the gas. The total pressure (dynamic pressure + static pressure) having the maximum pressure distribution near the central axis of the pipe 1 acts. On the other hand, on the downstream surface of the detection tube 2 in which the downstream detection hole 4 is formed, a negative pressure distribution corresponding to, for example, the flow velocity distribution of gas is generated. The upstream and downstream pressures P _H and P _L introduced from the detection holes 3 and 4 of the detection pipe 2 are respectively high-pressure side and low-pressure side transmitters (electronic differential pressure transmitter for low differential pressure). )
To the flow rate calculation system. The flow rate calculation system calculates the flow rate of the gas in the process pipe 1 by executing a predetermined calculation process based on the differential pressure.

The process pipe 1 constitutes a part of a desulfurization device in a refinery, for example. This desulfurization device is a device for separating a large amount of sulfur contained in the gas generated as a by-product when refining crude oil, and the measurement of the gas flow rate is essential for the operation of this device. It has become a thing. Further, inside the detection pipe 2, a low pressure side pressure guiding pipe 5 communicating with the downstream side detection hole 4 and a high pressure side pressure guiding pipe 6 communicating with the other space (a space communicating with the upstream side detection hole 3). Are provided, and the tip (lower end) of the detection tube 2 is closed by a blind plug 7. The blind plug 7 is screwed to a weld coupling 8 welded to the process pipe 1. The blind plug 7 and the weld coupling 8 are screwed to each other with a sealing material (not shown) interposed therebetween, whereby the detection pipe 2 The gap between the guide and the weld coupling 8 is fluid-tightly sealed.

[0005]

However, in the above-mentioned conventional differential pressure type flow meter, since the tip of the detection tube 2 is closed by the blind plug 7, the detection hole 3 of the differential pressure type flow meter 2 is provided. , 4 to low-pressure side and high-pressure side impulse pipes 5,
Moisture of the gas entering 6 condenses and stays inside these, or sulfides are further deposited inside the pressure guiding tubes 5 and 6, which impedes the gas flow and enables normal differential pressure detection. There was a problem that I could not do it. Therefore, it is necessary to remove the blind plug 7 from the process pipe 1 or the entire differential pressure type flow meter from the process pipe 1 to disassemble and clean the main part of the differential pressure type flow meter including the detection pipe 2. The operation of the system itself equipped with the pressure type flow meter had to be interrupted. Also, during this disassembling and cleaning work, if harmful gas in the process pipe 1 leaks to the outside, it is dangerous if it comes within a range of several tens of cm.
It is also necessary to wear a gas mask.

Further, the defective detection of the differential pressure due to the retention of condensed water becomes particularly noticeable when the detection tube is installed horizontally. For example, when the detection tube is installed in the vertical direction, it occurs about once every six months. On the other hand, in the case where the detection tube is installed in the horizontal direction, a defect occurs about once every several days, and such an installation cannot be practically adopted.

Even when the detector tube is oriented in the vertical direction, since the tip (lower end) of the detector tube is closed, condensed water will be retained, and periodic disassembly and cleaning cannot be avoided. Moreover, since the section in which the process pipe 1 extends horizontally is often a high place, disassembling and cleaning work is dangerous. Regarding the accumulation of condensed water, for example, it is conceivable to heat the detection tube moderately from the tip side to reduce condensation, but with the tip of the pressure guiding tube closed, the detection hole where the warm and moist fluid is small. When entering the impulse tube through
Moisture in the gas still tends to condense, and the above problems cannot be solved.

Further, if the composition of the fluid produces solids such as sulfides that are not easy to remove in the impulse line,
It took a long time to disassemble and clean it to remove it. For example, when the fluid in the process pipe 1 is a gas harmful to the human body and the place where the work is performed is at a high place, at least one disassembly and cleaning work takes about two days for reasons such as ensuring worker safety. Was needed.

The present invention has been made in view of the conventional problems as described above, and it is possible to constantly discharge the condensate condensed in the detection pipe without affecting the pressure in the pressure guiding pipe. SUMMARY OF THE INVENTION An object of the present invention is to provide a differential pressure type flow meter capable of surely preventing the differential pressure detection failure due to the retention of the oil and eliminating the need for periodic disassembly and cleaning work.

[0010]

In order to achieve the above-mentioned object, the invention according to claim 1 is inserted into a pipe in which a fluid flows inside in a direction substantially orthogonal to the inside of the pipe on the upstream side and the downstream side thereof. A detection pipe that generates a differential pressure of the fluid and has a first detection hole located on the upstream side and a second detection hole located on the downstream side is provided, and the detection pipe is the first detection hole. A first device that communicates with the detection hole on one end side to introduce the upstream pressure and measures the introduced pressure from the other end side
Differential pressure type flow rate having a pressure guiding pipe of No. 2 and a second pressure guiding pipe that communicates with the second detection hole at one end side to introduce the pressure on the downstream side and can measure the introduced pressure from the other end side. In the meter, a first drain pipe having a communication end communicating with the first pressure guiding pipe and an open end positioned lower than the communication end, and an open end of the first drain pipe are immersed. A drain pot that stores a liquid and that maintains the same pressure in the first drain pipe as the first pressure guiding pipe by the liquid, and the condensate condensed in the first pressure guiding pipe is drained. It was possible to always discharge to the drain pot via a pipe.

Therefore, the condensate generated in the first pressure guiding tube is apt to be generated without affecting the pressure in the first pressure guiding tube or leaking the fluid in the pipe to the outside. Since it is surely discharged to the drain pot, the differential pressure detection failure due to the retention of the condensate is prevented, and the frequent disassembling and cleaning operations are unnecessary. Also,
As described in claim 2, a second drain pipe having a communication end communicating with the second pressure guiding pipe and an open end located at a position lower than the communication end is provided, and the second drain pipe is provided. The open end of the first drain pipe to the drain pot containing the liquid in which the open end is immersed,
Immersion is preferred. In this case, back pressure can be applied to each of the first and second drain pipes using the liquid level in the drain pot as the same back pressure reference, and stable even if there is pressure fluctuation in the pipe and the detection pipe. It is possible to accurately detect the flow rate by detecting the differential pressure.

Further, according to a third aspect of the present invention, the communication end of the first or second drain pipe is connected to the detection pipe in the vicinity of the pipe via a connecting member that is substantially orthogonal to at least one end. It may be connected to the first or second pressure guiding tube and directed in a substantially vertical direction in the connected state. In this case, even if the detection tube is installed in the horizontal direction, the condensate is surely discharged to the drain pot, so that the differential pressure detection failure due to the retention of the condensate is more reliably prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, the differential pressure type flow meter of the present embodiment includes a detection tube 10 which is inserted in a direction substantially orthogonal to the piping 1 through which a fluid flows. The detection pipe 10 is configured to generate a pressure difference between the fluid flowing in the pipe 1 on the upstream side and the downstream side thereof, that is, to generate a pressure difference. One detection hole 11 and a second detection hole 12 located on the downstream side are formed. In addition, the detection pipe 10 communicates with the first detection hole 11 at one end side to introduce the upstream pressure and a first pressure guiding pipe 21 capable of measuring the introduced pressure from the other end side, The second detection hole 12
And a second pressure guiding pipe 22 that communicates with one end side to introduce the downstream pressure and can measure the introduced pressure from the other end side.

The differential pressure type flow meter further includes the first
First drain pipe 31 having a communicating end 31a communicating with the pressure guiding pipe 21 and an open end 31b located lower than the communicating end 31a, and the liquid L in which the open end 31b of the first drain pipe 31 is immersed. And a drain pot 35 for holding the inside of the first drain pipe 31 at the same pressure as the first pressure guiding pipe 21 by the liquid L. The condensate condensed in the first pressure guiding pipe 21 can be constantly discharged to the drain pot 35 via the drain pipe 31. Further, a communication end 32a communicating with the second pressure guiding tube 22 and an open end 32b located at a position lower than the communication end 32a.
And a second drain pipe 32 having an open end 32b of the second drain pipe 32 is provided in the drain pot 35 for containing the liquid L. It is immersed in the liquid L together with the end portion 31b. Further, the first and second drain pipes 31,
The communication end portions 31a, 32a of 32 are respectively connected to the first or second pressure guiding pipe via joints 49 and 58 as connecting members which are substantially orthogonal to the detection pipe 10 at least at one end near the pipe 1. It is connected to 21, 22 and is oriented in a substantially vertical direction in the connected state.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A differential pressure type flow meter according to an embodiment will be described in more detail with reference to FIGS. In the present embodiment, the pipe 1 is, for example, a large-diameter pipe forming a part of a desulfurization device in a refinery, for example, a process pipe having an inner diameter of about 440 mm. In the process pipe 1, a by-product when refining crude oil is produced. A gas containing a large amount of sulfur generated as is flowing in one direction. The extending direction of the process pipe 1 is substantially vertical, and the gas flow direction inside is downward. The differential pressure type flow meter of this embodiment is used for measuring the gas flow rate in the process pipe 1 which is indispensable for the operation of the desulfurizer.

Further, the detection tube 10 inserted in a direction substantially orthogonal to the pipe 1 has a diameter capable of generating a required differential pressure (for example, several tens to hundreds of mmH ₂ O) in the fluid flowing in the pipe 1, for example, 2
It has a diameter of 5.4 mm (1 inch). This detector tube
The ten first detection holes 11 are provided as at least one, for example, four circular holes of the same diameter (for example, about 9.525 mm = 3/8 inch) on the same straight line, and the second detection holes 11 are provided.
There is at least one 12, for example, the first detection hole 11 at a position (symmetrical position) displaced by 180 ° in the circumferential direction with respect to the first detection hole 11.
One hole having a smaller diameter (for example, 3.175 mm = 1/8 inch) is provided. The number and arrangement position of the first and second detection holes 11 and 12 are the flow velocity distribution in the pipe 1 and the total pressure before and after the detection pipe 10 (upstream side and downstream side).
It is decided to detect the average pressure in consideration of the static pressure distribution and the like.

In the detection pipe 10, one end of the first pressure guiding pipe 21 is inserted into the detection pipe 10 up to the vicinity of the central axis of the process pipe 1 and communicates with the first detection hole 11. The pressure is introduced into the inside of the detection tube 10 so that the pressure on the upstream side of the detection tube 10 is introduced by communicating with the second pressure guiding tube 22.
Of one end of the detection pipe up to near the central axis of the process pipe 1.
While being inserted into the inside of the detection tube 10, it is connected to the second detection hole 12 to introduce the pressure on the downstream side of the detection tube 10.

On the other hand, at the other end of the first pressure guiding pipe 21, a pressure receiving diaphragm portion of a high pressure side transmitter (not shown) is provided, and at the other end of the second pressure guiding pipe 22 a pressure receiving diaphragm of a low pressure side transmitter (not shown). The parts are connected in such a manner that the pressure can be detected. The high-pressure side and low-pressure side transmitters are each configured by, for example, an electronic differential pressure transmitter for low differential pressure, and the high-pressure side pressure introduced to the other end of the first pressure guiding tube 21 and the second
The low pressure side pressure introduced to the other end of the pressure guiding tube 22 is converted into an electric signal and transmitted by a flow rate measuring system (not shown). That is, the pressure introduced from one end of the first and second pressure guiding pipes 21 and 22 can be measured from the other end.

More specifically, the detection tube 10 is a tubular member which is screwed and welded to a part of the peripheral wall of the process pipe 1.
It is slidably inserted in 41, 51, and the gap for sliding is sealed by sealing means 42, 52. The sealing means 42 is a cylindrical seal holding member 43 screwed into the female screw hole of the tubular member 41, and the left end of the detection tube 10 in the figure so as to be housed inside one of the enlarged one ends of the seal holding member 43. A seal member (for example, an asbestos thread impregnated with tetrafluoroethylene resin is lattice-knitted and treated with silicone oil) 44 wound around the portion 10a (may be an extension pipe having the same diameter as the detection tube 10) 44, and a seal A holding member 45 provided adjacent to the seal member 44 so as to close the expanded one end of the holding member 43, and a tightening member 46 that is screwed to the seal holding member 43 and tightens the seal member 44 via the holding member 45. And have. The sealing means 52 is wound around the tubular seal holding member 53 screwed into the female screw hole of the tubular member 41, and the right end portion of the detection tube 10 in FIG. 1 so as to be housed inside the seal holding member 53. A seal member 54 (for example, asbestos yarn impregnated with tetrafluoroethylene resin is lattice-knitted) 54, and a tightening member 55 that is screwed to the seal holding member 53 and tightens the seal member 54.

A connecting pipe curved in an orthogonal direction is provided at one end (or an extension pipe thereof) 10a of the detecting pipe 10.
47 is screwed, and a flexible first drain pipe made of tetrafluoroethylene resin or the like is connected to the downward end of the connecting pipe 47 via a tubular connecting member 48 and a known pipe joint 49. The communication end 31a of 31 is connected. The first drain pipe 31 extends downward with the communication end 31a communicating with the first pressure guiding pipe 21 as the upper end, and is located lower than the communication end 31a.
The open end portion 31b of the above is immersed in the liquid L contained in the drain pot 35, for example, water. In the drain pot 35, when the water in the first drain pipe 31 lowers the liquid level due to the pressure from the first pressure guiding pipe 21, the back pressure corresponding to this liquid level lowering amount is detected inside the detection pipe 10. Also, the condensed water (condensate) which is applied to the first pressure guiding pipe 21 side and condensed into the detection pipe 10 through the first detection hole 11 can be always guided to the drain pot 35. That is, the first
The condensate condensed in the pressure guiding pipe 21 of the drain pipe 31
It can always be discharged to the drain pot via.

On the other hand, a pressure extracting member 56 is attached to the other end of the detecting tube 10, and the right end portions of the first and second pressure guiding tubes 21 and 22 in the figure are respectively attached to the pressure extracting member 56. The well-known pipe fittings 5 are connected to the high-pressure side and low-pressure side measurement pipes 61 and 62 made of stainless steel pipe or the like in the vertical direction orthogonal to the first and second pressure guiding pipes 21 and 22.
It is connected via 7,58. The communication end 32a of the flexible second drain pipe 32 made of tetrafluoroethylene resin or the like is connected to the measurement pipe 62 so as to communicate with the second pressure guiding pipe 22 via the measurement pipe 62 on the low pressure side. Is connected to the lower end of the vertically extending part of the same through a T-shaped branch pipe 71,
The open end 32b of the second drain pipe 32 is inserted into the drain pot 35 containing the liquid L at a position lower than the open end 32b and immersed in the liquid L. The drain pot 35
For example, in a container made of corrosion-resistant and heat-resistant resin, the drain hose portion 35a that defines the upper limit of the liquid level and the drain pipe
It has a lid portion 35b for guiding the open end portions 31b and 32b of the reference numerals 31 and 32.

In the differential pressure type flow meter of the present embodiment constructed as described above, the communicating end portion communicating with the first pressure guiding tube 21.
31a and a first drain pipe 31 having an open end portion 31b located at a lower position, a communication end portion 32 communicating with the second pressure guiding tube 22 and an open end portion 32b located at a lower position. The second drain pipe 32 and the open ends 31a, 32a of the first and second drain pipes 31, 32 contain the liquid L immersed therein, and the liquid L allows the first and second drain pipes 31, Since the drain pot 35 that maintains the same pressure inside the first and second pressure guiding pipes 21 and 22 is provided, the condensation condensed inside the first and second pressure guiding pipes 21 and 22 respectively. The liquid (condensed water) can be constantly discharged to the drain pot 35 via the first and second drain pipes 31 and 32.

In this state, the liquid level in the first drain pipe 31 becomes lower than the liquid level of the entire liquid L in the drain pot 35 in accordance with the pressure in the first pressure guiding pipe 21, while the second
The liquid level in the second drain pipe 32 rises above the liquid level of the entire liquid L in the drain pot 35 according to the pressure in the pressure guiding pipe 22 of Corresponding liquid level height (water level) differences occur, but the liquid level heights in the first pressure guiding pipe 21 and the second pressure guiding pipe 22 are respectively via the first and second drain pipes 31 and 32. Since a back pressure corresponding to that is applied, there is no pressure leakage or external influence. In addition, the first and second pressure guiding pipes do not leak harmful gas in the pipe 1 to the outside.
The condensate generated in 21 and 22 is always surely the drain pot
Discharged to 35. Therefore, the first and second pressure guiding tubes
The differential pressure detection failure due to the condensate staying inside 21 and 22 will not occur, and the pressure guiding tube will not be clogged with sulfide, etc., eliminating the need for frequent and difficult disassembly and cleaning work. . By the way, in the case of the above desulfurization apparatus, the differential pressure, the disassembly of the flow meter, and the cleaning work took more than 200 hours per year, but this work could be saved.

The open end of the second drain pipe 32
Since 32b is soaked in the liquid L in the drain pot 35 together with the open end 31b of the first drain pipe 31, the simple drain pot 35 that only defines the upper limit of the liquid level height.
The liquid level of the liquid L as the same back pressure reference surface
Since the back pressure can be applied to the second drain pipes 31 and 32, the differential pressure between the high pressure side and the low pressure side can be reliably obtained even if the pressure in the detection pipe 10 varies. The flow rate can be measured with high accuracy. Needless to say, the differential pressure detection failure and the clogging of the pressure guiding tube are more reliably prevented as compared with the case where the drain pipe 31 or 32 is provided only on one of the high pressure side and the low pressure side to discharge the condensate.

Further, the first and second drain pipes
The communication ends 31a and 32a of the pipes 31 and 32 are located near the pipe 1
10 is connected to the first or second pressure guiding tube via a connecting member that is substantially orthogonal to at least one end with respect to 10, and is oriented in a substantially vertical direction in the connected state, so that the detection tube 10 is installed horizontally. However, the condensate is surely discharged to the drain pot 35, and the differential pressure detection failure due to the retention of the condensate is prevented.

In the present embodiment, the pipe 1 extends in the vertical direction and the detection pipe 10 is oriented in the horizontal direction. However, in the present invention, the detection pipe is inserted in the horizontal pipe or the like to be vertically arranged. It can be applied even in the case of facing the direction, and in that case, it is possible to always reliably discharge the condensed water from the tip (lower end) of the detection tube. It is possible to surely solve the conventional problems such as the differential pressure detection failure and the pressure guiding tube clogging caused by the condensate staying at the tip of the.

Further, the tip portion 10a of the detection tube 10 is formed as a separate member, and the male screw portion of the seal holding member 43 is formed in correspondence with the female screw hole into which the existing blind plug (corresponding to the plug 7 of the conventional example) is attached. At the same time, a branch pipe similar to the branch pipe 71 is provided in a part of the measurement pipe on the low pressure side to enable connection of the first and second drain pipes 31, 32,
A device that can continuously discharge the condensate can be added to the existing differential pressure type flow meter at low cost and easily, enabling stable continuous operation of the system using the differential pressure type flow meter. , The maintenance cost can be greatly reduced.

[0028]

According to the invention described in claim 1, a first drain pipe having a communication end communicating with the first pressure guiding pipe and an open end positioned lower than the communication end,
A drain pot for accommodating the liquid in which the open end of the first drain pipe is immersed, and maintaining the same pressure in the first drain pipe as the first pressure guiding pipe by the liquid; Since the condensate condensed in the pressure guiding pipe of No. 1 can always be discharged to the drain pot via the drain pipe, it may affect the pressure in the first pressure guiding pipe or leak the fluid in the pipe to the outside. In this way, the condensate generated in the first pressure guiding tube where the condensate is likely to be generated can always be reliably discharged to the drain pot, and the differential pressure detection failure due to the retention of the condensate can be prevented.
Maintenance costs can be reduced by eliminating the need for frequent disassembly and cleaning work. As a result, the flow rate of the fluid in the large-diameter pipe can be continuously and accurately measured by the differential pressure type flow meter, and the system using the differential pressure type flow meter can be stably operated continuously.

Further, as described in claim 2, a second drain pipe having a communication end communicating with the second pressure guiding pipe and an open end located at a position lower than the communication end is provided, and If the open end of the second drain pipe is dipped in the drain pot containing the liquid in which the open end of the first drain pipe is dipped, the liquid level in the drain pot will be the same. As the pressure reference surface, the first and second drain pipes can be provided with a back thickness, and the differential pressure between the high pressure side and the low pressure side can be reliably detected even in the case of a low differential pressure. It is possible to perform stable and highly accurate flow rate measurement.

Further, according to a third aspect of the present invention, the communication end of the first or second drain pipe is connected to the detection pipe in the vicinity of the pipe through a connecting member that is substantially orthogonal to at least one end. Connected to the first or second pressure guiding tube,
If the connection tube is oriented in a substantially vertical direction, the condensate can be reliably discharged to the drain pot even when the detection tube is installed horizontally, and the condensate can be retained. It is possible to prevent defective detection of the differential pressure, and it is possible to reduce maintenance costs by eliminating the need for frequent disassembly and cleaning work.

[Brief description of drawings]

FIG. 1 is a system configuration diagram showing an embodiment of a differential pressure type flow meter according to the present invention.

FIG. 2 is a vertical cross-sectional view showing the internal structure of the detection tube of the differential pressure type flow meter of one embodiment.

FIG. 3 is a configuration diagram of a conventional differential pressure type flow meter, in which (a) includes a cross section of a pipe to be attached, and (b) includes a vertical cross section of the pipe.

[Explanation of symbols]

 1 Pipe (Large Diameter Pipe) 10 Detection Pipe 11 First Detection Hole 12 Second Detection Hole 21 First Pressure Pipe 22 Second Pressure Pipe 31 First Drain Pipe 31a Communication End 31b Open End 32 Second drain pipe 32a Communication end 32b Open end 35 Drain pot 42,52 Sealing means 49,58 Joint (connecting member) L Liquid

Claims (3)

[Claims] 1. A first member which is inserted in a direction substantially orthogonal to a pipe through which a fluid flows inside to generate a differential pressure of the fluid in the pipe on an upstream side and a downstream side thereof and which is located on the upstream side.
Detection hole and a second detection hole located on the downstream side are formed, and the detection tube communicates with the first detection hole at one end side to introduce the upstream pressure. Together with the first pressure guiding pipe capable of measuring the introduction pressure from the other end side, the second pressure is communicated with the first pressure guide pipe at one end side to introduce the downstream pressure and the introduction pressure is measured from the other end side. A differential pressure type flowmeter having a possible second pressure guiding pipe, and a first drain pipe having a communication end communicating with the first pressure guiding pipe and an open end positioned lower than the communication end. And a drain pot for accommodating a liquid in which the open end of the first drain pipe is immersed and for maintaining the same pressure in the first drain pipe as the first pressure guiding pipe by the liquid. The condensate condensed in the first pressure guide tube is used to remove the condensate. A differential pressure type flow meter characterized in that it can always be discharged to the drain pot via the Ip. 2. A second drain pipe having a communication end communicating with the second pressure guiding pipe and an open end located at a position lower than the communication end, the open end of the second drain pipe being provided. The differential pressure type flow meter according to claim 1, wherein the part is immersed in a drain pot that stores a liquid in which the open end of the first drain pipe is immersed. 3. The first or second communicating end of the first or second drain pipe is connected to the detecting pipe in the vicinity of the pipe via a connecting member that is substantially orthogonal to at least one end thereof.
The differential pressure type flow meter according to claim 1 or 2, wherein the differential pressure type flow meter is connected to the pressure guiding tube and is directed in a substantially vertical direction in the connected state.