JP3402431B2 - Gas detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the concentration of gas in an environment where a pressure difference exists across a partition without causing outflow of the gas. . 2. Description of the Related Art For example, in a pipeline for transporting LPG and the like, in order to prevent a disaster caused by a large amount of fluid flowing out due to breakage of a large-diameter pipe or the like, a road or a culvert which can be shut off from an external environment is constructed. Then, a pipe is laid here and a non-combustion gas pressurized to an atmospheric pressure or higher, such as nitrogen gas, is constantly purged, and then a leak of the fluid flowing through the pipeline is quickly detected. In addition, a gas detection device is provided. When measuring the concentration of a gas in an environment where a pressure difference exists across a partition wall as described above, usually, in order to prevent the gas from flowing in the two environments, the gas is measured with respect to the area to be measured. 2. Description of the Related Art A circulating flow path is formed, and a gas detection unit is provided in the flow path. However, there is a problem that a pump for circulating gas is required, and maintenance is troublesome. [0004] In order to solve such a problem, it is conceivable to install the detector so that it can be inserted into and removed from the environment to be measured through a window provided with a sealing mechanism. Is required, it is necessary to take out the detection unit, set a chamber and the like in each detection unit, and inject the standard gas into the detection unit. Therefore, there is a problem that the operation is troublesome. The present invention has been made in view of such a problem, and an object of the present invention is to provide a gas detection device capable of calibrating a sensor with a standard gas in an installed state without requiring removal of a sensor unit. It is to provide a device. According to the present invention, there is provided a gas detecting device having a gas detecting unit at a tip of a support, and a guide for moving the detecting unit. A guide member, a gas shut-off unit connected to a rear end of the guide member, through which the gas detection unit can be inserted, and a gas shut-off unit connected to a rear end of the gas shut-off unit, and An insertion port is formed in which the detection unit is housed in a state where the detection unit is pulled out to a position where the valve can be closed to form an injection space for a standard gas, and an insertion port for airtightly supporting the gas measuring device main body at a rear end side. And a member. When maintenance is required, when the gas detection unit is pulled out to the rear end of the gas shut-off means, the gas shut-off means can be closed and the two environments are shut off.
When the standard gas is injected in this state, the gas flows into the detection unit by diffusion, so that the calibration operation can be performed without removing the gas detection device main body from the partition. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 shows an embodiment of the present invention. FIG. 1A shows a gas detection device main body, and FIG. 1B shows a mounting device. First, the gas detection device main body 1 will be described. In the figure, reference numeral 2 denotes a detection unit, which has a cylindrical gas intake portion 3 made of a flame arrestor constituent material such as sintered metal at the tip, and has a sensitivity to a gas to be detected.
In this embodiment, the oxygen sensor 4 and the optical organic gas sensor 5 are housed side by side in the axial direction, and the bottom is sealed by a base 6. Reference numeral 7 denotes a support, which in this embodiment is constituted by a pipe. A base 6 of the detection unit 2 is coaxially fixed at the front end, and a base 8 serving also as a terminal box at the rear end. Is mounted, and a lead wire 9 for transmitting measurement signals from the sensors 4 and 5 is inserted thereinto so as to be connected to a cable 10 extending from the base 8 to an external monitoring device. In addition, reference numeral 11 in the drawing indicates a lid that seals the front end of the gas intake unit 3. Next, the mounting device 20 will be described. In the figure, reference numeral 21 denotes a guide member for guiding the movement of the detection unit 2 of the gas detection device main body 1, having a length penetrating a partition separating the environment to be measured, and having an opening 22 having one end exposed to the environment to be measured. And a flange 23 at the rear end.
And a cylindrical body having an inner diameter that forms a gap as small as possible so as to be slidable between them. Reference numeral 24 denotes a gas shut-off device. In this embodiment, a cock that can be opened and closed by a slight rotation of a valve body 24a such as a ball valve or a taper valve and that can secure a large-diameter flow hole 24b. It is constituted by a valve, and is hermetically attached to the flange 23 of the guide member 21 so that the flow hole 24b is located coaxially with the guide member 21. Reference numeral 25 denotes an insertion port forming member which is capable of accommodating the gas intake section 3 and capable of calibrating gas with the gas detection device main body 1 being pulled out to a position where the gas shutoff device 24 can be closed. A chamber 26 having a volume enough to secure an area, and a base 28 having an insertion port 27 for hermetically supporting the drawn-out gas measuring device main body 1 at the rear end side are provided. The device 24 is air-tightly connected to the rear end. In the chamber 26 of the insertion port forming member 25,
An inlet 26a and an outlet 26b for a standard gas for calibration and a gas for purging are provided, and are always sealed with a valve or a cap (not shown). In addition, in the insertion opening 27 of the base 28,
A sealing member 29 such as an O-ring for hermetically supporting the gas detection device main body 1 is also fitted on the inner surface thereof at the time of calibration, and when the gas detection device main body 1 is inserted to the measurement position, the base 6 and the base 6 are connected. A packing 30 for ensuring airtightness is provided between them. Reference numeral 31 in the figure denotes an operation lever that rotates the valve body 24a. In the embodiment configured as described above, FIG.
As shown in (a), a through hole H through which the guide member 21 can be inserted is formed in the wall W separating the measurement chamber and the environment to be measured. The guide member 21 is inserted through the guide member 21 as shown in FIG. Next, in a state where the flow hole 24b of the gas shutoff device 24 is opened with respect to the guide member 21 by the operation lever 31, the measuring device main body 1 is inserted from the insertion opening 27 of the base 28 to a prescribed position. It is fixed by fixing means (not shown) to prevent slipping out. In this state, since the detection unit 2 is exposed to the environment to be measured from the tip of the guide member 21, the gas to be measured flows into the gas intake section 3 by diffusion and is detected by the oxygen sensor 4 and the optical organic gas sensor 5. Is done.
In this state, even if the gas shut-off device 24 is open, the insertion port forming member 25 is sealed by the packing 30 and the sealing member 29 provided on the base 28 of the insertion device 20. Therefore, even if a pressure difference exists between the environment S to be measured and the measurement chamber, gas leakage between the two can be reliably prevented. On the other hand, when it becomes necessary to calibrate the gas sensors 4 and 5 using a standard gas due to maintenance or the like, the fixing means (not shown) is removed and the gas measuring device main body 1 is removed.
As shown in FIG. 2B, the front end of the detection unit 2 is located at the rear end of the gas shut-off device 24, and the gas intake unit 3 of the detection unit 2 is housed in the chamber 26 of the insertion port forming member 25. The gas shut-off device is closed. You. In this state, the chamber 26 is sealed at one end by the gas shut-off device 24 and at the other end by the base 6 and the sealing member 29 of the detection unit 2 to form a sealed space. When the standard gas is injected by opening the inlet 26a and the outlet 26b, the standard gas filled in the chamber 26 flows into the sensors 4 and 5 from the gas inlet 3 by diffusion, and a measurement signal corresponding to the sensitivity is output. I do.
Therefore, a predetermined calibration operation can be performed. After the calibration is completed, the gas for purging is injected from the gas inlet 26a to remove the standard gas from the chamber 26, and then the measuring device 1 is pushed back to the original position to perform the measurement. . When the sensors 4, 5 and the like need to be replaced, the detection unit 2 is pulled out to the rear end side from the gas shut-off device 24 in the same manner as in the calibration operation, and the operation lever 3 is moved.
1 closes the valve. This shuts off the environment S to be measured and the measurement chamber, so that the gas detection device main body 1 can be detached without further gas leakage by pulling out the gas detection device main body 1 from the insertion port 27. In the above-described embodiment, the insertion port forming member 25 is configured to have a size capable of performing a calibration operation. However, as shown in FIG. When the gas detecting device main body 1 is pulled out to the calibration position, the gas detecting device main body 1 and the base 2 of the insertion port forming member 25 are set.
In order to prevent a large moment from acting on the support member 8, it is desirable to provide a support member 31 in a cylindrical state. In addition, it is desirable to provide a stopper 32 as shown in FIG. 3B so that the measuring device main body 1 stops at a specified position when the detection unit 2 is pulled out to the gas shutoff device 24. The stopper 32 is constantly urged outward (upward in the figure) by a spring 33 provided on the support 7, and is connected to one end of a cord 34 extending to the terminal box 8 at the inner end of the support 7. Have been. Incidentally, reference numerals 35 and 36 in the figure each represent a guide roller. According to this embodiment, when the gas sensors 4 and 5 are calibrated by using a standard gas for maintenance or the like, the gas measuring device main body 1 is connected to the gas detecting device 2 in the same manner as described above. 24, and the gas intake portion 3 of the detection unit 2 is
When the stopper 32 is pulled out to the position accommodated in the chamber 26 of No. 5, the stopper 32 collides with the wall 26c of the chamber 26.
It can be stopped at a specified position. When the operating lever 31 is rotated to close the gas shut-off device, the gas inlet 26a and the gas outlet 26b are opened and the standard gas is injected, the calibration operation can be performed. At the end stage, the string 34 is pulled to retract the stopper 32 against the spring 33, and then the measuring device main body 1 is pushed back to the original position, whereby the measurement becomes possible. On the other hand, when it is necessary to replace the sensors 4, 5 and the like, the detection unit 2 is pulled out to the rear end side of the gas shut-off device 24 in the same manner as in the calibration operation, and
1 closes the valve. Then, when the string 34 is pulled, the stopper 32 retreats into the inside of the support 7, so that the support 7 can be further pulled out from the calibration position to the rear end side, and the measurement device main body 1 can be removed. In the above-described embodiment, the stopper 32 is moved forward and backward by a mechanical means such as a string. However, an electromagnetic drive means such as a solenoid is used, and the stopper 32 is electrically driven by an externally provided switch. A fluid element such as a diaphragm may be used to move the compressed inert gas as power to move forward and backward. FIG. 4 shows a second embodiment of the present invention, wherein reference numerals 41 and 42 denote gas flow path forming members.
The openings 41a and 42a at the front ends are penetrated through the wall W so as to be exposed to the environment to be measured, and the openings 41b and 42b at the rear end are long enough to connect a measurement box 43 described later, and are provided at a constant interval. Are located. 44 and 45 are gas flow path forming members 41 and 4
A three-way valve connecting the measuring box 43 and the measuring box 43 is operatively connected by a connecting rod 46, and connects the gas inflow and outflow ports 43a and 43b of the measuring box 43 to the gas box forming members 41 and 42 on the measuring box side. Select one of a measured gas intake position connected to the openings 41b and 42b, a standard gas injection position connected to the standard gas inlet 67 and the outlet 68, and a gas shutoff position to shut off the gas flow path forming members 41 and 42. It is configured to be. Reference numeral 43 denotes the above-mentioned measuring box, which is a three-way valve 4 at both ends.
It comprises a main body 47 connected to 4 and 45 and a lid 48 which can be opened and closed, and accommodates sensors 49 and 50 therein. The reference numerals 51 and 52 in the figure indicate the sensor 4
Reference numerals 9 and 50 denote bases that also serve as terminal boxes, and 53 denotes operating levers of the three-way valves 44 and 45. In this embodiment, when the three-way valves 44 and 45 are set at the gas intake position by the operation lever 53 as shown in FIG. 4, the gas to be measured is supplied from the opening 41a of one of the gas flow path forming members 41 to the measuring box. 43, and flows out of the opening 42a of the other gas flow path forming member 42 into the environment to be measured. Therefore, a measurement signal corresponding to the concentration of the target gas is output from each of the sensors 49 and 50. When it is necessary to calibrate the sensors 49 and 50, when the operating lever 53 is moved to the standard gas injection position, the two three-way valves 44 and 45 are simultaneously operated by the connecting rod 46, and The connection with the measurement environment S is cut off, and one three-way valve 44 communicates with the standard gas inlet 67 and the other three-way valve 45 communicates with the standard gas outlet 68. In this state, when a standard gas such as zero gas or span gas suitable for calibration of the sensors 49 and 50 is injected, the measuring box 43 is filled with the standard gas, so that a predetermined calibration operation can be performed. When the sensors 49 and 50 need to be replaced, the operating lever 53 is moved to the gas shut-off position or the standard gas injection position, and the measuring box 43 is shut off from the environment S to be measured. Since the lid 48 can be opened without causing gas leakage in the environment S to be measured or flowing of gas into the environment to be measured, the sensors 49 and 50 can be replaced. According to this embodiment, the diameter of the through-hole to be drilled in the wall W can be reduced to such an extent that gas can be circulated. A plurality of three-way valves 44, 45 corresponding to
Can be set to the gas inlet, the standard gas injection position, and the gas shut-off position, and it is impossible to take in the gas to be measured due to the inconsistent operation of the plurality of valves 44 and 45, to inject the standard gas, Leakage of the measurement gas can be prevented. When a fluid flow exists in the environment to be measured, the gas is introduced into the gas flow path forming members 41 and 12,
When a gas intake plate 54 is arranged near the outlets 41a and 42a to actively promote the flow of gas, or when a sensor 49 that needs to be maintained at a high temperature for detection, such as an oxygen sensor, is used. By arranging it below the measurement box 43, the gas flow can be promoted by the upward airflow A, and the responsiveness to a change in the gas concentration of the environment S to be measured can be improved. In the above-described embodiment, the sensors are arranged at two places, the upper part and the lower part. However, as shown in FIG. When configured as the sensor unit 58 and housed in the measurement box 53, maintenance work can be simplified. When the sensor unit 58 is used as described above, as shown in FIG. 6, when the sensor unit 58 is disposed above the measurement box 43 and the heating unit 59 having an explosion-proof structure is accommodated below, as described above. The gas flow can be promoted by the ascending air flow B by the ascending air flow A without using an operating member, and the responsiveness to a change in the gas concentration of the environment S to be measured can be improved. Further, two through holes 61 and 62 are provided in a base plate 60 having the same size as the lid 48, and a case 64 containing a pump 63 is provided on the outside, and the through holes 61 and 62 are provided on the measurement box 43 side. By preparing an adapter 66 provided with a separating plate 65 so as to separate the measuring box 43 from the measuring box 43 through the gas flow path forming members 41 and 42 by replacing it with the lid 48 as necessary.
Can generate the gas flows C and D for taking in the gas of the environment S to be measured. As described above, in the present invention,
A gas detection device main body provided with a gas detection unit at the tip of the support, a guide member for guiding the movement of the detection unit, and a gas shutoff means capable of inserting the gas detection unit connected to the rear end of the guide member, A gas detection unit is connected to the rear end of the gas shut-off means, and the gas detection unit is housed in a state where the gas shut-off means is pulled out to a position at which the gas shut-off means can be closed to form a standard gas injection space. Since an insertion port forming member having an insertion port for hermetically supporting the measurement device main body is provided, when maintenance is necessary, the gas detection unit is pulled out to the rear end of the gas shutoff means to remove the gas detection unit. Accordingly, the two environments can be shut off, and if the standard gas is injected in this state, the calibration operation can be performed without removing the gas detector main body from the partition.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 (a) and 1 (b) are diagrams showing a mounting device and a gas detector main body, respectively, which constitute one embodiment of a gas detection device of the present invention. FIGS. 2 (a) and 2 (b) are views showing one embodiment of the gas detection device of the present invention in a state where the gas detector main body is set at a gas detection state position and a calibration state position, respectively. is there. FIGS. 3 (a) and 3 (b) show another embodiment of the present invention in a state where the gas detector main body is set at a gas detection state position and an enlarged view showing the vicinity of a stopper. It is. FIG. 4 is a diagram showing another embodiment of the present invention. FIG. 5 is a diagram showing an embodiment in which a sensor is unitized. FIG. 6 is a diagram showing another embodiment of the present invention. FIG. 7 is a view showing an embodiment of an adapter suitable for the present invention in a state where the adapter is mounted on a measurement box. [Description of Signs] 1 Gas detection device main body 2 Detection unit 3 Gas intake portion 4, 5 Sensor 7 Support 8 Base 20 Mounting device 21 Guide member 24 Gas shutoff device 25 Insertion opening forming member 26 Chamber 27 Insertion opening 28 Base 29 sealing member

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-180284 (JP, A) JP-A-7-260740 (JP, A) JP-A-8-68734 (JP, A) JP-A-7- 229817 (JP, A) Fully open 1987-122545 (JP, U) Fully open, 52-138794 (JP, U) Fully open, 58-56858 (JP, U) Really open, 4-4258 (JP, U) Japanese Patent Publication 3-78924 (JP, B2) Japanese Patent Publication 54-6397 (JP, B2) Japanese Utility Model 62-16678 (JP, Y2) Japanese Utility Model Publication 3-42351 (JP, Y2) Japanese Utility Model 7-26683 (JP, Y2) Jikyo Hei 5-17641 (JP, Y2) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 1/00-1/44 JICST file (JOIS)

Claims (1)

(57) [Claim 1] A gas detection device main body having a gas detection unit at the tip of a support, a guide member for guiding the movement of the detection unit, and a rear end of the guide member. A gas shut-off means that allows the gas detection unit to be inserted therethrough, and is connected to a rear end of the gas shut-off means, and the gas detection unit is pulled out to a position where the gas shut-off means can be closed; A gas detection device comprising: a detection unit; a standard gas injection space formed therein; and an insertion port forming member provided with an insertion port at a rear end side of the gas measurement apparatus main body in an airtight manner.