JP6654088B2 - Gas detector - Google Patents

Description

  The present invention relates to a gas detector configured to enable, for example, remote measurement.

  For example, in closed spaces with poor ventilation such as tanks, manholes, sewers, and pits, the oxygen concentration may decrease due to biological respiration, chemical oxidation, and generation of other gases. In addition, hydrogen sulfide may be generated by the action of microorganisms, and there are many cases where air in an environmental atmosphere may be in a dangerous state or may be in a dangerous state.

  When performing construction or inspection work in an oxygen-deficient state or a dangerous place where hydrogen sulfide poisoning is likely to occur, measure the oxygen concentration in advance and confirm that the oxygen concentration is 18% or more of the safety limit value. is necessary. In addition, the concentration of hydrogen sulfide must be measured as necessary to confirm that the concentration of hydrogen sulfide is 10 ppm or less.

  For example, in measuring oxygen concentration in such a closed space, a gas detector having a remote sensor unit including an oxygen sensor is widely used (for example, see Patent Document 1).

JP 2013-104686 A

  Thus, a conventional so-called remote gas detector is configured to measure the oxygen concentration in a closed space while lowering the sensor unit. Therefore, it is possible to determine whether or not the oxygen concentration in the closed space is equal to or higher than the safety limit value (safety) based on the detected oxygen concentration. However, the opening surface of the sensor unit in the closed space can be determined. Since the position (depth) from is unknown, the state of the environmental atmosphere in the enclosed space cannot be grasped.

  The present invention has been made based on the above circumstances, and when remotely measuring the concentration of a gas to be detected in a closed space, it is necessary to accurately grasp the state of the environmental atmosphere in the closed space. It is an object of the present invention to provide a gas detector capable of achieving high safety.

Gas detectors of the present invention includes a gas detector body having a portable so configured remote cable attachment portion, which is connected via a remote cable to the gas detector body, and a sensor unit having at least a gas sensor The sensor unit itself is configured to be detachably mounted so that the remote cable mounting portion is replaceable with the remote cable, and the sensor unit is provided inside an opening having an opening that opens upward. A gas detector which is configured to be capable of being remotely measured by detecting a concentration of a gas to be detected in the closed space by being inserted into the formed closed space,
The sensor unit includes a depth detecting unit that detects a depth from an opening surface in the closed space ,
The depth detecting means is constituted by a pressure sensor, and the pressure sensor is mounted on the sensor unit .

  In the gas detector according to the present invention, the gas detector main body may include a display unit that displays a depth of the sensor unit in the closed space together with a type and a concentration of the detected gas. preferable.

  Still further, in the gas detector of the present invention, the gas detector main body further includes an alarm unit, and as an alarm point for performing an alarm operation by the alarm unit, a depth alarm point about the depth in the enclosed space is provided. It is preferable to be able to set.

  Still further, in the gas detector of the present invention, a sensor provided with an oxygen sensor or a hydrogen sulfide sensor can be used as the sensor unit.

  According to the gas detector of the present invention, the concentration of the detection target gas in the closed space as the measurement target space can be detected in association with the depth from the opening surface in the closed space. The state of the atmosphere can be accurately grasped, and high security can be obtained.

It is a front view showing roughly the example of 1 composition of the gas detector of the present invention. FIG. 2 is a block diagram schematically showing a configuration of a gas detector shown in FIG. 1. It is the schematic which shows an example of the usage form of the gas detector of this invention. It is a front view showing the state where the sensor unit was attached to the gas detector main part.

  Hereinafter, embodiments of the present invention will be described in detail.

FIG. 1 is a front view schematically showing a configuration example of the gas detector of the present invention. FIG. 2 is a block diagram schematically showing a configuration of the gas detector shown in FIG. Hereinafter, in this specification, the vertical direction in FIG. 1 is referred to as “vertical direction”, and the horizontal direction in FIG. 1 is referred to as “horizontal direction”, unless otherwise specified, but restricts the usage of the gas detector. is not.
The gas detector includes a gas detector main body 10 and at least a gas sensor 31 connected to the gas detector main body 10 via a remote cable 35 detachably attached to the gas detector main body 10. When the sensor unit 30 is lowered (closed) into a closed space formed inside a structure having an opening that opens upward, detection is performed in the closed space. The concentration of the target gas can be measured remotely.
Here, examples of the closed space that is the measurement target space include a tank, a manhole, a sewer, a pit, and the like.

The remote cable 35 has a sensor unit mounting portion 37 to which the sensor unit 30 is detachably mounted at one end of a cable 36 having a power supply line and a signal line, and a remote cable mounting in the gas detector main body 10 at the other end of the cable 36. It has a mounted part 38 that is detachably mounted on the part 15. 39a and 39b are coil-shaped linear protection members.
The sensor unit mounting portion 37 is configured such that one sensor unit selected from a plurality of identical sensor units 30 including the gas sensors 31 having different types of detection target gas is replaceably mounted with another sensor unit. Have been.
The length of the remote cable 35 can be appropriately selected depending on the purpose, for example, within a range of 5 to 30 m.

  As the sensor unit 30, for example, a sensor unit having an oxygen sensor for detecting oxygen gas, a sensor unit having a hydrogen sulfide sensor for detecting hydrogen sulfide, and the like can be used.

The gas detector main body 10 has a display unit 11 and an operation unit 12 in an upper half area in the front, and a remote cable mounting part 15 having a remote cable mounting opening opened downward in a lower half part. Reference numeral 13a in FIG. 1 denotes a warning light emitting unit.
The remote cable mounting section 15 of the gas detector main body 10 is configured such that the sensor unit 30 itself is detachably mounted so as to be exchangeable with the remote cable 35 (see FIG. 4).

Thus, the above-mentioned gas detector is provided with depth detecting means for detecting the depth of the sensor unit 30 from the opening surface (level position of the opening) in the closed space.
The depth detecting means can be constituted by, for example, a pressure sensor. As the pressure sensor, a sensor capable of measuring a pressure change (resolution is approximately ± 2 pa or less) with an accuracy in a range of, for example, ± 20 cm in terms of depth can be used.
In the above gas detector, as shown in FIG. 2, the pressure sensor 32 is mounted on the sensor unit 30.

  The configuration of the gas detector main body 10 will be specifically described. As shown in FIG. 2, the gas detector main body 10 calculates the concentration of the detection target gas based on the gas detection signal from the gas sensor 31 in the sensor unit 30. A gas concentration calculator 21, a depth calculator 22 for calculating the depth of the sensor unit 30 based on a pressure detection signal from the pressure sensor 32 in the sensor unit 30, and a recording unit 23 for recording measurement data including the gas concentration and the depth. And a control unit 25 that controls the operation of each unit including the display unit 11 and the alarm unit 13 based on the operation setting conditions input by the operation unit 12. The display unit 11 of the gas detector main body 10 displays the calculated gas concentration and depth (see FIG. 3). In the recording unit 23, data related to the calculation of the gas concentration, data related to the calculation of the depth, and the like are recorded in advance. The alarm unit 13 can be configured by an alarm notifying unit that issues an alarm by, for example, light emission by the alarm light emitting unit 13a, buzzer sound by an alarm buzzer, and vibration by an alarm vibration generator.

In this gas detector, a depth alarm point for depth can be set in addition to a concentration alarm point for gas concentration as an alarm point at which the alarm unit 13 performs an alarm operation. Specifically, for example, the concentration alarm point (reference concentration value) for oxygen gas can be set to, for example, 18 vol%, which is a safety limit value for the concentration of oxygen gas. Further, for example, the concentration alarm point (reference concentration value) for hydrogen sulfide gas can be set to 10 ppm which is a safety limit value for the concentration of hydrogen sulfide gas.
The depth warning point for the depth can be set based on a measurement result obtained by a measurement performed in advance for a closed space where an inspection work or the like is actually performed.
Note that a plurality of concentration alarm points and a plurality of depth alarm points may be set.

Hereinafter, the operation of the above gas detector will be described.
As described above, when an operator enters a closed space such as a manhole and performs an inspection or the like, it is necessary to check the state of the environmental atmosphere in the closed space to confirm safety.
First, for example, a sensor unit 30 for oxygen gas detection provided with an oxygen sensor is mounted on the gas detector main body 10 via a remote cable 35, and the sensor unit 30 is positioned at the level of the ground surface (opening level of the manhole). In this state, the power of the gas detector main body 10 is turned on. Thereby, the zero point setting for the depth of the sensor unit 30 is performed, and the operating conditions of the gas detector main body 10 are automatically set to those according to the mounted sensor unit 30.

Then, as shown in FIG. 3, when the remote cable 35 is fed out and the sensor unit 30 is lowered into the closed space S, the air in the environmental atmosphere in the closed space S reaches the oxygen sensor by natural diffusion and the oxygen gas is discharged. Concentration detection is performed, and the pressure of the environmental atmosphere at the level Ls where the sensor unit 30 is located is detected by the pressure sensor 32. That is, the gas detection signal from the oxygen sensor in the sensor unit 30 is input to the gas concentration calculator 21 in the gas detector main body 10, and the gas concentration calculator 21 calculates the oxygen gas concentration based on the gas detection signal. . Further, a pressure detection signal from the pressure sensor 32 in the sensor unit 30 is input to the depth calculation unit 22 in the gas detector main body 10, and the depth calculation unit 22 determines the depth H1 of the sensor unit 30 from the ground level GL. It is calculated based on the pressure detection signal. The calculated oxygen gas concentration value and depth H1 are displayed on the display unit 11 of the gas detector main body 10, and the gas concentration data and the depth data are linked and recorded in the recording unit 23.
Further, the same operation may be performed by replacing the sensor unit 30 with a sensor unit having, for example, a hydrogen sulfide sensor as necessary.

  When such work (preliminary measurement) is performed and the safety of the environmental atmosphere in the enclosed space S is confirmed, the operator actually carries the gas detector and enters the enclosed space S. In this case, as shown in FIG. 4, the gas detector in a state where the sensor unit 30 is mounted on the remote cable mounting portion 15 of the gas detector main body 10 is mounted on the worker's body. It is carried and used. Then, the concentration of the oxygen gas in the closed space S is constantly monitored by detecting the concentration of the oxygen gas in the process of the worker descending in the closed space S, and the concentration alarm point at which the concentration of the oxygen gas is set is set. When exceeding is detected, an alarm is issued by the alarm unit 13. Further, when a depth warning point is set based on the measurement data obtained for the closed space S, the depth calculated based on the pressure of the environmental atmosphere corresponds to the depth warning point (for example, the safety limit value). An alarm is issued by the alarm unit 13 when the exceeding is detected. For example, assuming that the oxygen gas concentration at the level position of H2 [m] is 18 vol%, which is the safety limit value, from the measurement result obtained by the preliminary measurement, the depth is set as the depth alarm point. It is set and an alarm is issued when it is detected that the worker has descended to the depth.

  In the above gas detector, the pressure sensor 32 as depth detecting means is configured to be mounted on the sensor unit 30. Thereby, in the process in which the sensor unit 30 is lowered in the closed space S, by detecting the pressure of the environmental atmosphere in the closed space S by the pressure sensor 32, the concentration of the gas to be detected in the closed space S is determined. It can be detected in association with the depth position (depth) where the sensor unit 30 is located in the closed space S. Therefore, according to the above gas detector, the state of the environmental atmosphere in the closed space S can be accurately grasped, and high safety can be obtained. For example, according to the above-described gas detector, the height (depth) in the closed space S is provided by having the recording unit 23 in which the detected concentration value of the detection target gas and the depth are associated (linked) and recorded. The concentration distribution of the oxygen gas (the concentration distribution of the hydrogen sulfide gas) in the direction S) can be obtained, and the state of the environmental atmosphere in the closed space S can be accurately grasped from the gas concentration distribution.

  Actually, when a region where the concentration of oxygen gas is lower than the reference value or a region where the concentration of hydrogen sulfide gas exceeds the reference value exists in the closed space S, measures such as ventilation are taken. By grasping the state of the environmental atmosphere in S, there is an advantage that work such as ventilation can be performed efficiently.

  Further, according to the above gas detector, the display unit 11 which displays the depth together with the concentration value of the detected gas to be detected can monitor the state of the environmental atmosphere in the closed space S in real time. it can.

  Furthermore, according to the gas detector described above, the depth alarm point for the depth can be set as an alarm point at which the alarm unit 13 performs an alarm operation, so that the actual situation in the closed space S can be set. Therefore, an alarm operation is issued in accordance with the condition (1), so that higher safety can be obtained.

As mentioned above, although one embodiment of the present invention was described, the present invention is not limited to the above-mentioned embodiment, and various changes can be added .

Reference Signs List 10 Gas detector body 11 Display unit 12 Operation unit 13 Alarm unit 13a Alarm light emitting unit 15 Remote cable mounting unit 21 Gas concentration calculation unit 22 Depth calculation unit 23 Recording unit 25 Control unit 30 Sensor unit 31 Gas sensor 32 Pressure sensor 35 Remote cable 36 Cable 37 Sensor Unit Mounting Section 38 Mounted Section 39a Linear Protective Member 39b Linear Protective Member

Claims (4)

A gas detector body that is configured to be portable and has a remote cable mounting portion, and a sensor unit including at least a gas sensor connected to the gas detector body via a remote cable, wherein the remote cable mounting portion is The sensor unit itself is configured to be detachably mounted so as to be replaceable with a remote cable, and the sensor unit is inserted into a closed space formed inside a structure having an opening that opens upward. A gas detector configured to be capable of remotely measuring the concentration of the gas to be detected in the enclosed space,
The sensor unit includes a depth detecting unit that detects a depth from an opening surface in the closed space ,
A gas detector, wherein the depth detecting means is constituted by a pressure sensor, and the pressure sensor is mounted on the sensor unit .   2. The gas detector according to claim 1, wherein the gas detector main body includes a display unit that displays a depth of the sensor unit in the closed space together with a type and a concentration of the detected gas. 3. The gas detector body further includes an alarm unit, and a depth alarm point for a depth in the enclosed space can be set as an alarm point at which an alarm operation is performed by the alarm unit. The gas detector according to claim 1 or 2. The gas detector according to any one of claims 1 to 3, wherein the sensor unit includes an oxygen sensor or a hydrogen sulfide sensor .

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