JP2007256131A - Concentration measuring instrument for fumigation gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure the concentration of ethylene oxide in a fumigation housing, with the elapse of time and with accuracy. <P>SOLUTION: The concentration measuring instrument of a fumigation gas G is equipped with a detection part 10, having a catalyst causing catalytic combustion upon the contact with the combustible gas in the fumigation gas and a catalytic combustion type gas sensor DS fluctuating in its electrical resistance value by the combustion heat due to the catalytic combustion; a fumigation gas inlet pipe 20 for introducing the fumigation gas G in the fumigation housing C into the catalytic combustion type gas sensor DS and solenoid valves SV1-SV3 for the fumigation gas, an air inlet pipe 30 for introducing air A into the catalytic combustion type gas sensor DS and a solenoid valve SV4-1 for air, and a control part 40 for intermittently and repeatedly performing operation for introducing the fumigation gas G into the catalytic combustion type gas sensor DS only for a predetermined time by intermittently operating the solenoid valves SV1-SV3 and the solenoid valve SV4-1 for air for the fumigation gas G to measure the concentration of the combustible gas in the fumigation gas G, and subsequently making air A introduced into the catalytic combustion type gas sensor DS to sweep the fumigation gas G around the sensor DS. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fumigation gas concentration measuring device. More specifically, when fumigation objects (for example, cultural assets, arts, etc.) are stored in the fumigation chamber (fumigation chamber) and fumigation gas is placed in the fumigation chamber to fumigate the fumigation objects, The present invention relates to a fumigation gas concentration measuring device for measuring the concentration of fumigation gas over time.

Conventionally, the fumigation gas used for fumigation of cultural properties, etc., has been mainly mixed gas of methyl bromide and ethylene oxide (trade name “Ekibon”). Since this conventional fumigation gas (exibone) has both sterilization and insecticidal ability for both methyl bromide and ethylene oxide, sterilization (sterilization and sterilization) has been conventionally performed by measuring the total amount of “exibone” that is put into the fumigation chamber. We were able to grasp the degree of (insecticidal) ability.
For this reason, conventionally, if the concentration of the mixed gas (trade name “EXBON”) is measured using an optical interferometer-type gas concentration meter, the degree of sterilization (sterilization / insecticidal) ability in the fumigation chamber can be ascertained. I was able to.

However, in recent years, the use of methyl bromide contained in the above-mentioned “Ekbon” has been restricted as a measure against ozone holes, and several types of gases other than Ekbon have come to be used for fumigation of cultural properties. It was.
A mixed gas of ethylene oxide and HFC134a (R134a) (trade name “Exfume”) is a representative example of such a cultural property fumigation gas, and is currently used in many museums and art galleries.

By the way, as described above, ethylene oxide has a sterilizing and insecticidal ability, but HFC134a (chemical formula: CH2FCF3) contained in the “exfume” does not have a sterilizing and insecticidal ability.
In addition, the concentration ratio of “exfume” ethylene oxide to HFC134a is 1: 2.5, and HFC134a is more common. Further, during fumigation, ethylene oxide is adsorbed on the fumigation object, but HFC134a is hardly adsorbed. For this reason, in the fumigation store, the concentration of HFC134a having no sterilizing / insecticidal ability increases with time.
Therefore, even if the concentration measurement (total amount measurement) of the above “exfume” is performed using an optical interferometer type gas concentration meter (even if it is performed over time), the sterilization (sterilization / insecticing) capability of the fumigation chamber The degree cannot be grasped.

Therefore, in order to grasp the degree of sterilization (sterilization and insecticidal) ability in the fumigation chamber when fumigation is performed using the above “exfume”, the ethylene oxide concentration in the fumigation chamber space in the presence of HFC134a is determined. There is a need to measure.
The concentration of ethylene oxide when fumigating cultural assets using “Exfume” is 1.5 to 2.0% at the beginning of fumigation, and 1% or more after 24 hours.
On the other hand, since ethylene oxide contained in “Exfume” is a flammable gas, it is possible to measure the concentration up to the lower explosion limit concentration (3%) with a catalytic combustion type (catalytic combustion type) sensor.
Therefore, at present, the detection unit having a contact combustion type sensor is used to measure the ethylene oxide concentration in the fumigation chamber during fumigation over time.

FIG. 4 is a principle diagram for explaining the principle of concentration measurement by a detection unit using a contact combustion type sensor.
As shown in the figure, the detection unit 10 is made of platinum or palladium having a high catalytic activity for the oxidation reaction of combustible gas, and is a gas detection element (contact combustion) that is heated to a relatively low temperature with a constant current. DS) is incorporated. When the combustible gas in the test gas comes into contact with the gas detection element, it burns by catalytic action (catalytic combustion), and the heat generated by the combustion increases the electrical resistance of the gas detection element DS. Since the amount of increase in electric resistance is proportional to the concentration of the combustible gas in the test gas, the concentration can be displayed by the meter M in the electric circuit (for example, see Patent Document 1, paragraphs 0007 to 0009).
The CS in the electric circuit is a temperature compensation element that has been subjected to insensitive processing to compensate for measurement errors due to temperature changes and pressure fluctuations other than gas catalytic combustion. It has a covered structure.
Since fumigation of cultural assets is usually performed with the inside of the fumigation chamber maintained at a negative pressure, it is desirable to use a detection unit corresponding to the pressure fluctuation as described above.

  At present, the time-dependent measurement of the ethylene oxide concentration in the fumigation storage space during fumigation is continuously performed using the above-described detection unit (for example, 24 hours of continuous fumigation).

JP 2005-321216 A

Currently, the main component of the gas detection element (contact combustion sensor) of the detection unit 10 that is put into practical use is palladium.
On the other hand, since the chemical formula of HFC134a coexisting with “Exfume” used for fumigation of cultural assets, etc. is CH2FCF3, the F component (fluorine) serves as a catalyst poison to function as a catalyst (main component palladium) of the gas detection element. It was found that it was lowered.
In the above-described measurement of the ethylene oxide concentration in the fumigation chamber, since the measurement is continuously performed during fumigation, the gas detection element is continuously contacted (exposed) continuously with the fumigation gas as the measurement gas. For this reason, there is a problem that the sensitivity of the gas detection element decreases with time and accurate concentration measurement cannot be performed.
As described above, the concentration ratio of ethylene oxide and HFC134a in “Exfume” is 1: 2.5, which is higher in HFC134a. In addition, during fumigation, ethylene oxide is adsorbed by the fumigation target, whereas HFC134a. Is hardly adsorbed, so that the concentration of HFC134a increases with time and relatively, and if additional dosage is given during fumigation, the concentration of HFC134a increases for the same reason. The action is accelerated, making it more difficult to accurately measure the ethylene oxide concentration.
An object of the present invention is to provide a fumigation gas concentration measuring device that solves the above-described problems and can accurately measure the combustible gas (ethylene oxide) concentration in the fumigation chamber over time. is there.

In order to achieve the above object, the fumigation gas concentration measuring device of the present invention stores a fumigation object in a fumigation chamber, and includes fumigation / insecticidal and flammable gas and gas acting as catalyst poison. A gas concentration measuring device for measuring the concentration of fumigation gas in the fumigation chamber over time when fumigating a fumigation object by putting gas into the fumigation chamber,
A catalytic combustion type gas sensor having a catalyst that generates catalytic combustion in contact with the combustible gas in the fumigation gas, the electrical resistance value of which varies with the heat of combustion by catalytic combustion, and the electrical resistance value of the catalytic combustion type gas sensor; A detector having an electric circuit for converting the fluctuation amount into an electric quantity;
A fumigation gas introduction pipe for introducing the fumigation gas in the fumigation chamber into the catalytic combustion type gas sensor, and a fumigation gas solenoid valve interposed in the fumigation gas introduction pipe,
An air introduction pipe for introducing air that does not contain the fumigation gas into the catalytic combustion gas sensor, and an air solenoid valve interposed in the air introduction pipe;
The fumigation gas solenoid valve and the air solenoid valve are operated intermittently, the fumigation gas is introduced into the catalytic combustion gas sensor only for a predetermined time, and the concentration of the combustible gas in the fumigation gas is measured, Thereafter, a control unit that intermittently repeatedly performs the operation of introducing the air into the catalytic combustion gas sensor and scavenging the fumigation gas around the sensor,
It is characterized by having.

According to such a configuration, the fumigation gas is intermittently introduced into the catalytic combustion type sensor only for a predetermined time by the intermittent operation of the fumigation gas solenoid valve and the air solenoid valve by the control unit. The concentration of the combustible gas in the fumigation gas is measured, and then air containing no fumigation gas is introduced into the catalytic combustion type gas sensor to scavenge the fumigation gas (and hence catalyst poison) around the sensor. Measures the combustible gas concentration in the fumigation chamber over time and accurately by shortening the time that the combustion sensor contacts (exposure) with the fumigation gas, thereby suppressing the decrease in sensitivity of the contact combustion sensor. It becomes possible.
Preferably, a fumigation gas return pipe is provided for returning the fumigation gas after contacting the catalytic combustion type gas sensor into the fumigation chamber.
If comprised in this way, the fumigation gas (flammable gas which has bactericidal and insecticidal property) used for the measurement can be used again for fumigation without wasting it.
Desirably, air exhaust means for exhausting air scavenging the fumigation gas around the catalytic combustion gas sensor to a space other than the space inside the fumigation chamber is provided.
If comprised in this way, it can prevent that the fumigation gas density | concentration (concentration of the combustible gas which has sterilization / insecticidal property) in the fumigation store | warehouse | chamber is reduced by mixing of the air which was used for scavenging.
Desirably, a plurality of fumigation gas inlets by the fumigation gas introduction pipe are provided in the vertical direction of the space inside the fumigation chamber.
If comprised in this way, the fumigation gas density | concentration (concentration of the combustible gas which has bactericidal and insecticidal property) of the space in a fumigation store | warehouse | chamber will be grasped more correctly.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a piping and circuit diagram showing an embodiment of a fumigation gas concentration measuring apparatus according to the present invention.

As shown in the figure, the fumigation gas concentration measuring device 1 stores a fumigation object (for example, a cultural property or a work of art (not shown)) in a fumigation chamber C, and has bactericidal, insecticidal and flammable properties. Gas for measuring the concentration of the fumigation gas G in the fumigation chamber C over time when the fumigation gas G containing the gas and the gas acting as a catalyst poison is put in the fumigation chamber C and the fumigation object is fumigated A concentration measuring device,
A catalytic combustion gas sensor DS that has a catalyst that causes catalytic combustion when in contact with the combustible gas in the fumigation gas G, the electrical resistance value of which varies with the heat of combustion due to catalytic combustion, and the electrical resistance of the catalytic combustion gas sensor DS A detection unit 10 having an electric circuit for converting a fluctuation amount of the value into an electric quantity;
A fumigation gas introduction pipe 20 for introducing the fumigation gas G in the fumigation warehouse C to the contact combustion type gas sensor DS, and fumigation gas solenoid valves (SV1 to SV3) interposed in the fumigation gas introduction pipe 20;
An air introduction pipe 30 for introducing air A containing no fumigation gas G into the catalytic combustion type gas sensor DS, and an air solenoid valve (SV4-1) interposed in the air introduction pipe 30;
The fumigation gas solenoid valve (SV1 to SV3) and the air solenoid valve (SV4-1) are operated intermittently to introduce the fumigation gas G into the contact combustion gas sensor DS for a predetermined time. A control unit 40 that measures the concentration of the combustible gas therein, and then intermittently repeatedly performs the operation of introducing air A into the catalytic combustion gas sensor DS and scavenging the fumigation gas G around the sensor DS; It has.
Moreover, the display unit 60 for displaying a measurement result is provided.

In this embodiment, the “exfume” described above is used as the fumigation gas G including the gas having sterilizing / insecticidal and flammability and the gas acting as the catalyst poison, and the fumigation gas concentration measuring device 1 is a fumigation gas ( Exfume) A device for measuring the ethylene oxide concentration in G.
The catalytic combustion type sensor DS is composed of the sensor described above with reference to FIG. The detection unit 10 has an electric circuit based on the principle described above with reference to FIG.
Reference numeral 11 denotes an amplifier circuit for amplifying the sensor output from the detection unit 10.

FIG. 2 shows a specific example of the detection unit 10 and the amplifier circuit 11.
As shown in FIG. 2, in this embodiment, temperature compensation is performed to compensate for measurement errors due to temperature changes and pressure fluctuations other than catalytic combustion of gas (that is, measurement errors due to temperature changes and pressure fluctuations in the fumigation chamber C). Similarly to the catalytic combustion type gas sensor DS, the fumigation gas G or air A is also introduced into the element CS.
Since the fumigation of the cultural property or the like in this embodiment is performed with the inside of the fumigation warehouse C maintained at a negative pressure, the detection unit 10 corresponding to the pressure fluctuation as described above is used.
In FIG. 2, DS1 is a gas chamber in which a catalytic combustion gas sensor DS is accommodated and fumigation gas G or air A is introduced, and CS1 is a gas chamber in which a temperature compensation element CS is accommodated and fumigation gas G or air A is introduced. It is.
The chambers DS1 and CS1 communicate with each other through a communication path 12. A fumigation gas introduction pipe 20 (which is also an air introduction pipe 30) described later is connected to the inlet of the chamber DS1, and an exhaust pipe 51 described later is connected to the outlet of the chamber CS1.

As shown in FIG. 1, one end of the fumigation gas introduction pipe 20 is connected to the contact combustion type sensor DS, and the other end is branched into three introduction pipes 21, 22, 23 and connected to the fumigation chamber C. ing.
The introduction pipe 21 is connected to the upper part of the fumigation chamber C to form the upper introduction port 21a for the fumigation gas, and the introduction pipe 22 is connected to the middle of the fumigation room C to form the middle introduction port 22a for the fumigation gas. The pipe 23 is connected to the lower part of the fumigation chamber C to form a lower inlet 23a for the fumigation gas.
The introduction pipes 21, 22, and 23 are provided with the fumigation gas solenoid valves SV1 to SV3, the air filter 24, and the manual operation valve 25, respectively. All three manually operated valves 25 are manually opened at the start of measurement of the fumigation gas concentration.

  A part of the air introduction pipe 30 is formed of a common pipe with the fumigation gas introduction pipe 20, one end is connected to the contact combustion type sensor DS, and the other end is opened to the atmosphere via the air filter 31. ing. The air introduction pipe 30 is provided with the aforementioned air solenoid valve SV4-1.

A pump P and a first switching valve (three-way solenoid valve) SV5 are interposed in the common pipe portion of the fumigation gas introduction pipe 20 and the air introduction pipe 30. A bypass pipe 50 is connected to the first switching valve SV5. The first switching valve SV5 is normally switched to the bypass pipe 50 side (see “NO” in the figure).
An exhaust pipe 51 is connected to the other end of the catalytic combustion type gas sensor DS. The exhaust pipe 51 and the bypass pipe 50 are joined at a junction 52, and a second switching valve (three-way) is connected to the tip of the junction pipe 53. (Electromagnetic valve) SV4-2 is provided.

The second switching valve SV4-2 is connected to a fumigation gas return pipe 54 for returning the fumigation gas G after contacting the catalytic combustion gas sensor DS into the fumigation chamber C. A manual operation valve 55 is provided in the fumigation gas return pipe 54. The manual operation valve 55 is manually opened at the start of measurement of the fumigation gas concentration. The second switching valve SV4-2 normally closes the fumigation gas return pipe 54 side (see “NC” in the figure). As will be described later, the second switching valve SV4-2 constitutes an air exhaust means.
The exhaust pipe 51 is provided with a check valve 56 between the junction 52 with the bypass pipe 50 and the contact combustion gas sensor DS.

The solenoid valves SV1 to SV3, SV4-1, the first switching valve SV5, the second switching valve SV4-2, and the pump P are electrically connected to the control unit 40, respectively. Control is performed as described later.
The amplifying circuit 11 described above is connected to the control unit 40, and an output signal from the amplifying circuit 11 is A / D converted by an A / D converter provided in the control unit 40, the concentration is calculated, and the display unit 60 It is digitally displayed as a concentration measurement result on a display unit (not shown). The display unit 60 includes a printer and can print out the measurement result.

  The control unit 40 has a timer function, and this timer mechanism allows the user of this measuring apparatus to set the measurement standby time. Based on the measurement waiting time set by the user, the control unit 40 controls the solenoid valves SV1 to SV3, SV4-1, the first switching valve SV5, the second switching valve SV4-2, and the pump P as follows. Operate to measure the ethylene oxide concentration in the fumigation chamber C over time. When performing the measurement operation, the manual operation valves 25 and 55 are opened in advance as described above. As described above, the first switching valve SV5 is normally switched to the bypass pipe 50 side, and the second switching valve SV4-2 is normally closed to the fumigation gas return pipe 54 side.

FIG. 3 is a flowchart showing a measurement sequence by the control unit 40.
The sequence shown in FIG. 3 shows the case where the measurement standby time is set to 60 minutes by the timer provided in the control unit 40 and the measurement operation of the fumigation gas G is set to be performed for 3 minutes every 60 minutes. In this embodiment, the pump P and the solenoid valves SV1 to SV3 and SV4-1 are operated intermittently during the measurement standby time. However, during the measurement standby time, the pump P and the solenoid valve are operated. You may comprise so that SV1-SV3 and SV4-1 may not be operated.

The control by the control unit 40 is as follows.
(1) Control starts in step ST1.
(2) The measurement standby operation is started in step ST2, the pump P is operated, the electromagnetic valve SV1 of the introduction pipe 21 (CH.1) is turned on (opened), and the second switching valve SV4-2 is fumigated. Switching to the gas return pipe 54 side, the fumigation gas G in the fumigation chamber C is sucked to the first switching valve SV5 through the introduction pipe 21 for 58 seconds.
At this time, as described above, the first switching valve SV5 is switched to the bypass pipe 50 side, and the second switching valve SV4-2 is switched to the fumigation gas return pipe 54 side. The fumigation gas G is returned into the fumigation chamber C through the bypass pipe 50, the second switching valve SV4-2, and the fumigation gas return pipe 54 without being introduced into the catalytic combustion gas sensor DS.
(3) In step ST3, the solenoid valve SV1 of the introduction pipe 21 (CH.1) is turned off (closed) and the pump P is stopped (the operation takes 2 seconds).

(4) In step ST4, the pump P is operated, the solenoid valve SV2 of the introduction pipe 22 (CH.2) is turned on (opened), and the fumigation gas G in the fumigation chamber C is first passed through the introduction pipe 22 for 58 seconds. Suction to the switching valve SV5.
At this time, as described above, the first switching valve SV5 is switched to the bypass pipe 50 side, and the second switching valve SV4-2 is switched to the fumigation gas return pipe 54 side. The fumigation gas G is returned into the fumigation chamber C through the bypass pipe 50, the second switching valve SV4-2, and the fumigation gas return pipe 54 without being introduced into the catalytic combustion gas sensor DS.
(5) In step ST5, the electromagnetic valve SV2 of the introduction pipe 22 (CH.2) is turned off (closed) and the pump P is stopped (the operation takes 2 seconds).

(6) In step ST6, the pump P is operated, the electromagnetic valve SV3 of the introduction pipe 23 (CH.3) is turned on (opened), and the fumigation gas G in the fumigation chamber C is first passed through the introduction pipe 23 for 58 seconds. Suction to the switching valve SV5.
At this time, as described above, the first switching valve SV5 has been switched to the bypass pipe 50 side, and the second switching valve SV4-2 has been switched to the fumigation gas return pipe 54 side. The fumigation gas G is returned into the fumigation chamber C through the bypass pipe 50, the second switching valve SV4-2, and the fumigation gas return pipe 54 without being introduced into the catalytic combustion gas sensor DS.
(7) In step ST7, the solenoid valve SV3 of the introduction pipe 23 (CH.3) is turned off (closed) and the pump P is stopped (the operation takes 2 seconds).

The operations in steps ST2 to ST7 as described above are repeated until the standby time elapses (in this case, 60 minutes, and operations in steps ST2 to ST7 are performed 20 times).
Therefore, during this time (that is, during standby operation), the fumigation gas G is introduced up to the first switching valve SV5, but is returned to the fumigation chamber C without being introduced into the catalytic combustion gas sensor DS. The ethylene oxide concentration is not measured.
After the standby operation, the measurement operation after step ST8 is performed.

(8) In step ST8, the measurement operation is started. First, zero adjustment is performed. That is, the pump P is operated, the air solenoid valve SV4-1 is turned on (opened), the first switching valve SV5 is placed on the contact combustion type gas sensor DS side, and the second changeover valve SV4-2 is placed on the air exhaust side ( The air is introduced into the catalytic combustion type gas sensor DS for 38 seconds. The air introduced into the contact combustion type gas sensor DS comes into contact with the contact combustion type gas sensor DS, and is then discharged into the atmosphere through the exhaust pipe 51, the junction pipe 53, and the second switching valve SV4-2.
The zero adjustment is performed by the control unit 40 setting the measured value to zero (that is, resetting the measured value) when the output of the catalytic combustion type gas sensor DS is stabilized during the air introduction.
After the zero adjustment (that is, after 38 seconds), the air solenoid valve SV4-1 is closed.

(9) The air solenoid valve SV4-1 is closed, and in step ST9, the solenoid valve SV1 of the introduction pipe 21 (CH.1) is turned on (opened), and the second switching valve SV4-2 is turned on. Switching to the return pipe 54 side, the fumigation gas G in the fumigation chamber C is introduced into the contact combustion gas sensor DS through the introduction pipe 21 for 20 seconds, and the ethylene oxide concentration in the fumigation gas G is measured.
In the measurement of ethylene oxide concentration, the control unit 40 calculates the gas concentration when the output of the catalytic combustion type gas sensor DS is stabilized during the introduction of the fumigation gas G, and displays the result on the display unit 60. Is done. Thereby, the ethylene oxide concentration (namely, sterilization / insecticidal ability) in the upper part in the fumigation warehouse C can be grasped.
The fumigation gas G introduced into the contact combustion type gas sensor DS comes into contact with the contact combustion type gas sensor DS, and then passes through the exhaust pipe 51, the junction pipe 53, the second switching valve SV4-2, and the fumigation gas return pipe 54. It returns to the inside of the fumigation warehouse C (the upper part of the fumigation warehouse C).
After the concentration measurement (20 seconds after the solenoid valve SV1 is turned on), the solenoid valve SV1 of the introduction pipe 21 (CH.1) is closed (turned off).
(10) The electromagnetic valve SV1 is closed and the pump P is stopped for 2 seconds in step ST10.

(11) In step ST11, the pump P is operated, and similarly to step ST8, the air solenoid valve SV4-1 is turned on (opened), and the second valve SV4-2 is turned on the air exhaust side ("NO" in FIG. 1). The air solenoid valve SV4-1 is closed after air is introduced into the contact combustion type gas sensor DS for 38 seconds and zero adjustment is performed. The air introduced into the catalytic combustion type gas sensor DS comes into contact with the catalytic combustion type gas sensor DS, and then is discharged into the atmosphere through the exhaust pipe 51, the merging pipe 53, and the second switching valve SV4-2.

(12) The air solenoid valve SV4-1 is closed, and in step ST12, the solenoid valve SV2 of the introduction pipe 22 (CH.2) is turned on (opened), and the second switching valve SV4-2 is turned on as fumigation gas. By switching to the return pipe 54 side, the fumigation gas G in the fumigation chamber C is introduced into the contact combustion gas sensor DS through the introduction pipe 22 for 20 seconds, and the ethylene oxide concentration in the fumigation gas G is measured as before. Thereby, the ethylene oxide concentration (that is, sterilization / insecticidal ability) in the middle of the fumigation warehouse C can be grasped.
The fumigation gas G introduced into the contact combustion type gas sensor DS is returned to the fumigation chamber C as before, after contacting the contact combustion type gas sensor DS.
After the concentration measurement (20 seconds after the solenoid valve SV2 is turned on), the solenoid valve SV2 of the introduction pipe 22 (CH.2) is closed (turned off).
(13) The electromagnetic valve SV2 is closed and the pump P is stopped for 2 seconds in step ST13.

(14) The pump P is operated in step ST14, the air solenoid valve SV4-1 is turned on (opened), and the second valve SV4-2 is turned on the air exhaust side ("NO" in FIG. 1) as in step ST8. The air solenoid valve SV4-1 is closed after air is introduced into the contact combustion type gas sensor DS for 38 seconds and zero adjustment is performed. The air introduced into the catalytic combustion type gas sensor DS comes into contact with the catalytic combustion type gas sensor DS, and then is discharged into the atmosphere through the exhaust pipe 51, the merging pipe 53, and the second switching valve SV4-2.

(15) The air solenoid valve SV4-1 is closed, and in step ST15, the solenoid valve SV3 of the introduction pipe 23 (CH.3) is turned on (opened), and the second switching valve SV4-2 is turned on as a fumigation gas. By switching to the return pipe 54 side, the fumigation gas G in the fumigation chamber C is introduced into the contact combustion gas sensor DS through the introduction pipe 23 for 20 seconds, and the ethylene oxide concentration in the fumigation gas G is measured as before. Thereby, the ethylene oxide concentration (namely, sterilization / insecticidal ability) in the lower part in the fumigation warehouse C can be grasped.
The fumigation gas G introduced into the contact combustion type gas sensor DS is returned to the fumigation chamber C as before, after contacting the contact combustion type gas sensor DS.
After the concentration measurement (20 seconds after the solenoid valve SV3 is turned on), the solenoid valve SV3 of the introduction pipe 23 (CH.3) is closed (turned off).
(16) The solenoid valve SV3 is closed and the pump P is stopped for 2 seconds in step ST16.

  The measurement operation of one time (one cycle) is completed in the above steps ST8 to ST16, but when the above step 16 is completed, the fumigation gas G is still introduced into the catalytic combustion gas sensor DS. If left unattended, the contact combustion gas sensor DS is brought into contact with the HFC 134a (catalyst poison) contained in the fumigation gas G, resulting in a decrease in sensitivity.

Therefore, in this embodiment, the scavenging operation is performed in the following step ST17. That is,
(17) In step ST17, the pump P is operated, the air solenoid valve SV4-1 is turned on (opened), and the second replacement valve SV4-2 is turned to the air exhaust side (see “NO” in FIG. 1). After switching, air is introduced into the contact combustion gas sensor DS for 38 seconds to scavenge the gas chamber DS1 of the contact combustion gas sensor DS (see FIG. 2) and the gas chamber CS1 of the temperature compensation element CS. The air scavenged in the chamber is discharged to the atmosphere through the exhaust pipe 51, the junction pipe 53, and the second switching valve SV4-2.
After the scavenging operation, the pump P is stopped and the air solenoid valve SV4-1 is closed.

(18) Thereafter, in step ST18, the measurement results obtained in steps ST8 to ST16 are printed out by the printer of the display unit 60, and the control from step ST2 is repeated. For example, if measurement for 24 hours is required, repeat until 24 hours have passed.

According to the fumigation gas concentration measuring apparatus 1 as described above, the following operational effects can be obtained.
(A) The fumigation gas concentration measuring device 1 stores a fumigation object (for example, cultural property or art work (not shown)) in a fumigation chamber C, and has a sterilizing / insecticidal and flammable gas and a catalyst poison. A gas concentration measuring device for measuring the concentration of the fumigation gas G in the fumigation chamber C over time when the fumigation gas G containing the gas acting as the fumigation gas is put into the fumigation chamber C and the fumigation object is fumigated. Yes,
A catalytic combustion gas sensor DS that has a catalyst that causes catalytic combustion when in contact with the combustible gas in the fumigation gas G, the electrical resistance value of which varies with the heat of combustion due to catalytic combustion, and the electrical resistance of the catalytic combustion gas sensor DS A detection unit 10 having an electric circuit for converting a fluctuation amount of the value into an electric quantity;
A fumigation gas introduction pipe 20 for introducing the fumigation gas G in the fumigation warehouse C to the contact combustion type gas sensor DS, and fumigation gas solenoid valves (SV1 to SV3) interposed in the fumigation gas introduction pipe 20;
An air introduction pipe 30 for introducing air A containing no fumigation gas G into the catalytic combustion type gas sensor DS, and an air solenoid valve (SV4-1) interposed in the air introduction pipe 30;
The fumigation gas solenoid valve (SV1 to SV3) and the air solenoid valve (SV4-1) are operated intermittently to introduce the fumigation gas G into the contact combustion gas sensor DS for a predetermined time. A control unit 40 that measures the concentration of the combustible gas therein, and then intermittently repeatedly performs the operation of introducing air A into the catalytic combustion gas sensor DS and scavenging the fumigation gas G around the sensor DS; Therefore, the control unit 40 intermittently operates the fumigation gas solenoid valves SV1 to SV3 and the air solenoid valve SV4-1, intermittently (every 60 minutes in this embodiment) for a predetermined time. (In this embodiment, it is 3 minutes, more precisely, 20 × 3 times = 60 seconds) Only the fumigation gas G is introduced into the contact combustion type sensor DS and the combustible gas (ethylene oxide) in the fumigation gas G is introduced. ) Measured concentration After that, air A that does not contain fumigation gas is introduced into the catalytic combustion type gas sensor DS and the fumigation gas (and therefore catalyst poison) around the sensor DS is scavenged (see step ST17). , The time that the contact combustion type sensor DS contacts (exposure) with the fumigation gas G is shortened, thereby suppressing the decrease in sensitivity of the contact combustion type sensor DS, and the measurement of the combustible gas concentration in the fumigation chamber C over time. And accurate and accurate.

(B) Since a fumigation gas return pipe for returning the fumigation gas G after contacting the contact combustion type gas sensor DS to the fumigation warehouse C is provided, the fumigation gas used for the measurement (a combustible gas having sterilization and insecticidal properties) ) G can be re-fumigated without wasting it.
(C) Since the air exhaust means SV4-2 for exhausting the air A scavenging the fumigation gas G around the catalytic combustion type gas sensor DS to a space other than the fumigation chamber space is provided, the fumigation gas concentration (sterilization in the fumigation chamber)・ The concentration of the flammable gas having insecticidal properties can be prevented from being reduced by the mixture of air used for scavenging.
(D) Since the fumigation gas introduction port by the fumigation gas introduction pipe 20 is provided at the three locations 21a, 22a, and 23a in the upper, middle and lower sides in the vertical direction of the fumigation chamber C, the fumigation gas concentration ( The concentration of combustible gas having bactericidal and insecticidal properties can be grasped more accurately.

(E) As described above, the pump P and the solenoid valves SV1 to SV3 and SV4-1 are not operated during the measurement standby time, and the pump P and the solenoid valves SV1 to SV3 and SV4 are only operated during the measurement. The intermittent concentration measurement of the fumigation gas G can also be performed by configuring so that the pump 1 is operated, but in this embodiment, the pump P and the electromagnetic wave are also measured during the measurement standby time (steps ST2 to ST7). Since the valves SV1 to SV3 are operated intermittently, the fumigation gas G sequentially sucked from the upper, middle and lower fumigation gas introduction ports 21a, 22a and 23a is returned to the fumigation chamber C through the fumigation gas return pipe 54. The fumigation gas G in the fumigation chamber C is stirred to some extent, and the fumigation effect in the fumigation chamber C is promoted.
Since a check valve 56 is provided between the junction 52 with the bypass pipe 50 and the contact combustion gas sensor DS, the fumigation gas G passes through the exhaust pipe 51 to the contact combustion gas sensor DS during the stirring operation. Intrusion can be prevented.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be appropriately modified within the scope of the gist of the present invention.
For example, the fumigation gas to be used is not limited to “exfume”, and the present invention can be applied to the case of using a fumigation gas including a gas having a sterilizing / insecticidal and flammable property and a gas acting as a catalyst poison.

The piping and circuit diagram which show one Embodiment of the fumigation gas concentration measuring apparatus which concerns on this invention. The figure which shows the specific example of the detection part 10 and the amplifier circuit 11. FIG. 5 is a flowchart showing a measurement sequence by the control unit 40. The principle figure explaining the principle of the density | concentration measurement by the detection part using a contact combustion type sensor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fumigation gas concentration measuring apparatus 10 Detection part 11 Amplification circuit 20 Fumigation gas introduction pipe 30 Air introduction pipe 40 Control part SV4-1 Solenoid valve for air SV1-SV3 Solenoid valve for fumigation gas A Air C Fumigation chamber DS Contact combustion type gas sensor G Fumigation gas

Claims (4)

When the fumigation object is stored in the fumigation chamber, and the fumigation gas containing the gas which has sterilizing / insecticidal property and flammability and the gas acting as the catalyst poison is placed in the fumigation chamber, the fumigation object is fumigated. A gas concentration measuring device for measuring the concentration of fumigation gas in a fumigation chamber over time,
A catalytic combustion type gas sensor having a catalyst that generates catalytic combustion in contact with the combustible gas in the fumigation gas, the electrical resistance value of which varies with the heat of combustion by catalytic combustion, and the electrical resistance value of the catalytic combustion type gas sensor; A detector having an electric circuit for converting the fluctuation amount into an electric quantity;
A fumigation gas introduction pipe for introducing the fumigation gas in the fumigation chamber into the catalytic combustion type gas sensor, and a fumigation gas solenoid valve interposed in the fumigation gas introduction pipe,
An air introduction pipe for introducing air that does not contain the fumigation gas into the catalytic combustion gas sensor, and an air solenoid valve interposed in the air introduction pipe;
The fumigation gas solenoid valve and the air solenoid valve are operated intermittently, the fumigation gas is introduced into the catalytic combustion gas sensor only for a predetermined time, and the concentration of the combustible gas in the fumigation gas is measured, Thereafter, a control unit that intermittently repeatedly performs the operation of introducing the air into the catalytic combustion gas sensor and scavenging the fumigation gas around the sensor,
A fumigation gas concentration measuring device comprising:   The fumigation gas concentration measuring device according to claim 1, further comprising a fumigation gas return pipe for returning the fumigation gas after contacting the catalytic combustion gas sensor into the fumigation chamber.   3. The fumigation gas concentration measuring device according to claim 1, further comprising air exhaust means for exhausting air scavenging the fumigation gas around the catalytic combustion type gas sensor to a space other than the space inside the fumigation warehouse.   The fumigation gas concentration measuring device according to claim 1, 2 or 3, wherein a plurality of fumigation gas introduction ports by the fumigation gas introduction pipe are provided in the vertical direction of the space inside the fumigation chamber.

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