EP0508966B1 - Toxic gas detection - Google Patents

Toxic gas detection Download PDF

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Publication number
EP0508966B1
EP0508966B1 EP92830173A EP92830173A EP0508966B1 EP 0508966 B1 EP0508966 B1 EP 0508966B1 EP 92830173 A EP92830173 A EP 92830173A EP 92830173 A EP92830173 A EP 92830173A EP 0508966 B1 EP0508966 B1 EP 0508966B1
Authority
EP
European Patent Office
Prior art keywords
sensor
microprocessor
signal
alarm
circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP92830173A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0508966A3 (en
EP0508966A2 (en
Inventor
Gian Pietro Beghelli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Beghelli SpA
Original Assignee
Beghelli SpA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Beghelli SpA filed Critical Beghelli SpA
Publication of EP0508966A2 publication Critical patent/EP0508966A2/en
Publication of EP0508966A3 publication Critical patent/EP0508966A3/en
Application granted granted Critical
Publication of EP0508966B1 publication Critical patent/EP0508966B1/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B21/00—Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
    • G08B21/02—Alarms for ensuring the safety of persons
    • G08B21/12—Alarms for ensuring the safety of persons responsive to undesired emission of substances, e.g. pollution alarms
    • G08B21/16—Combustible gas alarms
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B21/00—Alarms responsive to a single specified undesired or abnormal condition and not otherwise provided for
    • G08B21/02—Alarms for ensuring the safety of persons
    • G08B21/12—Alarms for ensuring the safety of persons responsive to undesired emission of substances, e.g. pollution alarms
    • G08B21/14—Toxic gas alarms

Definitions

  • the present invention refers to a toxic gas detection device according to the preamble of claim 1.
  • WO90/12315 Devices of this kind are known from WO90/12315.
  • a circuit is described which tests whether an amperometric electrochemical gas sensor monitoring the concentration of toxic gases in an atmosphere is working properly.
  • the sensor has sensing electrodes, a reference electrode and a counter electrode and in normal operation the potential between the sensing and reference electrodes id fixed by means of an operational amplifier.
  • the sensor is periodically tested to see whether it is working properly by applying a pulse potential between the sensing and reference electrode. If the sensor is working properly, this results in a flow current through the sensor and through the circuit which is detected by an alarm device connected to the potentiometer by a switch during the test periods. If no current is detected by the alarm device the sensor is not working properly and an alarm is given by the device.
  • U.S. 4,219,806 Another device of the above mentioned kind is disclosed in U.S. 4,219,806.
  • This device being a detector of a significant gas conditions in the atmosphere comprises one or more elements for sensing the conditions.
  • This elements are connected to an alarm channel which sounds a warning alarm or control a corrective device such as a gas valve in the event of an excessive atmospheric condition.
  • the detector includes a threshold sensing the alarm amplifying channel and a trouble sensing electronic valve or stage responsive to a failure of one of the sensing elements both to enable operation of a trouble channel to cause the alarm to indicate the failure and also to inhibit operation of the alarm channel.
  • the trouble channel may also relay power supply failures such as decrease in battery voltage.
  • the object of the present invention consist in providing a toxic gas detector of the above mentioned kind which is able to execute testing routines comprising self-monitoring and diagnosis of the detection devices capable of monitoring the critical parameters for the devices together with the function of critical components therein, indicating any faults or abnormalities by suitable means as well as the functioning of the alarm device as a whole by checking the fact that the components downstream of the sensors are in a perfect operating condition.
  • the invention solves the above mentioned problem by means of the combination of features of the characterising part of claim 1.
  • a monitoring circuit 1 has an alarm LED 2 and a test signal LED 3. Power is supplied by a supply block 4. A gas sensor 6 and an acoustic sensor 7 are connected to the monitoring circuit 1 through an interface 5. A manual test switch 8 is provided; 8' is the corresponding relay.
  • an electrical mains connection 10 feeds through a continuous transformer 11 to feeds 9 and 9' fitted with a voltage regulator 12.
  • FIG 3 shows the monitoring circuit microprocessor with its electrical signal inputs and outputs for controlling the timing of the operations which mainly affect user unit 14, alarm 15, sensor 16, input 1/ (RS > MAX) or input 18 (RS ⁇ MIN), buzzer 19, LEDs 21, 22, test switch 23 and the other circuit components, relay 25, buzzer control 20 and logic input 24 (voltage or current).
  • microprocessor 1 switches off sensors 31 or 31' (logic signal 16 or 16') by means of the circuit illustrated in Figure 4 or Figure 5, according to the type of heating elelment operation. Switching off the sensor for a predetermined period (a few seconds) causes it to cool. Subsequent switching on of the sensor provides an opportunity for examination of the thermal transient (through an analysis of the output voltage "V out" from the measuring side of the sensor).
  • microprocessor 1 When this signal is detected by microprocessor 1 a check is made to ensure that the alarm condition has been generated correctly.
  • a manual or timed command in the form of signal 19 (BUZZER 32) is activated and logic signal 20, which represents the functioning of the acoustic indicator from the electrical point of view is detected and checked for correctness.
  • the acoustic efficiency of the indicator must be checked by the user, who must recognise a particular acoustic message when the test is activated.
  • Relay 25 is tested by means of a manual or timed control, by activating relay 25' by microprocessor 1 and subsequently checking logic signal 26 generated by an auxiliary relay contact.
  • the acoustic and/or visual signals will be of a different type and quality (for example flashing of the test LED 3) so as not to mislead users, giving rise to an unjustified panic situation. Flashing of the LED when the test has a positive outcome (the equipment is functioning correctly) implicitly provides a check on the functioning of the LED itself. If this were not the case a steady light or no light from the LED in the event of a positive test result would not allow any fault in the signalling device to be detected.
  • FIGS 4 and 5 illustrate two possible embodiments of the circuit for measuring the resistance of the heating element.
  • FIG. 4 shows an embodiment in which the heating element is operated at constant current.
  • Circuit 27 (consisting of R1, R2, R3, R4, R5, Q1, Q2, Q3, U1 and D1) forms a current generator which can be switched off by means of logic input 16 and which can provide two different values of current which can be selected through logic input 24 (I1/I2). In this case the resistance is measured by detecting the voltage across the heating element (comparators U2 and U3).
  • circuit 27' consisting of R1, R2, R3, R4, R8, R9, Q1, Q2, Q3 and U1 forms a voltage generator which can be switched off by means of logic input 16' and which can provide two different voltage values which can be selected by means of logic input 24' (V1/V2).
  • the resistance is measured by monitoring the current flowing in the heating. element (by measuring the voltage at terminals 30 of R7).

Landscapes

  • Toxicology (AREA)
  • General Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Environmental & Geological Engineering (AREA)
  • Emergency Management (AREA)
  • Physics & Mathematics (AREA)
  • Business, Economics & Management (AREA)
  • Combustion & Propulsion (AREA)
  • Chemical & Material Sciences (AREA)
  • Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
  • Emergency Alarm Devices (AREA)
  • Investigating Or Analyzing Materials By The Use Of Fluid Adsorption Or Reactions (AREA)
EP92830173A 1991-04-09 1992-04-08 Toxic gas detection Expired - Lifetime EP0508966B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITBO910109A IT1246641B (it) 1991-04-09 1991-04-09 Sistema circuitale di autocontrollo e diagnosi di dispositivi atti al rilevamento di gas tossici e/o nocivi e/o esplosivi.
ITBO910109 1991-04-09

Publications (3)

Publication Number Publication Date
EP0508966A2 EP0508966A2 (en) 1992-10-14
EP0508966A3 EP0508966A3 (en) 1994-09-14
EP0508966B1 true EP0508966B1 (en) 2001-08-16

Family

ID=11337382

Family Applications (1)

Application Number Title Priority Date Filing Date
EP92830173A Expired - Lifetime EP0508966B1 (en) 1991-04-09 1992-04-08 Toxic gas detection

Country Status (4)

Country Link
EP (1) EP0508966B1 (it)
DE (1) DE69231998T2 (it)
ES (1) ES2161689T3 (it)
IT (1) IT1246641B (it)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103544798A (zh) * 2012-07-12 2014-01-29 成都科盛石油科技有限公司 适用于石油提炼厂的防盗自检有害气体泄漏报警器

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4242936A1 (de) * 1992-12-18 1994-06-23 Beckhausen Karlheinz Sicherheitseinrichtung mit Mikroprozessor
AT404077B (de) * 1993-08-17 1998-08-25 Verband Laendlicher Genossensc Schaltungseinrichtung zur überwachung der konzentration von gärgasen in weinkellern
DE69631142T2 (de) 1996-10-29 2004-06-03 Zellweger Analytics Ltd., Poole Zustandsüberwachung eines Gasdetektors

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4088986A (en) * 1976-10-01 1978-05-09 Boucher Charles E Smoke, fire and gas alarm with remote sensing, back-up emergency power, and system self monitoring
US4219806A (en) * 1978-09-15 1980-08-26 American District Telegraph Company Dual alarm gas detector
DE3168996D1 (en) * 1980-05-02 1985-03-28 Ici Plc Method of checking the responsiveness of detection systems employing electrochemical sensor
GB8907564D0 (en) * 1989-04-04 1989-05-17 Neotronics Technology Plc Fault detection in electrochemical gas sensing equipment

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103544798A (zh) * 2012-07-12 2014-01-29 成都科盛石油科技有限公司 适用于石油提炼厂的防盗自检有害气体泄漏报警器

Also Published As

Publication number Publication date
EP0508966A3 (en) 1994-09-14
DE69231998D1 (de) 2001-09-20
ITBO910109A0 (it) 1991-04-09
ES2161689T3 (es) 2001-12-16
IT1246641B (it) 1994-11-24
EP0508966A2 (en) 1992-10-14
DE69231998T2 (de) 2002-04-11
ITBO910109A1 (it) 1992-10-09

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