SIMRAD GD100 MKII GAS DETECTOR

Operating Manual 5th edition P3183E January 1997

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CONTENTS Section Page 1. PRODUCT DESCRIPTION 3 1.1 General Description 3 1.2 Construction 3 1.3 Application Areas 4 1.4 Technical Data 4 1.5 Certification 6 1.6 Ordering Information 6 2. TECHNICAL DESCRIPTION 7 2.1 Introduction 7 2.2 GD100 Concept 7 2.3 Performance Characteristics 9 2.3.1 Gas Data 9 2.3.2 Interferential Gases 10 2.4 Gas Detection System 10 3. INSTALLATION 11 3.1 Mounting the GD100 MKII 11 3.1.1 Location 11 3.1.2 Ventilation Duct or Pipe Mounting 11 3.1.3 Pump Room Mounting 12 3.1.4 Orientation 14 3.1.5 Fastening the GD100 MKII 14 3.2 Electrical Connections 15 3.2.1 Terminal Compartment 15 3.2.2 Output Cable Connections 16 3.2.2.1 3-Wire Output Cable Connections 16 3.2.2.2 4-Wire Output Cable Connections 16 3.2.2.3 Retrofit Wiring 17 3.2.2.4 Recommended Cable Types 18 3.2.2.5 Initial Wiring Checks 18 4. OPERATION 19 4.1 Start-up Procedure 19 5. MAINTENANCE 20 5.1 General 20 5.2 Failure Indications 20 5.3 Cleaning the Optical Window and Mirror 22 5.4 Calibration Check 22 Figures Figure 1.1 GD100 MKII, Outline Dimensions 5 Figure 2.1 Transmittance as a Function of Wavelength 7 Figure 2.2 Block Diagram, GD100 MKII 8 Figure 2.3 Typ. Response for a Methane Calibrated Detector 9 Figure 3.1 Ventilation Duct or Pipe Mounting 12 Figure 3.2 Pump Room Mounting 13 Figure 3.3 GD100 MKII Fastened by its Three Legs 14 Figure 3.4 GD100 MKII Fastened by the Interface Brackets 14

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Figure 3.5 Terminal Cover 15 Figure 3.6 Terminal Compartment 15 Figure 3.7 Bridge Interface Installation 17 Figure 4.1 Output Signal during Start-up Period 19 Figure 5.1 Test Procedure 21 Figure 5.2 Calibration Check Set-up 22 Ordering Information 23 APPENDIX 24 4.1 Utgangssignal under oppstarting 25 5. VEDLIKEHOLD 26 5.1 Generelt 26 5.2 Feilindikasjoner 26 5.3 Rengjøring av optikken 26 5.4 Kalibreringssjekk 27

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1. PRODUCT DESCRIPTION 1.1 General Description The GD100 MKII Gas Detector is a point detector for gas concentration monitoring in potential hazardous and/or poisonous environments. The GD100 MKII is based on infrared absorption, and uses the latest developments in analog and microprocessor technologies. Solid state design improves reliability, long term stability and accuracy in continuous measurement of gas concentrations in ambient air. Compared to catalytic sensors, the GD100 MKII has the following advantages: - Presence of Oxygen is not required for a correct measurement, which makes the GD100

MKII suitable even in an inert gas atmosphere. There is no possibility for poisoning of the detector since no chemical reaction occurs, i.e. silicon vapours and H2S have no effect on the detector or the measurement.

- The gas flow rate has no influence on accuracy. - There are no saturation effects which could lead to false measurements. Thus the

detector is capable of measuring gas concentrations up to 100% vol. - The detector has continuous self-test function, and reports faults to the central system. - Total system costs can be dramatically reduced with the GD100 MKII : - High detector reliability results in low test frequency and no calibration costs. Cabling and termination costs can be reduced by using the possibility of connecting the

GD100 MKII to digital bus systems. Voting systems to increase reliability are not required, reducing the number of detectors

up to 66%. 1.2 Construction The GD100 MKII Gas Detector consists of three main units; an optical unit, an electronic unit and a power unit, all housed in an explosion proof housing with connections for power input and signal output. The modular design makes field repairs simple and cost effective. The complete housing consists of two sections; the front section and the rear section. The front section of the housing contains the electro-optical assembly where the detector has access to the gas through an infrared transmitting window made of sapphire. The rear section of the housing comprises the main electronics compartment which is EExd rated, and a terminal compartment which is rated EExe. The terminal compartment is covered by a field removable non-static plastic cover. Different cable entries are provided and all electrical connections are made by a 3- or 4-terminal list inside the terminal compartment.

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1.3 Application Areas The GD100 MKII was initially designed for detection of hydrocarbon gases in hazardous areas on offshore platforms and petrochemical plants, but during the past years it has also been used in a variety of applications in other branches of industry. The detector is fully compatible with computer based alarm systems using digital communication and addressable detectors. For retrofit applications, a bridge interface is available allowing the detector to be connected directly to catalytic systems, using the existing cabling and control modules. With the gas Sample Flow Housing mounted, the detector can be used in aspirator systems. The GD100 MKII is housed in a compact stainless steel enclosure which is certified flame proof, meeting the requirements of EN 50018. It is classified EExd IIC T6, and it is sealed according to IP67. 1.4 Technical Data Detection range 0-100% LEL (0-5% Vol) Methane - option 0-100% Vol Methane - option Other HC gases on request Long term stability Better than ±5% Accuracy Better than ±5% of full scale Better than ± 3% by 0-50% scale Response time 5 seconds (Faster response optional) Start-up time <90 seconds Self test Continuous Calibration Factory set Sensor warnings: - Clean optics Dirt accumulation on windows with more than 70% reduction in

transmittance. - Sensor failure Internal malfunction in the sensor. Output signal: - Standard Current source 4-20 mA, max load impedance 250 Ω - Option Current sink 4 - 20 mA - Option Digital bus - Option DC voltage 1-5 V Electrical: - Power supply 18-32 V DC - Power consumption Approx. 5 W - Electrical connection 3 or 4 wires

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Temperature range: - Storage -40°C to +70°C - Operating -20°C to +45°C - Operating (option) -20°C to +60°C Explosion proof housing: - Main compartment EExd IIC T6 - Terminal compartment EExe Protection category IP67 DIN 40050 Housing material Stainless steel SIS2343 (ASTM 316) Weight 5 kg Accessories Weather Protection Sample Flow Housing Duct Mounting Brackets Humidity (operation) 99% RH non-condensing Humidity (storage) 95% max Withstands vibrational tests according to DEF STAN 07-55 and EN 50054, 4.4.13 (HD323.2.6 S2)

Figure 1.1 GD100 MKII, Outline Dimensions (mm)

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1.5 Certifications The GD100 MKII has been certified by NEMKO according to the requirements for "Electrical apparatus for explosive atmospheres" given by CENELEC in the standards EN 50014 General EN 50018 Main housing EN 50019 Terminal compartment and is classified EExd II C T6 in the NEMKO certification document 87.052. The measuring performance for the GD100 MKII has been approved by The Directorate for Fire and Explosion Protection in Norway based on tests carried out at Center for Industrial Research (SI) in Oslo according to selected parts of the CENELEC documents EN 50054 and EN 50057. The sensor is sealed to IP 67. Electromagnetic field immunity is according to IEC 801-3/Dec. 1992. Radiated emission is according to EN 55022/1987, class B. 1.6 Ordering Information The GD100 MKII is supplied with cable gland and Weather Protection . The GD100 MKII standard version is calibrated on 100% LEL Methane. Refer to page 23 for further ordering information.

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2. TECHNICAL DESCRIPTION 2.1 Introduction The new and unique GD100 MKII Gas Detector from Simrad Optronics is a point detector for use in hazardous areas. A patented high stability infrared radiation source, combined with the latest developments in optical and electronic design, have led to the realization of a compact, accurate and cost-effective instrument able to monitor reliably explosion dangers in real-world environments. 2.2 The GD100 Concept The concept is based on measurement of infrared radiation passing through a volume of gas. The GD100 employs a dual beam dual wavelength measuring principle with separate optical detectors for maximum stability and reliability. Since different types of gas have very distinct absorption lines, they can easily be identified by proper selection of the infrared wavelenght ( λ1 ) at which absorption is measured. Radiation at another wavelenght ( λ2 ) close to ( λ1 ), but not absorbed by the actual gas, measures the overall transmittance through the optical path. By comparing the transmittance at the two wavelenghts, the concentration of a predefined gas in the air can be uniquely determined. Having chosen a wavelenght ( λ1 ) which is characteristic of the gas to be measured, other types of gas will not cause a false alarm. By choosing a wavelength ( λ1 ) characteristic of some other gas, various types of gas can be distinguished and measured using the same concept.

Figure 2.1 Transmittance as a Function of Wavelength

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Refer to Figure 2.2. Radiation from the two infrared sources passes through two narrow-band filters, which select a measuring wavelength ( λ1) and a reference wavelength ( λ2 ). The sources are electronically chopped. Radiation is divided by a beamsplitter into an internal and external path. The internal path is viewed by the compensation detector, and the external path is viewed by the measuring (main) detector. The compensation detector monitors and compensates for drift in sources or detectors. The main detector monitors the external path and detects if the selected gas is present. The four signals, two from the compensation detector and two from the main detector are amplified, digitized and fed to the microprocessor. The signal amplitudes are used by the microprocessor to calculate the gas concentration. The gas response is then linearized and presented as either a voltage, current or a digital output signal. Internal signals are compared with test limits to monitor electronics and optical parts. If values outside test limits are found, specific error messages are given. Optical filter characteristics remain constant over time, and drift in the other components are monitored and compensated by the dual wavelength, dual path concept. This means that the zero and gas span factory calibration will remain stable in spite of component drift, and that the detector needs no manual recalibration after factory calibration.

Figure 2.2 Block Diagram, GD100 MKII

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2.3 Performance Characteristics 2.3.1 Gas Data The GD100 MKII standard version is factory calibrated and linearized with Methane gas in the 0-100 % LEL range. Calibration/linearization to other gases or concentrations can also be done. A list of gases/concentrations is available. Gases like Ethane, Propane, Butane, Pentane and Hexane are detected by the GD100 MKII. The GD100 MKII has a higher sensitivity to these gases than to Methane. Explosion danger related to the specified gases will be detected, since any interference causes an increase in the output signal. This means that using the GD100 MKII there will never be a situation where explosion danger from other HC-gases is not detected. Due to tolerances in the infrared filters, exact readings of other gases than Methane are not guaranteed when the detector is calibrated to 100% LEL Methane. Figure 2.3 shows typical responses to some other gases when the GD100 MKII is calibrated on Methane.

Figure 2.3 Typical Response for a Methane Calibrated Detector

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2.3.2 Interferential Gases Hydrocarbon gases such as Methane, Ethane, Propane, Butane etc, are absorbing at a signal wavelength λ1 of 3.3 µm. These gases do not interfere at the reference wavelength λ2 at 3.0 µm. If the atmosphere to be monitored contains gases that absorb at the reference wavelength 3.0 µm, such as acetylene, misleading measurements may be obtained depending on the interfering gas concentration. In such cases, contact Simrad Optronics for information. A modified GD100 MKII using another reference wavelength will eliminate such problems. Water vapour, Carbon Dioxide, Oxygen, Nitrogen and other gases present in normal air will not influence the measurements. 2.4 Gas Detection System Since the GD100 MKII is a point detector, it must be mounted where a gas leakage is most likely to occur. It should be considered whether the gas is heavier or lighter than air. The number of sensors recommended depends on room size, shape, airflow etc. The GD100 MKII can also be mounted on an air duct wall with its optical path inside the duct. Due to the high reliability and extensive self-testing performed by the GD100 MKII, the amount of sensors needed is dramatically reduced, and voting between sensors is no longer necessary. Maintenance routines could be relaxed without loosing system confidence, and repair work is reduced significantly. For detailed mounting descriptions, see section 3.1

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3. INSTALLATION NOTE: The GD100 MKII electronics and optics are enclosed in the main housing containing inert atmosphere. To preserve the detector long term stability it is therefore not recommended to open the main housing. The main housing is classified EExd IIC T6. The terminal compartment contains a terminal list for the electrical connections and is classified EExe. 3.1 Mounting the GD100 MkII 3.1.1 Location The location of each detector should preferably be determined at the system design stage. NOTE: The area in which the detector may be mounted must be in accordance with the certification of the detector and in accordance with the standards of the appropriate authority in the country concerned. Choice of mounting area: - The detector should be mounted where the gas occurance is most likely. To detect

Methane, which is lighter than air, the detector should be mounted at the top of an enclosed area or immediately above potential leakage sites.

To detect gases heavier than air, e.g. Propane, the detector should be mounted at a low level.

- The detector should be mounted on a place where maintenance, i.e. the cleaning of the optics is easily performed.

- The detector may be mounted in areas where no Oxygen is present. - The detector may be mounted in areas where high airflow is present. - The detector should NOT be mounted where it might be exposed to water drenching. NOTE: The detector must always be used with the Weather Protection or Sample Flow Housing mounted. Exception to this must be discussed with Simrad Optronics. 3.1.2 Ventilation Duct or Pipe Mounting If installed in a ventilation duct, the mounting arrangement and accessories shown in Figure 3.1 should be used. NOTE: Avoid direct light on lens and mirror if mounted without Weather Protection.

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The Weather Protection must be oriented with the “UP” mark facing away from the air flow direction for minimum response time. The sensor must be mounted in straight parts of the duct where air flow is laminar. Avoid mounting the sensor in duct bends and places where the air flow is turbulent.

Figure 3.1 Ventilation Duct or Pipe Mounting 3.1.3 Pump Room Mounting If installed in a pump room, the mounting arrangement and accessories shown in Figure 3.2 should be used.

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Figure 3.2 Pump Room Mounting

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3.1.4 Orientation The detector should be mounted so that the longitudinal axis of the detector is horizontal in order to obtain a vertical position of the detector mirror and window. The vertical position will prevent accumulation of water and dust on the optics. The Weather Protection must always be oriented correctly for optimal performance. 3.1.5 Fastening the GD100 MKII The detector is fastened by the three projecting legs with three M8 mounting screws and washers, or by the Interface Brackets fixed to its front flange (4 x M8 screws).

Figure 3.3 GD100 MKII fastened by its three legs.

Figure 3.4 GD100 MKII Fastened by the Interface Brackets.

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3.2 Electrical Connections 3.2.1 Terminal Compartment The terminal compartment is accessible by removing the circular terminal cover. (Loosen the four M5 screws.) Refer to Figure 3.5. The terminal compartment including the 4-terminal list for the electrical connections is shown in Figure 3.6. The installation wiring enters the terminal compartment via a single EExe cable gland which can be mounted on either side of the compartment. The unused entry is blanked with an EExe cover. Several options of gland fittings are available.

Figure 3.5 Terminal Cover

Figure 3.6 Terminal Compartment

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3.2.2 Output Cable Connections The detector has four output modes: A) Current source 4-20 mA (standard) B) Current sink 4 - 20 mA (option) C) Digital bus (option) D) DC-Voltage 1-5 V (option) The mode is factory set. 3.2.2.1 3-wire Output Cable Connection This is the most commom way to interface the detector to the gas detection system. The cable connections are as follows: Terminal No l: +24V DC Terminal No 2: Signal output Terminal No 3: 24 V return (0 V) Terminal No 4: Signal return (not used) The output signal is measured between (2) signal output and (3) 24 V return (0 V). The shield of the cable should be connected to instrument earth in the central control module. 3.2.2.2 4-wire Output Cable Connection (digital communication option) The 4-wire cable should be used for the digital communication option. The cable connections are as shown below: Terminal No l: +24V DC Terminal No 2: Signal output Terminal No 3: 24 V return (0 V) Terminal No 4: Signal return The output signal shall be measured between signal output (2) and signal return (4). A separate signal ground cable will improve power supply related noise in long cables. Make sure that the cable used has sufficient cross-section to keep the cable resistance as low as possible. The cable shield should be connected to instrument earth in the central control module.

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3.2.2.3 Retrofit Wiring The GDl00 MKII Gas Detector has been designed to be fully interchangeable with existing catalytic sensors, using the same 3-wire cable and the same bridge input control modules. This application requires the Bridge Interface to be employed as shown in Figure 3.7. The Bridge Interface (Simrad reg. no. 109-804511.4 ) converts the standard 4 - 20mA active current output from the GDl00 MKII to a bridge signal input, which is a typical standard for several control modules used today. The Bridge Interface operates on a standard 24V DC supply. The complete Bridge Interface assembly is contained in a plastic housing which clips onto a standard DIN mounting rail. This allows several channels to be interfaced in a space saving way. A typical Bridge Interface installation is shown in Figure 3.7. NOTE: As signal levels, polarity, loading, stability and fault testing differ between manufacturers of catalytic modules, Simrad Optronics must be contacted for correct setting of variables in the Bridge Interface.

Figure 3.7 Bridge Interface Installation

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3.2.2.4 Recommended Cable Types The cable selected for interfacing the control equipment should be approved for use in the actual area. The cables should have a cross-section between 0.5 mm2 and 2.5 mm2. The cable enters the terminal compartment via an EExe cable gland. Several options of gland fittings are available. 3.2.2.5 Initial Wiring Checks After wiring as detailed above, and before applying power, make certain that - +24V DC is connected to terminal l only - signal output is connected to terminal 2 - if both 24 V return and signal return are used, check that they are not interchanged - the cable shield is terminated in the central control module only NOTE: If 24V DC is applied to another terminal than no. 1, damage may occur in the sensor electronics.

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4. OPERATION 4.1 Start-up Procedure When the system wiring and the control equipment has been tested, the power to the detector can be switched on. The detector will then perform self-test and internal signal adjustments which last for approx. 90 seconds. The output signal from the detector during this period is shown in Figure 4.1 (current output of the GD100 MKII standard version).

Figure 4.l Signal Output during the Start-up Period

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5. MAINTENANCE NOTE: There are no user adjustable parts within the GD100 MKII. It is not recommended to open the GD100, as this will remove the internal inert atmosphere, and the initial calibration may be affected. 5.1 General The GD100 MKII is designed to require a minimum of maintenance. The only maintenance suggested is to visually inspect that the Weather Protection is not clogged in heavily contaminated areas. 5.2 Failure Indications The internal microprocessor performs continous self-testing of optical and electronic functions. If the IR-beam energy in the optical path should be reduced with more than 70% of its original value, the processor will generate a l mA (or 0.25V) output signal. This signal "clean optics" tells you that you have to clean the window and mirror of the detector to restore normal operation. If a fatal error should occur in the electronics or optics, the processor will generate a 0 mA ( 0 V ) output signal, indicating sensor failure. The detector should then be checked as follows: (See Figure 5.1.) Inspect the mirror and window for heavy contamination. Wipe the optics with a clean cloth. If power is applied, switch off power and after 5 seconds, switch it on again. Control the start-up period as described in chapter 4.1. If the signal output still reads zero after the restart procedure, the detector should be returned to Simrad Optronics or the nearest service agent for repair.

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The following test must be performed before the sensor is returned to Simrad Optronics for repair: NOTE: Avoid direct light on lens and mirror if tested without Weather Protection. NOTE: Ensure that no gas is present in the measuring chamber when testing.

Figure 5.1 Test Procedure

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5.3 Cleaning the Optical Window and Mirror If the optical window and mirror have to be cleaned (as described in chapter 5.2), use a soft and clean tissue and rub off the contamination. Window and mirror are made of sapphire which is highly resistant to rubbing. Make sure that the optics are properly cleaned also in its outer circumference. NOTE: For difficult contaminants the mirror and lens can be cleaned with an equal part mixture of isopropyl alcohol and water. Do not perform any testing of the sensor before cleaning solution is dried away. 5.4 Calibration Check If it should be necessary to check the sensor calibration, use a calibrated gas which is applied to the Sample Flow Housing (reg. no. 499-803969.5). Apply gas as shown in Figure 5.2 and check the output reading at the control module or use a current meter. NOTE: Use the same type of gas as the detector has been calibrated for.

Figure 5.2 Calibration Check Set-up

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APPENDIX

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4. OPERASJON 4.1 Utgangssignal under oppstarting Etter at kablingen og kontrollsystemet har blitt testet kan strømmen til detektoren slås på. Detektoren vil deretter utføre selvtest og interne signaljusteringer som varer ca. 90 sekunder. Utgangssignalet fra detektoren i denne perioden er vist i figur 4.1 (strømutgang).

Figur 4.1 Utgangssignalet i oppstartingsperioden

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5. VEDLIKEHOLD NB: Gassdetektoren innholder ingen justerbare deler. GD100 MKII-boksen bør ikke åpnes

inn til kretskortene, da den tørre nitrogengassen vil lekke ut, og fabrikk-kalibreringen kan forandres.

5.1 Generelt GD100 MKII er konstruert for å trenge et minimum vedlikehold. Nødvendig vedlikehold begrenser seg til å etterse at værbeskyttelsen ikke tettes til i svært forurensede områder. 5.2 Feilindikasjoner Den interne mikroprosessoren i detektoren utfører kontinuerlig testing av detektorens måle- og kalibreringsfunksjoner. Hvis energien i IR-strålen reduseres med mer enn 70% av opprinnelig verdi, vil prosessoren generere et 1 mA (eller 0.25 V) utgangssignal. Dette signalet ("rengjør optikk") indikerer at detektorens vindu og speil må rengjøres for å gjenopprette normal operasjon. Oppstår det feil i detektoren, vil prosessoren generere et utgangsignal på 0 mA (0 V ). Detektoren bør da sjekkes som følger (se Figure 5.1 Test Procedure): - Er optikken ren? - Er spenning tilført? - Hvis spenning er tilført, slå av spenningen og etter 5 sekunder slå den på igjen. - Kontroller oppstartingsfasen som beskrevet i kapittel 4.1. Skulle utgangssignalet være 0 mA ( 0 V ) etter at ovennevnte punkter er sjekket, skal detektoren returneres til Simrad Optronics eller til nærmeste service agent. 5.3 Rengjøring av optikkdelen Dersom det optiske vinduet og speilet bør rengjøres (som beskrevet i kapittel 5.2), benytt en myk og ren klut og fjern forurensingen. Vinduet og speilet er laget av safir, som tåler kraftig gnidning. Se til at speilet og vinduet er forsvarlig rengjort også i den yttere omkrets. NB: Forurensninger som er vanskelige å fjerne kan fjernes fra speil og linse med like deler

isopropyl alkohol og vann. Detektoren må ikke testes før rensemiddelet er tørket.

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5.4 Kalibreringssjekk Detektoren trenger ikke å rekalibreres. Skulle man imidlertid ønske å kontrollere kalibreringen, benytt da en kalibrert gass som tilføres ved hjelp av Sample Flow Housing (reg. nr. 499-803969.5). Tilfør gass som vist i figur 5.2, og kontroller måleresultatet vist i kontollenheten. NB: Benytt samme gass som detektoren er kalibrert for.

Figur 5.2 Oppstilling ved kontroll av kalibrering