Authorised Gas and Safety Tester Training

T H Azad AliHaldia Petrochemicals LimitedHaldia

Safety is built on integrity,trust and leadership, createdand sustained by effectivecommunication.

AGST Training SynopsisFor all jobs requiring hot work permit and many jobs with Cold work permit and also for production jobs like lighting furnace etc., it is mandatory to test (commonly referred to as GAS TEST) the environment before allowing the task to be carried out

( e.g.) entry in an equipment or a confined space, any hot job like welding concrete chipping etc.).

Explosion TriangleGenerally the requirements for an explosion to take place are:

Flammable substanceOxygen (air)Source of ignition

What is GAS TESTINGThe gas testing includes checking for absence of flammable atmosphere presence of required level of oxygen absence of toxic gases ( e.g. Cl2, Hydrocarbon, SOx etc.)

Authorised Gas and Safety TesterA list of employees who have been trained in gas testing is issued from time to time by the Team Leaders (NCU, AU, IOP, HDPE, LLDPE, PP).

Only such authorised persons can carry out the gas testing in their respective Safety districts.

In case no qualified/autorised a gas tester, (AGST) is available in a department, Safety department may be requested to carry out the required gas tests.

ResponsibilitiesOn the instruction of SIC, he carries out gas test ( to ensure the absence of flammable atmosphere), oxygen test and/or toxicity and enters into permit.

Regular checking at inerval is also AGSTs responsibility.

In the case of high risk jobs like confined space entry, hot work in tank farm the tests may need endorsement from the central laboratory.

In case of any abnormalities after start of job, AGST should stop job

High Risk JobsHigh risk jobs

For work permit with open fire in certain high risk areas like

tank farm, or hot work in confined space High Hydrocarbon inventory areasRadiography in G-shift hours etc

needs to be counter signed by Head (Mfg) or Head (Plant) after the safety district head has signed.

Confined SpaceThe confined space can be defined as

*an enclosed or partially enclosed space, *where entry is possible. *which may be situated either below or above, the ground or deck level.

*there is a likelihood of hazard of oxygen deficiency/enrichment or *accumulation of dust, mist, gases or vapours which are irritants, hazardous to health (toxic or corrosion or flammable)

What is a Confined Space?Is large enough and so configured that an employee can enter bodily and perform work;Has limited or restricted means of entry or exit;Is not designed for continuous human occupancy.A space that:

Examples of Confined Spaces:TanksManholesBoilersFurnacesSewersSilosHoppersVaultsPipesTrenchesTunnelsDuctsBinsPits

Potential Hazards in Confined SpacesOxygen Deficiency23.5% oxygen concentrationCombustiblesMethaneHydrogenAcetylenePropaneGasoline fumesToxic MaterialsCarbon MonoxideHydrogen SulfideWelding fumesCorrosivesElectricityMechanical HazardsMixersCrushersNoiseEngulfment hazard

Oxygen Deficient Atmospheres19.5 %Minimum acceptable oxygen level.15 - 19%Decreased ability to work strenuously.Impair coordination. Early symptoms.12-14%Respiration increases. Poor judgment.10-12%Respiration increases. Lips blue.8-10%Mental failure. Fainting. NauseaUnconsciousness. Vomiting.6-8%8 minutes - fatal, 6 minutes - 50% fatal4-5 minutes - possible recovery.4-6%Coma in 40 seconds. Death

Oxygen Enriched AtmospheresOxygen level above 21%.Causes flammable and combustible materials to burn violently when ignited.Hair, clothing, materials, etc.Oil soaked clothing and materials.Never use pure oxygen to ventilate.Never store or place compressed tanks in a confined space.

Flammable Atmospheres2 Critical Factors:Oxygen content in the air.Presence of a flammable gas, or vaporPresence of dust (visibility of 5 or less)Proper air/gas mixture can lead to explosionTypical Ignition Sources:Sparking or electric tool.Welding / cutting operations.Smoking

EXPLOSIVE RANGEScale that indicates the explosive nature of gases or vaporsRelationship of the concentration of the vapor present, its temperature & pressure Expressed as percent by volume in air

EXPLOSIVE RANGEIf Explosive Range falls below the Lower Explosive Limit (LEL), the mixture of air and vapor is too lean for an explosionIf Explosive Range is above the maximum explosive range or Upper Explosive Limit (UEL), the mixture of vapor and air is too rich to be explosive

% OF LOWER EXPLOSIVE LIMIT(LEL)LEANRICH0%LELUEL100%

TOO RICH FOR COMBUSTIONCOMBUSTIBLE MIXTURETOO LEAN FOR COMBUSTIONGAS CONCENTRATION(MIXTURE IN AIR)100%0%UELLELUpper and Lower Flammability Levels

Toxic AtmospheresProduct stored in a confined space:Gases released when cleaning.Materials absorbed into walls of confined space.Decomposition of materials in the confined space.Work performed in a confined space:Welding, cutting, brazing, soldering.Painting, scraping, sanding, degreasing.Sealing, bonding, melting.Areas adjacent to a confined space.

Exposure LimitsAir ContaminantsOSHAPEL, STEL, CeilingNIOSHTWA, STEL, CeilingACGIHTWA, STEL, Ceiling

Exposure LimitsAir ContaminantsTWAtakes into account variable exposure through a full shift, 8 hour work daySTELlimit of exposure during a short period, 15 minutes CEILINGabsolute maximum level of exposure not to be exceeded

Hydrogen SulfideDecomposition of materials. Human waste.Rotten egg odor at low concentrations.Possibly no warning at high concentrations. PPMEffectTime10 ppmPermissible Exposure Level8 Hours50 - 100Mild Irritation - eyes, throat1 Hour 200 - 300Significant Irritation1 Hour 500 -700Unconsciousness, Death1/2 - 1 Hour >1000Unconsciousness, DeathMinutes

Carbon MonoxideOdorless, Colorless Gas.Combustion By-Product.Quickly collapse at high concentrations. PPMEffectTime 50Permissible Exposure Level8 Hours 200Slight headache, discomfort3 Hours 600Headache, discomfort1 Hour 1000-2000Confusion, nausea, headache2 Hours 1000-2000Tendency to stagger1 1/2 Hours 1000-2000Slight heart palpitation30 Min. 2000-2500Unconsciousness30 Min.

Testing The AtmosphereVerify presence of safe work atmosphere.Test all areas of a confined space.Top, Middle, BottomMethane is lighter than air.Carbon Monoxide is the same as air.Hydrogen Sulfide is heavier than air.Oxygen Deficiency.

Always test theair at various levels to be sure that theentire space is safe.Good AirPoor AirDeadly AirGood air near the opening does NOT mean there is good air at the bottom!

Atmosphere Testing Shall Be Performed:Prior to every entry when the space is vacant;After a 10 minute ventilation period (if ventilation is necessary);At least hourly for all confined spaces.More frequently, if conditions or suspicions warrant.

Equipments Multigas Detector

MSA Multigas DetectorExplosimeters or LEL DetectorsMSA Manual ExplosimeterDraeger LEL DetectorDI Explosimeter

Oxygen meterDraeger Oxygen MeterDI Oxygen MeterMSA oxygen meter.

Multi Gas DetectorMSA Multigas Detector is equipped with

LEL SensorOxygen SensorH2S SensorCO Sensor

Explosimeter Operating PrincipleDraeger Explosimeter

Principle of catalytic combustion on the surface of a heated element, catalyst- coated thermistor (Pellistor). The catalytic combustion heats up the element causing a change in resistance which is sensed by the circuitry(wheatstone bridge) which has a compensator element and converted into a meter reading. Environmental conditions, thermal conductivity, affect both the element same way.

To switch on press button marked IMeasure at place with source as close possibleTo switch off press both button marked O (i.e. O & )To know battery level press BATTo light press

Equipment DetailsMeasuring range : 0 to 100% LEL or 0 to 100% CH4 by VolEx approval: Ex s IIC T4Operating Temp: -20 to 40 CHumidity: 10 to 95%Storage Temp: -40 to 60 CPower Supply: Rechargable NiCd BatteryOperating time : 10 Hrs ( with full charge and without alarm)Freq. Of charging : at least every 2 weeksSound level (Alarm): 85dB(A) (at 30 cm distance)Dust water protection : IP55Dimension: 68mm X 156 mm X 37 mmWeight: 370 gms

Limitation Explosimeter *Oxygen required for combustion is taken from the ambient air.*In case of Oxygen deficient atmosphere, LEL detector will not show proper reading.*In case conc. above LEL, sensitivity of detector reduces as air required for combustion is displaced. But compensator element measures the thermal conductivity of air and displays the reading according to the value.

MSA Explosimeter Operating PrincipleMSA Explosimeter*Wheat stone bridge *Combustibles in the sample are burned on the filament which raises it temperature an increases its resistance in proposition of concentration ofcombustibles in the sample which is shown as reading in meter*MAS 2A(1) Explosimeter is not designed for testing mixtures of hydrogen, acetylene or other combustables, in which the oxygen content exceeds that of normal air.*Instrument will not indicate the potential explosive hazard of combustible gases and vapours when they are present in concentration above their Upper Explosive Limits* not designed to measure Flammable atmosphere in Steam or inert atmosphere

Oxygen meter Draeger Details Type: Pac III gas detection instrumentCompany: Drager , GermanDetails:Pac : Personal air controlApproval: Intrinsic safety IP64 EEx ia II c T4/T6 EEx ia IW x H x D: 66 x 110 x 32 mmWeight: 185 gMeasures: TLV / TWA STEL/ TWAAlarm level: 85 db ( A), 30 cm

Advantage:Only one unit for 18 intelligent Drager sensors ( 47 different toxic chemicals)

Type: Electrochemical sensors, Plug in type , Data being programmed in EEPROMsVessel Entry: Gas intake can be effected by diffusion or external pump operation. Intake is possible up to 45 m.

Note: If i has come, it means that the instrument is to be calibrated. Please send it to the Safety department. Calibration frequency: Every 3 to 6 months. Service life of electrochemical sensor : 18-36 months.

Operating PrincipleThe dragger O2 sensor is an electrochemical transducer for measuring the O2 concentration in the atmosphere.

The ambient air to be monitored diffuses through a diffusion barrier into the liquid electrolyte of the sensor.

The electrolyte contains a measuring electrode, a counter electrode and a reference electrode.

An external potentiostat circuit provides for a constant bias between the measuring electrode and the reference electrode. This voltage, the electrolyte and the electrode materials are selected such that O2 is electrochemically converted at the measuring electrode.

During this process the current flows which is proportional to the O2 concentration which is shown as reading in.

Permit System AGST ResponsibilityOn the instruction of SIC, AGST carries out gas test, oxygen test and/or toxicity. Enters into permit and signs.

In the case of high risk jobs like confined space entry, hot work in tank farm the tests may need endorsement from the central laboratory.

Frequent testing should be done on field based on criticality of the job and to be entered in second sheet of the permit.

General Precautions Do not open the explosimeter case or attempt to adjust it yourself in any way.

Do not leave the meter switched on when not in use as this will run the batteries down

Always watch the meter pointer throughout the aspiration of sample.

If the concentration above UFL, the pointer move above 100 % and quickly back to 0 %

Do not use the explosimeter in steamy atmosphere, which can give low readings and cause damage to the filament.

When Nitrogen purging of vessel is carried out as a step in gas freezing, an Explosimeter cannot be used to test the atmosphere, as there is not enough oxygen present to burn the combustible on the filament. If such tests are required, a Drager or Kitagawa test equipment can be used

When using the sampling extension tube, remember that at least one extra aspiration ( squeezing of rubber bulb) is required for every metre of 6 mm (diameter ) tubing.

The explosimeters cannot be used to test atmospheres at higher than that of the Explosimeter and containing high boiling point components, as the vapours will condense in the instrument

Any Questions?????????!!!!!!!!!!!!THE END

This triangle illustrates the three basic ingredients necessary for combustion to occur. In hazardous locations the fuel source can be in the form of flammable vapours, liquids, gases, combustible dust or fibres with the oxidiser being oxygen in the surrounding air. With these two ingredients present in their most easily ignitable concentration and the introduction of sufficient electrical or thermal energy, ignition will result. Providing a means of explosion protection can be achieved by either confining or preventing this combustion from occurring.