GAS TESTING DETECTION AND MONITORING

GAS TESTING

GAS TESTING IS AN ESSENTIAL PART OF AN EFFECTIVE PERSONAL SAFETY PROCEDURE.HUMAN SENSES CAN BE RELIED UPON,AT VERY LOW CONCENTRATION,H2S PARALYZES THE SENSE OF SMELL.THEREFORE INSTRUMENTATION MUST BE USED FOR DETECTIONS AND MONITORING.

GAS TESTER MAY BE A COMPANY EMPLOYEE OR A CONTRACTOR

TEST FOR:

• OXYGEN DEFICIENCY/ENRICHMENT
• FLAMMABLE GASES/VAPOURS
• TOXIC GASES/VAPOURS

GAS TESTING IS INTEGRATED PART OF PTW PROCEDURE,ONLY AUTHORISED GAS TESTERS TO CONDUCT GAS TESTING

• USE OF PORTABLE GAS DETECTORS SHOULD BE RESTRICTED TO COMPETENT PERSONS.
• AGT CAN TEST ALL AREAS INCLUDING CONFINED SPACES
• H2S IS HEAVIER THAN AIR SO CHECKS SHOULD BE CONCENTRATED BUT NO RESTRICTED AT LOW AREAS
• CONSIDER WIND DIRECTION,AIR CURRENTS AND CHANGE IN TEMPERATURE
• THE USE OF DIRECT READING GAS DETECTION INSTRUMENTATION IS MANDATORY BEFORE ENTERING CONFINED SPACES SUCH AS MANHOLES,TANKS,VESSELS THAT COULD HAVE H2S GAS

H2S SAFE WORKING LIMIT PEL

THRESHOLD LIMIT VALUE-TIME WEIGTED AVERAGE

• NORMALLY ABBREVIATED AS TLV-TWA
• MAXIMUM CONCENTRATION OF TOXIC GAS THAT A WORKER CAN BE EXPOSED TO DAY AFTER DAY WITHOUT SUFFERING HEALTH PROBLEM
• TLV IS AVERAGE TAKEN OVER 8 HOUR DAY OR A 40 HOUR WEEK

H2S HAS A TLV-TWA OF 10 PPM FOR 8 HOURS EXPOSURE

• RECOMMENDED INDUSTRY PRACTICE IS TO WEAR BA AT 10 PPM AND ABOVE
• BEST SAFE PRACTICE IS TO WORK AT ZERO EXPOSURE TO H2S

TOXIC CONTAMINANTS ARE MEASURED IN 

• PARTS PER MILLION (PPM)
• IF A MILLION PARTS OF AIR BY VOLUME CONTAINS ONE PART OF H2S IT IS 1 PPM H2S IN AIR

 SHORT TERM EXPOSURE LIMIT OF HYDROGEN SULPHIDE IS 15PPM

• THIS IS HIGHER TLV WHICH DEFINES THE MAXIMUM CONCENTRATION THAT A PERSON MAY BE EXPOSED TO FOR A MAXIMUM OF 15 MINUTES
• THERE SHOULD BE NO MORE THAN FOUR SUCH EXPOSURES PER DAY,WITH AT LEAST 1 HOUR BETWEEN EXPOSURES

 MAXIMUM EXPOSURE LIMIT OF H2S IS 20 PPM

• THIS IS THE CONCENTRATION LEVEL BEYOND WHICH WORKERS MUST NEVER BE EXPOSED  EVEN FOR AN INSTANT

HYDROGEN SULPHIDE ADVERSE EFFECT

EFFECT OF HYDROGEN SULPHIDE IS BASE ON FOUR FACTORS WHICH IS GIVEN BELOW

1. DURATION
2. INTENSITY
3. FREQUENCY
4. INDIVIDUAL SUSCEPTIBILITY

H2S HAZARD

• KILL SENSE OF SMELL
• MOST LETHAL GASES
• IRRITANT
• CORROSIVE

EXPOSURE AFFECT ON BODY

• WHEN A PERSON INHALES H2S 
• THROUGH LUNGS IN TO THE BLOOD THE PERSON BECOME POISONED.
• NERVES CENTER IN THE BRAIN BECOME PARALYZED 
• AND LUNG STOP WORKING AND THE PERSON IS ASPHYXIATED,
• HEART STOP AND BRAIN DIES

ACUTE EFFECT OF HYDROGEN SULPHIDE

SHORT TERM

1. EYE IRRITATION
2. HEADACHES
3. NAUSEA
4. IRRITATION RESPIRATORY TRACT
5. DIZZINESS
6. SNEEZING
7. DIARRHOEA
8. EXCITEMENT
9. RESPIRATORY EFFECT
10. CARDIAC EFFECT

CHRONIC EFFECT OF HYDROGEN SULPHIDE

LONG TERM

1. EYE IRRITATION
2. HEADACHES
3. NAUSEA
4. IRRITATION RESPIRATORY TRACT
5. SLEEP PROBLEM
6. ANOREXIA
7. PULMONARY OEDEMA
8. CORNEAL BLISTERING
9. CORNEAL PITTING
10. BRAIN DAMAGE

FATALITIES DUE TO HYDROGEN SULPHIDE

FATALITIES DUE TO H2S

ADCO

• 3 MEN DIED FROM UNNECESSARY EXPOSURE IN FEB 2009

ADGAS-ABU DHABI

• DAS ISLAND INCIDENT RESULTED THE DEATH OF 1 MAN IN NOVEMBER 2008

GASCO-ABU DHABI

• THE TOXICITY OF THE GAS WAS RESPONSIBLE FOR THE DEATH OF 3 MEN IN ONE INCIDENT

SAUDI ARABIA:

• 19 PEOPLE WERE KILLED IN ONE INCIDENT DUE TO H2S POISONING IN 1980

CHINA

• DECEMBER 2003 OVER 230 PEOPLE DIED DUE TO H2S

OCCUPATIONAL FATALITIES DUE TO H2S EXPOSURE- ALBERTA, CANADA 1976-1994

       

INDUSTRY: OIL AND GAS                                                          FATALITIES 1976-1994

OPERATION OF OIL AND GAS WELLS                                        (5)
NATURAL GAS PROCESSING PLANTS                                        (4)
OILFIELD MAINTENANCE AND CONSTRUCTION                   (3)
OPERATION OF BATTERY TANKS                                                (2)
GAS WELL BLOW OUT CONTROL                                               (2)
WELL SERVICING WITH SERVICE RIGS                                     (1)
OTHERS                                                                                              (7)
TRANSPORTATION                                                                           (6)
TOTAL                                                                                                (30)

H2S GAS PROPERTIES AND SOURCES

H2S GAS 

H2S gas is the invisible killer gas,and it is

• Toxic
• Highly flammable, and Corrosive

Its smell like rotten eggs. H2S is mostly found in

1. Coal pits
2. Sulfur springs
3. Gas wells.
4. Sewers,
5. Sewage treatment plants

H2S is found in

• Petroleum and natural gas extraction and refining,
• Paper and Pulp manufacturing,
• Rayon textile Production,
• Leather Tanning,
• Chemical manufacturing and 
• Waste disposal.

Others names for Hydrogen Sulphide

• H2S
• SOUR GAS
• STINK DAMP
• ROTTEN EGG GAS
• HYDROSULPHURIC ACID
• SULPHUR HYDRIDE
• SEWER GAS
• SULPHURATED HYDROGEN

PHYSICAL AND CHEMICAL PROPERTIES

• COLORLESS
• HEAVIER THAN AIR
• CORROSIVE
• HIGHLY FLAMMABLE ( EXPLOSIVE )
• SOLUBLE IN WATER
• SMELL LIKE ROTTEN EGGS
• IRRITANT
• EXTREMELY TOXIC

HYDROGEN SULPHIDE HAS A DENSITY GREATER THAN AIR

• H2S DENSITY : 1.19
• AIR DENSITY :  1.0

THIS IS IMPORTANT TO REMEMBER IT IS FOUND IN LOW LYING AREAS SO THIS INVISIBLE GAS WILL COLLECT IN

• DEPRESSIONS IN THE GROUND
• PITS
• DITCHES
• TRENCHES
• CONFINED SPACES