hydrogen h2
TRANSCRIPT
HYDROGEN H2
PHYSICAL / CHEMICAL PROPERTIES :
1. PHYSICAL APPEARANCE : COLOURLESS
2. ODOUR : ODOURLESS
3. VAPOUR DENSITY : 0.07 AT 25 DEG. C (AIR=1)
LIGHTEST GAS
4. FLAMMABILITY : HIGHLY FLAMMABLE /
EXPLOSIVE
5. FLAMMABILITY LIMIT : 4% TO 75% IN AIR
6. FLASH POINT : <-50 DEG.C
7. AUTO IGNITION TEMPERATURE : 500 DEG CENTIGRADE
8. INCOMPATIBILITY : OXYDISING MATERIALS E.G.
CHLORINE, BROMINE ETC.
9. MINIMUM SPARK IGNITION
ENERGY AT 1 ATM IN AIR : 0.02 MJ.
HYDROGEN H2
HAZARDOUS PROPERTIES OF GASEOUS HYDROGEN
• UNDETECTABILITY: HYDROGEN GAS IS COLOURLESS, ODOURLESS
AND NOT DETECTABLE BY HUMAN SENSES. HYDROGEN LEAKS ARE
MORE FREQUENTLY HEARD THAN SEEN.
• FLAMMABILITY : MIXTURES OF HYDROGEN WITH AIR, OXYGEN OR
OTHER OXIDIZERS ARE HIGHLY FLAMMABLE OVER A WIDE RANGE OF
COMPOSITIONS.
• AUTOIGNITION : TEMPERATURES OF ABOUT 1050OF (565OC) ARE
USUALLY REQUIRED FOR MIXTURES OF HYDROGEN WITH AIR OR
OXYGEN TO AUTO IGNITE AT 14.7 PSIA. HOWEVER, AT PRESSURES
FROM 3-8 PSIA, AUTOIGNITIONS HAVE OCCURRED NEAR
650OF(343OC).
HYDROGEN H2
• IGNITION AT LOW ENERGY INPUT : HYDROGEN AIR MIXTURES CAN
IGNITE WITH VERY LOW ENERGY INPUT, 1/10TH THAT REQUIRED TO
IGNITE A GASOLINE - AIR MIXTURE FOR REFERENCE, AN INVISIBLE
SPARK OR A STATIC SPARK FROM A PERSON CAN CAUSE IGNITION.
• LACK OF FLAME COLOUR : HYDROGEN – OXYGEN AND HYDROGEN
– PURE AIR FLAMES ARE COLOURLESS (ANY VISIBLE FLAME IS CAUSED
BY IMPURITIES). COLOURLESS HYDROGEN FLAMES CAN CAUSE
SEVER BURNS.
HYDROGEN H2
EMERGENCY PROCEDURE
• MAKE SURE THAT SOURCE OF IGNITION IS AVOIDED. EVEN AFTER
ENSURING THAT THERE IS NO SOURCE SUSPECT THE PRESENCE OF A
SOURCE OF IGNITION.
• AS SOON AS LEAKS ARE DETECTED, IMMEDIATELY STOP OPERATIONS,
SHUT OFF THE SOURCE OF SUPPLY, AND RELIEVE THE LINE OR
SYSTEM OF ANY PRESSURE.
• DON’T ACTUATE ELECTRICAL OR OTHER DEVICE HAVING
QUESTIONABLE NON SPARKING CHARACTERISTICS RESUME
OPERATIONS ONLY AFTER THE REPAIRS ARE COMPLETED.
HYDROGEN H2
DO THE FOLLOWING IN CASE OF LEAKAGE OF HYDROGEN
• TAKE ACTIONS TO ENSURE THE SAFETY OF PERSONNEL (I.E. DON’T
ALLOW PERSONS TO ENTER THE AREA AS THERE CAN BE FIRE / AND
EXPLOSION).
• CALL FIRE SERVICE
• EVACUATE THE AREA
• COOL DOWN ADJACENT EQUIPMENT TO PROTECT IT FROM POSSIBLE
FIRE.
HYDROGEN H2
FIRE FIGHTING TECHNIQUES:
FLAME TEMPERATURE OF THE ORDER OF 3800OF (2093OC) CAN BE
EXPECTED IN HYDROGEN GAS FIRES. CATASTROPHIC RESULTS FROM
FIRES CAN BE PREVENTED BY TRAINING PERSONNEL TO :
• PREVENT THE FIRE FROM SPREADING AND LET IT BURN UNTIL THE
HYDROGEN IS CONSUMED (USE OF WATER TO KEEP ADJACENT
EQUIPMENT COOL, DON’T ARREST THE FIRE.
• BE AWARE THAT IF THE FIRE IS EXTINGUISHED WITHOUT STOPPING
THE HYDROGEN FLOW, AN EXPLOSIVE MIXTURE MAY FORM, CAUSING
A MORE SERIOUS HAZARD THAN THE FIRST ITSELF.
• THE INVISIBLE FLAME CAN BE MANY FEET LONG AND CAN SHIFT
QUICKLY WITH THE SLIGHTEST BREEZE. THEREFORE, PERSONNEL
SHOULD WEAR PROTECTIVE CLOTHING WHILE FIGHTING HYDROGEN
GAS FIRES.