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.