Hydrogen is a colorless, odorless, highly flammable gas with a wide flammability range in air. It is not detectable by human senses and leaks are often first heard rather than seen. Mixtures with air or oxygen are highly flammable and can ignite with very little energy, such as a static spark. Hydrogen fires burn with an invisible flame that can cause severe burns, so protective clothing should be worn when fighting hydrogen fires. Allowing the fire to burn until the hydrogen is consumed is safer than extinguishing it if the source is still active, as an explosive mixture may form.

1. 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.

2. 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).

3. 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.

4. 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.

5. 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.

6. 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.