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No. 80

EH&S Fact Sheet

Created 2/4/13

Environment, Health and Safety Information for the Berkeley Campus

Hydrogen Safety
Introduction Hydrogen (H2) is an extremely flammable, colorless
odorless compressed gas that is used in many
research laboratories. It has virtually no toxic effects
on the human body, but it can displace air causing
asphyxiation if enough is released in an enclosed
room. The biggest danger when dealing with
hydrogen is that is has a wide explosive/flammability
range (4%-74% in air). This means that even a small
leak can cause a hazardous fire.

Hydrogen is very light and quickly rises if released, and also has the unique
characteristic of making certain metals brittle after prolonged use. So, use caution
when working with metal tools and devices.

Fire Hazards When hydrogen is in air it can ignite with extremely low energy input. For instance,
hydrogen only needs 10% of the energy (0.02 millijoules) required to ignite a gasoline-
air mixture. Even a static spark from a person or clothing can ignite
4 hydrogen gas. Hydrogen needs only a minimum of 10% oxygen or a
0 0 maximum of 41% of oxygen in air to ignite. Also, because the flame is
almost invisible in daylight, finding and fighting a hydrogen fire can be
difficult.

Protective • There should be no open flames or smoking in areas where hydrogen is used.
Measures • Work in an area with plenty of ventilation. If possible, work in a fume hood or use
a canopy hood as fugitive vapors, if not captured, may collect near the ceiling.
• Ground all equipment and piping used with hydrogen, and make sure that you are
properly grounded before working with hydrogen. Rubber soled shoes prevent
you from being grounded, so you should touch a grounded object to discharge
built up static electricity before beginning work.
• Wear appropriate lab safety gear for the work being performed: safety glasses/
goggles, lab coat, gloves and preferably a face shield.
• If working with liquid hydrogen you must have appropriate insulated gloves
and protective shoes in addition to the appropriate safety gear. (Cryogenic
liquid hydrogen can cause severe burns to the skin due to the extremely low
temperature.) Presently, there is no known liquid hydrogen use at UCB. If you plan to
use or are using liquid hydrogen you must first check with EH&S and the Campus Fire
Marshall.
• Remove electrical equipment or electronic devices from the vicinity of hydrogen
gas unless the device is certified "intrinsically safe". Even invisible small sparks
from electronic devices could ignite hydrogen.
• Use metal piping with hydrogen. Do not use non-conductive or plastic tubing.
E H Office of Environment, Health & Safety
University of California Be sure to dissipate static charge when flowing hydrogen gas by electrically
& S
317 University Hall #1150
Berkeley, CA 94720-1150 bonding and grounding the cylinder, metal piping and apparatus being used.
UC BERKELEY
http://www.ehs.berkeley.edu
(510) 642-3073
 Fact Sheet: Hydrogen safety Page 2 of 2

Storage and • Hydrogen cylinders must be stored with valve’s protective cap in place. If the
cap has been removed, the cylinder must be stored upright and secured with non-
handling combustible straps or chains.
• Hydrogen cylinders must be stored more than 20 feet away from cylinders of oxygen
or other oxidizers, e.g., bromine, chlorine, fluorine (which we do not have) or be
separated by a noncombustible wall extending not less than 18” above and to the
sides of the stored material.
• Never open the cylinder valve before making sure all your connections are secure as
the static discharge from flowing gas may cause hydrogen to be ignited.
• NEVER USE ADAPTERS.
• Be aware of leaks! Hydrogen has a low viscosity which makes it to have a high
leakage rate. A leak as small as 4 micrograms/second can support combustion.
• Due to hydrogen’s low molecular weight, this gas will diffuse rapidly in a room and
will collect near the ceiling. It is important to only use hydrogen in well ventilated
locations.
• There must be no more than 1000 cubic feet of flammable gases per fire control
area unless there are adequate engineering controls. Contact EH&S for an
evaluation if there will be more than one large cylinder used in a room and one in
storage. A standard large cylinder contains about 260 cubic feet of hydrogen. If
there are inadequate engineering controls the fire marshal may restrict the volume
of H2, request that they be stored in an exhausted location and require hydrogen
monitoring and alarms, or other safety controls. There should be fire sprinklers
wherever hydrogen is used.
• All electronic equipment used near hydrogen gas must be grounded.
• Check that the pressurized system does not leak hydrogen with leak detection
solution or pressure sensing.
• Close the cylinder valve when not in use. Do not leave the piping pressurized if not
is use.

Hydrogen is incompatible with many materials and situations (check your MSDS for list
of incompatibles):

• It ignites easily with oxygen, could explode when heated.

• It reacts violently or explosively or forms heat- and/or-shock sensitive explosive
mixtures with oxidizers, halogens, halogen compounds, acetylene, bromine
pentafluoride, chlorine oxides, fluorine perchloride, oxides of nitrogen (check
MSDS for list of incompatibles).
• Mixtures with chlorine may explode on exposure to light.
• Mixtures with oxygen may explode in presence of platinum catalyst.
• It is incompatible with copper (II) oxide, difluorodiazene, iodine heptafluoride,
lead trifluoride, liquid nitrogen, lithium perchlorate trihydrate, metals, nitrogen
trifluoride, nitryl fluoride, palladium (II) oxide, palladium trifluoride, polycarbon
monofluoride, potassium tetrafluorohydrazine, xenon hexafluoride.
• It forms hydrides when heated with alkalis, alkaline earth, and some other elements.

If you are using hydrogen in a research laboratory, you should prepare a standard
operating procedure (SOP). The safety information in this fact sheet may assist you in
drafting the SOP.
E H
& S
UC BERKELEY
Office of Environment, Health & Safety • University of California • 317 University Hall #1150 • Berkeley, CA 94720-1150 • http://www.ehs.berkeley.edu • (510) 642-3073