PurityPlus supplies a large selection of hydrogen grades,along with various other specialty gases to our specialty gas customers throughout North America. PurityPlus frequently supplies hydrogen and other specialty gases to research laboratories and several other industries, so we felt it would be beneficial for our customers to be up to date on the safe use of hydrogen in laboratories.
With
escalating costs associated with the limited volume of available
helium,
operators and designers of laboratory equipment are increasingly turning to
their gas suppliers for
hydrogen. From
universities, to medical research facilities, analytical laboratories, and
chemical process buildings, hydrogen is used at nearly all facilities. However, it is imperative to understand the
risks that hydrogen storage, distribution, and use present along with the fire
and safety code requirements governed by the National Fire Protection
Association’s Compressed Gases and Cryogenic Fluids Code (NFPA 55) along with
the International Fire Code (IFC) and International Building Code (IBC).
Recent
updates to NFPA 55 have redefined the Maximum Allowable Quantities (MAQ)
spelled out specifically for hydrogen.
These MAQ’s are distinguished for each storage area, determined by storage
in either an unsprinklered or fully sprinklered building and further limited
based on the hydrogen cylinders being contained in gas cabinets or not. The corresponding volumes are expressed as
standard cubic feet (cuft) of hydrogen at 1 atmosphere of pressure. In an unsprinklered building where not all
cylinders are stored in gas cabinets, the MAQ is limited to 1,000 cuft, whereas
that quantity is doubled to 2,000 cuft if all cylinders are stored in gas
cabinets. Likewise, for sprinklered
buildings where not all cylinders are stored in gas cabinets, the MAQ is also 2,000
cuft. That volume is doubled to 4,000
cuft if all cylinders are stored in gas cabinets. NFPA further defines limitations based on
hydrogen use in control areas or employing outside storage, part II of this
series will detail the infrastructure requirements for compliance.
We
will further our discussion by selectively describing some of the main areas and
requirements for hydrogen installation in terms of fire-resistance rating and
ventilation.Section 6.3.1.3.1 of NFPA details that for flammable
gases stored or used in quantities larger than 250 cubic feet, a 1-hour
fire-resistance rated construction shall be used to separate the area. The compressed gas cylinders must be
separated by 10’ or a noncombustible wall; however, they must be separated by
20’ or a noncombustible wall having a minimum fire resistance rating of .5
hours from incompatible materials like oxygen.
For areas containing hydrogen systems, appropriate safety placards must
also be permanently affixed.
Similarly, Section 6.16 declares that indoor storage and
use areas must be provided with ventilation, either mechanical or natural, so
long as the natural ventilation is proven to be acceptable for the gas
used. If using mechanical ventilation,
the system must be operational while the building is occupied, with the rate of
ventilation being no less than 1 ft3/min per square foot of floor area of
storage/use and being equipped with an emergency power system for alarms,
vents, and gas detection. The system
must also account for gas density to ensure proper exhaust ventilation. Part III of this series will expand on the
remaining NFPA 55 requirements for separation and controls.
In continuing the series detailing
updates to NFPA 55 governing the safe use of hydrogen in laboratories, we will further
our discussion by selectively describing some of the main areas and
requirements for hydrogen installation in terms of separation and controls.Section 7.1.6.2 of NFPA 55 dictates that any flammable or
oxidizing gases must be separated by 20’ from each other, while section
7.1.6.2.1 states that this distance can be limitlessly reduced when separated
by a barrier comprised of noncombustible material a minimum of 5’ tall that
provides a fire resistance rating of at least .5 hours.
The safe use of controls in hydrogen systems are dictated
by NFPA 55, IFC, & IBC, creating a slightly more nuanced requirement for
compliance. Section 414.4 of the IBC
demands that controls must be suitable for the intended application, with
automatic controls being required to operate fail-safe. Section 2703.2.2.1 of the IFC requires
suitable materials for hazardous media, the main ramification being that 316L
SS or copper piping shall be used and identified in accordance with ASME A13.1 with
directional arrows every 20’. The system
should also contain no concealed valves or breakable connections, using welded
or copper brazed joints where the piping is concealed. NFPA 55 demands that these brazing materials
should have a melting point above 10,000°F.Aside from piping requirements, these codes also require
the use of emergency shutoff valves on supply piping at the point of use and
source of compressed gas, along with backflow prevention and flashback
arrestors at the point of use.
As the final installment in
the NFPA 55 series governing the safe use of hydrogen in laboratories, we will conclude
our discussion by describing applications where the need for hydrogen gas
cylinders is higher than the Maximum Allowable Quantities (MAQ’s).It is not unusual to find installations where the
requirement for hydrogen is larger than the MAQ’s, typically in instrumentation
applications and/or chemical reactions like hydrogenation. These are commonly found in installations
using hydrogen where outside storage is unavailable and control to line
pressures of less than 150 PSIG is unobtainable. The NFPA 55 code along with the IBC and IFC requirements
will allow for these volumes to be present inside a building; however,
significant upgrades to the building are required, effectively dictating that
the facility build a hydrogen shelter.
These upgrades consist of improvements to the structure fire rating,
transportation, fire detection, a limitation on the number of occupants, and a
limit to the number of stories a building can have. These installations also have strict
distancing requirements and floor and wall ratings as well. Although feasible, this scenario is not ideal
and should be avoided in possible. A
more effective solution would be to parcel the facility’s requirements into
numerous, smaller systems where the compressed gas cylinders can be installed
exclusively in gas cabinets.
PurityPlus is a trusted supplier of
hydrogen, along with many other
specialty gases and advanced
specialty gas equipment. Whether you are in need of specialty gases for use in your
laboratory research, or any other
industry, PurityPlus will have the products you need to efficiently carry out your operations. To find out more about PurityPlus and our
specialty gas products, browse our website and
catalog. We can be reached at 877-81P-PLUS (877-817-7587) or
contacted via our website.
Larry Gallagher
CONCOA
2/10/2016