Safely Using Hydrogen In Laboratories

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.

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.