Safely Using Hydrogen In Laboratories

Rocky Mountain Air Solutions supplies a large selection of hydrogen to Denver, along with many other specialty gases. Rocky Mountain Air Solutions frequently supplies hydrogen and other specialty gases to research laboratories and many other industries, so we felt it would be helpful for our Denver customers to be updated on the safe use of hydrogen in laboratories.

Recent updates to NFPA 55 have redefined the Maximum Allowable Quantities (MAQ) expressly created for hydrogen. These MAQ’s are distinguished for each storage area, decided by storage in either an unsprinklered or completely sprinklered building and restricted further based on whether or not the hydrogen cylinders are being contained in gas cabinets. 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 restricted to 1,000 cuft, whereas that number is multiplied to 2,000 cuft if all cylinders are stored in gas cabinets. Similarly, for sprinklered units where not all cylinders are stored in gas cabinets, the MAQ is also 2,000 cuft. That number is increased to 4,000 cuft if all cylinders are stored in gas cabinets. NFPA further states limitations determined by hydrogen use in control areas or using outside storage, part II of this series will discuss the infrastructure requirements for compliance.

Additionally, Section 6.16 details that indoor storage and use areas must be given either natural or mechanical ventilation, so long as the natural ventilation is verified to be adequate for the gas employed. If using a mechanical ventilation process, the system must function while the building is occupied, with the rate of ventilation not reaching lower 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 keep track of gas density to guarantee correct exhaust ventilation. Part III of this series will detail the other NFPA 55 requirements for separation and controls.

To continue the series that explains updates to NFPA 55 governing the safe use of hydrogen in laboratories, we will further our discussion selectively explaining some of the important areas and requirements for hydrogen installation in terms of separation and controls.Section 7.1.6.2 of NFPA 55 states that any flammable or oxidizing gases are required to be separated by 20’ from each other, while section 7.1.6.2.1 dictates that this length 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 declared by NFPA 55, IFC, & IBC, creating a slightly more nuanced neccessity 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 demands suitable materials for hazardous media, the main consequence being that 316L SS or copper piping shall be utilized 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 dictates that these brazing materials should have a melting point higher than 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 concluding part in the NFPA 55 series governing the safe use of hydrogen in laboratories, we will conclude our discussion by explaining uses where the Maximum Allowable Quantities (MAQ’s) is less than the demand for hydrogen gas cylinders.

It is not unusual to come across installations where the requirement for hydrogen is greater than the MAQ’s, frequently in instrumentation employements and/or chemical reactions like hydrogenation. These are frequently come across in installations using hydrogen where there is no outside storage and control to line pressures of less than 150 PSIG is not achievable . The NFPA 55 code and the IBC and IFC requirements will allow for these volumes to be present inside a building; however, important enhancements to the building are necessary, effectively demanding that the facility build a hydrogen shelter. The upgrades include improvements to the structure fire rating, transportation, fire detection, a limitation on the number of occupants, and a building story limit. 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 if possible. A more efficient resolution would be to combine the facility’s requirements into several, smaller systems where the compressed gas cylinders may be set up entirely in gas cabinets.