Inert cryogenic liquids, such as liquid nitrogen, are commonly used in non-production (public and private research and development, academic, and/or medical institution) laboratories. There are universal storage and handling practices that must be followed, regardless of where the laboratory is located. Cryogenic liquid containers must have pressure relief devices and must be stored in areas with adequate ventilation. Laboratory door signage should also indicate the presence of cryogenic liquids. If cryogenic liquid is transferred into another container, such as a dewar, the vessel must have adequate integrity to withstand the cold temperature, and appropriate personal protective equipment (PPE) must be worn when dispensing.
In New York City (NYC), the Fire Department of the City of New York (FDNY) has implemented additional requirements when storing and using inert cryogenic liquids in non-production laboratory units. If there are more than 60 gallons of cryogenic liquids in a laboratory unit, an oxygen sensor must be installed and maintained, in accordance with 5006.6.10.2 of the current NYC Fire Code. Since a standard liquid nitrogen tank is 63 gallons (240L), the storage of one or more cryogenic liquid tanks warrants an oxygen sensor.
In most municipalities outside of NYC, there is no limit to the maximum allowable quantity (MAQ) of inert cryogenic liquid that can be stored in a laboratory. However, in NYC, if quantities exceed a particular threshold, there are additional requirements.
In Section 5501.3.3 of the NYC Fire Code, it states that “inert cryogenic fluids shall additionally comply with the requirements of CGA P-18,” which is the American National Standards Institute (ANSI)/Compressed Gas Association (CGA) Standard for Bulk Inert Gas Systems. A bulk inert gas system is defined as an area with a storage capacity exceeding 20,000 cubic feet of inert gas. Therefore, a laboratory unit that stores more than four 63-gallon inert cryogenic liquid tanks is considered a bulk inert gas system. While CGA P-18 does not apply to carbon dioxide (CO2), the FDNY will factor in liquid CO2 quantities when determining whether a laboratory unit’s inert cryogenic liquid storage is considered a bulk inert gas system.
In general, storage and use of hazardous material in laboratory units is enforced through the FDNY’s Fire Code and Non-Production Laboratory Unit Permit. However, the FDNY considers bulk inert gas systems as hazardous beyond standard laboratory unit requirements. As a result, the storage of more than four 63-gallon inert cryogenic liquid tanks in a laboratory unit requires a Technology Management (TM) Variance. The fire department will usually identify bulk inert gas systems during permit inspections. If the FDNY determines that a variance is required, they will not issue a new Laboratory Unit Permit or process a renewal until a TM is approved.
A TM variance submission must include floor plans and other documents that demonstrate that the laboratory unit has appropriate ventilation in accordance with the current NYC Mechanical Code, and that cryogenic liquid manifolds and piping are installed in accordance with gas piping plans by licensed personnel. The FDNY might also require documentation that oxygen sensors are hard wired into building systems.
While the additional requirements for bulk inert gas systems might seem extensive, the rationale is understandable when taking into consideration that many NYC laboratories are small and are in high rise, multi-tenant buildings in densely populated neighborhoods. The additional requirements are in place to keep everyone safe.
For assistance with compliant cryogenic liquid use and storage procedures at your facility, or for more information on bulk inert gas systems and Technology Management Variances, please contact us!
This blog was written by Rae Moore, Safety Partners’ Senior Quality, Research, and Training Specialist.
