ISSUES IDENTIFIED 

• Many fre departments use higher pressure cylinders (i.e., 4500 and 5500 psi cylinders with 30, 45, 

60, and 75-minute durations) that require slower fll rates for routine flling. 

• Rapid flls, or “hot flls” of higher-pressure cylinders can result in lower operating pressures afer 

the compressed air cools, decreasing the amount of breathing air for frefghters if not properly 

topped of. 

• Higher pressure cylinders may require greater compressor and/or cascade system capacity to 

safely and completely fll cylinders to their full operating pressure. 

BEST PRACTICE REMINDERS 

• Ensure performance at the rated capacity by flling the cylinder to the proper operating pressure, 

at the proper fll rate, per the manufacturers’ guidelines. Remember that the rated service time is 

based on a full cylinder. 

• Know the SCBA and compressor manufacturers’ guidelines regarding cautions and hazards of over 

pressuring a cylinder. 

• Develop and implement standard operating guidelines for flling higher pressure cylinders to 

achieve full operating pressure and breathing air capacity, including topping of as needed. 

• Consider upgrading the capacity of the breathing air fll systems in the department when upgrading to the higher-pressure cylinders. Verify with the SCBA and air fll system manufacturers that 

the system(s) can fll the expected number of cylinders to capacity. 

• Ensure personnel who operate compressors and cascade systems to fll SCBA cylinders are 

trained per the manufacturers’ instructions and qualifed as part of the department’s respiratory 

protection program. 

• Refer to SCBA and compressor manufacturers’ guidelines providing direction on cylinder flling, 

as well as other important resources—for example, current editions of NFPA 1989, NFPA 1852, 

NFPA 1500, and NFPA 1901. 

Hot Filling 

Hazards with 

SCBA Air 

Cylinders 

The National Institute for Occupational Safety and Health (NIOSH) Fire Fighter Fatality Investigation 

and Prevention Program (FFFIPP) monitors issues related to self-contained breathing apparatus (SCBA). 

The NIOSH FFFIPP has identified a potential hazard associated with rapid filling of compressed 

breathing air cylinders and the associated latent pressure/breathing time loss. Rapidly filling a breathing air cylinder, also known as “hot filling,” generates excessive heat and can result in a loss of pressure 

as the cylinder cools leaving the user with reduced breathing air. Fire departments should ensure that 

cylinders are stored fully charged to maximize use and capacity.

PPE CASE Notes 

Personal Protective Equipment Conformity Assessment Studies and Evaluations Notes 

Photo courtesy of Sufolk Fire and Rescue 

All SCBA cylinders should be filled per the manufacturer’s guidelines. A hot filled cylinder will have less breathing 

air and must be topped off after it cools. Those responsible for filling cylinders should be trained on the proper 

techniques to achieve the correct cylinder operating pressure. 

Bottom Line 

Get More Information 

Find NIOSH products and get answers to workplace safety and health questions: 

1-800-CDC-INFO (1-800-232-4636) | TTY: 1-888-232-6348 

CDC/NIOSH INFO: cdc.gov/info | cdc.gov/niosh 

Monthly NIOSH eNews: cdc.gov/niosh/eNews

https://doi.org/10.26616/NIOSHPUB2021111 

DHHS (NIOSH) Publication No. 2021-111 

December 2020