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Compressed or Liquefied Gases in Laboratories


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Origination Date: 07/12/2010

Last Amended: 12/05/2019

Next Review Date: 12/05/2021

Policy Statement

All employees engaged in the use of compressed or liquefied gases and cryogenic liquids in research shall adhere to the requirements stated in this Policy and all related safety programs of the Office for Research. 

Reason for Policy/Purpose

The use of hazardous chemicals in the laboratory is regulated by the Occupational Safety and Health Administration (OSHA) Occupational exposure to hazardous chemicals in laboratories (29 CFR 1910.1450). Areas outside laboratorie§ where compressed or liquefied gases are handled are regulated by the OSHA Hazard Communication Standard (29 CFR 1910.1200) and Compressed Gases (29 CFR 1910 Subpart H, Mand Q). The storage of gases is also regulated by the currently adopted version of the International Fire Code, applicable standards of the Compressed Gas Association (CGA) and the National Fire Protection Association (NFPA). The University requires research laboratories using compressed or liquefied gases to maintain concentrations and/or quantities below the thresholds as promulgated by the Department of Homeland Security (DHS) Chemical Facilities Anti-Terrorism Standards (CFATS). There are also some chemicals of concern that can be illegally diverted for illicit drug manufacturing. 

Who Needs to Know this Policy

Northwestern faculty, staff, postdocs, research associates, students, and visitors working in laboratories or laboratory support facilities using compressed or liquefied gases. 


Specific instructions and procedures can be found in the Guide to Compressed or Liquefied Gases in Laboratories.


A table of the abbreviations used in this policy is included as Appendix 2.

Control area

  • As defined by the International Building Code: “Spaces within a building where quantities of hazardous materials not exceeding the maximum allowable quantities per control area are stored, dispensed, used or handled.”

Emergency Alarm System

  • A system to provide indication and warning of emergency situations involving hazardous material releases.

Highly Toxic

  • A chemical that has a median lethal dose (LC50) in air of 200 parts per million (ppm) by volume or less of gas or vapor as defined by the International Fire Code (IFC). A chemical that has a LC50 of more than 200 ppm but not more than 2,000 ppm in air is defined as toxic.

Maximum Allowable Quantity (MAQ)

  • MAQs are defined by the International Fire Code Table: 5003.1 and the National Fire Protection Association (NFPA) 55 Compressed Gases and Cryogenics Fluids Code. It is the maximum allowable gas volume or liquefied gas weight per hazard class and control area. A record of MAQs per control area is maintained by Research Safety. Further information is in the Guide to Compressed or Liquefied Gases in Laboratories.

Restricted Commodity

  • Certain gaseous chemicals above their threshold concentrations are classified as Chemicals of lnterest per Department of Homeland Security (DHS) Chemical Facility Anti-Terrorism Standards (CFATS) and are Restricted Commodities at Northwestern University. The acquisition of Restricted Commodities requires approval from Research Safety.


A sustainable safety culture in research is built on leadership engagement, hazard awareness, enhanced communication, and behavior changes. Everyone involved has a role in fostering and maintaining a safe environment and this policy assigns related responsibilities. 


Principal Investigator or Laboratory Supervisor Responsibilities

The Principal Investigator (PI) or laboratory supervisor shall ensure that the laboratory workers using compressed or liquefied gases and cryogenic liquids are informed of the hazards of chemicals present in their work area. Specifically, the PI or laboratory supervisor shall: 


  • Ensure that workers know and follow the guidelines for compressed and liquefied gases.
  • Determine the required levels of protective apparel and equipment, and availability.
  • Assure that the quantity of compressed and liquefied gases does not exceed Maximum Allowable Quantities (MAQs) or Restricted Commodity Thresholds of Consequence.
  • Develop standard operating procedures and a hazard release risk assessment for high hazard gases.
  • Maintain an up-to-date inventory record.
  • Notify the business office to select the commodity category LAB=HAZARDOUS_GASES_RESTRICTED for orders of gases listed in the Appendix.
  • Properly classify and record the acquisition of any Restricted Commodity within 30 days in the Research Hazards Registry Lumen.
  • Ensure that facilities and training for use of any material being ordered are adequate.
  • Maintain Safety Data Sheets or other medical data sheet for exposure symptoms and medical treatment for toxic gases. Inform the Emergency Medical Service providers of any unique supplies that are necessary for treatment.

The PI or laboratory supervisor shall develop a written response protocol for activation of any emergency alarm system that is mutually agreed upon by University Police, Risk Management, Research Safety, and Facilities and disseminate the protocol to the designated responders. Research Safety shall work with the PI or laboratory supervisor to provide hazard awareness training to designated Northwestern first responders. 

The PI or laboratory supervisor shall also ensure that all laboratory workers using compressed or liquefied gases and cryogenic liquids attend mandatory Laboratory Safety training in accordance with the Research Safety Training program. Training shall be conducted at the time of the laboratory worker’s initial assignment to a work area where compressed or liquefied gases are present and prior to assignments involving new exposure situations. 


Laboratory Worker Responsibilities

Laboratory workers shall:

  • Conduct all work with compressed or liquefied gases and cryogenic liquids in accordance with standard operating procedures.
  • Wear appropriate personal protective equipment.
  • Check that laboratory safety equipment indicator lights show normal conditions (gas sensors, ventilation systems).
  • Ensure that access to safety equipment such as fire extinguishers and safety showers are not blocked.
  • Notify the PI/Supervisor and Research Safety of any accidents, incidents involving material releases, and adverse health, safety, and environmental conditions.
  • Complete all assigned safety training certificates.


Research Safety Responsiblities

The University’s Chemical Hygiene Officer (CHO) is a designated Research Safety staff member. The CHO or other designated Research Safety personnel shall: 

  • Monitor the maintenance of the chemical inventory program.
  • Review and approve purchase requests for any Restricted Commodity.
  • Maintain a list ofMAQs for each control zone.
  • Develop and offer safety training modules.
  • Assess the use of personal protective equipment.
  • Provide guidance in environmental detection.
  • Provide guidance and act as a resource to departmental safety committees and personnel.
  • Assist in the development of specific standard operating and emergency response procedures.
  • Review laboratory designs.
  • On a monthly basis, report the Chemicals oflnterest inventory to UPD.


Facilities Management Responsibilities

The designated Facilities Management (FM) project manager shall coordinate the review of gas installation design and assist in developing a mutually agreed-upon emergency response plan. 

FM Operations shall complete the periodic maintenance of required gas detection and emergency alarm systems that are designed and installed through FM. 

FM shall maintain a record of control area boundaries in Facilities Connect. 



University Police Responsibilities 

University Police staffs a central station 24/7 and follows the mutually agreed-upon response protocol in case of an alarm activation of a required emergency alarm system. 


Risk Management Responsibilities

Risk Management staff review laboratory designs and assist in the development of emergency response procedures.


Appendix 1 – Restricted Commodities

Table of Restricted Commodities including chemical, CAS#, concentration and quanity
Arsine 7784-42-1 >0.6 15
Boron trichloride 10294-34-5 >84.7 45
Boron trifluoride 7637-07-2 >26.87 45
Bromine chloride 13863-41-7 >9.67 45
Carbonyl fluoride 353-50-4 >12 45
Carbonyl sulfide 463-58-1 >56.67 500
Chlorine 7782-50-5 >9.77 500
Chlorine dioxide 10049-04-4 ACG any amount
Chlorine pentafluoride 13637-63-3 >4.07 15
Chlorine trifluoride 7790-91-2 >9.97 45
Cyanogen 460-19-5 >11.67 45
Cyanogen chloride 506-77-4 >2.67 15
Diborane 19287-45-7 >2.67 15
Dichlorosilane 4109-96-0 >10.47 45
Dinitrogen tetroxide 10544-72-6   15
Fluorine 7782-41-4 >6.71 15
Germane 7782-65-2 >20.73 45
Germanium tetrafluoride 7783-58-6 >2.11 15
Hexafluoroacetone 684-16-2 >15.67 45
Hydrogen bromide (anhydrous) 10035-10-6 >95.33 500
Hydrogen chloride (anhydrous) 7647-01-0 ACG* 500
Hydrogen cyanide 74-90-8 dsaf 15
Hydrogen fluoride (anhydrous) 7664-39-3 >4.67 45
Hydrogen iodide (anhydrous) 10034-85-2 >42.53 500
Hydrogen selenide 7783-07-5 95.33 15
Hydrogen sulfide 7783-06-4 >0.07 45
Methylchlorosilane 993-00-0 >23.73 45
Methyl mercaptan 74-93-1 >20 500
Nitric Oxide 10102-43-9 >3.83 15
Nitrogen trioxide 10544-73-7 >3.83 15
Nitrosyl chloride 2696-92-6 >1.17 15
Oxygen difluoride 2696-92-6 >0.09 15
Perchloryl fluoride 7616-94-6 >25.67 45
Phosgene 75-44-5 >0.17 15
Phosphine 7803-51-2 >0.67 15
Selenium hexafluoride 7783-79-1 >1.67 15
Silane1 7803-62-5 >1.37 any amount
Silicon tetrafluoride 7783-61-1 >15 45
Stibine 7803-52-3 >0.67 15
Sulfur dioxide (anhydrous) 7446-09-5 >84 500
Sulfur tetrafluoride 7783-60-0 >1.33 15
Tellurium hexafluoride 7783-80-4 >0.83 15
Trifluoroacetyl chloride 354-32-5 >6.93 45
Trifluorochloroethylene 79-38-9 >66.67 500

Quantities in each building must be managed below the Threshold of Consequence or MAQ, whichever threshold is lower.


Appendix 2 – Table of Abbreviations

Table of abbreviations used in compressed gas policy
ACG Any commercial grade
CFATS Chemical Facilities Anti-Terrorism Standards
CGA Compressed Gas Association
CHO Chemical Hygiene Officer
DHS U.S. Department of Homeland Security
FM Facilities
IFC International Fire Code
MAQ Maximum Allowable Quantity
NFPA National Fire Protection Association
RM Risk Management
RS Research Safety
OSHA Occupational Safety and Health Administration
PI Principal Investigator
UP University Police

1 Not a CFATS regulated gas