Use of Hazardous Compressed Gases in Research
Definitions
Hazardous compressed gases are gases or mixtures of gases having, in a container, an absolute pressure exceeding 40 psi at 70 deg. F (21.1 deg. C); or a gas or mixture of gases having, in a container, an absolute pressure exceeding 104 psi at 130 deg. F (54.4 deg. C) regardless of the pressure at 70 deg. F (21.1 deg. C) and which exhibit one or more of the following characteristics.
- Corrosive-A gas that causes visible destruction of or irreversible alterations in living tissue by chemical action at the site of contact.
- Flammable – A material that is a gas at 68°F (20°C) or less at an absolute pressure of 14.7 psi (101.3 kPa); or is ignitable at an absolute pressure of 14.7 psi (101.3 kPa) when in a mixture of 13 percent or less by volume with air;or has a flammable range at an absolute pressure of 14.7 psi (101.3 kPa) with air of at least 12 percent, regardless of the lower limit; or is a liquefied compressed gas that, when under a charged pressure, is partially liquid at a temperature of 68°F (20°C) and is flammable.
- Highly Toxic – A chemical that has a median lethal concentration in air of 200 ppm by volume or less of gas or vapor, or 2 mg/L or less of mist fume or dust, when administered by continuous inhalation for one hour (or less if death occurs within one hour) to albino rats weighing between 200 and 300 grams each.
- Toxic – A chemical that has a median lethal concentration in air of more than 200 ppm but not more than 2,000 ppm by volume of gas or vapor, or more than 2 mg/L but not more than 20 mg/L of mist fume or dust, when administered by continuous inhalation for one hour (or less if death occurs within one hour) to albino rats weighing between 200 and 300 grams each.
- Oxidizing – A gas that can support and accelerate combustion of other materials more than air does.
- Pyrophoric – A gas with an auto-ignition temperature in air at or below 130°F (54.4°C).
- Unstable/ Reactive – A gas that, in the pure state or as commercially produced, will vigorously polymerize, decompose, or condense; becomes self-reactive; or otherwise undergoes a violent chemical change under conditions of shock, pressure, or temperature.
- Class 1 Unstable Reactive Gas- Materials that are normally stable, but that can become unstable at elevated temperatures and pressures;
- Class 2 Unstable Reactive Gas- Materials that readily undergo violent chemical change at elevated temperatures and pressures;
- Class 3 Unstable Reactive Gas- Materials that are capable of detonation or explosive decomposition or explosive reaction, but that require a strong ignition source or that must be heated under confinement before initiation;
- Class 4 Unstable Reactive Gas- Materials that are readily capable of detonation or explosive decomposition or explosive reaction at normal temperatures and pressures.
Inert gases– while not characteristically hazardous, inert gases are capable of displacing oxygen in confined spaces resulting in asphyxiant atmospheres that are immediately dangerous to life and health.
Liquefied Gases – are gases which exist as liquids at normal temperatures when contained in pressurized cylinders. These gases exist in the cylinder in a liquid-vapour balance or equilibrium. Initially the cylinder is almost full of liquid, and gas fills the space above the liquid. As gas is removed from the cylinder, enough liquid evaporates to replace it, keeping the pressure in the cylinder constant. Anhydrous ammonia, chlorine, propane, nitrous oxide and carbon dioxide are examples of liquefied gases. Cryogenic liquefied gases consist of gases that have been cooled below their boiling points.
Non-Liquefied Gases – are also known as compressed, pressurized or permanent gases. These gases do not become liquid when they are compressed at normal temperatures, even at very high pressures. Common examples of these are oxygen, nitrogen, helium and argon.
Getting Started
Researchers who wish to use hazardous compressed gases in research must submit a hazardous gas use request to the PSC Facilities Management Team. The request must include the name and type of gas, how it will be used, expected volume that will be ordered, storage and use locations and process pressure. The information provided will be used to conduct a risk assessment, which will define the necessary training, safety procedures, controls and safe work practices for the handling, use and storage of hazardous compressed gas cylinders associated with a research protocol. Hazardous compressed gases must not be ordered prior to receipt of approval for use.
The use of certain hazardous gases in research poses a heightened risk to personnel and may also require review by the department safety committee.
These gases are:
- Arsine, disilane, diborane, germane, phosphine, silane
- Cyanogen (hydrogen cyanide)
- Chlorine, Fluorine
- Hydrogen sulfides
When selecting materials for use, researchers are encouraged to anticipate the risk for chemical accidents, releases, explosions and fires and in doing so, consider using less hazardous alternatives (substitution) or smaller volumes of material. Researchers should also allocate sufficient time between proposal and expected start dates for the appropriate reviews to be conducted.
Process Outline:
- The Principle Investigator (PI) completes a hazardous gas use request.
- The completed survey is routed to the Physical Sciences Complex Safety Manager and Facilities Director for review.
- The PSC Safety Manager determines if the information provided is sufficient to proceed with the review. If the information provided is insufficient, the PSC Safety Manager follows up with the researcher to obtain the information needed to move forward.
- On receipt of the required information, the Hazardous Gas Use Review Team (HGURT) will convene to determine the type and degree of the hazard, possible exposure pathways inherent in the process design, and use subject to MAQ limitations and other applicable statutes.
- The HGURT team will review the available controls and determine if they are adequate and appropriate given the risk.
- The HGURT will provide a report of findings and recommendations for risk mitigation to the initiating Principle Investigator (PI).
- The PI will engage the location specific facilities and research team members to provide and implement the controls outlined in the HGURT report.
- The HGURT team will reconvene to review the controls prior to startup. Approval to proceed will be granted if controls are deemed sufficient to mitigate the risk.
- The PI may then order the requested material per volume and/or concentration restrictions.