Key Instruction Points
- Read the Label
- Use Engineering Controls to Protect Against Unforeseen Hazards
- Use Appropriate PPE as required
An industrial research lab used arsine gas in a semiconductor- related research project. It had been decided (appropriately in the joint decision of the researcher and health and safety personnel) to use 100 percent arsine at 200 psig cylinder pressure rather than a ten percent arsine / hydrogen mixture which had a cylinder pressure of over 2000 psig. The gas cabinet was equipped with normally-closed pneumatic shutoff valves, a flow restrictor in the cylinder valve, and in-cabinet continuous monitoring for arsine, in addition to other engineering controls. The side of the gas cylinder received from the gas supplier was stenciled with the word "arsine." The regulator had been chosen for 100 percent arsine gas. When the cylinder was connected to the regulator assembly (with personnel using SCBA) and turned on, the gauge needle immediately pegged itself off scale on the regulator. The bourdon gauge in the regulator burst and the researcher headed for the door. In moving to the door he heard the sound of the pneumatic valve closing. The gas detection system had immediately signaled for automatic shutdown of the pneumatic valve. No arsine was detected in the lab area outside of the gas cabinet and in-cabinet readings quickly dropped to zero. Subsequent examination of the cylinder contents tag (attached to the cylinder neck) indicated the researcher had actually received a ten percent arsine mixture in hydrogen, at the elevated cylinder pressure of 2200 psig. The researcher had not doubled checked the manufacturers identification tag and had relied on the cylinder stenciling, which should not be considered reliable. Fortunately, the engineering controls and personal protective equipment handled the situation effectively
Research staff was informed to check the manufacturer’s tag against their order information and not to rely on cylinder stencils. They were also reminded to utilize engineering controls and protective equipment to minimize the impact of highly hazardous materials incidents when the unexpected occurs.