Overview
- Many different styles
- Lids fit loosely if present
The images provided show examples of dewars. Note the lack of valves or gauges. All will have either no lid or just a loose fitting one so that volatilizing gases can escape. These are not subject to compressed gas rules but are dangerous since they contain cryogenic liquids. The use of appropriate PPE is important when filling or transferring cryogenic liquids. Note the lack of appropriate PPE in Exhibit D. This person should be wearing a lab coat, safety glasses/face shield and ‘cryogenic gloves’ when conducting this operation. In addition to this, her pants should extend to the top of their shoes.
Note: On the Hazard Assessment form, dewars such as these should be noted under the “Cryogenic Materials” class, but not under “Gas Cylinders under Pressure”.
The EHS SOP Cryogenic Material is a good reference for lab occupants using cryogens where there is a safe work practice concern.