Heat-sealable bag for chemical vapor testing

Integrated sensor array identifies toxic vapors and flammable hydrocarbon materials on or in an enclosed device or gauge before usage

Electronics Sensors

Navy researchers have developed a sealed transport bag for devices that measures off-gassing hydrocarbon contaminant materials and chemical solvent vapors. The patent-pending technology is available via license agreement to companies that would make, use, or sell it commercially.

The bag was designed for the storage and testing of critical oxygen gauges.

Hydrocarbon materials are incredibly flammable in oxygen-enriched environments and therefore pose a serious safety hazard to personnel. Oxygen pressure gauges and other components are transported in heat-sealed polyethylene bags to off-site calibration facilities. Upon receipt, the bag is opened, and its contents are inspected for hydrocarbon contamination using visible and ultraviolet (UV) light. Any remaining levels of chemical cleaning solvent in a critical-air or oxygen gauge must be verified to be at safe levels to protect users.

The current approach for measuring these levels of solvent vapor remaining in a device requires that the cleaned pressure gauge be connected to a source of pressurized clean air or nitrogen. Laboratories sample the gas as it is expelled from a gauge using a flow-through monitoring instrument, but this dilutes the gas with atmospheric air from the laboratory. Furthermore, the types of devices used require a constant flow of gas at a relatively high rate, which doesn’t allow enough time for accurate measurements.

Navy researchers have addressed these issues by inventing a heat-sealable bag for safe transportation of an enclosed device and verification of its purity before usage. The bag incorporates a sensor array facing the bag’s interior for direct contact with enclosed chemical vapors on one side, and the bag’s exterior to display a test reading on the other side. Additionally, a device (gauge) can be tested by cleaning it first with a chemical solution and then pumping nitrogen into the instrument until the pressure gauge reaches either 100 psi or the maximum pressure allowed. Once the device is connected to the bag’s first gas port, gas from inside the device flows into the sensor bag for testing.

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