News | Aug 1, 2019

US Navy invents special bag for testing, storing oxygen gauges after calibration and cleaning

Private businesses can license and manufacture it for civilian or military customers

A U.S. Navy sailor inspects oxygen regulator hoses prior to a pressure decay test in the Aircraft Intermediate Maintenance Department's Oxygen Shop, aboard the nuclear-powered aircraft carrier USS Nimitz.

Navy photo

Two U.S. Navy researchers have invented a way to accurately test and store oxygen and air pressure gauges for residual solvents after being cleaned.

The heat-sealable chemical vapor-sensor bag was invented by Mike Bishop and Christopher Clark of the Naval Surface Warfare Center, Corona Division, in California.

The new bag solves a problem for testing oxygen and air pressure gauges used by the Navy after they’ve been calibrated and cleaned with toxic and flammable hydrocarbon solvents.

The level of chemical solvent in a solvent-cleaned critical-air or oxygen gauge must be verified to be below stated levels to protect users of these components from breathing unsafe amounts of chemical vapors, according to the Navy’s patent application that was made public for the first time on Thursday.

The U.S. Navy uses thousands of Bourdon pressure gauges, which require periodic calibration and cleaning.

“The existing capabilities for measuring the level of solvent vapor remaining in a device under test (e.g., a closed-end Bourdon-tube pressure gauge) require that the cleaned pressure gauge be connected to a source of pressurized clean air or nitrogen and pressurizing the gauge to the lesser of 100 PSIG or the maximum pressure limit of the gauge,” the Navy’s filing reads.

“After the gauge is held at pressure for a prescribed length of time, the gas in the gauge must be accurately sampled and measured to obtain a true verification of remaining solvent vapors.”

The U.S. Navy uses thousands of gauges to monitor critical oxygen systems onboard aircraft, surface ships, submarines, and by SCUBA divers. The gauges require periodic calibration and cleaning with hydrocarbon solvents.

But the testing laboratories are trying to sample for toxins as the gas comes out of the gauge using a flow-through monitoring instrument, but the gas from within the gauges gets thinned by the air in the lab leading to inaccurate results.

And that’s why the inventors want to keep the gauges sealed in a plastic bag with two gas ports and an integrated sensor system. This allows the gauges to be tested without ambient air diluting the gas as it’s tested, and when Navy personnel take the gauge out of transport or storage, they can check the bag’s integrated sensor for trace chemicals immediately before opening and installing the gauge.

“The bags have at least one sensor array integrated into the bag such that gas inside the bag will contact an interior surface of the sensor array. An exterior surface of the sensor array can display a reading (e.g., a binary yes/no reading) indicating whether a contaminant has been detected. Sealing a device in the bag allows an end-user of the device to know immediately prior to use whether or not the device is free from contaminants,” the patent application states.

TechLink, the Navy’s technology transfer partnership intermediary, can help businesses evaluate the technology and prepare a license application, the first step in turning the heat-sealable chemical vapor-sensor bag into a market-ready product.

Through technology transfer agreements, private businesses, large or small, can acquire intellectual property rights to Navy inventions and then manufacture them for civilian or military customers, said Sean Patten, senior technology manager at TechLink.

“It’s a great invention and when a business realizes the opportunity, we help them navigate the Navy’s patent licensing process and support the preparation of the license application and commercialization plan,” Patten said. “And we don’t charge for our services.”

Companies with licensing inquiries can contact Sean Patten at or 406-994-7721.