SAMPLING of ALL CONFINED CHAMBERS
SUMMARY: Hyperbaric (Recompression) chambers can be sampled “at Depth” as well as ambient pressure using our manual pump. The same pump can also sample closed rooms, SRC’s, Saturation Chambers and submersible vehicles and with or without pressurization. In all cases, it is crucial to purge the sample container well, and obtain at least a 200 cc sample to allow a detailed analysis, especially in the case of an injury investigation.
Some of the situations where we have sampled closed chambers are: (1) accident investigation; (2) space launch vehicles; (3) post painting of spheres, recompression chambers and Submarine Rescue Chambers (SRCs); (4) re-entry protocols for closed spaces; and (5) equipment off-gassing checks. We have even sampled the air in diving bells 50 ft underwater to discover the reason dive instructors on observation platforms were becoming ill.
There are 3 types of pumps currently used by laboratories: a bicycle pump (no joke); a rubber bulb with a small glass vial on it; and a manual piston pump. The bicycle pump is inappropriate because it is laden with hydrocarbons that off-gas and prevent a trustworthy analysis. The rubber bulb device cannot be attached to a chamber fitting, and, therefore, requires that the technician climb into the chamber and work the rubber bulb. The breath of the person sampling nearly always accumulates and essentially guarantees that the chamber will fail the CO2 criteria.
We manufacture a manual piston pump of our own design that has evolved from extensive research and field testing. It works with our standard air canister, and has fittings to attach to any connection. It also contains a non-contaminating inert polymer tubing which allows us to pull samples in any situation. (Did we mention that it has been used for 10 years to check for off gassing and breathing air purity in the US Navy’s Sea Cliff, Mystic, Avalon and Turtle deep submergence vehicles?)
USE OF OUR MANUAL PUMP
The operation of the pump plus sampling canister is intuitively obvious: it is attached to any convenient valve or threaded port (i.e. the Dragon valve on the gauge line of the hyperbaric chamber. After purging the lines with 10 strokes of the pump the canister is pumped up to 35 psi. The process is the same for any other enclosed space or piping. It could even be used to draw sample out of an “empty” SCUBA or SCBA tank that had no pressure.
The photographs below show a few of the uses of our sampling pump.
Top: Sampling a Recompression Chamber for gases and volatile compounds. Middle: Sampling the Breathing Air in the Halo of a Deep Submergence Vehicle.
Bottom: Sampling a Space Launch Vehicle’s Bulkhead for Helium Leaks at 2 ppmv.