Oxygen leak

Since the system design is driven by the requirement for anaerobiosis, the electrodes must fit inside a spectrophotometric cuvette whose contents have previously been made anaerobic by the procedure described in the following section. The electrodes must also be custom made to fit inside without leaking oxygen, either around the joints or through the tips. They must also be stored anaerobically between experiments (see following section). 

Carrying out a combustion. The apparatus (Fig. 85, p. 469) will have been left with the bottle W connected to the beak of the combustion tube via the guard tube V and with all the taps shut, the combustion tube, which is dways allowed to cool down while connected to the oxygen source, will therefore be full of oxygen at slightly above atmospheric pressure, thus preventing any leaking in of carbon dioxide or water vapour from the air. 

Propylene is a colorless gas under normal conditions, has anesthetic properties at high concentrations, and can cause asphyxiation. It does not irritate the eyes and its odor is characteristic of olefins. Propjiene is a flammable gas under normal atmospheric conditions. Vapor-cloud formation from Hquid or vapor leaks is the main ha2ard that can lead to explosion. The autoignition temperature is 731 K in air and 696 K in oxygen (80). Evaporation of Hquid propylene can cause skin bums. Propylene also reacts vigorously with oxidising materials. Under unusual conditions, eg, 96.8 MPa (995 atm) and 600 K, it explodes. It reacts violentiy with NO2, N2O4, and N2O (81). Explosions have been reported when Hquid propylene contacts water at 315—348 K (82). Table 8 shows the ratio TJTp where is the initial water temperature, and T is the superheat limit temperature of the hydrocarbon. 

Foulants enter a cooling system with makeup water, airborne contamination, process leaks, and corrosion. Most potential foulants enter with makeup water as particulate matter, such as clay, sdt, and iron oxides. Insoluble aluminum and iron hydroxides enter a system from makeup water pretreatment operations. Some well waters contain high levels of soluble ferrous iron that is later oxidized to ferric iron by dissolved oxygen in the recirculating cooling water. Because it is insoluble, the ferric iron precipitates. The steel corrosion process is also a source of ferrous iron and, consequendy, contributes to fouling. 

Oxygen leaks into glycol storage tanks, etc. 

Use jointing eompound or tape to eure leaks in oxygen equipment, e.g. at eylinder eonneetions. Cut off the supply of oxygen by nipping or kinking flexible hose when ehanging equipment. 

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