Brass fittings containing lead

Samples may be retained in syringes if analysed within 24 hours, apparently without loss of He. For storage over longer periods, glass or metal containers should be used. Metal cylinders, fitted with septa for injection and sealed by brass nuts with lead washers, can retain He for several weeks. Prior to use, the cylinders are evacuated and then filled with sample to about two atmospheres pressure. Possible errors due to preferential gain of He when evacuated, or loss when filled, can be detected by duplicate sampling. 

The original saltwater condenser tube made of admiralty brass was found to be susceptible to erosion-corrosion at tube ends. Aluminum brass containing 2% aluminum was more resistant to erosion in saltwater. Inhibition with arsenic is necessary to prevent dezincification as in the case of admiralty brass. The stronger naval brass is selected as the tube material when admiralty brass mbes are used in condensers. Cast brass or bronze alloys for valves and fittings are usually Cu-Sn-Zn compositions, plus lead for machinability. Aluminum bronzes are often used as tube sheet and channel material for exchangers with admiralty brass or titanium tubes exposed to cooling water. 

The process is generally carried out in two wooden vats, covered with closely fitting lids, furnished with the ne(5essary draw-off cocks, the first vat containing a lead coil and the other a brass steam coil. 

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