Safety Device for Wet Test Meters with Mercury Manometers The haeards of mercury contaminations have been well discussed in the literature.' When apparatus containing mercury is used, often the slightest accident results in spillage and only a partial cleanup of the mercury. After a well-engineered cleanup procedure, both liquid and vapor still remain exposed. The safety enclosure for mercury filled McLeod gauges that has been s will be a welcome addition to vacuum lines in this presented in n t ~ JOURNAL' laboratory. The mercury manometers attached to wet test meters used to measure total gas flow and to calibrate rotsmeters are also potential sources of mercury spillage and contamination. Under certain flow conditions sudden increases of pressure occur in the wet test meter and the mercury may be forced out of the manometer. This source of spillage may be eliminated by attaching a special baffle to the open end of the manometer. A very effective mercury baffle may be constructed with a 250-ml polyethylene bottle snd 8 mm 0.d. Tygon tubing. The baffle is illustrated in the figure. A 6 c m length of Tygon tubing is heat sealed at one end, and small holes are cut a t three places in the wall of the tubing. The purpose of the small holes is to allow the mercury to escape Into the polyethylene bottle in the event of a pressure surge and to allow the return to the manometer once the pressure has been reduced. The Tveon tubine is then inserted in an onenine cut in the can of +,henolvethvlene ho& and t,hi lowest onenine in the
