Simple Vacuum Monitor
nrovides a-~articularlyinexpensive device, although the glass types are more pasit,ive in their movements. The needle is removed fram the syringe, and a rubber stopper, bored half-way through, is fitted tightly to the syringe in place of the needle. The rubber stopper serves as 8 seal for the open end of the syringe and also supports the syringe in a vertical posiis This ioint, as well as the svrinee nluneer should be~liehtlv- coated t,ion ~ ~ if -that ~ ~-~ ~ desired. - " " with vacuum grease to provide a good seal around the stopper and to lubricate the plunger. Alternatively, the needle can be left on the syringe and can then he driven into a solid rubber stopper which again serves as both a seal and a support for the device. Before affixing the rubber stopper to the syringe a small amount of air should be drawn into the svrinae (if a 5-ml syrinae .. is used about 0.5 ml of air will suffice). The assem,.. ,. . 4 Idrd dtvire is then plawd in thr rnruum dczicwtor, 1,rll-jar, or otlrrr
