Whenever possible use an enclosed nonsparking

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Unformatted text preview: are less than those autoignition temperatures. ■ Make certain that the temperature control device and the stirring/ventilating motor (if present) do not spark. ● Whenever possible, use an enclosed, nonsparking electric heater or hot plate or use steam in place of a gas burner. Use only nonsparking motors (e.g., air motors) in the chemical laboratory when flammables are present. ● Support and orient large separatory funnels so that the stopcock will not be loosened by gravity. Use retainer rings on stopcock plugs. ● Use securely positioned clamps to support condensers; secure attached water hoses with wire or clamps. ● Secure stirrer motors and vessels firmly to maintain proper alignment. Magnetic stirring is preferable, except for viscous materials. ● Position apparatus that is attached to a ring stand so that the center of gravity of the system is over the base and not to one side. Arrange the apparatus so that burners and baths can be removed quickly. Standards bearing heavy loads should be firmly 26 students short index ● ● ● ● ● ● 1/15/03 12:45 PM Page 27 attached to the bench top. Anchor equipment racks securely at both the top and the bottom. Never place any apparatus, equipment, boxes (empty or filled), containers of chemicals, or any other objects on the floor. Never heat a closed container. Make sure the heating apparatus has a vent. Before you heat more than a few milliliters of a liquid in an unstirred vessel, add some boiling stones or a short glass tube with one end closed (as described in “Distillations,” page 7). If, as in some distillations, there is the possibility of a dangerous exothermic reaction or decomposition, use a thermometer with its bulb in the liquid. This will provide a warning and may allow time to remove the heat and apply external cooling. Use an appropriate gas trap whenever evolution of hazardous gases or fumes is possible. Laboratory hoods are recommended for all operations in which toxic or flammable vapors are ev...
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This document was uploaded on 02/27/2014 for the course PHYS 1B at UCSD.

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