Plumbing In
plumbing a smoke test forces non-toxic,
artificially created smoke through waste and drain pipes under a slight pressure to find leaks. Plumes of smoke form where there are defects. This test can be performed when the plumbing is brand new, but more often it is used to find
sewer gas leaks that may plague a building or an area. Described in a repair manual written in the 1930s, smoke testing is considered obsolete, and is no longer used by reputable technicians. The usual alternative to smoke is to place a bright light inside the instrument then check for light appearing around pads and joints.
Automotive repair In the same way that plumbing and woodwind instruments are tested, the
vacuum systems of automobiles may be tested in order to locate difficult-to-find vacuum leaks. Artificial smoke is deliberately introduced into the system under slight pressure and any leaks are indicated by the escaping smoke. Smoke can also be used to locate difficult-to-find leaks in the fuel evaporative emissions control (
EVAP) system. In
infectious disease control a smoke test is done to see whether a room is under
negative pressure. A tube containing smoke is held near the bottom of the negative pressure room door, about two inches in front of the door. The smoke tube is held parallel to the door, and a small amount of smoke is then generated by gently squeezing the bulb. Care is taken to release the smoke from the tube slowly to ensure the velocity of the smoke from the tube does not overpower the air velocity. If the room is at negative pressure, the smoke will travel under the door and into the room. If the room is not at negative pressure, the smoke will be blown outward or will stay stationary. ==References==