The Energy Audit 181SPECIALIZED AUDIT TOOLS
Smoke Sources
Smoke is useful in determining airfl ow characteristics in buildings,
air distribution systems, exhaust hoods and systems, cooling towers,
and air intakes. There are several ways to produce smoke. Ideally, the
smoke should be neutrally buoyant with the air mass around it so that
no motion will be detected unless a force is applied. Cigarette and
incense stick smoke, although inexpensive, do not meet this require-
ment.
Smoke generators using titanium tetrachloride (TiCl 4 ) provide an
inexpensive and convenient way to produce and apply smoke. The
smoke is a combination of hydrochloric acid (HCl) fumes and titanium
oxides produced by the reaction of TiCl 4 and atmospheric water vapor.
This smoke is both corrosive and toxic, so the use of a respirator mask
utilizing activated carbon is strongly recommended. Commercial units
typically use either glass or plastic cases. Glass has excellent longevity
but is subject to breakage, since smoke generators are often used in
diffi cult-to-reach areas. Most types of plastic containers will quickly
degrade from the action of hydrochloric acid.
Small Tefl on* squeeze bottles (i.e., 30 ml) with attached caps de-
signed for laboratory reagent use resist degradation and are easy to use.
The bottle should be stuffed with 2-3 real cotton balls, then fi lled with
about 0.15 fl uid ounces of liquid TiCl 4. Synthetic cotton balls typically
disintegrate if used with titanium tetrachloride. This bottle should yield
over a year of service with regular use. The neck will clog with debris
but can be cleaned with a paper clip.
Some smoke generators are designed for short time use. These
bottles are inexpensive and useful for a day of smoke generation but will
quickly degrade. Smoke bombs are incendiary devices designed to emit a
large volume of smoke over a short period of time. The smoke is available
in various colors to provide good visibility. These are useful in determin-
ing airfl ow capabilities of exhaust air systems and large-scale ventilation
systems. A crude smoke bomb can be constructed by placing a stick of
elemental phosphorus in a metal pan and igniting it. A large volume of
white smoke will be released. This is an inexpensive way of testing labo-
ratory exhaust hoods, since many labs have phosphorus in stock.
More accurate results can be obtained by measuring the chemical
composition of the airstream after injecting a known quantity of tracer