steam-heated detergent tank, and pump.
Operating pressures are generally less than
35 kg/cm^2. Stationary units may operate at
the main hot water supply pressure or may
use a pump. These units are used because no
free steam or environment fogging is present,
splashing during the cleaning operation is
minimal, soaking operations are impractical
and hand brushing is difficult and time-con-
suming, and the detergent stream is easily
directed onto the soiled surface.
High-Pressure Hot-Water Units
This equipment utilizes steam at 3.5 to 8.5
kg/cm^2 and unheated water at any pressure
above 1 kg/cm^2. These units convert the
high-velocity energy of steam into pressure
in the delivery line. The cleaning compound
is simultaneously drawn from the tank and
mixed in desired proportions with hot water.
Pressure at the nozzle is a function of the
steam pressure in the line; for example, at
40 kg of steam pressure, the jet pressure is
approximately 14 kg/cm^2. This equipment
is easy to operate and maintain but has the
same inefficiency as the high-pressure, high-
volume water pumps.
Steam Guns
Various brands of steam guns are avail-
able that mix steam with water and/or clean-
ing compounds by aspiration. The most
satisfactory units are those that use sufficient
water and are properly adjusted to prevent a
steam fog around the nozzle. Although this
equipment has applications, it is a high-
energy-consuming method of cleaning. It
also reduces safety through fog formation
and increases moisture condensation, some-
times resulting in mold growth on walls and
ceilings, and increased potential for the
growth ofL. monocytogenes. High-pressure,
low-volume equipment is generally as effec-
tive as steam guns if appropriate cleaning
compounds are incorporated.
High-Pressure Steam
High-pressure steam may be used to
remove certain debris and to blow water off
processing equipment after it has been
cleaned. Generally, this is not an effective
method of cleaning because of fogging and
condensation, and it does not sanitize the
cleaned area. Nozzles for high-pressure steam
and other high-pressure, high-volume equip-
ment should be quickly interchangeable and
have a maximum capacity below that of the
pump. An orifice of approximately 3.5 mm is
considered satisfactory for an operating pres-
sure of approximately 28 kg/cm^2.Hot-Water Wash
This technique should be considered a
method instead of a kind of equipment or a
cleaning system. Because only a hose, nozzle,
and hot water are required, this method of
cleaning is frequently used. Sugars, certain
other carbohydrates, and monovalent com-
pounds are relatively soluble in water and
can be cleaned more effectively with water
than can fats and proteins. Investment and
maintenance costs are low, but the hot-water
wash is not considered a satisfactory clean-
ing method. Although hot water can loosen
and melt fat deposits, proteins are denatured;
removal from the surface to be cleaned is
complicated because these coagulated de-
posits are more tightly bound to the surface.
Without high pressure, penetration of areas
of poor accessibility is difficult, and labor is
increased if a cleaning compound is not
applied. As with the other equipment that
uses hot water, this method increases both
energy costs and condensation.Portable High-Pressure, Low-Volume
Cleaning Equipment
A portable high-pressure, low-volume unit
contains an air- or motor-driven high-pressure
pump, a storage container for the cleaningSanitation Equipment 195