(10 kg/cm^2 boost to 20 kg/cm^2 ) and high-
pressure (40 kg/cm^2 boost to 55 kg/cm^2 ).
Medium-pressure systems are normally
used in processing plants where heavy
soils dominate. High-pressure equipment is
found mostly in beverage and snack food
plants where soils are light and cutting
action is needed to clean processing equip-
ment. However, several factors must be con-
sidered to determine which equipment will
provide the best long-term results for each
specific plant.
There is normally an inverse relationship
between the rinse nozzle flow rates and pres-
sure. Each cleaning task requires a specific
impingement force to dislodge the soil and
flush it off the equipment. At high pressures
of 40 to 55 kg/cm^2 , the nozzle flow rates can
average approximately 5 L/min; however,
lower pressure requires high flow rates at the
nozzles to achieve the same impingement.
For example, if a plant has a medium-pres-
sure 20 kg/cm^2 system with 30 to 40 L/min
rinse nozzles and management wants to con-
serve water usage, the method to accomplish
this is to increase the pressure to 40 or 50
kg/cm^2 and reduce the nozzle flow rates to 10
or 15 L/min. The result is the same impinge-
ment force with a 50% reduction in rinse-
water usage.
Water conservation, in addition to being
responsible management, carries additional
benefits that are not always obvious.
Reduced nozzle flow means less sewage and
less energy used to heat the water. Paybacks
of less than 6 months are not unusual and
often run as low as 3 months.
During the past, a trend has existed to use
lower pressure in plants with a heavy soil
because high pressure tends to dislodge par-
ticles with such force as to move them to
another undesired location (splatter). Heav-
ier soils require heavier impingement. Most
processors with less heavy soil use medium
pressure.
For long-term water conservation pur-
poses, 40 to 50 kg/cm^2 with an average rinse
hose nozzle flow rate of 10 to 20 L/min is
suggested. The usual exception is if the
plant has an unusually short time period
with which to prepare for production. If
only 4 or 5 hours are available for cleanup,
higher flow rates will be required. This con-
dition is usually temporary but must be
planned for, i.e., the central system must
have the flow capacity.
The price of central equipment is usually
the main determinant in the purchasing deci-
sion. High-pressure equipment requires the
largest investment to buy and maintain. The
pumps are more expensive than medium-
pressure pumps, and all of the piping, valves,
and other components cost more because of
the high-pressure ratings required. Usually,
the benefits of low water usage outweigh the
initial cost and operating expenses over the
long term.
Medium-pressure equipment requires less
investment to purchase and operate. The
pumps are mechanically less sophisticated,
and none of the piping, valves, or related
components requires a high-pressure rating;
therefore, maintenance is usually lower than
on high-pressure systems.
If water usage is not a critical factor in
overall plant operations, a medium-pressure
system should be considered. Water conser-
vation cannot be accomplished with medium
pressure. Many processors utilize 20 kg/cm^2
with 20 to 30 L/min nozzles in most areas of
the plant. Proper utilization of the equip-
ment and training in sanitation procedures
are the key elements.Portable Foam Cleaning
Because of the ease and speed of foam
application, this cleaning technique has been
popular during the past two decades. With
this method, foam is the medium for appli-
cation of the cleaning compound. The clean-