Frick AcuAir, Manual, Page: 41 / 58

210.100-IOM (JUL 2018)
Page 41
ACUAIR
®
HYGIENIC AIR UNITS
MAINTENANCE
2. Infrared Temperature Scanner –
Focus the scanner on the tip of the temperature sensor.
Use the temperature reading on the infrared scanner to
calibrate the AcuAir controller input channel.
Submerge Tip in Ice Bath or
Focus Infrared Scanner Here
Figure 48 – Temperature Sensor
UNIT CLEANING AND SANITATION
The AcuAir hygienic unit requires frequent and thorough
cleaning. Your chemical supplier should be consulted when
picking the proper cleaning chemicals.
CAUTION
DISCONNECT ALL ELECTRICAL POWER BEFORE CLEAN-
ING THE UNIT.
Before cleaning, any capped drain pipes should be uncapped,
and motors should be draped with plastic. During cleaning,
the following components should
NOT be directly sprayed
with water: Motors, Damper Motors, Bearings, Pitot Tubes,
Filters, and Electronic Sensors.
NOTICE
High pressure water has the potential to dislodge caulk
and sealing putty. It is important to thoroughly inspect
all seam caulking and electrical conduit sealing putty
following a sanitary wash down.
WHITE RUST AND WET STORAGE STAIN OF
GALVANIZED STEEL
Many AcuAir rooftop units are purchased with simple mill
galvanized exterior finish. Galvanizing is the result of applying
a coating of zinc to sheet metal. The zinc coating is intended
to provide long lasting protection of the underlying steel.
Raw zinc, by nature, is reactive and tends to corrode quite
readily when exposed to moisture. To develop the long lasting
protective quality for which it is applied, the zinc must undergo
a sequence of chemical reactions. First the zinc must react
with oxygen to create zinc oxide. Second, the zinc oxide reacts
in the presence of moisture to create zinc hydroxide. Finally,
the zinc hydroxide reacts with CO
2
within dry air to create a
thin layer of impermeable zinc carbonate. The carbonate layer
is what forms the long lasting passive coating that drastically
slows down any further reaction of the zinc and provides
corrosion protection of the underlying steel. When properly
formed, the zinc carbonate layer is identified by a dull-gray
appearance.
If the zinc coating of new galvanized material is prevented
from thoroughly drying and receiving exposure to CO
2
the
passive carbonate layer is not formed. If the Zinc hydroxide
to carbonate reaction does not take place, excessive zinc
hydroxide accumulates as a layer of soft, white, fluffy product
of corrosion. Instead of being dense and protective, this
powdery substance is porous and non-protective of the
substrate material. When the zinc oxide-hydroxide reaction
is allowed to progress, it can rapidly degenerate the substrate
layer of zinc. This buildup of zinc hydroxide is known as white
rust. It is created by small localized corrosion cells and will
appear as stain patterns in contrast to the uniform dull-gray
zinc carbonate layer mentioned previously.
Addressing A Light Coating Of White Rust
Also Known As Wet Storage Stain
Occasionally AcuAir units may arrive on site with patches of
visible zinc hydroxide deposits. In other cases white patches of
the deposit may become visible shortly after arrival. In either
case, because the AcuAir products are built and are shipped
very shortly thereafter, these hydroxide zones are quite young
and any deterioration of the underlying zinc is insignificant.
In most cases the zinc hydroxide is so light it will erode over
time and the desirable zinc carbonate layer will form naturally
with the rain and drying cycles. However, in a few instances
and for cosmetic reasons it may be necessary to intervene
and expedite the passivation process.
Light coatings of zinc hydroxide can be removed using
readily available cleaning products. A study presented by
the American Galvanizers Association (AGA) suggests the
following five cleaning products to successfully handle the task.
Available at any local grocery store:
• Lime Juice
• White Vinegar
Commercial Cleaners tested:
• Picklex 10G (best solution according to the test – only
available direct from the manufacturer)
• CLR
• Navel Jelly Rust Dissolver (not recommended for heavy wet
storage stain)
Cleaning White Rust
1. Use a nylon bristle brush to apply one of the cleaners to
the affected area.
2. Thoroughly scrub the surface using the nylon bristle brush,
applying water as necessary.
3. Finally, rinse with plain water to completely remove all
traces of the powdery hydroxide as well as the cleaner.
4. Allow the cleaned surface to dry completely.
The drying process facilitates the formation of the passive zinc
carbonate boundary layer that will mature over time with the
naturally occurring rain and dry cycles.