be maintained as closely as possible, but a variation of
5 percent is permissible. The inhibited acid solution is
made up of the following:
2. Commercial hydrochloric (muriatic) acid with
specific gravity of 1.19. Eleven quarts of acid should be
used for each 10 gallons of water.
3. Three and two-fifths ounces of inhibitor powder
for each 10 gallons of water used.
4. Place the required amount of water in a
nongalvanized metal tank or wooden barrel, and add the
necessary amount of inhibitor powder while stirring the
water. Continue stirring the water until the powder is
completely dissolved; then add the required quantity of
NEVER add water to acid; this mistake
may cause an explosion.
In charging the system with an acid solution when
GRAVITY FLOW is used, introduce the inhibited acid
as shown in figure 7-18. Do not add the solution faster
than the vent can exhaust the gases generated during
cleaning. When the condenser has been filled, allow
the solution to remain overnight.
When FORCED CIRCULATION is used, the
valve in the vent pipe should be fully opened while the
solution is introduced into the condenser but must be
closed when the condenser is completely charged and
the solution is circulated by the pump. When a
centrifugal pump is used, the valve in the supply line
may be fully closed while the pump is running.
The solution should be allowed to stand or be
circulated in the system overnight for cleaning out
average scale deposits. The cleaning time also
depends on the size of the condenser to be cleaned. For
extremely heavy deposits, forced circulation is
recommended, and the time should be increased to 24
hours. The solution acts more rapidly if it is warm, but
the cleaning action is just as thorough with a cold
solution if adequate time is allowed.
After the solution has been allowed to stand or has
been circulated for the required time through the
condenser, it should be drained and the condenser
thoroughly flushed with water. To clean condensers
with removable heads by using inhibited acid, use the
above procedure without removing the heads.
A well-planned maintenance program avoids
unnecessary downtime, prolongs the life of the unit,
and reduces the possibility of costly equipment failure.
It is recommended that a maintenance log be
maintained for recording the maintenance activities.
This action provides a valuable guide and aids in
obtaining extended length of service from the unit.
This section describes specific maintenance
procedures, which must be performed as a part of the
maintenance program of the unit. Use and follow the
manufacturers manual for the unit you are to do
maintenance on. When specific directions or
requirements are furnished, follow them. Before
performing any of these operations, however, ensure
that power to the unit is disconnected unless otherwise
However, extra precaution must be exercised in
flushing out the condenser with clear water after the
acid has been circulated through the condenser to
ensure acid removal from all water passages.
W h e n m a i n t e n a n c e c h e c k s a n d
procedures must be completed with the
electrical power on, care must be taken to
a v o i d c o n t a c t w i t h e n e r g i z e d
components or moving parts. Failure to
exercise caution when working with
electrically powered equipment may
result in serious injury or death.
Refrigerant coils must be cleaned at least once a
year or more frequently if the unit is located in a dirty
environment. This action helps maintain unit
operating efficiency and reliability. The relationship
between regular coil maintenance and efficient/
reliable unit operation is as follows:
Clean condenser coils minimize compressor
head pressure and amperage draw and promote
Clean evaporator coils minimize water
carry-over and helps eliminate frosting and/or
compressor flood-back problems.