Data Aire gForce DX series - Brazed-Plate Condensers

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6.2.1.2 Scale treatment
In daily use, scale accumulates at the water side of heat exchangers therefore regular scale treatment
is a must.
Variations in water quality from place to place and variations in applications of plate heat exchangers
make it di󰀩cult to dene in simple terms the water quality requirements for minimum maintenance. It is
important to ensure the right water quality and reduce scale by establishing the requirements for local
conditions or utilizing specialist water treatment companies.
The following should be paid attention to in daily maintenance.
6.2.1.2.1 Undissolved solids (turbid water)
If undissolved solids and other bres are in the water, the channels of the condenser are easily blocked.
Fibrous debris cannot pass the heat exchanger and must be disposed of. To reduce undissolved solids
blocking the condenser, granules should kept smaller than 0.8mm and is recommended to t a 40-70
mesh strainer. Regular maintenance of this unit is required to ensure continued performance.
6.2.1.2.2 Dissolved products
Under certain circumstance crystallized deposits of calcium and magnesium ion in the water will attach
to the condenser surface and scale. The higher the concentration of Ca2+ and Mg+ and the water
temperature, the greater the possibility of scale formation. Thick scale will not only gravely a󰀨ect heat
transfer capability but even block the channels. As a result, never use this kind of water directly and
always carry out water treatment beforehand.
6.2.1.2.3 Cleaning
Although cleaning of in situ condensers is a di󰀩cult process, it may be necessary in extreme
circumstances. Fouling of a condenser can be corrected by chemical cleaning, reverse ushing or a
combination of both. Both of these procedures will require temporarily disconnecting the condenser on
the water side and preforming these procedures. Reverse ushing in situ is the simplest option and
may be the only treatment necessary if fouling is predominantly caused by sedimentation. If however,
scaling has occurred, chemical cleaning will be necessary. This should be performed using a weak acid
cleaning liquid pumped through the heat exchanger in reverse ow direction at approximately twice the
normal ow rate. Remember that the cleaning acid should be circulated in reverse ow for usually 24
hours. At the completion of the cleaning process, it is important that the condenser be ushed with
clean water for at least 30 minutes.
6.2.1.3 Corrosion protection
Stainless steel has a high resistance to most chemicals but is sensitive to chloride ion concentration so
this must be limited to 280ppm or less in systems operating at less than 131°F (55°C). The copper used
in the brazing process is mainly sensitive to strong acid and ammonia so the pH must be maintained
between 6 and 8. Hydrochloric acid should never be used to clean the exchangers.