Liebert XDK user manual Water Purity Requirements, Prevalent impurities and removal methods

Water Purity Requirements

8.0WATER PURITY REQUIREMENTS

To ensure the maximum service life of the air/water heat exchangers, water must comply with the VGB water regulations (VGB-R 455 P). The water used must be soft enough to prevent deposits, but it must not be so soft that heat exchanger corrosion occurs.

The following table contains the most important impurities and methods for removing them.

Table 4	Prevalent impurities and removal methods
Water Impurity		Method of Removal
Mechanical pre-treatment (dp < 1 mm)		Filtering the water
Excessive hardness		Soften the water using ion exchange
Moderate content of mechanical impurities and hardness formers		Addition of dispersing or stabilizing agents
Moderate content of chemical impurities		Addition of passivation agents and inhibitors
Biological impurities (bacteria and algae)		Addition of biocides

It is recommended to achieve the following hydrological data as far as possible:

Table 5	Suggested hydrologic levels
Hydrological Data		Suggested	Units
		Amount
pH values		7 - 8.5
Carbonate hardness		>3 <8	°dH
Free carbon dioxide		8 - 15	mg/dm3
Bound carbon dioxide		8 - 15	mg/dm3
Aggressive carbon dioxide		0	mg/dm3
Sulfides		< 10	mg/dm3
Oxygen		< 50	mg/dm3
Chloride ions		< 250	mg/dm3
Sulfate ions		< 10	mg/dm3
Nitrates and nitrides		< 7	mg/dm3
CSB		< 5	mg/dm3
Ammonia		< 5	mg/dm3
Iron		< 0.2	mg/dm3
Manganese		< 0.2	mg/dm3
Conductivity		< 2200	μS/cm
Solid evaporation residue		< 500	mg/dm3
Potassium permanganate consumption		< 25	mg/dm3
Suspended matter		< 3	mg/dm3
(Partial flow cleaning is recommended)		> 3 < 15	mg/dm3
	(Continuous cleaning)	> 15	mg/dm3

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