Pfannenberg PWT 6402 230V Manuel D'utilisation page 47

GB
3.4.7 Water quality requirements
 Adhere to VGB cooling water guidelines to ensure safe operation of air/water heat exchangers (VGB-R 455).
The cooling water must meet the following requirements:
• It must not cause any scale deposits or loose precipitates.
• It must have a low degree of hardness, especially a low carbonate hardness (especially with recooling).
• In the case of recooling, the salt content must not increase excessively due to evaporation of large quantities of
water.
 When the concentration of dissolved substances increases, the electrical conductivity increases and the water
becomes more corrosive.
• The degree of softness of the water must be in a range which does not attack any materials.
• Regularly add fresh water to the cooling water and drain off parts of the enriched water.
• Water containing gypsum is not suitable for cooling purposes. It causes scale to form, which is difficult to
remove.
• Cooling water must be free of iron and manganese, since deposits lead to pipe blockages.
• It must only contain very small amounts of organic substances (e.g. sludge separations or microbiological
contamination).
The most common impurities and most common procedures for clearing are:
Type of impurity
Mechanical impurities
Comparatively high hardness
Moderate content of mechanical impurities and hardness minerals
Moderate content of chemical impurities
Biological impurities (e.g. slime bacteria and algae)
The properties of the additive or system water used must correspond to the hydrological data listed below:
Hydrological data
pH value
Carbonic acid
Free carbonic acid
Associated carbonic acid
Aggressive carbonic acid
Sulphides
Oxygen
Chloride ions
Sulphate ions
Nitrates and nitrites
COD
Ammonia
Iron
Manganese
Conductivity
Evaporation residue
Potassium permanganate consumption
Suspended solids
Operating Manual PWT 6402 230V / 400V 086100107b © Pfannenberg GmbH
°dH
mg/dm³
mg/dm³
mg/dm³
mg/dm³
mg/dm³
mg/dm³
mg/dm³
mg/dm³
mg/dm³
mg/dm³
mg/dm³
S/cm
mg/dm³
mg/dm³
mg/dm³
Clearing procedure
Filter water using:
• screen filters, gravel filters, cartridge
filters or precoat filters
Soften water by ion exchange
Inoculate water with stabilizers or dispersing
agents
Inoculate water with passivators and or
inhibitors
Inoculate water with biocides
7 - 8.5
>3 <8
8 - 15
8 - 15
0
free
< 10
< 50
< 250
< 10
< 7
< 5
< 0.2
< 0.2
< 2200
< 500
< 25
< 3
> 3 < 15 Partial flow cleaning recommended
> 15 continuous cleaning recommended
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