Maintenance Of Water Quality; Water To Be Used; Criteria Of Water Criteria Of Water - Hitachi RCUE40AG2 Service Manual

Maintenance

6.3. Maintenance of Water Quality

6.3. Maintenance of Water Quality

6.3. Maintenance of Water Quality
This air-conditioning device uses water as a heat source (for cooling) or as a media (chilled water, heat water) for use of
heat. Therefore, it is necessary to select suitable water and control it to maintain the quality and performance and avoid
possible problems.
Serious failure of plate heat exchanger may stop the units function and cause high expenses for its repair. Therefore, it is
indispensable to promote the maintenance and selection of water for the chiller installation.
Read the below criteria of water quality very carefully to avoid any troubles.
In case of using some chemical products for water treatment, it is recommended to consult with manufacturers
specialised in water treatment, since characteristics of chemical agents may differ with product specifi actions.

6.3.1. Water to be used

Water to be supplied to the chiller should be running water (clean water), industrial water or groundwater.
Other special water like pure water cannot be used in the standard product.
6.3.2. Criteria of Water
The later table shows the guideline of water quality regulated by JRAIA. Each criteria is set for water for
cooling and for heating. The compliance of this criteria is premised on the product guarantee.
Explanation of Main Items in Water Quality Maintenance>

pH (hydrogen-ion concentration)
−
pH is used as a measure to judge acidity, neutral and alkalinity of water. It is a big factor in taste, corrosion,
purifi cation effect in water treatment, disinfection effect in chloride treatment, water stain formation, and other
fi elds like analytic chemistry, biochemistry etc. The below fi gure shows an example of relation between pH
value and corrosion.
Electrical conductivity
−
To know the outline of water quality, it is effective to measure electrical conductivity. This value is determined
by quality and quantity of dissolved chlorine, and generally water with a greater value of electrical
conductivity is not suitable since it has a lot of substance causing corrosion and lime.
Chloride ion
−
Chloride ion has a important property regarding corrosion and corrosion is higher in water with big amount
of chloride ion although pH value is free of corrosion. Chloride ion does not have oxidise property, however
precious metal is penetrated if chloride ion combines with oxidant or dissolved oxygen.
Sulfate ion
−
Sulfate ion is a cause of corrosion, but it gives an indication for line formation. If running water has a great
amount of sulfate ion, it will become rusty water.
pag. 153
SMGB0003 rev.0 - 11/2006
Relation between pH and corrosion of soft steel
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