Mitsubishi Electric CITY MULTI PKFY-WL NKMU-E Series Installation Manual page 10

4. Connecting water pipes
4.1.3. Water treatment and quality control
To preserve water quality, use the closed type of water circuit. When the circulating
water quality is poor, the water heat exchanger can form scales, leading to a
reduction in heat-exchange power and possible corrosion. Pay careful attention
to water processing and water quality control when installing the water circulation
system.
• Removing of foreign objects or impurities within the pipes.
During installation, make sure that foreign objects, such as welding fragments,
sealant particles, or rust, do not enter the pipes.
• Water Quality Processing
1 Depending on the quality of the cold-temperature water used in the
airconditioner, the copper piping of the heat exchanger may corrode.
Regular water quality processing is recommended.
If a water supply tank is installed, keep air contact to a minimum, and keep
the level of dissolved oxygen in the water no higher than 1mg/ℓ.
2 Water quality standard
Items
pH (25°C) [77°F]
Electric conductivity
(mS/m) (25°C) [77°F]
(μS/cm) (25°C) [77°F]
Chloride ion
Sulfate ion
Acid consumption (pH4.8)
Total hardness
Calcium hardness
Ionic silica
Iron
Copper
Sulfide ion
Ammonium ion
Residual chlorine
Free carbon dioxide
Ryznar stability index
Reference : Guideline of Water Quality for Refrigeration and Air Conditioning
Equipment. (JRA GL02E-1994)
3 Consult with a specialist about water quality control methods and calculations
before using anti-corrosive solutions.
4 When replacing a previously installed air conditioning device (even when only
the heat exchanger is being replaced), first conduct a water quality analysis
and check for possible corrosion.
Corrosion can occur in cold-water systems even if there has been no prior
signs of corrosion.
If the water quality level has dropped, adjust water quality before replacing the unit.
en
8
Low to mid-range
temperature water system
Recirculating
water Make-up
[20<T<60°C] water
[68<T<140°F]
7.0 ~ 8.0 7.0 ~ 8.0
30 or less 30 or less
[300 or [300 or
less] less]
(mg Cl-/ℓ) 50 or less 50 or less
(mg SO4 2 -/ℓ) 50 or less 50 or less
50 or less 50 or less
(mg CaCO /ℓ)
3
(mg CaCO /ℓ) 70 or less 70 or less
3
(mg CaCO /ℓ) 50 or less 50 or less
3
(mg SiO /ℓ) 30 or less 30 or less
2
(mg Fe/ℓ) 1.0 or less 0.3 or less
(mg Cu/ℓ) 1.0 or less 0.1 or less
(mg S -/ℓ) not to be not to be
2
detected detected
(mg NH4+/ℓ) 0.3 or less 0.1 or less
(mg Cl/ℓ) 0.25 or less 0.3 or less
(mg CO /ℓ) 0.4 or less 4.0 or less
2
6.0 ~ 7.0 –
Tendency
Scale-
Corrosive
forming