Fig. 26 - Water quality standard values for cooling water, chilled water, mid-range temperature water and make-up water
++
NOTES
* The nomenclature of items, definition of terms and units shall comply with the JIS K 0101. The units and values in ( ) are conventional ones put here for reference.
** The mark X indicates factors affecting the corrosive or scale-forming tendency.
*** When temperature is high (above 40°C), corrosiveness generally increases. Especially, when iron/steel surface has no protective film and is in direct contact with water, it is desirable to take adequate countermeasures against corrosion, such as addition of corrosion inhibitor and
deaeration treatment
**** For the cooling water system using a closed-type cooling tower, the water quality standard for the mid-range temperature water sysem shall be applied to the closed-circuit recirculating/spray water and its make-up water, while the water quality standard for the recirculating
cooling water system shall be applied to the spray water and its make-up water, respectively.
++ City water, industrial water and ground water shall be used as source water, and demineralized water, reclaimed water, softened water, etc. shall be excluded.
+++ The 15 items listed above show typical factors of corrosion and scale problems.
Cooling water systems**** Chilled water systems Mid-range temperature (20-90°C) water systems*** Tendency**
Lower mid-range temperature
water system
Higher mid-range teperature
water system***
Recirculating
water
Make-up
water
Once
through
water
Recirculating
water (T 20°C)
Make-up water Recirculating
water
(20<T<=60°C)
Make-up
water
Recirculating
water
(60<T<=90°C)
Make-up
water
Corrosive Scale-forming
Standard items (see footnotes)
pH (25°C) 6.5 - 8.2 6.0 - 8.0 6.8 - 8.0 6.8 - 8.0 6.8 - 8.0 7.0 - 8.0 7.0 - 8.0 7.0 - 8.0 7.0 - 8.0 X X
Electrical conductivity (25°C) mS/m <= 80 <= 30 <= 40 <= 40 <= 30 <= 30 <= 30 <= 30 <= 30 X X
µS/cm <= 800 <= 300 <= 400 <= 400 <= 300 <= 300 <= 300 <= 300 <= 300
Chroride ion mg Cl
-
/l <= 200 <= 50 <= 50 <= 50 <= 50 <= 50 <= 50 <= 30 <= 30 X
Sulfate ion mg SO
4
-2
/l <= 200 <= 50 <= 50 <= 50 <= 50 <= 50 <= 50 <= 30 <= 30 X
Acid consumption (pH 4.8) mg CaCO
3
/l <= 100 <= 50 <= 50 <= 50 <= 50 <= 50 <= 50 <= 50 <= 50 X
Total hardness mg CaCO
3
/l <= 200 <= 70 <= 70 <= 70 <= 70 <= 70 <= 70 <= 70 <= 70 X
Calcium hardness mg CaCO
3
/l <= 150 <= 50 <= 50 <= 50 <= 50 <= 50 <= 50 <= 50 <= 50 X
Ionic silica mg SiO
2
/l <= 50 <= 30 <= 30 <= 30 <= 30 <= 30 <= 30 <= 30 <= 30 X
Reference items (see footnotes) X
Iron mg Fe/l <= 1.0 <= 0.3 <= 1.0 <= 1.0 <= 0.3 <= 1.0 <= 0.3 <= 1.0 <= 0.3 X
Copper mg Cu/l <= 0.3 <= 0.1 <= 1.0 <= 1.0 <= 0.1 <= 1.0 <= 0.1 <= 1.0 <= 0.1 X
Sulfide ion mg S
2-
/l Not detected Not detected Not detected X
Ammonium ion mg NH
4
+
/l <= 1.0 <= 1.0 <= 1.0 <= 1.0 <= 0.1 <= 0.3 <= 0.1 <= 0.1 <= 0.1 X
Residual chlorine mg Cl/l <= 0.3 <= 0.3 <= 0.3 <= 0.3 <= 0.3 <= 0.25 <= 0.3 <= 0.1 <= 0.3 X
Free carbone dioxide mg CO
2
/l <= 4.0 <= 4.0 <= 4.0 <= 4.0 <= 4.0 <= 0.4 <= 4.0 <= 0.4 <= 4.0 X
Ryzner stability index - 6.0 - 7.0 - - - - - - - - X X
To Next Page
Loading...
