TASK 70-00-05-800-006
1 . General.
This chapter defines all types of water used in the shop or in quality testing. The types are grouped under three headings. The water type designations are intended to give satisfactory results when applying standard methods and will give information to obtain the correct equipment to supply the different water types.
2 . Water Types.
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A.Water (drinking water, potable water, tap water).
(1)The term water is used to refer to currently available drinking water. This water is approved for general use in cleaning, stripping, and rinsing solutions. This water must meet the Secondary Standards for drinking water published by the U.S. EPA or similar standards such as those issued by the World Health Organization and the European Union. In all cases, this water must meet the following requirements:
 
Characteristic
Requirement
 
pH
6.0-10.0
 
Total Dissolved Solids (TDS) (Maximum)
500 ppm
 
Chlorides (Maximum)
250 ppm
 
Fluoride (Maximum)
2 ppm
 
Resistivity (Minimum) or
1800 ohm-cm
 
Conductivity (Maximum)
550 Microsiemens/cm
NOTE:
The use of deionized water with a minimum resistivity of 10000 ohm-cm (a maximum conductivity of 100 Microsiemens/cm) is recommended for general use. The use of deionized water can extend solution life, reduce spotting and staining of parts, and help waste treatment.
B.Deionized water. This water is characterized by its resistivity and is divided in the Standard Practices Manual into three types:
NOTE:
Deionized water can be prepared by distillation, ion exchange, continuous electro-deionization reverse osmosis, electrodialysis, or a combination thereof.
(1)Deionized water with a minimum resistivity of 50000 ohm-cm (a maximum conductivity of 20 Microsiemens/cm) to be used for preparing and topping baths prone to contamination by mineral and organic impurities. These baths include:
(a)Electrolytic and chemical treatment baths, and copper, nickel, silver, cadmium, zinc, and other plating baths, except for chromium plating.
(b)Sulfuric and chromic anodizing treatments with sealing baths.
(2)Deionized water to be used for rinsing titanium and titanium alloys must meet the following requirements:
(a)If parts will be exposed to subsequent processing that operates above 500°F (260°C) (for example, welding or heat treating) the final rinse water used on the parts must not be more than 50 ppm chloride. (10000 ohm-cm minimum resistivity, 100 Microsiemens/cm maximum conductivity).
NOTE:
For parts that will not be exposed to subsequent processing that operates above 500°F (260°C), the final rinse water used on the parts can be potable water that must not be more than 250 ppm chloride. (1800 ohm-cm minimum resistivity, 550 Microsiemens/cm maximum conductivity).
(3)Deionized water with a minimum resistivity of 10000 ohm-cm (100 Microsiemens/cm maximum conductivity) to be used for preparing and topping the following.
(a)Chromium baths.
(b)Chemical conversion baths (chromium, phosphorus, etc.).
C.Distilled Water.
(1)The quality specifications for distilled water suitable for laboratory and reagent use are as follows:
 
Characteristic
Requirement
 
Ph
5.0-8.0
 
Resistivity (Minimum) or
200,000 Ohms/cm minimum
 
Conductivity (Maximum)
5 Microsiemens/cm
NOTE:
These requirements are consistent with the requirements for ASTM D1193-06 Type IV Reagent Water. Type IV grade of reagent water can be prepared by distillation, ion exchange, continuous electro-deionization reverse osmosis, electrodialysis, or a combination thereof.
3 . Definitions and Test Protocol.
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D.Chloride analysis must be according to ASTM D1125 Electrical Conductivity and Resistivity of Water, ASTM D512 Standard Test Methods for Chloride Ion in Water, or other procedures that meet currently acceptable analytical methods.
E.Chloride content can be controlled and monitored by any currently acceptable analytical method given that substantiating data is maintained and that the method and instrumentation used are calibrated to a certified standard.