Operating Control

Table 7 gives a typical schedule of parameters that must be monitored on a daily basis to produce a quality phosphate coating.

Table 7 Monitoring requirements for quality control of phosphate coating production


Phosphating solution titrations

Total acid Free acid

Visual coating appearance Chemical-supply pumps

All stages

Temperature Pressure Solution level

Neutralizing rinse

Add 30 mL (0.08 gal) activator, as indicated by visual check of coating continuity Check pH

Check film thickness of soap lubricant

Twice per shift

Alkaline cleaner stage titrations Alkalinity of water rinses before phosphating Acidity of water rinse after phosphating Activating rinse concentration

Once per shift

Conductivity of recirculated deionized rinse, 100 ^mho maximum

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