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Rules, equations or theories to guide inhibitor development or use are very limited. A synergism, or cooperation, is often present between different inhibitors and the environment being controlled, and mixtures are the usual choice in commercial formulations. The first step in selecting an inhibitor system is to consider was is usually adopted.
|
System |
Inhibitor |
Metals |
Concentration |
|
Acids |
|||
|
HCl |
Ethylaniline |
Fe |
0.5% |
|
.. |
Mercaptobenzotriazole |
.. |
1% |
|
.. |
Pyridine + phenylhydrazine |
.. |
0.5% + 0.5% |
|
.. |
Rosin amine + ethylene oxide |
.. |
0.2% |
|
Sulfuric |
Phenylacridine |
.. |
0.5% |
|
Phosphoric |
Sodium iodide |
.. |
200 ppm |
|
Others |
Thiourea |
.. |
1% |
|
.. |
Sulfonated castor oil |
.. |
0.5-1.0% |
|
.. |
Arsenic Oxide |
.. |
0.5% |
|
.. |
Sodium arsenate |
.. |
0.5% |
|
Water |
|||
|
Potable |
Calcium bicarbonate |
Steel, cast iron |
10 ppm |
|
.. |
Polyphosphate |
Fe, Zn, Cu, Al |
5-10 ppm |
|
.. |
Calcium hydroxide |
Fe, Zn, Cu |
10 ppm |
|
.. |
Sodium silicate |
.. |
10-20 ppm |
|
Cooling |
Calcium bicarbonate |
Steel, cast iron |
10 ppm |
|
.. |
Sodium chromate |
Fe, Zn, Cu |
0.1% |
|
.. |
Sodium nitrite |
Fe |
0.05% |
|
.. |
Sodium phosphate monobasic |
.. |
1% |
|
.. |
Morpholine |
.. |
0.2% |
|
Boilers |
Sodium phosphate monobasic |
Fe, Zn, Cu |
10 ppm |
|
.. |
Polyphosphate |
.. |
10 ppm |
|
.. |
Morpholine |
Fe |
variable |
|
.. |
Hydrazine |
.. |
O2 scavenger |
|
.. |
Ammonia |
.. |
neutralizer |
|
.. |
Octadecylamine |
.. |
variable |
|
Engine coolants |
Sodium chromate |
Fe, Pb, Cu, Zn |
0.1-1% |
|
.. |
Sodium nitrite |
Fe |
0.1-1% |
|
.. |
Borax |
.. |
1% |
|
Glycol/water |
Borax + MBT |
All |
1% + 0.1% |
|
Oil field brines |
Sodium silicate |
Fe |
0.01% |
|
.. |
Quaternaries |
.. |
10-25 ppm |
|
.. |
Imidazoline |
.. |
10-25ppm |
|
Seawater |
Sodium silicate |
Zn |
10 ppm |
|
.. |
Sodium nitrite |
Fe |
0.5% |
|
.. |
Calcium bicarbonate |
All |
pH dependent |
|
.. |
Sodium phosphate monobasic + Sodium nitrite |
Fe |
10 ppm + 0.5% |
