Surface pretreatment
The insulator surface to be coated should be clean and free of dust and grease. For cleaning the following operations are suggested:
a) Proper cleaning by using water and a suitable detergent might be sufficient,
b) Insulators that show and adhering pollution, such like cement, other mineral or chemical pollution layers should be cleaned by either “cob corn-“or carbon dioxide blasting,
c) Any type of grease or fatty pollution is to be removed by using a suitable solvent like White Spirit or turpentine,
d) Residual contaminants should be removed by thoroughly wiping,
e) Finish the cleaning just before spraying POWERSIL® N 553 DARKGREY with Isopropanol or an equivalent alcohol.
Check carefully that there is no residue of dirt or grease left before spraying!
In most cases it is not necessary to apply a primer before coating.
Proper shaking of drum is mandatory before material is used.
Coating Application
POWERSIL® N 553 DARKGREY us preferably applied by spraying. It can be applied by brushing or dipping as well. For spraying application, the airless process was found to be efficient. The following equipment settings were found to be suitable:
- Flat nozzle of 0.33 mm, 20°
- Setting of pressure output 50 – 150 bar
The spray gun should be moved evenly across the surface at a distance of about 30 – 50cm. Due to the thixotropic properties of POWERSIL® N 553 DARKGREY it is usually possible to apply the first layer with a good cover. A second layer can be applied after approximately 10-20 minutes.
A typical dry film thickness is 0.4 mm to 0.5 mm. Thus, the theoretical consumption is 0.7 kg to 0.9 kg of POWERSIL® N 553 DARKGREY per square meter of insulator surface. Take losses for overspray and cleaning of the equipment into consideration.
Rain can damage the coating. In case of rain, please protect the job site or stop application.
Full cure is obtained in 8 – 12 hours after coating application depending on thickness, temperature and humidity.
Curing of the coating released by-products that lead to the formation of siloxanes. These may condensate at the surface, especially at low temperature and low ventilation rate. Therefore it is recommended to process the coating at a temperature above 20°C at well ventilated conditions.
All spraying equipment should be cleaned with a nonpolar solvent (e. g. Xylene or White Spirit) immediately after use.
Maintenance
The product contains migratable matter that is able to encapsulate contaminants and to provide a hydrophobic surface. Coated insulators may appear dirty after some time in service. Nevertheless, washing and cleaning, especially with detergents and other chemicals is not recommended.In case of necessity of any cleaning, we recommend using WACKER® E 10.
Inspection
The water repellent appearance can be evaluated by spraying with water. IEC 62073, “Guidance on the measurement of wettability of insulator surfaces” provides further information. A partly lowering of the effect does not necessarily require immediate action. Experience shows that the remaining parts of the insulator will provide the necessary insulation ability.
Physical damage, such like scratching can be easily repaired by brushing of fresh coating after partly cleaning with White Spirit.
To allow an instant replacement of broken insulators it is recommendable to store a number of coated spare insulators. These should be stored in a protective covering
