Hydraulic characteristics of ductile iron socket pipes with inner polyurethane coating

Summary

The extensive use of ductile iron socket pipes with inner polyurethane coating in Europe proves their efficiency. In Russia such pipes have been also used. Pipelines with polyurethane coating combine the properties of plastic (they do not corrode, do not have scale) and metal pipe (high strength, lifetime and ability to endure high pressure) advantages. The roughness of the inner pipe surface effects significantly the resistance coefficient value along the length, i. e. the hydraulic characteristics of the pipelines. However up to now no studies of the roughness value of foreign-made polyurethane coating have been carried out. The authors of the article have conducted these studies. Based on the measured roughness parameters of the ductile iron socket pipe inner surface (manufactured by vonRoll hydro, Switzerland) with polyurethane coating the friction coefficient along the length was calculated. To estimate the capacity of pipes with polyurethane coating the hydraulic calculation is given (compared to the domestic pressure polyethylene pipes).

Key words

ductile iron , socket cast iron pipes , polyurethane coating , hydraulic characteristics

Helical filter elements and their hydraulic characteristics

Summary

The description of two constructional designs of helical filter elements with reduced adhesive properties capable of operating in «filtration-regeneration» mode without replacement for more than 10⁵ cycles is presented. Owing to the special property of the filter element residing in the fact that the filtering flow passage of the element expands during regeneration and recovers to the original state during filtration; and owing to the vibration of the filter baffle during regeneration complete recovery of the filtering properties of the elements after each filtration-regeneration cycle is provided. The scheme of the unit for determining the hydraulic characteristics of helical filter elements both in the presence of the dynamic membrane made of filter perlite powder and in the absence of it is presented. The helical filter element capacity is determined (pore size: 8, 11, 17, 28, 38, 51, 77, 114, 154 and 248 μm) during filtration of water free of any pollutants and when using precoated dynamic membranes made of filter perlite powder. Sample weight of dry filter perlite powder for precoating one helical filter element was 4, 8, 12 and 24 g. The dependences of the filtration rate from the pressure of the filtered flow, filter baffle porosity and filter perlite powder weight precoating the helical filter element were determined.

Key words

filtration , hydraulic characteristics , helical filter element , dynamic membrane , filter perlite powder