Most irrigation
components, such as filters, pipes, meters and valves have been
constructed of metal. However, the trend over recent years have been
pointing more and more towards using thermoplastics.
Why would an
irrigation system designer choose to include plastic valves over
metal components that have demonstrated their efficacy? Is it just
cost-cutting, or is there more?
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Chemical
resistance: one of the biggest advantages of plastic valves is
that they do not typically corrode when exposed to saline or acidic
water. This is especially important for systems that often apply
fertilisers and chemicals by water. Standard metals like ductile
iron eventually corrode under acidic conditions. Plastics, on the
other hand, can tolerate high and low pH, and are very chemically
inert.
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Cost
efficiency: when the issue is cost, plastics are without a doubt
the material of choice. Both the raw material and the manufacturing
process are more cost competitive than metal. Because of their lower
weight, plastics also cost much less to transport.
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Ease of
installation and maintenance: plastic valves are lighter and
easier to handle during installation. Because of their smooth
interior surface, and lack of corrosion, they are less prone to
sediment build-up, and are usually virtually maintenance free.
