In my latest article about the different materials used for chemical pumps I wrote a brief guide helpful for a first materials selection according to their properties and characteristics. Now I would like to analyze each material from the point of view of their typical applications.
Polypropylene (PP):
Mechanical applications: PP is used for mechanical parts in corrosive environments. Compared to polyethylene with a high molecular weight, polypropylene has a higher traction resistance.
Alimentary applications: physiologically inert when it has a natural color, polypropylene is suitable for use in contact with foods.
Electrical applications: good dielectric characteristics and weather-proof.
Chemical applications: PP is widely used in chemical industries because of its high resistance to acids and alkali. Thanks to its higher resistance to temperature than PVC it’s used for valves, flanges gears etc. in chemical, galvanic and petrochemical industry. It’s not suitable for use with high concentration oxidizing acids.
PVDF:
Chemical applications: the high chemical resistance to acids and alkali is typical of fluorinate polymers (PVDF) that’s why it’s mainly used for parts in petrochemical and chemical industries.
Alimentary applications: physiologically inert when it has a natural color, it’s approved by different organizations for use in contact with foods. It’s often used because of this characteristics, especially in alimentary machines and in pumps for alimentary liquids.
Electrical applications: good dielectric characteristics, self-extinguishing without adding halogens and weather-proof
Mechanical applications: the low friction coefficient makes is suitable for bearings even if they work in water.
PTFE
Mechanical applications: the low coefficient of friction makes it useful for bearings unless they have to support a great weight.
Alimentary applications: physiologically inert, it’s approved for use in contact with food by some organizations, but in some countries it’s questioned the possible use in contact with food.
Electrical applications: thanks to the good dielectric characteristics, the self-extinguishing and the stability to bad weather it’s used more and more in this field.
Chemical applications: typical of fluorinate polymers is the high chemical resistance to acids and alkali. It’s main use is for components in petrochemical and chemical industry.
EPDM
Mechanical applications: Gaskets, section bars and technical items for cars, handmade articles for anti-acid protections.
AISI316
Suitable for plants for production of nitric and sulphuric acid and for the relative equipment (pumps, valves and pipes). It’s used in very aggressive environments (textile industry, paper industry, oenological- alimentary industry, and especially naval industry).