Lined Pumps

To provide chemical resistance for a metallic pump, it is possible to install a flexible, rigid, or sprayed-on liner inside the pump housing. With a flexible lined pump, a metal casing is made to the design shape and pressure. Then a loose liner is fitted inside the pump housing and bonded to the metal casing with an adhesive. This type of liner can come loose under vacuum conditions. There also can be problems at the termination of the liner to the mating pipe flanges.

A resin used in some lined pumps is PTFE (polytetrafluoroethylene). By itself, PTFE does not have the physical properties needed for a pump housing. When it is supported by a metal housing, however, it provides an excellent lining material due to its outstanding range of chemical resistance at high temperatures.

Rigid pump liners are machined out of plastic stock shapes or molded into a near net shape. The liner is then mechanically compressed between bolted steel plates to provide the support. Such pumps are usually small in size.

A sprayed-on composite lining is made by taking a metal casing of the required pressure rating, heating it, and then spraying the composite material inside the housing and flanges. At 0.030 in (0.76 mm) thickness, the lining will not have pinholes and is suitable for pump applications. This lining process is usually limited to pumps that require up to 100 horsepower (75 kW) drives.

Table 2 gives an overview of the comparative advantages and disadvantages of the different styles of pumps.

Renewable Energy 101

Renewable Energy 101

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable. The usage of renewable energy sources is very important when considering the sustainability of the existing energy usage of the world. While there is currently an abundance of non-renewable energy sources, such as nuclear fuels, these energy sources are depleting. In addition to being a non-renewable supply, the non-renewable energy sources release emissions into the air, which has an adverse effect on the environment.

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