PH and Rubber Lining
The PH levels in the transport fluids is always a concern when selecting the proper rubber liner for pipe or chutes. If the transport fluid is Acidic, natural rubber can be the right selection. When using natural rubber with acids, swelling occurs dependent on concentration and you may not get the same abrasion resistance you would normally get from a liner. Alternately extremely alkaline solution or caustic materials can also be problematic.
As a general rule of thumb, any high corrosive or caustic application, will change the rubber selection from Natural rubbers to Chlorobutyls or Bromobutyls which can handle high chemical compositions and higher temperatures. The challenge with the Butyl family is that they sometime have difficulties adhering to sub-straights.
Rubber manufacturers know the adhesion problem and will some time use a pure natural gum layer on the bottom of the sheet. This helps adhere the sheet to the sub-straight. Liner applicators must be aware, that the natural rubber layer (tie gum layer) is there. If this is the case closed skives are recommended for all chemical applications.
When a rubber sheet has a tie gum layer it is susceptible to chemical and temperature attack. Many liners have failed due to this layer being dissolved or weakened because of the lower chemical resistance and temperature threshold of the tie gum layer.
When selecting rubber liners an understanding of the PH levels and the effect on the liner is critical to the selection of rubber for the application. Being able to describe the PH, material particle size and velocity can help you in designing the perfect piping system.