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Material selection

Gaskets

  •  The sealing quality has a decisive influence on the service life of a gasket. In addition to the geometry, the mixture and the production process are decisive for the function and service life. In spite of the same chemical designations, gaskets differ on the basis of the additives and particularly, the degree of cross-linkage.
  • An abundance of analysis procedures are available for the gasket qualities, but there are no standards or guidelines which make it easier to measure the performance of a gasket.

 

Gaskets can be optimized only in comprehensive tests.

  • The following information is required for the selection of gaskets:
    • Product (also CIP/SIP) in contact with gasket, including
      • duration of contact
      • concentration
      • temperature or temperature change
      • switching cycles
  • Exceptionally high product temperatures can also destroy the structure of the gasket. Gaskets may be defective even though they appear to be intact.
    • The usual temperature specifications are based on dry air and are therefore not relevant for practical applications.
    • The permissible temperatures for liquid or steam are considerably lower in general.
  • In addition to the resistance to temperature and corrosion, the swelling characteristics of gaskets are decisive for their suitability.
  • The materials for Nocado butterfly valve gaskets are produced according to FDA directive.
  • Frequently, an on-site test is required to determine the optimum gasket for the specific application. The following information is intended to facilitate selection; it is based on experience from practical applications and does not represent any guaranteed values.
    • Silicone in Nocado quality has very good allround characteristics.
      • Economical
      • Resistant to:
        • hot water up to 110°C
        • caustic soda solution 2 %, 90 °C (effective time max. 45 minutes, at solution temperatures greater than 60°C the valve should not be switched)
        • nitric acid 1.5 %, 40°
        • phosphoric acid 1.5 %, 40°C
        • acidic acid/hydrogen peroxide 0.7 %, 40°C
        • can be sterilized with steam 121°C (effective time max. 60 minutes)
    • EPDM in Nocado quality has exceptional allround characteristics.
      • High service life
      • Resistant to:
        • hot water 160 °C
        • caustic soda solution 3%, 95°C
        • nitric acid 2%, 80°C
        • phosphoric acid 4%, 70°C
        • peracetic acid, hydrogen peroxide 0.7 %, 40°C
        • can be sterilized with steam at 160°C
    • HNBR in Nocado quality is an extremely robust, very universal material with the following properties:
      • Extremely high service life
      • Can also be used for fully desalinated water (at low switching frequency) and products containing grease
      • Resistant to :
        • hot water 130°C
        • fully desalinated water 85°C
        • caustic soda solution 5%, 100°C
        • nitric acid is not recommendable for HNBR
        • phosphoric acid 2 %, 60°C
        • peracetic acid, hydrogen peroxide 0.7 %, 40°C
        • can be sterilized with steam at 130°C (141°C, effective time max. 20 minutes)
    • FPM in Nocado quality; particularly for applications where this material has proven itself, such as with certain hydrocarbon compounds, aromatics and products containing grease.

Nocado GmbH
Brendelweg 159
27755 Delmenhorst

Phone: +49 4221 800 99 830
Fax:       +49 4221 800 99 8930
sales@nocado.de |  www.nocado.de