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Parker Hannifin Corporation
Tube Fittings Division
Columbus, Ohio
4300 Catalog
General Technical
Choosing the Tube
Material and Type
Selection of tubematerial depends on the fluid, corrosive nature
of the service environment, the operating temperature range
and the maximum operating pressure. The tube O.D. and wall
thickness selection depends on these four parameters.
A simple method of selecting the proper tube type and material
is described below.
stsseveral common tube typeswith their recommended
operating temperature ranges, general application, and fitting
compatibility. Based on the fluid system parameters and media,
select the appropriate tube type and material.
If media and/or service environment is different from the com-
monly used ones listed in the general application column, please
or
For selecting proper tube O.D. and wall thickness use the pro-
cedure given on
Caution:When working with highly corrosive media,
alway
Fluid Compatibility
The fluid compatibility chart on the following page is intended
as a guide only and is not to be considered as a sole selection
criteria touseParkerTubeFittings ina specific application or with
a specific fluid. Other factors that must be considered include,
but are not limited to: Fluid temperature, ambient temperature,
system pressure (both operating and peak) and applicable
standards or regulations. For media not listed, please contact
your Parker representative or the Tube Fittings Division.
Protective Coatings on Steel
Protectivecoatingssuchaselectroplatedzincandcadmium
1)
and
zinc phosphate are usually applied to steel fittings for extending
their useful service life in corrosive environments.Cadmiumand
zinc corrode sacrificially, protecting the steel substrate fromnor-
mal atmospheric rustingdue to the commonpresenceof oxygen,
moisture and acidic gases. They are, however, rapidly attacked
by many fluids including those containing acidic hydrogen and
reactive fluorine, chlorine, bromine, iodine, and nitrogen. Zinc
plating will further be attacked by strong bases or water with pH
> 12.
Zinc reacts with glycol based fire resistant fluids and
formsagelatinouscompound that canplugupfiltersandbe
harmful otherwise, in a system with many zinc plated tube
and hose fittings.
Steel fittings with zinc phosphate coating or
stainless steel fittings, along with brass fittings in low pressure
applications, are viable options.
The other option is to run the fluid through the system, without
components with moving parts in it, with an auxiliary power
source, to generate and flush the gelatinous compound. Then
re-connect all components, change filters and charge the system
with new fluid.
The corrosion resistance of the Chromium-6 Free standard
surface treatment is a minimum of 25% improved over tradi-
tional zinc gold (hexavalent) chromate surface. Additionally, the
Chromium-6 Free surfacemeets the EU end of life vehicle direc-
tive and ROHS compliance.
Zinc phosphate coatings protect steel by covering its surface
and will retard rusting as long as the inhibiting barrier is not
broken.
Caution: Where low toxicity and low corrosion are re-
quired,as in foodor beverageapplications,steel coated
with any formof zinc or other protective coatings is not
recommended.
Notes:
1) Cadmium is not allowed by SAE and ISO stardards for
general industrial and commercial use. Some military
applications still require cadmium plating. These require-
ments are met with special (non-standard) processing at
extra cost.
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