NSF ANSI CAN 372-2020 pdf free download – Drinking Water System Components – Lead Content.
2Definitions
2.1coating: A covering or barrier applied to a substrate by electro,chemical deposition or via mechanicaladhesion (paint).
2.2liner. A barrier component which is mechanically attached and sealed to prevent water contact withanother component. (Example: a tubular or cast brass spout with a thermoplastic sleeve inserted insideand sealed with an O-ring or other sealing material, such that water does not come into contact with thebrass spout material.)
3 General requirements
Solders and fluxes shall have a lead content less than or equal to 0.2%.All other products shall have aweighted average lead content less than or equal to 0.25% based on the average of their wetted surfaceareas.
3.1All components ≤0.25%
lf each component of a product has a wetted surface with a lead content of not more than 0.25%, then theproduct is considered compliant and no further evaluation is required.
3.2Any components > 0.25%
lf any wetted components of a product have a surface area with a lead content of more than 0.25% lead,then the weighted average lead content shall be calculated according to Section 4 to determine compliance.3.3Restriction on the use of lead containing materials
There shall be no lead added as an intentional ingredient in any product, component,material, or theircoatings submitted for evaluation to this standard with the exception of brass or bronze meeting thedefinition of “lead free” under the specific provisions of the Safe Drinking Water Act of the United States.
4 Weighted average lead content calculation
The weighted average lead content of the product shall be calculated using the surface area and leadcontent information established under Section 4.1.For internal NPT (pipe) threads, engagement of malecomponents into female threads will assume that 25% of the length of the female thread remains exposedas wetted surface area.
All of the wetted surfaces are to be included in the weighted average lead content calculation, not just thosesurfaces that contain lead.
The results of the weighted average lead calculation shall be rounded to two decimal places prior todetermination of compliance.
4.1Component surface areas and lead content
The following information shall be established to determine the weighted average lead content
– a list of all components and materials and their corresponding surface areas that come into directcontact with water; and
⎯ the maximum lead content of each material as specified by reference to a national or international
standardized material specification (e.g., UNS copper alloy specification). If the material is not formulated to a national or international standardized specification, the manufacturers material specification shall be used.
4.2 Formula for determining weighted average lead content
The following formula shall be used when calculating the weighted average lead content of products:
Where:
WLC = weighted average lead content of product
LC c = maximum lead content of the c th component
WSA c = wetted surface area of the c th component
WSA
t = total wetted surface area of all components
n = number of wetted components in product
NOTE — An example calulation of the weighted average lead content of a product is provided in Annex I-1.
5 Percentage lead content of water contact surfaces
The maximum lead content of the material specification used to produce wetted components shall be used to determine compliance with this standard. When the actual percent of lead in the chemical composition of individual components is to be determined, the procedures in Section 7 shall be followed.NSF ANSI CAN 372 pdf download