Drinking-water and food-contact approvals for rubber seals

Document

PP-TB-003

Version

0.1

Date

2026-10-23

Type

Technical briefing

1. Purpose and status of this document

Seal makers who sell into water, food, beverage and pharmaceutical markets are asked for approvals by name: NSF 61, WRAS, KTW, FDA. This briefing explains what those names mean, how an application usually works, and what a compounder has to do. It is based on public sources named in section 9 and on general knowledge that we flag as such. It is not legal or regulatory advice. It contains no test data, and at the date of this document no Pascalor compound holds any approval named here. Approval rules change. Check each scheme's current documents before relying on this briefing.

2. Summary

• Approvals are granted to a specific formulation, made by a specific manufacturer at a specific facility, for a defined use. A name on a seal does not carry the approval.
• Different regions run different schemes. Germany, the UK, the US, Italy and Austria each have their own drinking-water scheme, and several include lists of permitted starting materials.
• Food-contact rules (FDA, EU) work differently from drinking-water listings. They often rely on positive lists of ingredients plus extraction limits.
• A compounder supports the application by supplying a full ingredient list to the certifier under confidentiality, controlling the recipe, and keeping the production site and lot records that the certifier audits.
• Some lists mix water and gas standards. Read the scope of each one.

3. The schemes, in plain terms

Watch the scope. The supplier page we read lists EN 549 and EN 14241-1 beside drinking-water approvals. It describes them as covering gas appliances, gas equipment and flue systems. They are not drinking-water approvals. Another entry on the same page, ACS, is listed without a country or description. When a datasheet lists approvals, find out what each one covers.

4. Who holds an approval

Approval attaches to three things together: the formulation (the exact list of ingredients), the manufacturer, and the facility. The supplier source we read says NSF audits the compound maker's facility annually. If you change the recipe, the supplier of a major ingredient, or the production site, you should assume the approval does not carry over until the certifier says it does.

A compound maker who sells to a seal maker is often the party that holds the listing. A seal maker who buys approved compound still has to control the way it moulds, post-cures and handles parts. The final device manufacturer usually applies for approval of the finished component.

5. How an application usually runs (NSF/ANSI 61, as described by one supplier)

1. The device manufacturer asks the certifier for approval and receives a two-part application form.
2. The device manufacturer completes the first part, which defines the application, including the exposed contact area of the seal.
3. The compound maker completes the second part. It lists the compound's ingredients and, where relevant, the section of the US Code of Federal Regulations that applies.
4. The compound maker sends the second part directly to the certifier.
5. The certifier reports results to the device manufacturer.

Other schemes differ in the steps but not in the principle: a formulation disclosed to the certifier, a defined use, laboratory testing, audit, and a listing that names the formulation.

6. What a compounder must have ready

• A controlled recipe with revision history, and the ability to freeze it.
• Full ingredient identities (CAS numbers where applicable), with suppliers' declarations.
• A confidentiality agreement with the certifier. Ingredient lists are not shared with customers.
• A production site with documented process control.
• Batch records that link every lot to a recipe revision.
• Agreement with the customer on the intended use, temperature, contact area and exposure time.
• A realistic lead time. Testing, audit and listing take time, and the sources we read give no schedule. Ask the certifier.

7. Design choices that help or hurt

These are general engineering points, not scheme requirements.

• Peroxide and ingredient choices matter. Some ingredients are excluded from positive lists or limited in migration. Choose from the permitted ingredients from the start rather than modifying a finished recipe.
• Post-cure and volatile content. A well-done post-cure removes volatiles that would otherwise migrate. Do not assume it is enough.
• Carbon black grade and colour. Many schemes restrict fillers and pigments. Check every one.
• Not all polymers are on all lists. Some schemes list approved base elastomers. If your polymer is not on the list, a compound will not qualify however clean the recipe.

8. Approvals tracker (template)

9. Sources and verification

Sources were read on 23 October 2026. Web pages change.