Hygienic pump standards: EHEDG, 3-A, FDA and surface finish

Five terms do the work on a hygienic pump specification, and each one covers something different. Read a quotation and you will see them used as though they were interchangeable. The gaps between them are where a specification goes wrong.

A pump can hold all of the first four and still be the wrong pump for your duty. None of them describe flow, head, viscosity, temperature or the seal.

An EHEDG certificate is issued against a named class, and the class tells you how the equipment is meant to be cleaned. Type EL covers equipment cleaned with liquids; Type ED covers equipment that is dry cleaned only. Within EL, Class I is "closed or open equipment, wet cleaned-in-place (CIP) without dismantling" and Class II is "closed or open equipment dismantled for wet cleaning". The Aseptic variants of each add steam sterilisable and bacteria tight.

The work behind a closed EL certificate is real. An Authorised Evaluation Officer reviews the design against the manufacturer's official drawings, and an Authorised Test Laboratory runs the in-place cleanability method of EHEDG Doc 2, which must be completed successfully at least three times. Type ED certification is a design review only, with no test. Certificates run five years, need annual prolongation by the end of December, and a full renewal requires a new design review with re-testing if required.

So a Class II certificate is not a weaker badge than Class I. It is a different statement: this equipment cleans when you strip it down. If your process runs CIP without dismantling, Class II does not give you what you asked for, and asking for "EHEDG certified" without naming the class is how that gets missed.

The 3-A Sanitary Standard that covers pumps is number 02-12, Centrifugal and Positive Rotary Pumps, last revised in 2020. 3-A Sanitary Standards, Inc. publishes it, and the 3-A Symbol is the registered mark used to identify equipment meeting 3-A Sanitary Standards for design and fabrication. The Symbol has been in commercial use since 1956.

The part worth knowing is that it is no longer self-declared. A licensee must engage a Certified Conformance Evaluator to carry out an on-site evaluation of finished equipment, and any deficiency the inspection finds must be corrected before the equipment can be authorised to display the Symbol.

That is a different mechanism from EHEDG. 3-A is conformance to a written standard, checked by an inspector. EHEDG, for wet-cleaned equipment, adds a physical cleanability test. Neither one substitutes for the other, which is why hygienic ranges carry both rather than picking one.

Regulation (EC) No 1935/2004 is the general framework for materials and articles intended to come into contact with food. Article 3 requires that they are manufactured under good manufacturing practice so that they do not transfer their constituents to food in quantities which could endanger human health or bring about an unacceptable change in the composition of the food. Article 16 is the one that reaches your goods-in: where a specific measure applies, materials and articles must be accompanied by a written declaration stating that they comply with the rules applicable to them.

It still applies here. The Regulation is assimilated law in Great Britain, and the Food Standards Agency guidance states that all food contact materials must comply with the requirements of assimilated Regulation 1935/2004.

FDA works differently, and "FDA approved" is not a thing a pump can be. The FDA clears materials, section by section. 21 CFR 177.2600 covers rubber articles intended for repeated use, which is where a pump's O-rings and lip seals sit. 21 CFR 177.1550 covers perfluorocarbon resins, which is where PTFE sits. A supplier claiming FDA compliance for a pump should be able to name the sections that cover the wetted polymers on your build.

What to ask for, then, is not a badge. It is the declaration of compliance and the material certificates for the wetted parts, part by part.

EHEDG Doc 8 gives the working figure: large areas of product contact surface should have a surface finish of 0.8 µm Ra or better, with Ra defined per ISO 4287:1997. Two qualifications sit in the same clause and both change how you should read it.

Cold-rolled steel has a roughness of Ra 0.2–0.5 µm and usually needs no polishing at all, provided the product contact surfaces are free from pits, folds and crevices in the final fabricated form. And a roughness above 0.8 µm Ra is acceptable where test results show the required cleanability is achieved by other design features, or by procedures such as a high flow rate of the cleaning agent.

Read together, those say something a specification often misses: topography governs cleanability, not the number. A polished surface with a fold in it is worse than an unpolished one without. The number is still worth writing down, because it is the part you can measure and evidence. The Alfa Laval SRU rotary lobe pump, for one, states an inside surface finish of mechanically polished Ra ≤ 0.8 in its product leaflet, and high-purity builds go tighter than that. Specify the figure, and ask for a surface finish certificate where you need to prove it. Do not accept "polished" as a specification.

A certificate belongs to a configuration, not to a range name. The Alfa Laval SRU is a fair example, because its own leaflet says so. Seals are available single, single flush, double mechanical and packed gland, flushed and unflushed, and the leaflet notes that EHEDG compliance applies only to the Hyclean type mechanical seal. The same pump, on the same page, is compliant or not depending on a seal option. Alfa Laval also states at range level that SRU pumps meet the requirements of global hygienic standards including 3-A Sanitary Standards and FDA standards. That is a useful statement, and it is a different thing from a certificate for the build on your order. So check the certificate against the configuration you are buying. If a supplier cannot produce it against a part number, treat the claim as unmade.

The certificate also stops at your flange. EHEDG certifies the equipment as designed. A dead leg in the pipework, an undrainable run, a gasket sitting proud at the connection: none of that is on the certificate, and all of it will show up in a swab.

And it says nothing about the failure modes you will meet in service. On a wastewater duty the three things that kill pumps are rag, grit and dry running. On food and hygienic duties there is no rag. What bites instead is high temperature, frying processes especially, where sealing gets hard and the choice of pump narrows. The other is cleaning. Where there is no cleaning-in-place, or the cleaning procedure is weak, you get product contamination. High pressure, and running a positive displacement pump too fast in an abrasive medium, are the other two ways to shorten a pump's life quickly.

Which is why, in the order we ask the questions, the seal step asks what a seal failure would do to the product. On a hygienic duty that is the question. It decides single, flushed, double or cartridge long before any certificate does, and it is the one a datasheet will not answer for you.

Send us the medium, the temperature, the cleaning regime and the certificate you have to satisfy, and we will tell you which build meets it. Start from the hygienic pumps we supply, then work down to the seal and the paperwork.