Aventics Pneumatics in Washdown & Packaging Environments

How IP69K components, FKM seals, stainless cylinders, and hygienic air preparation change when moving from dry industrial use to food-zone specifications.

The Problem Nobody Specs For

A pneumatic package that runs flawlessly on a dry assembly line will begin to fail within weeks of being installed near a high-pressure washdown station. The failures are not random. They follow directly from material chemistry, and every one of them is predictable if you understand what a caustic spray at 1,400 PSI and 80°C does to standard industrial components.

Four failure modes account for the overwhelming majority of washdown warranty claims:

• Anodized aluminum corrodes. The anodize layer is porous and thin. Chlorinated and caustic sanitizers penetrate it, then attack the base aluminum underneath. Pitting starts at machined edges and thread roots, and once it starts it accelerates.
• NBR (Buna-N) seals swell and harden. Nitrile has poor resistance to oxidizers, quaternary ammonium compounds, and peracetic acid used in food sanitation. The seal swells, loses its set, then embrittles — and the cylinder or valve leaks.
• Grease washes out. Standard mineral-oil greases are not emulsion-stable. Repeated hot-water spray strips lubricant from bearing surfaces and rod seals. The result is stiction, then galling, then premature wear.
• Crevices trap bacteria. Standard valve bodies have blind pockets, lap joints, exposed fastener heads, and horizontal ledges. These hold water and product residue, and they are exactly where Listeria and other pathogens establish harborage.

Moving from dry industrial to food-zone specification is therefore not an upgrade in ingress rating alone. It is a change in body material, seal compound, lubricant, surface geometry, and air quality — all at once.

The Three-Zone Framework

Before selecting a single part, classify the location. The hygienic-design community divides a wet processing area into three zones, and the classification dictates the entire bill of materials.

IP Ratings, Understood Properly

The IP code from IEC 60529 has two digits: the first for solids, the second for water. Engineers treat a higher second digit as "more waterproof" on a single scale. It is not a single scale. IP69K tests a fundamentally different threat than IP67.

The distinction that trips up most specifiers: IP67 immersion does not imply IP69K spray resistance, and a component can pass one and fail the other. Specify IP69K for anything in the splash zone, full stop.

Aventics CL03 — The Valve Built for the Wet Room

The Aventics CL03 valve series is the reference component for Zone 1 and Zone 2 pneumatic control — carrying both EHEDG certification and an IP69K rating. The design choices illustrate every hygienic-design principle in one product:

• PA12 fiberglass-reinforced polymer body — no exposed aluminum to corrode
• HNBR seals throughout, chosen for sanitizer resistance
• NSF H1 food-grade lubrication
• Smooth, drainable contours with no horizontal ledges — water sheets off rather than pooling
• Stainless hardware; fasteners are not left as bacterial harborage points

Aventics S Series — Stainless Cylinders for the Food Zone

For linear actuation in the food zone, the Aventics S Series is a stainless NFPA cylinder engineered for washdown:

• All-stainless construction — barrel, end caps, rod, and hardware. Nothing corrodes.
• Carboxylated-nitrile plus PTFE T-seal piston as standard; FKM (Viton) seal option for aggressive chemistry and higher temperatures
• Food-grade grease option and NSF certification
• Bore range 1.5” to 8” — max 150 PSI
• Keeps the NFPA footprint — drops into an existing American-built machine without re-engineering the mount

Seal Material Selection

Hygienic Air Preparation

Clean bodies and correct seals are wasted if the air itself is dirty. The reference target for direct-food-contact air is ISO 8573-1 Class 1.2.1: particles ≤ 0.1 µm, pressure dew point ≤ –40°C, and residual oil ≤ 0.01 mg/m³. SQF requires 0.01-micron final filtration at the point of use, not merely at the compressor room.

1. Coalescing filtration — A coarse then fine coalescing stage removes bulk water aerosol and liquid oil down to the sub-micron range.
2. Activated-carbon adsorption — Removes oil vapor and odor that coalescing filters pass. This gets residual oil under 0.01 mg/m³.
3. Sterile / final 0.01-micron filtration at point of use — The last barrier before air enters the food zone. Locate it at the machine, not upstream.

Tubing

Standard polyurethane tubing hydrolyzes, absorbs water, softens, and is not FDA compliant for food zones. Specify hydrolysis-resistant material:

• PUN-H — hydrolysis-resistant polyurethane. FDA compliant and chemically resistant; the practical default for most food-zone routing.
• PTFEN — PTFE-based tubing for the most aggressive chemistry and higher temperatures. FDA compliant.

7 Common Engineering Mistakes

1. Specifying IP67 for splash zones. Immersion rating does not survive a hot pressure wand. Use IP69K in Zone 2.
2. Leaving anodized-aluminum components in the wet zone. Anodize is porous; caustic penetrates it. If it gets sprayed, it will pit.
3. Reusing NBR seals "because they were in stock." Buna-N is a dry-industrial compound. In sanitation chemistry it swells and fails. Match the compound to the chemistry.
4. Filtering only at the compressor room. Point-of-use 0.01-micron filtration is the requirement. Piping between the compressor and the machine re-contaminates the air.
5. Mounting components with horizontal ledges and exposed fasteners. These are bacterial harborage points. Orient components so water drains.
6. Ignoring exhaust routing. A hygienic valve exhausting raw shop air into the food zone defeats the purpose. Route exhaust away or protect it.
7. Using standard PU tubing. It hydrolyzes and is not FDA compliant. Specify PUN-H or PTFEN.