For process engineers responsible for product quality, the risk of a non-representative or contaminated sample is unacceptable. The Alfa Laval Unique Sampling Valve (Double Seat) addresses that risk directly: it is a hygienic double seat sampling valve that lets operators draw repeatable samples while keeping the production line under sterile conditions. The valve replaces compromise solutions with a purpose-built design that combines a single-piece stainless steel body, a stretchable rubber membrane plug, and the ability to sterilize the full seat between draws.

How the double-seat design prevents cross-contamination in sterile sampling

The valve uses a double-seat arrangement in which the seat can be sterilized between samples. A rubber membrane mounted on the stem acts as a stretchable plug, sealing the product side from the sampling side. Between samples, the entire seat can be sterilized with dry steam, so each draw begins from a fully sterilized seat. This is the core advantage of a sterile sampling valve: there is no carry-over of contamination from one sample to the next, and there is no need to break hygienic boundaries on the process line.

316L construction and hygienic material traceability

Product-wetted steel parts are manufactured from 1.4404 (316L) and supplied with a 3.1 material certificate, giving QA teams the traceability they need for regulated processes. Actuator components use 1.4301 (304) and 1.4404 (316L) for corrosion resistance in washdown environments. Product-wetted elastomers are available in EPDM or silicone, allowing the membrane to be matched to the chemical and thermal profile of the product and CIP regime.

Modular sizing and actuation: Type 4, Type 10, and Type 25

Three sizes — Type 4, Type 10, and Type 25 — are available across the range. Manual handles and pneumatic actuators are interchangeable on the same valve body, so a unit specified today for manual operation can be upgraded to automated sampling later without replacing the wetted parts. This modular path protects the investment and simplifies spares inventory across multiple production lines.

Connection options for hygienic piping

The valve is available with tank (welding) connections for direct mounting on vessels, collared tube (welding) connections for in-line installation, and Tri-Clamp connections for fast service access. An optional pressure relief valve on the outlet adds a further layer of operator safety during sampling.

The operating envelope covers 1°C to 130°C with a maximum inlet pressure of 600 kPa (6 bar), and dry-steam sterilization is supported up to 121°C at 2 bar. The result is a sampling solution that scales across hygienic production lines while delivering representative samples and audit-ready material traceability.