Sterile (aseptic) sampling valve

01

Size the valve for viscosity and particles

Keofitt's catalogue sizes its Classic sampling valves by product: the 4KAI (5 mm bore) for 0–100 cP with particles under 1.5 mm, the W9 (9 mm) for 0–1,000 cP with particles under 3 mm, the W15 for 0–50,000 cP with particles up to 8 mm, and the W25 for 0–250,000 cP with particles under 17 mm. More viscous liquids can be sampled, but take longer depending on process pressure. [2] On its W9 page, Keofitt notes that the 3 mm particle limit applies with a PTFE membrane and 2 mm with silicone or EPDM. [4]

Alfa Laval sizes its Unique sampling valve the same way: Size 4 for 0–100 cP products such as water, beer, wine and milk with particles up to 2.5 mm, Size 10 for 0–1,000 cP products such as fruit yoghurt and syrup with particles up to 7 mm, and Size 25 for very viscous products such as jam with particles up to 20 mm. [1]

Editorial note: different makers set different particle limits for similar viscosity classes, so give the supplier your product's viscosity range, particle size and process pressure rather than a valve size alone.

Give the supplier the product, its viscosity and largest particles, process pressure and temperature, the connection (tank weld, pipe weld, clamp, sterile connector), manual or pneumatic operation, sterilising medium (steam pressure and temperature, or chemical), CIP sequence, sample container (bottle, bag, syringe), seal material and certificates, surface finish, and documentation required.

02

Plan steam sterilisation and seal life

Alfa Laval's leaflet for its single-seat Unique sampling valve gives a temperature range of 1–130 °C and a maximum sterilisation temperature of 121 °C with dry steam at 2 bar, warns that condensate will damage the membrane, and recommends changing the membrane seal every 500 samples or sterilisations, or according to conditions. It recommends an optional pressure relief valve on the outlet when steam is used, to keep the proper temperature, and lists a maximum working pressure of 6 bar, a 316L body with 3.1 certificate, and EPDM or silicone membranes. [1]

Rieger's white paper explains that steam sterilisation of a sampling valve is done immediately before taking the sample, for about one minute in a recommendation it attributes to the German Dairy School in Kempten, with steam injected at the sampling point so that 121 °C is reached quickly. [5] Keofitt describes its Classic valves as coaxial steam-sterilisable designs with a separate inlet for SIP and CIP, so the valve can be cleaned and sterilised between samples. [2]

Keofitt's Sesame design adds a second seat so that the sampling seat and the steam seat cannot open at the same time; Keofitt notes that with conventional valves the steam inlet stays open during sampling, which risks steam or CIP fluid entering the process or airborne contamination of the sample. [3] Editorial note: write the sampling procedure (sterilise, sample, re-sterilise or clean) into the batch instructions and validate it on site.

03

Compare membrane, diaphragm and bellows sealing

Rieger's white paper defines an aseptic valve as one that hermetically seals the stem so that stem travel cannot pull contaminants from the environment into the process, and groups the seals into elastomer diaphragms and bellows (metal or PTFE). It argues that soft diaphragms can pump product into dead spaces at the seal interface, that metal bellows suit sterilisation above 135 °C for long periods, and that PTFE bellows withstand 135 °C for up to about 20 minutes. [5]

Keofitt offers silicone, EPDM and PTFE membranes for its W9 and BASIX valves. [2] [3] Editorial note: Rieger, Keofitt and Alfa Laval each describe their own sealing concept; ask suppliers for drainability, dead-space and cleaning test evidence for the exact valve and orientation.

04

Sanitary sample valves and aseptic sampling valves with weld, clamp or KF ends

Listings range from sanitary sample valves to aseptic sampling valves with weld, clamp or KF ends; ask each for the sterilisation rating, seal options, surface finish and certificates.

05

Valve body, membrane or bellows, steam inlet, sample outlet, actuator and pressure relief

The steam inlet and the seal decide whether sampling stays aseptic: Keofitt's Sesame design stops the sampling seat and the steam seat opening at the same time, and Alfa Laval warns that condensate damages its membrane. [3] [1]

06

Connection, pressure and temperature, sterilisation cycles, body and seal materials for a sampling valve order

Seal life is counted in sterilisations, not years: Alfa Laval recommends a new membrane every 500 samples or sterilisations, so the replacement interval follows from how often you sample. [1]

07

Send the product, connection and sterilisation data together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Product: [viscosity; particles; pressure; temperature]
Connection: [tank weld; pipe weld; clamp; size]
Operation: [manual; pneumatic]
Sterilisation: [steam pressure and temperature; CIP]
Seals: [membrane or bellows; material]
Sampling: [container; volume]
Documents: [material certificates; seal compliance]

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