Sanitary flow control valve: hygienic angle-seat control valve with integrated positioner for DN 15–50 beverage loops
Angle-seat hygienic control valves with integrated positioners, DN 15–50, for beverage flow and dosing loops · Kvs from about 3 to 34 m³/h in DN 15–50, linear or equal-percentage plugs, actuator size against the differential pressure it must close
Where an on/off hygienic valve opens or closes a line, a sanitary flow control valve holds it part-open; in the small-bore form covered here the body is an angle seat and the positioner sits on the actuator: a positioner moves a contoured plug against a seat so that flow, pressure, level or dosing follows a 4–20 mA or pneumatic signal. Uses named by one maker include flow rate control, dosing of liquids and gases, pressure regulation, level control in buffer tanks and carbon dioxide dosing for beverages. It is chosen by flow coefficient (Kv or Cv) and characteristic, by whether its actuator can hold position against the line's differential pressure, and by the same hygienic finish, seal and cleaning limits as other product-contact valves.
Hygienic angle-seat control valves in DN 15–50 with integrated or mounted positioners and exchangeable plug and seat trims, used in beverage, food and dairy flow, pressure and dosing loops: Kvs per size, linear or equal-percentage plugs, actuator size against differential pressure, seal temperatures and seat tightness; other hygienic modulating valves are cited for comparison. Hygienic straight-through regulating valves as a product, with their surface finish, approvals, Kv at part stroke and actuator types, are covered on the Hygienic pneumatic regulating valve page. Weir-type valves are covered on the Sanitary diaphragm valve for dairy processing page and their actuators on the Pneumatic actuator for sanitary diaphragm valves page; tank relief valves on the Sanitary pressure relief valve page and clamp gaskets on the Food-grade sanitary gasket page. On/off seat, butterfly and ball valves are outside this page.
CNFX editorial research · Sources checked October 12, 2026 · 3 sources
Kvs per nominal size and the choice between linear and equal-percentage plugs
The flow coefficient at full stroke, Kvs, fixes the largest flow the valve can pass at a given pressure drop; Schubert & Salzer publishes it per size and characteristic for its 7025 hygienic angle-seat control valve.
The same datasheet lists reduced-trim Kvs values for some sizes, for example 5.8 m³/h (linear) in DN 25 against the full 12.6, and a separate table for ASME BPE welding ends. [1] Südmo names flow rate control, dosing, pressure regulation, split-range control, buffer-tank level control and CO₂ dosing for beverages as applications; its SVP Select control valves come with three Kv values per nominal diameter as standard, and Kv can be changed later by replacing plug and seat, which requires separable connections on all ports; linear and equal-percentage plugs can be exchanged for one another. [3] APV's DELTA RG4 likewise changes Kvs by changing the shaft and seat, and states a correcting ratio of 50:1 with linear and equal-percentage characteristics. [2]
Editorial calculation: Kv is the flow of water in m³/h at a 1 bar pressure drop, and flow scales with the square root of the drop. A DN 25 linear 7025 at Kvs 12.6 would pass about 8.9 m³/h of water fully open at 0.5 bar drop; a DN 50 at Kvs 34, about 24 m³/h. In US units Cv ≈ 1.156 × Kv, so Kvs 12.6 is about Cv 14.6. With a 50:1 correcting ratio, the RG4's smallest controllable flow is 2% of its Kvs flow.
Give the supplier the minimum, normal and maximum flow, the pressure drop available across the valve at each, the liquid's density and viscosity (or gas data for CO₂ dosing), and the control task (flow, pressure, level, dosing), so the Kvs and characteristic can be chosen with margin at both ends.
02
Actuator size, spring set and supply air against the differential pressure the valve must hold
A modulating valve has to hold its plug at part stroke, and close where required, against the pressure difference across the seat; the actuator and its springs set that limit.
For smaller sizes the same 80 mm actuator is enough for much higher pressure: Schubert & Salzer gives 17 bar for DN 15 and DN 20 with two springs and a digital positioner. The analog positioner 8047 lowers the limits; for DN 50 with an 80 mm piston and one spring it gives 0.5 bar. [1] Editorial calculation: moving a DN 50 valve from the 80 mm to the 250 mm actuator with 8 springs raises the admissible differential pressure from 2 to 15.5 bar, nearly eight times.
The control signals differ by maker: APV's RG4 uses a diaphragm actuator, spring-raising or spring-lowering, with a pneumatic positioner (0.2–1.0 bar) or an electro-pneumatic positioner (4–20 mA), with NAMUR or integrated positioners and options for HART, Profibus PA and Foundation Fieldbus. [2] Südmo specifies 6–8 bar control air for its standard actuator and 5–7 bar for its membrane actuator, and offers an 8692 control head with an optional PID controller for stand-alone loops with a temperature or flow meter. [3]
7025 configuration (DN 50, digital positioner 8049)
State the maximum pressure upstream and the lowest downstream, the fail position needed on air or signal loss (open or closed), the available control air pressure, and the signal (4–20 mA, fieldbus) when ordering actuator and positioner.
03
EPDM limits of 130–140 °C, PN ratings and seat leakage class across three hygienic control valves
The angle-seat 7025 is compared here with APV's RG4, which has a ball-shaped housing, and Südmo's SVP Select range, offered in angle and straight-way housings; its PTFE seat and Class VI leakage rating matter where the control valve also has to shut off.
APV notes that VMQ and FPM seals are not suited for hot water and steam unless a steam-resistant FPM is chosen. [2]
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Compiled and source-reviewed by the CNFX editorial team.
Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review
· Page last updated 13 October 2026
Buyer questions
What Kvs does a DN 25 hygienic control valve have?
Schubert & Salzer lists 12.6 m³/h (linear) and 9.7 m³/h (equal percentage) at full stroke for its DN 25 7025 with DIN/ISO welding ends. [1]
Can the Kv of a hygienic control valve be changed later?
Südmo and APV change Kv by replacing plug (or shaft) and seat; Südmo requires separable connections on all ports for this. [3][2]
What rangeability can a hygienic modulating valve achieve?
APV gives a 50:1 correcting ratio for its DELTA RG4 with linear and equal-percentage characteristics. [2]
Sources and what still needs a direct check
Sources checked 2026-10-12. Schubert & Salzer, SPX Flow (APV) and Pentair Südmo publish data for their own control valves; values apply to the models named.
