Alfa Laval regulating valves offer precise flow rate or pressure control in hygienic processing lines. They are well-suited for various applications, including metering, blending, weighing, and filling systems in industries like dairy, food, beverage, home-personal care, biotech, and pharmaceuticals. These valves ensure safe and efficient operations, easy maintenance, superior product quality, and increased productivity.

Alfa Laval's hygienic regulating valve range covers three distinct platforms. Each one solves a different control problem, and the right choice depends on whether the priority is mechanical pressure maintenance, electronic precision control, or a combination of regulating and shut-off functions in one body.

CPM-2 constant pressure modulating valve

The CPM-2 is a pneumatic regulating valve that maintains a constant pressure at either the valve inlet or outlet. The CPMI-2 variant regulates inlet pressure, while the CPMO-2 regulates outlet pressure. Maximum product pressure is 10 bar (1000 kPa), with air pressure between 0 and 6 bar (600 kPa) used to set the regulating point. The valve adjusts position automatically against process changes, with no electronic control loop required. Kv values cover 23 m³/h at full flow and 2 m³/h for low-capacity regulating, with an alternative 15 m³/h CIP area for cleaning flow. A booster is available when product pressure exceeds available air pressure.

Unique RV-P regulating valve

The Unique RV-P is an automatic hygienic regulating valve with an electro-pneumatic actuator. An integrated I/P converter changes the electrical input signal into a pneumatic signal, which is then transmitted to a positioner operating on the force-balance principle. The actuator piston position is directly proportional to the input signal. Maximum product pressure is 10 bar (1000 kPa) with full vacuum capability on the minimum side, and Kv values range from 0.5 to 110 m³/h at 1 bar differential pressure. Standard and aseptic models are available, with aseptic configurations using a seat and O-ring arrangement. Documented weights for the Unique RV-P range from 8.2 kg in the 38 mm body to 24.9 kg in the 101.6 mm body.

Unique RV-ST regulating valve

The Unique RV-ST is the third generation single-seat regulating valve, with sizes ranging from 25 mm to 101.6 mm (DN100). Sizes from 38 mm to 101.6 mm include a plug seal that allows the valve to also function as a shut-off valve, while the 25 mm size omits the plug seal. The 8692 and 8694 positioners cover top control with display and basic control without display respectively, both with IP65 and IP67 protection. Maximum product pressure is 10 bar (1000 kPa), with an EPDM temperature range of -10 °C to +140 °C as standard. On the fully maintainable RV-ST actuator, the NC/NO configuration can be changed in the field by rotating the cylinder with a service tool, removing the lock wire, reversing the piston/spring assembly, and reassembling with components repositioned for the desired movement.

Hygienic flow control valves are specified wherever a process line needs to hold a flow rate, pressure, or temperature setpoint while staying compatible with CIP and SIP cleaning routines. The product-wetted parts are AISI 316L (1.4404) with EPDM seals as standard, and FPM or HNBR seal options cover higher temperatures and specific chemical exposures. Internal surface finish is Bright (polished) with Ra below 0.8 µm on the Unique RV-P and Unique RV-ST platforms, which keeps the valves usable in product contact positions across regulated industries.

Where they sit in the process line

A regulating valve typically sits downstream of a centrifugal pump or positive displacement pump and upstream of a process step that needs a stable inlet condition. In a pasteuriser, a CPMI-2 holds the inlet pressure constant so the heating section sees consistent flow. In a filler feed line, a Unique RV-P with positioner can be slaved to a level transmitter on a buffer tank, modulating to keep tank level within a narrow band. In brewing, an RV-ST upstream of a carbonator regulates wort pressure so dissolved CO2 stays within recipe targets. The valve is almost always installed against the closing direction of flow to prevent water hammer on the actuator (recommended as flow against spring closing for RV-ST), and minimum clearance has to be left around the body—ranging from 100 mm to 180 mm for RV-P actuator removal—so the unit can be serviced without cutting pipework.

How requirements differ by sector

Dairy lines run frequent CIP at 70 °C with 1% NaOH and 0.5% HNO3, and the EPDM standard seal handles both. Brewing prioritises plug seal integrity because the valve is often expected to shut off cleanly between batches, which makes the RV-ST with plug seal a natural fit from 38 mm upward. Pharmaceutical and aseptic food applications drive selection toward the Unique RV-P aseptic model, where specialized sealing eliminates contamination paths. Personal care lines with cream or lotion products lean on the Kv flexibility of the RV-ST, where the wide Kv selection lets the engineer match the valve to the actual viscosity and flow envelope. Across every sector, the warranty depends on Alfa Laval genuine spare parts, and keeping a stock of wear parts like diaphragms and O-rings is recommended to minimize down time.

A hygienic flow control valve regulates a process variable by modulating the position of a valve plug inside a body. The plug moves against a seat, varying the open area through which liquid flows. The position is held by a pneumatic actuator, and the actuator is driven either by a fixed air pressure for mechanical regulation (CPM-2) or by an electrical signal converted to pneumatic action via an I/P converter (Unique RV-P, Unique RV-ST with positioner).

Operating principle

On the CPM-2, the setpoint is established by an air pressure regulating valve installed close to the actuator. Compressed air loads one side of a diaphragm assembly while product pressure acts on the other side. When product pressure rises above the setpoint, the plug moves toward the closed position. When it falls below, the plug opens further. The whole loop is mechanical, with no electronics, which makes the CPM-2 suitable for plants that want a simple pressure regulating valve without the cost of a positioner. Manuals specify that air must be released after use.

On the Unique RV-P, the loop is closed electronically. The IP-converter translates a 4–20 mA control signal into a pneumatic signal that is fed to the positioner. The positioner uses the force-balance principle so the actuator piston position is proportional to the input. Signal conversion is extremely insensitive to pressure shocks, which keeps the valve stable in plants where compressed air pressure fluctuates. The Unique RV-ST adds the option of an 8692 positioner with display or an 8694 positioner without display, both supporting 4–20 mA setpoint and IP65/IP67 protection.

Key components

The internal stack on a Unique RV-P includes an O-ring (21) and lip seal (25) at the bonnet, a plug (23) running through a bushing (24), and a seat (63) at the valve body (26). The actuator (110) sits on top, connected through the bonnet (112) and secured by a clamp (19). On the Unique RV-ST, the wetted assembly is similar but adds a plug seal in 38 mm to 101.6 mm sizes for shut-off duty. Actuators for RV-ST are available as fully maintainable or non-maintainable variants; non-maintainable actuators carry a laser-marked or labeled warning and must not be cut open or disassembled because of the spring under load (spring tension danger).

Selection criteria

Sizing a regulating valve starts with Kv—the flow in m³/h at 1 bar differential pressure with water (measured at 20 °C per VDI 2173). On the Unique RV-P, Kv ranges from 0.5 to 110 m³/h. On the CPM-2, the standard plug delivers approximately 23 m³/h at full flow with a low-capacity 2 m³/h option for fine regulation. The operating point should be selected based on the pressure drop capacity diagram so the valve has authority in both directions. Other selection factors:

CIP compatibility

All three valves are designed for cleaning in place. Recommended cleaning agents include 1% by weight NaOH at 70 °C and 0.5% by weight HNO3 at 70 °C, using clean water free from chlorides. During CIP, the CPMI-2 requires no air pressure to remain fully open, while the CPMO-2 requires sufficient air pressure for maximum flow. On Unique RV-P and RV-ST, the actuator is activated to the fully open position. Safety warnings emphasize never touching the valve or pipelines during sterilisation due to burn hazards.

Comparison to alternative approaches

A basic pressure-reducing valve drops a high upstream pressure to a lower fixed downstream pressure. It works well where the downstream demand is steady. A flow control valve, by contrast, holds a controllable setpoint against changing flow and can be re-tuned for different process conditions. A quick exhaust valve is used for fast actuator venting often for on/off valves and does not provide modulating control. Where a process needs continuous modulation, a CPM-2, Unique RV-P, or Unique RV-ST is the standard. For lines needing both shut-off and regulation, the Unique RV-ST with plug seal removes the need for a separate shut-off valve, reducing the total footprint of the installation.