Alfa Laval Unique SSV Reverse Acting

The Unique Single Seat Reverse Acting valve meets the highest demands of your process in terms of hygiene and safety. Built on the well-proven Unique SSV platform it provides multiple solutions to prevent pressure shocks when the pipe work does not permit closing against product flow with standard single seat valves.

Working principle

The valve is a pneumatic seat valve in a hygienic and modular design for a wide field of duties, e.g. as a shut-off valve with two (2) or four (4) ports or as a change-over valve with three (3) to six (6) ports. The valve is remote-controlled by means of compressed air.

Standard Design

The Unique SSV Reverse Acting valve comes in a two or three body configuration. With its module built structure it is designed for flexibility and easy customization through the electronic configurator. The valve features an optimized life span of the seals through a defined compression design. The actuator is connected to the valve body using a yoke and all components are assembled with clamp rings.

Technical Data


Temperature range, standard lip seal: . -10°C to +140°C (EPDM)


Max. product pressure: . . . . . . . . . . 1000 kPa (10 bar)
Min. product pressure: . . . . . . . . . . Full vacuum
Air pressure: . . . . . . . . . . . . . . . . . 500 to 700 kPa (5 to 7 bar)

Valve Body Combinations

Actuator function

– Pneumatic downward movement, spring return.
– Pneumatic upward movement, spring return.
– Pneumatic upward and downward movement (A/A)

Physical Data


Product wetted steel parts: . . .1.4404 (316L)
Other steel parts . . . . . . . . . .1.4301 (304)
External surface finish . . . . . .Semi-bright (blasted)
Internal surface finish . . . . . . .Bright (polished), Ra < 0.8 µm
Product wetted seals: . . . . . .EPDM
Other seal . . . . . . . . . . . . . .NBR


A. Male parts or clamp liners in accordance with required standard.
B. Control and Indication: IndiTop, ThinkTop or ThinkTop Basic.
C. Product wetted seals in HNBR or FPM
D. Plug seals HNBR, FPM or TR2 plug (floating PTFE design)
E. High pressure actuator
F. Maintainable actuator
G. External surface finish bright

Note! For further details, see instruction ESE00202.

Other valves in the same basic design

The Unique SSV valve range includes several purpose built valves. Below are some of the valve models available, though please use the Alfa Laval computer aided selection tool (Anytime configurator) for full access to all models and options.
– Long stroke valve.
– Manually operated valve.
– Extended stroke available for 4″

The actuator comes with a 5 years warranty

Dimensions (mm)

Please note!
Opening/closing time will be effected by the following:

– The air supply (air pressure).
– The length and dimensions of the air hoses.
– Number of valves connected to the same air hose.
– Use of single solenoid valve for serial connected air actuator functions.
– Product pressure.

Air Connections Compressed air:
R 1/8″ (BSP), internal thread.

Pressure Drop/Capacity Diagrams

For the diagrams the following applies:
Medium: Water (20°C)
Measurement: In accordance with VDI2173
Pressure drop can also be calculated in Anytime configurator.
Pressure drop can also be calculated with the following formula:
Q = Kv x √∆p
Q = Flow in m3/h.
Kv = m3/h at a pressure drop of 1 bar (see table above).
∆ p = Pressure drop in bar over the valve.
How to calculate the pressure drop for an ISO 2.5″ shut-off valve if the flow is 40 m3/h 2.5″ shut-off valve, where Kv = 111 (See table above).
Q = Kv x √∆p
40 = 111 x √∆p

Pressure data for Unique Single Seat Valve Reverse Acting