Alfa Laval Unique RV-P Regulating Valve

Unique RV-P is a hygienic electro-pneumatic regulating valve for use in applications which require precision control of pressure, flow, temperature, level in tanks etc.

Working principle

It is remotely-controlled by an electrical signal and compressed air. The IP-converter, which is an integrated part of the actuator, converts the electrical signal to a pneumatic signal. This signal conversion is based on a highly accurate and reliable contactless AMR sensor making it insensitive to vibrations and pressure shocks. The pneumatic signal is transmitted to the integrated positioner which operates by means of the force-balance principle, ensuring that the position of the actuator piston is directly proportional to the input signal. Signal range and zero point can be adjusted individually. The actuator can be used for split-range operation by using a different measuring spring.

Standard design

The valve is built on the Unique SSV platform and consists of valve body, valve plug, lip seal, bonnet and an external actuator. The actuator with the bonnet is fitted to the valve body by means of a clamp. The Kv value is flexible as lower element can be exchanged.

Technical Data

Valves
Max. product pressure: . . . . . 1000 kPa (10 bar).
Min. product pressure: . . . . . Full vacuum.
Temperature range: . . . . . . . . 10°C to 140°C (EPDM).
Flow range Kv (∆ P = 1bar): . . 0.5 to 110 m3/h.
Max. pressure drop: . . . . . . . 500 kPa (5 bar).

Actuator
Air quality
Air connection: . . . . . . . . . . . 6/4 air tube with air fitting R1/8″ (BSP)
Max. pressure: . . . . . . . . . . . 600 kPa (6 bar).
Working pressure: . . . . . . . . 400 kPa (4 bar).
Max. size of particles: . . . . . . 0.01 mm.
Max. oil content: . . . . . . . . . 0.08 ppm.
Dew point: . . . . . . . . . . . . . 10°C below ambient temp. or lower.
Max. water content: . . . . . . . 7.5 g/kg.

I/P converter
Signal range: . . . . . . . . . . . . 4 – 20 mA (standard).
Input resistance: . . . . . . . . . . 200
Inductivity/capacitance: . . . . . Negligible.

Physical Data

Materials, Valves

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

Materials, Actuator

Actuator cases: . . . . . . . . . .Aluminium with plastic coating.
Diaphragms: . . . . . . . . . . . .NBR with reinforced fabric insert.
Springs: . . . . . . . . . . . . . . .Stainless steel uncovered/spring steel epoxy resin coated.
Actuator stem: . . . . . . . . . . .Polyamide.
Screws, nuts: . . . . . . . . . . . .Stainless steel, polyamide.
Other parts: . . . . . . . . . . . . .Stainless steel.

Valve body combinations

Accuracy

Deviation: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≤1.5%
Hysteresis: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≤0.5%.
Sensitivity: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . <0.1%.
Influence of air supply pressure: . . . . . . . . . . . . . . . . . . . . . . . . . . ≤0.1% between 1.4 and 6 bar.
Air consumption at steady state condition: . . . . . . . . . . . . . . . . . . . With 0.6 bar signal pressure and supply pressures up to 6 bar ≤100 In/h.
Ambient temperature: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -25°C to +70°C.
Protection class: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . IP 66

Flow sizes/tube connections

Options

A. Male parts or clamp liners in accordance with required standard.                                                                                                                                                                                                                                       B. Lip seal of HNBR or Fluorinated rubber (FPM).
C. Profibus communication
D. Aseptic configuration Max 8 bar

Dimensions (mm)

Capacity diagram

For ∆ P= 100 kPa (1bar).                                              

                                                                Standard                                                                           Aseptic

Note! For the diagram the following applies:
Medium: Water (20°C).
Measurement: In accordance with VDI 2173.
Alfa Laval recommend max. flow velocity in tubing and valves to be 5 m/sec.

Pressure drop calculation

The Kv designation is the flow rate in m3/h at a pressure drop of 1 bar when the valve is fully open (water at 20°C or similar liquids). To select the Kv value it is necessary to calculate the Kvq value using the following formula:

Where:
Kvq = Kv value at specific flow and specific pressure drop.
Q = Flow rate (m3/h).
∆ P = Pressure drop over valve (bar).

Electrical connection – Analoug 4-20 mA

4-20 mA control signal
Route the two-wire line to the screw terminals marked “11 and 12”, whereby the correct polarity has to be ensured
1. Open the cover of the positioner for electrical connection                                                                                                                                                                                                                                                         2. Fit the cable through the cable gland and connect the cable wires to the terminal screws. (+11 and -12)
3. Tighten the cable gland and close the cover of the positioner

Electrical connection – Profibus PA

Bus control signal

Route the two-wire bus line to the screw terminals marked “IEC 1158-2”, whereby no polarity has to be observed

1. Open the cover of the positioner for electrical connection
2. Fit the bus cable through the cable gland and connect the cable wires to the terminal screws. (IEC 1158-2)
3. Tighten the cable gland and close the cover of the positioner
By searching on positioner type 3730-4 you can either retrieve the GSD files for PROFIBUS PA communication directly from the World Wide Web server of Samson or the PROFIBUS User Organization.