BURKERT 20051631 is an electromotive 2-way globe control valve belonging to Type 3361, engineered for continuous, dynamic flow control under demanding chemical, process, and hygienic operational conditions. Powered by a 24 V DC supply, this specific assembly integrates a cast stainless steel CF3M valve body with G 1 internal thread connections (DN 25) and an AG2 linear electromotive actuator generating 1,300 N of positioning thrust. A precision ground ball screw translates motor rotation into a 6 mm/s linear stem displacement without slip or back-drive, maintaining steady plug positioning despite process pressure fluctuations. With an orifice seat diameter of 15 mm and a PEEK soft seat seal, this valve achieves DIN EN 60534-4 Leakage Class VI bubble-tight shut-off across an operating pressure span from 0 to 25 bar. Media travels below the valve seat with an equal percentage flow profile (50:1 theoretical rangeability) and a nominal capacity rating of Kvs 5.3 m³/h (Cv 6.2 gpm). The assembly incorporates an internal SAFEPOS energy-pack storage module, driving the valve to a normally opened (NO) fail-safe position upon line voltage failure.

Technical Data and Operating Specifications

Operating performance conforms to DIN EN 60534 standards for industrial process control valves. Actuator force, timing, and environmental limits are detailed below:

Parameter	Specification
Valve Type	Type 3361 electromotive 2-way globe control valve
Article Number (MPN)	20051631
Nominal Diameter (Port)	DN 25 (NPS 1)
Port Connection Type	G 1 internal thread (DIN ISO 228-1)
Seat Diameter (Orifice)	15 mm (9/16")
Flow Coefficient (Kvs)	5.3 m³/h (water at +20 °C)
Theoretical Rangeability	50:1 (equal percentage curve)
Flow Direction	Below seat (marked 2 → 1 on body)
Operating Pressure Range	0 to 25 bar(g)
Nominal Pressure Class	PN 25 (DIN EN 1333), Class 150 (DIN EN 1759)
Medium Temperature Range	-10 °C to +185 °C
Ambient Temperature Range	-25 °C to +65 °C (derating curves apply at high fluid temperatures)
Fluid Viscosity	Up to 600 mm²/s
Operating Voltage	24 V DC ±10% (maximum residual ripple 10%)
Current Consumption	Maximum 3 A at peak mechanical load (includes 1 A SAFEPOS charging current); +2 A at minimum operating temperature
Standby Power	2 to 5 W
Positioning Speed	6 mm/s
Typical Closing Time	3.3 s
Deadband (Positioning)	±0.1%
Duty Cycle	100% continuous
Fail-Safe Energy Return	Integrated SAFEPOS energy-pack (normally opened delivery setting)
Protection Class	Class III (DIN EN 61140)
Enclosure Rating	IP65 / IP67 (DIN EN 60529), NEMA 4X
Conformity & Certification	Regulation (EC) No 1935/2004, Ecolab detergent resistance (F&E/P3-E No. 40-1)

Construction Materials

The closed actuator housing and smooth exterior surfaces resist atmospheric corrosion, mechanical impacts, and washdown chemicals.

Item No.	Actuator Component (AG2)	Material
1	Blind cover / dummy cover	PPS (Polyphenylene sulphide)
2	Actuator cover	PPS
3, 6	O-ring seals	EPDM
4	Actuator main housing	Powder-coated aluminium
7	Actuator base	PPS

Item No.	Valve Body & Trim Component	Material
1	Spindle (Stem)	Stainless steel 1.4401 (316) / 1.4404 (316L)
2	Spindle packing seal	PTFE V-rings (filled) with stainless steel spring compensation
3	Spindle guide	Stainless steel 1.4404 (316L)
4	Packing gland tube	Stainless steel 1.4401 (316)
5	Body gasket seal	Graphite or PTFE
6	Valve seat seal	PEEK (Polyetheretherketone) seal disc
7	Control cone	Stainless steel 1.4571 (316Ti)
8	Screwed-in valve seat	Stainless steel 1.4571 (316Ti)
9	Valve seat O-ring	EPDM or PTFE
10	Valve body	Stainless steel CF3M (cast 316L equivalent)

Dimensional Data

BURKERT 20051631 comprises an AG2 actuator atop a DN 25 G 1" threaded globe body. Dimensions below are expressed in millimeters.

Dimension	Description	DN 25 (G 1") Value
H1	Actuator height above pipe centerline (standard blind cover)	446 mm
H2	Actuator height with integrated fieldbus gateway module	518 mm
D	Port connection thread size	G 1 (DIN ISO 228-1)
E	Thread engagement depth	18 mm
LM	Valve body face-to-face installation length	90 mm
AF	Width across flats on pipe ports	41 mm

In the fully seated closed position, the actuator raises an additional 2 mm when adjusting without tight seating function.

Electrical Connections and Terminal Assignments

Electrical connections interface through standard industrial M12 connectors located on the side of the AG2 actuator base.

Connector Identifier	Connector Format	Description
X1	M12 male plug, 8-pin, A-coded	Analogue/digital input and output control signals
X3	M12 male plug, 5-pin, A-coded	24 V DC power supply and büS/CANopen communication

Pin Assignment for Control Signals (X1)

Pin No.	Signal Assignment
1	Digital input + (10 to 30 V DC = High, 0 to 5 V DC = Low)
2	GND reference for digital input and digital outputs
3	Digital output 2 + (PNP, max. 100 mA)
4	Digital output 1 + (PNP, max. 100 mA)
5	Analogue output - (galvanically isolated)
6	Analogue output + (0/4 to 20 mA, max. 800 Ω load; or 0 to 5/10 V, max. 10 mA)
7	Setpoint / analogue input -
8	Setpoint / analogue input + (0/4 to 20 mA at 70 Ω, or 0 to 5/10 V at 22 kΩ)

Pin Assignment for Supply Voltage and büS (X3)

Pin No.	Signal Assignment
1	CAN shield / cable shield
2	Operating voltage +24 V DC (±10%)
3	GND / CAN_GND
4	CAN_H (büS communication line)
5	CAN_L (büS communication line)

Fluidic Characteristics and Flow Curves

The valve features an equal percentage flow profile conforming to DIN EN 60534-2-4. Water flow capacity across stroke progression for seat size 15 mm in a DN 25 body is given below:

Stroke (%)	Kv Value (m³/h)
5%	0.14
10%	0.17
20%	0.22
30%	0.35
40%	0.52
50%	0.80
60%	1.2
70%	1.8
80%	2.9
90%	4.0
100% (Kvs)	5.3 (Cv 6.2 gpm)

The KvR value represents the lowest flow coefficient at which the profile tolerance complies with DIN EN 60534-2-4. For seat sizes greater than 10 mm, KvR is evaluated at 5% stroke.

Operating Limits: Pressure, Temperature, and Seat Materials

Permissible line pressure depends on fluid temperature in accordance with DIN EN 12516-1 (PN 25) and ASME B16.34 (Class 150). For a PEEK soft seal, temperature boundaries and leakage ratings compare against alternate seat options as follows:

Seat Material	Tight Sealing Required	Seat Leakage Class (DIN EN 60534-4)	Permissible Medium Temperature	Application Recommendations
Stainless steel 1.4571	No	Class III / IV	-40 °C to +230 °C	Permissible leakage 0.1% to 0.01% of nominal flow. Impervious to cavitation and abrasive particles.
Hardened stainless steel	No	Class III / IV	-40 °C to +230 °C	For extreme erosion, high velocities, and wet steam throttling.
PTFE	Yes	Class VI	-40 °C to +130 °C	Bubble-tight soft seal; recommended for applications up to +130 °C.
PEEK (20051631)	Yes	Class VI	-10 °C to +185 °C (rated to +230 °C in dry heat)	Bubble-tight closure. Recommended for elevated temperatures above +130 °C.

Ambient Temperature Derating

At maximum medium temperatures of +185 °C, the permissible ambient operating temperature must be derated according to the AG2 thermal limit curves. For units fitted with the SAFEPOS energy-pack, high ambient exposure combined with continuous motor duty reduces internal capacitor service life.

Actuator Drive, Control, and SAFEPOS Energy-Pack

Position control operates as a closed loop utilizing an internal non-contact displacement transducer.

An external analogue setpoint CMD (0/4–20 mA or 0–5/10 V) is continuously compared against the measured stem stroke POS. If a deviation Xd1 exists, motor controller CTRL modulates the brushless motor to align position with a deadband accuracy of ±0.1%.

Local User Interface

Local configuration on 20051631 is managed via four DIP switches and two push buttons positioned under the plastic blind cover:

• DIP Switch 4: Toggles between AUTOMATIC mode (downward position) and MANUAL mode (upward / ON position).
• Internal Buttons: Provide electrical manual OPEN and CLOSE actuation.
• 360° LED Light Ring: Emits status colors through the translucent ring on the dummy cover, indicating operating mode, valve opening position, warnings, and device diagnostics.
• Mechanical Indicator: A yellow indicator pin beneath the transparent viewing window tracks stem position independently of electrical power.

SAFEPOS Energy-Pack Functions

The integrated SAFEPOS storage unit consists of high-reliability supercapacitors designed for automated fail-safe operation:

• Safety Position: Drives the valve to the fully open position (factory default for 20051631) when external power drops below operating threshold.
• Charging Time: Reaches full charge within a maximum of 120 seconds after 24 V DC power application.
• Service Life: Up to 10 years depending on operating ambient temperature. An automated monitoring algorithm generates diagnostic warnings through the LED ring and büS interface before end of life is reached.

Manual Override Operation

When electrical supply is disconnected, the valve position can be adjusted using the mechanical manual override located beneath the blind cover.

Mechanical Override Precautions

Actuate the mechanical override only when the supply voltage is disconnected and the SAFEPOS energy-pack is completely discharged. Never apply more than 2 Nm torque to the 3 mm hex socket; exceeding this limit damages internal gears.

1. Disconnect 24 V DC supply voltage. Confirm that the 360° LED ring is completely dark.
2. Rotate the dummy cover counter-clockwise and lift off.
3. Insert a 3 mm Allen key into the central manual override socket.
4. Press downward gently to engage the mechanical drive coupling.
5. Rotate counter-clockwise to open the valve; rotate clockwise to close the valve.
6. Observe position changes on the yellow mechanical position indicator.
7. Remove the Allen key, refit the dummy cover, and rotate clockwise until alignment marks align.

Maintenance, Trim Replacement, and Commissioning

Routine maintenance covers replacement of the control cone, spindle chevron packing seals, and the threaded valve seat ring.

Tightening Torques for Maintenance

Adhere strictly to factory assembly torques during reassembly:

• Actuator base to valve body (DN 25): 60 ±3 Nm (44 ±2 lbf·ft)
• Valve seat ring (15 mm seat in DN 25 body): 20 +3 Nm (using installation tool 652606)
• Spindle guide in packing gland tube (14 mm spindle): 25 Nm
• Actuator housing cover screws (T25): 5 Nm
• SAFEPOS bracket locking screw (T10): 1.1 Nm

Commissioning with X.TUNE

After replacing the valve seat, control cone, or seal set, calibrate the positioner by running the automatic X.TUNE function:

1. Isolate fluid pressure completely. Never run X.TUNE while process pressure is applied.
2. Remove the dummy cover and switch DIP 4 to MANUAL.
3. Simultaneously hold down the internal OPEN and CLOSE buttons for 5 seconds.
4. The 360° LED ring illuminates orange while the actuator detects mechanical stop limits.
5. Once the LED resets to its standard operational state, restore DIP 4 to AUTOMATIC.

Compatible Accessories

Accessory Description	Order Number
Replacement SAFEPOS energy-pack (AG2)	285834
SIM card for device parameter backup	291773
M12 female socket with 5 m cable, 4-pin, A-coded (X3 power supply)	918038
M12 female socket with 2 m cable, 8-pin, A-coded (X1 signal interface)	919061
USB büS-Interface Set 1 (includes power supply, büS stick, terminating resistor, Y-splitter, 0.7 m cable)	772426
büS adapter cable (M12 to Micro-USB service interface, 0.3 m)	774931
Valve seat installation wrench for DN 25	652606
Modified packing gland socket wrench (SW21, 14 mm spindle)	683223
Holding device for pipe sizes DN 25 to DN 50	693771