BURKERT 20011744 (Type 2875) is a direct-acting 2/2-way proportional solenoid control valve configured for closed-loop regulating circuits. Operating under circuit function A (normally closed), the valve uses an elastomeric seat seal that closes bubble-tight up to its 10 bar nominal pressure rating. The plunger assembly is supported in a frictionless suspension, eliminating mechanical stick-slip behavior and ensuring sensitive adjustment characteristics across its 1:100 operating range.

This specific article 20011744 is built with a stainless steel body, G 3/8 female threaded process ports, and a DN 3.0 mm orifice. It delivers a water flow coefficient Kv of 0.25 m³/h and a nominal air flow rate QNn of 270 l/min. Configured with a 12 V DC electromagnetic coil and FKM seals, it is specially degreased and tested for oxygen service in compliance with DIS 1000020797, making it suitable for clean gas delivery and analytical control applications.

Combinable System Components

Type 2875 valves operate as the final control element in electronic process loops and can be combined with standard Bürkert control electronics and connection hardware:

• Type 8605: Digital PWM control electronics designed for proportional solenoid valves. Converts standard analog command signals (4...20 mA or 0...10 V) into a pulse-width modulated current signal, featuring integrated coil temperature compensation, programmable ramp profiles, and adjustable minimum/maximum current thresholds.
• Type 2518: Cable plug connector conforming to DIN EN 175301-803 Form A, ensuring IP65 ingress protection when properly tightened to the solenoid coil interface.
• Type 8611 eCONTROL: Universal electronic controller designed for compact flow, pressure, or temperature regulation loops.

Technical Specifications

Parameter	Specification Details
Circuit Function	Circuit function A (CF A): 2/2-way, normally closed, flow below seat
Actuation Principle	Direct-acting proportional plunger valve, frictionless plunger guide
Orifice Size (DN)	3.0 mm
Port Connection	G 3/8 internal thread
Flow Coefficients	Kv (water): 0.25 m³/h; QNn (neutral gas): 270 l/min
Operating Pressure Range	-1.0 bar to 10.0 bar (gauge pressure relative to atmosphere)
Maximum Differential Pressure	10.0 bar
Body Material	Stainless steel
Seal Material	FKM (fluor rubber) seat seal and outer seal
Operating Voltage	12 V DC (±10%)
Nominal Power Consumption	16 W
PWM Frequency	400 Hz to 500 Hz (variant for higher differential pressures)
Positioning Behavior	Hysteresis < 5%; Repeat accuracy < 0.5% FS; Response sensitivity < 0.25% FS
Actuating Time (10% to 90%)	< 25 ms
Duty Cycle	100% continuous operation (ED)
Fluid Temperature Range	-10 °C to +60 °C (extended capability -10 °C to +90 °C with FKM)
Ambient Temperature Range	-10 °C to +55 °C
Fluid Kinematic Viscosity	Max. 21 mm²/s (21 cSt)
Electrical Connection	Plug pattern Form A according to DIN EN 175301-803 (plug not included)
Ingress Protection Rating	IP65 with properly mated Type 2518 cable plug
Cleanliness Standard	Oxygen version, free of oil, grease, and silicone per DIS 1000020797

Flow Calculation and Sizing

Accurate nominal diameter sizing ensures proper control stability and avoids valve saturation. The sizing must account for both sub-critical and supercritical flow regimes across the valve seat:

Pressure Drop Regime	Kv Value for Liquids [m³/h]	Kv Value for Gases [m³/h]
Sub-critical ($p_2 > \frac{p_1}{2}$)	$= Q \cdot \sqrt{\frac{\rho}{1000 \cdot \Delta p}}$	$= \frac{Q_N}{514} \cdot \sqrt{\frac{T_1 \cdot \rho_N}{p_2 \cdot \Delta p}}$
Supercritical ($p_2 < \frac{p_1}{2}$)	$= Q \cdot \sqrt{\frac{\rho}{1000 \cdot \Delta p}}$	$= \frac{Q_N}{257 \cdot p_1} \cdot \sqrt{T_1 \cdot \rho_N}$

Where:

• $K_v$: Flow coefficient [m³/h], measured for water at $\Delta p = 1\text{ bar}$
• $Q_N$: Standard flow rate [m³_N/h] at 1.013 bar absolute and 0 °C (273 K)
• $p_1$: Inlet absolute pressure [bar]
• $p_2$: Outlet absolute pressure [bar]
• $\Delta p$: Differential pressure $p_1 - p_2$ [bar]
• $\rho$: Fluid density [kg/m³]
• $\rho_N$: Gas standard density [kg/m³]
• $T_1$: Medium absolute temperature $[(273 + t)\text{ K}]$

Pressure Drop and Sizing

For proportional valves to maintain a linear system characteristic, the nominal diameter must be selected so that at full opening, approximately 25% of the total circuit pressure drop occurs across the valve ($\Delta p_{valve} \approx 25%$ of total $\Delta p$). If the differential pressure exceeds half the nominal pressure value, flow discontinuities may occur.

Dimensions

Type 2875 valves are available in threaded body and sub-base configurations. The dimensional values for standard threaded variants are tabulated below:

Port Connection Size	Thread Type	Thread Depth F1/F2 [mm]	Thread Identification G1/G2
3/8"	G internal thread (F1, G1)	12.0 mm	G 3/8
3/8"	NPT internal thread (F2, G2)	10.3 mm	NPT 3/8
1/2"	G internal thread (F1, G1)	14.0 mm	G 1/2
1/2"	NPT internal thread (F2, G2)	13.7 mm	NPT 1/2

Product Operation and Control

Control of Type 2875 is achieved through pulse-width modulation (PWM). The duty cycle of the PWM control signal determines the average effective coil current, which counteracts an opposing spring to set the exact plunger lift position.

Type 8605 control electronics modulate the current between the set minimum and maximum operating thresholds. When operating the higher differential pressure variant with a 12 V DC coil, a recommended PWM switching frequency of 400 Hz to 500 Hz provides stable positioning dynamics. Integrated coil temperature compensation inside Type 8605 automatically offsets coil resistance changes resulting from ohmic heating during continuous operation.

Ordering Information and Product Variants

Type 2875 covers multiple orifices and pressure ratings across brass and stainless steel bodies. Article 20011744 represents the 12 V DC stainless steel execution with oxygen cleaning. The standard 24 V DC product variants for higher differential pressures are detailed below for technical cross-reference:

Circuit Function	Port Connection	Orifice [mm]	Approvals	Kvs (Water) [m³/h]	Nominal Pressure [bar]	Article No. Brass Body	Article No. Stainless Steel Body
CF A (NC)	G 3/8	2.0	None	0.12	25	239040	239085
CF A (NC)	G 3/8	2.0	UR	0.12	25	275000	275005
CF A (NC)	G 3/8	3.0	None	0.25	10	239086	239087 (24 V DC)
CF A (NC)	G 3/8	3.0	UR	0.25	10	275001	275006
CF A (NC)	G 3/8	4.0	None	0.45	8	239088	239089
CF A (NC)	G 3/8	4.0	UR	0.45	8	274090	274091
CF A (NC)	G 1/2	6.0	None	0.80	4	239090	239091
CF A (NC)	G 1/2	6.0	UR	0.80	4	275002	275007
CF A (NC)	G 1/2	8.0	None	1.10	2	239092	239093
CF A (NC)	G 1/2	8.0	UR	1.10	2	275004	275008
CF A (NC)	G 1/2	9.5	None	1.40	0.7	291586	314558

Specific Article Configuration

Article 20011744 is configured with a 12 V DC coil, G 3/8 stainless steel body, DN 3.0 mm orifice, 10 bar nominal pressure, and special oil-, grease-, and silicone-free preparation for oxygen duty.

Accessories Ordering Chart

Accessory Description	Electrical Interface / Connection	Voltage Rating	Article Number
Type 2518 Cable Plug Form A	Without wiring (straight pass-through)	0...250 V AC/DC	314802
Type 8605 Control Electronics	Cable plug with PG cable gland (200...1000 mA)	12 V DC / 24 V DC	316530
Type 8605 Control Electronics	Cable plug with M12 connection (200...1000 mA)	12 V DC / 24 V DC	316528
Type 8605 Control Electronics	Cable plug with PG cable gland (500...2000 mA)	12 V DC	316529
Type 8605 Control Electronics	Cable plug with M12 connection (500...2000 mA)	12 V DC	316526
Type 8605 Control Electronics	DIN-rail mounting module (200...1000 mA)	12 V DC / 24 V DC	316532
Type 8605 Control Electronics	DIN-rail mounting module (500...2000 mA)	12 V DC	316533

Installation and Maintenance Guidelines

• Mounting Orientation: Mountable in any orientation, preferably with the solenoid actuator upright.
• Flow Direction: Flow enters port 1 and discharges beneath the valve seat (flow direction indicated by body markings). Reverse flow is not permitted.
• Pipeline Preparation: Flush piping clean of debris before valve insertion. When sealing G 3/8 pipe threads with PTFE tape, ensure tape remains strictly outside the wetted internal flow path to prevent seat contamination.
• Electrical Termination: Connect through a Form A DIN EN 175301-803 connector. Ensure the grounding terminal is firmly connected to protective earth.

Oxygen Service and Cleanliness

Because article 20011744 is certified free of oil and grease per DIS 1000020797 for oxygen applications, avoid contacting the wetted passages with unwashed tools, hydrocarbon-based thread sealants, or contaminated compressed air lines during installation.

Auxiliary Explosion Protection Option (Coil Type 072x)

For hazardous location installations, the Type 2875 platform can be supplied with the encapsulated Type 072x coil (ATEX II 2 G Ex mb IIC T4 Gb / II 2 D Ex mb IIIC T130 °C Db; IECEx EPS 15.0066X). In such applications, the coil must be connected via an upstream fuse rated to nominal current (max. $3 \times I_N$ per IEC 127) or motor protection switch, and metallic valve bodies are mandatory for fuel dispensing service.