BURKERT 378776 (Type 2873) is a direct-acting 2/2-way proportional solenoid control valve designed for regulating gaseous media in continuous control loops. Operating under circuit function A (normally closed, flow directed below the seat), this unit combines a wetted stainless steel body, NPT 1/4 female process connections, a 2.0 mm orifice, and FKM seat seals. Engineered for specialized dry gas and oxygen systems, article 378776 is delivered oil-, fat-, and silicon-free according to DIS 1000020797 standards. Its frictionless plunger suspension eliminates stick-slip behavior, yielding a 1:200 control range, repeatability under 0.5% FS, and an operating response time under 20 ms across nominal pressures from -1 to 8 bar.

Technical Specifications

Parameter	Value
Valve Type	Type 2873 direct-acting proportional solenoid valve
Article Number	378776
Circuit Function	A (2/2-way, normally closed, inlet port 1 P/NC)
Actuator Type	Plunger valve with frictionless suspension
Orifice Size (DN)	2.0 mm
Flow Direction	Below seat
Fluidic Port Connection	2 ports, NPT 1/4 internal thread
Wetted Body Material	Stainless steel
Seat & External Seal	FKM (Fluor rubber)
Suitable Media	Gaseous media (not suitable for liquid media in this configuration)
Nominal Pressure Range	-1.0 bar to 8.0 bar
Maximum Differential Pressure	4.0 bar
Flow Coefficient Kv (Water)	0.100 m³/h
Nominal Flow Rate QNn (Gas)	108 l/min
Operating Voltage	12 V DC (rated min/max 12 V DC)
Maximum Power Consumption	9 W
PWM Frequency	1100 Hz to 1200 Hz (nominal 1200 Hz)
Duty Cycle	100% continuous operation
Setting Range	1:200
Medium Temperature	-10 °C to +60 °C
Ambient Temperature	-10 °C to +55 °C
Electrical Connection	Plug pattern Form A according to DIN EN 175301-803
Cable Plug Delivery Status	Not included (must be ordered separately)
Degree of Protection	IP65 (with properly mounted Type 2518 cable plug)
Cleanliness Standard	Free of oil, grease, and silicon per DIS 1000020797 (Oxygen version)

Control Performance and Dynamics

Type 2873 functions as an actuator in closed control loops. The solenoid core is mounted without mechanical sliding friction, preventing hysteresis spikes and stick-slip resistance when modulating flow.

Positioning behaviour is characterized by the following verified values:

• Hysteresis: < 5%
• Repeat accuracy: < 0.5% FS (with flow measurement)
• Response sensitivity: < 0.25% FS (with flow measurement)
• Setting range: 1:200
• Actuating time (10% to 90%): < 20 ms
• Tight shut-off: integrated elastomeric seat seal provides bubble-tight isolation up to the DN-specific nominal pressure of 8 bar.

Valve positioning is executed through pulse-width modulation (PWM). The duty cycle of the PWM signal sets the coil current and armature stroke position. The 12 V DC coil operates at a PWM frequency between 1100 Hz and 1200 Hz.

Dimensional Details

The threaded version of Type 2873 provides female pipe ports in brass or stainless steel. Dimensions for female thread depth are standardized per connection type:

Port Connection	Thread Specification (A)	Thread Depth B (mm)
NPT 1/4 (Article 378776)	NPT 1/4	10
G 1/4	G 1/4	12
G 1/8	G 1/8	8
NPT 1/8	NPT 1/8	7

INFO

Article 378776 features an NPT 1/4 female thread connection with a thread engagement depth of 10 mm and a compact stainless steel valve body.

Flow Characteristics and Sizing

Flow rate through the valve orifice is calculated using standardized pneumatic formulas for subcritical and supercritical flow regimes:

• Subcritical flow regime ($p_2 > \frac{p_1}{2}$): $$K_v = \frac{Q_N}{514} \sqrt{\frac{T_1 \rho_N}{p_2 \Delta p}}$$

• Supercritical flow regime ($p_2 < \frac{p_1}{2}$): $$K_v = \frac{Q_N}{257 p_1} \sqrt{T_1 \rho_N}$$

Where:

• $K_v$: Flow coefficient in m³/h
• $Q_N$: Standard flow rate in m³_N/h (reference conditions: 1.013 bar, 0 °C / 273 K)
• $p_1$: Absolute inlet pressure in bar
• $p_2$: Absolute outlet pressure in bar
• $\Delta p$: Differential pressure ($p_1 - p_2$) in bar
• $\rho_N$: Standard gas density in kg/m³
• $T_1$: Medium temperature in Kelvin ($273 + t$)

Sizing Recommendation

To prevent the linear valve characteristic curve from degenerating into a curved system characteristic, design the process such that $\Delta p_{valve} > 25%$ of the total system pressure drop at maximum flow. Discontinuities in the characteristic curve can occur if the differential pressure between inlet and outlet exceeds half the nominal pressure rating.

Oxygen Service and Media Conditions

Article 378776 is manufactured for gaseous service and oxygen applications:

• Cleanliness rating: certified oil-, fat-, and silicon-free according to BURKERT internal standard DIS 1000020797.
• Media suitability: neutral gases and oxygen. Liquids are not permissible for this specific article execution.
• Operating pressure: spans from a partial vacuum of -1 bar up to an overpressure of 8 bar.
• Temperature threshold: medium temperature must remain between -10 °C and +60 °C, and ambient temperature between -10 °C and +55 °C.

Compatible System Electronics

Operating the 12 V DC proportional coil requires an external electronic driver capable of generating the required PWM signal:

Accessory	Type / Designation	Details & Article Reference
Cable Plug	Type 2518, Form A	DIN EN 175301-803 connector without internal circuitry (0–250 V AC/DC), Article 314802. Must be ordered separately.
Control Electronics	Type 8605 Cable Plug	Converts 4–20 mA or 0–10 V analogue setpoints to PWM. Features coil temperature compensation and ramp profiling. Suitable for 12 V DC coils up to 2000 mA (e.g., Article 316529 / 316526).
Universal Controller	Type 8611 eCONTROL	Multi-parameter continuous controller supporting proportional valve loop integration.

Installation and Maintenance Guidelines

• Mounting position: universal, preferably with the solenoid coil facing upright.
• Flow direction: ensure inlet pressure enters at port 1 (P/NC) to flow underneath the valve seat.
• Pipe preparation: flush piping before installation to eliminate particulates; upstream filtration is required to prevent orifice contamination.
• Thread sealing: apply PTFE sealing tape to male pipe threads only; do not allow loose tape edges to enter the valve cavity.
• Wrench points: use an open-end wrench on the valve body flats; do not use the solenoid coil housing as a lever arm.
• Electrical connection: ensure electrical continuity between the protective conductor of the coil and the core guide tube.
• Duty cycle: designed for 100% continuous energization; do not open the hermetically sealed magnetic core during operational maintenance.