Bürkert 367641 (Type 2871) direct-acting solenoid control valve is used as the regulating unit in control loops. Due to an elastomeric seat seal, the valve closes tight (integrated shut-off function) up to the DN specific nominal pressure. The plunger of the valve is assembled frictionless, which leads to an extraordinary adjustment characteristic. This valve is particularly suitable for demanding control tasks, offering an excellent range, very good response, and a compact valve design.

Product Structure

Item	Description	Item	Description
1	Adjusting screw (do not adjust!)	2	Valve body
3	Labelling flow direction

Type Label (Example)

Item	Description	Item	Description
1	Type	2	Circuit function
3	Seat size	4	Seal material
5	Body material	6	Permitted pressure range
7	Current type, power consumption	8	PWM frequency
9	Manufacture code	10	Article number
11	Operating voltage	12	Port connection

General Technical Data

Product Properties	Value
Material
Seal	EPDM (FKM available for other variants)
Body	Stainless steel (Brass available for other variants)
Performance Data
Hysteresis	< 5%
Repeat accuracy	< 0.25% FS
Response sensitivity	< 0.25% FS
Setting range	1:100 (High differential pressure variant)
Actuating time (10...90%)	< 15 ms
Pressure range	-1...3 bar (also applicable for technical vacuum)
Duty cycle	100% continuous operation
Electrical Data
Operating voltage	12 V DC
Power consumption	Max. 5 W
PWM frequency	800...1000 Hz (High differential pressure variant)
Medium Data
Operating medium	Neutral gases, liquids on request
Medium temperature	-30 °C...+90 °C (with EPDM)
Viscosity	Max. 21 mm²/s (21 cSt)
Product Connections
Electrical connection	Strands or plug (cable plug Type 2507, form B according to industry standard)
Port connection size	Sub-base (Flange)
Environment and Installation
Degree of protection	IP65
Installation position	As required, preferably with actuator upright
Ambient temperature	Max. +55 °C

Circuit Function

Circuit function (CF)	Description
A	2/2-way solenoid proportional control valve, Direct-acting, Normally closed

Approvals and Conformities

• Conformity: In accordance with the Declaration of conformity, the product is compliant with the EU Directives.
• North America (USA/Canada): Optional UL Recognized for the USA according to UL 429 (Electrically operated valves).
• Foods and beverages/Hygiene:
  • USP: United States Pharmacopeial Convention (USP). All wetted materials are biocompatible.
  • FDA: Code of Federal Regulations. All wetted materials are compliant with the FDA.
  • EC 1935/2004: All wetted materials are compliant with EC Regulation 1935/2004/EC.

Dimensions

Sub-base variant for DN from 0.6 mm

(Applies to the 2.0 mm orifice configuration of this model)

Performance Specifications

Flow Characteristic

Determination of the Kv value:

Pressure drop	Kv value for liquids [m³/h]	Kv value for gases [m³/h]
Sub-critical $p_2 > \frac{p_1}{2}$	$= Q \sqrt{\frac{\rho}{1000\Delta p}}$	$= \frac{Q_N}{514}\sqrt{\frac{T_1\rho_N}{p_2\Delta p}}$
Supercritical $p_2 < \frac{p_1}{2}$	$= Q \sqrt{\frac{\rho}{1000\Delta p}}$	$= \frac{Q_N}{257p_1}\sqrt{T_1\rho_N}$

Exemplary Characteristic Curve

Note on Sizing

The dimensioning of the nominal diameter is very important for proportional valves to function properly within the application. The nominal diameter must be selected so that the desired flow range is achieved and, when the valve is fully open, a sufficient portion of the total pressure drop occurs across the valve.

Reference value: $\Delta p_{valve} > 25%$ of the total pressure drop.

If the differential pressure exceeds half the value of the nominal pressure, discontinuities may occur.

Product Operation and Installation

Control Unit

Valve control takes place through a PWM signal (pulse-width modulation). The duty cycle of the PWM signal determines the coil current and hence the position of the plunger. The Bürkert control electronics Type 8605 converts an analogue signal to a reference value corresponding to the valve type PWM signal and provides additional functions such as temperature compensation.

Installation

DANGER!

Risk of injury due to high pressure and escaping medium.

• Switch off the pressure before working on the device or system. Vent or drain the pipes.
• For valve body with flange connection: check seals are seated correctly.

NOTE!

• Do not uninstall proportional valve.
• Adjusting screw (see Product Structure) do not adjust.

Prior to installation:

• Clean pipes and flange connections.
• Install a dirt trap in the direction of the current before the valve (mesh width 0.02... 0.4 mm, depending on nominal diameter).
• For valve body with flange connection: check the seals are correctly seated on the underside of the valve body.

Install valve on base block (flange connection):

• Fasten the valve to the base block using both fastening screws.
• Tightening torque 0.8...1.2 Nm.

PWM Frequency Settings

NOTE!

Functional impairment with incorrect PWM frequency. Set correct PWM frequency.

Type	Voltage [V]	Power rating [W]	$f_{LO}$ [Hz]	$f_{HI}$ [Hz]	$I_{max}$ [mA]
2871 for high Δp (NF64)	12	5	800	1000	420