Burkert Type 2873 (Model 321213) is a direct-acting 2-way standard solenoid proportional control valve 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 such as high control range and dry gases.

Key Features

• Excellent range
• Very good response
• Compact valve design
• Orifice sizes 0.8 ... 6 mm
• Optional: Explosion-protected coil

General Technical Data

Product properties	Description
Material
Seal	FKM, EPDM
Body	Brass, stainless steel
Circuit function	A (2/2-way solenoid proportional control valve, Direct-acting, Normally closed)
Performance data
Hysteresis	< 5 %
Repeat accuracy	< 0.5 % FS
Response sensitivity	< 0.25 % FS
Setting range	1:200
Actuating time (10...90 %)	< 20 ms
Pressure range	0...16 bar
Duty cycle	100 % continuous operation
Electrical data
Operating voltage	24 V DC (at 5 W and 24 V coil) (12 V on request)
Power consumption	Max. 9 W
Maximum coil current	420 mA (at 9 W and 24 V coil)
PWM frequency	1200 Hz
Medium data
Operating medium	Neutral gases, liquids on request
Medium temperature	-10 °C...+ 90 °C (with FKM) / - 30 °C...+ 90 °C (with EPDM)
Viscosity	Max. 21 mm²/s (21 cSt)

Note on Performance Data

Characteristic data of control behaviour depends on process conditions. Pressure data: overpressure to atmospheric pressure, depending on nominal diameter, tightness seal or nominal pressure.

Approvals and Conformities

Depending on the specific configuration, the Type 2873 series can be supplied with the following approvals:

• Explosion protection (Optional): ATEX (II 2 G Ex mb IIC T4...T5 Gb, II 2 D Ex mb IIIC T130 °C Db) and IECEx (Ex mb IIC T4...T5 Gb, Ex mb IIIC T130 °C Db).
• North America: Optional UL Recognized for the USA (UL 429).
• Foods and beverages/Hygiene: USP, FDA (Code of Federal Regulations), and EC Regulation 1935/2004.

Performance Specifications

Flow Characteristic

Pressure drop	$K_v$ value for liquids [m³/h]	$K_v$ 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

Important Sizing Note

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, on the one hand, the desired flow range is achieved and, on the other hand, 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. Otherwise, an ideal, linear valve characteristic is deformed into a curved system characteristic. If the differential pressure exceeds half the value of the nominal pressure, discontinuities may occur.

Product Operation

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 (coil heating), ramp function and the adjustment of minimum and maximum duty cycle/coil current for the control range.

Dimensions

Threaded Version

Port connection	A	B
G 1/4	12	-
G 1/8	8	-
NPT 1/4	10	-
NPT 1/8	7	-

(Dimensions in mm)

Optional: Explosion-Protected Coil (Type 06xx)

For applications requiring explosion protection, the Type 2873 can be equipped with the Type 06xx solenoid coil (ATEX/IECEx approved).

Risk of Explosion

Following assembly, the solenoid coil is part of a closed system. If used in the potentially explosive area, there is a risk of explosion if the system is opened during operation. Do not remove or open the system during operation.

Electrostatic Discharge

In the event of a sudden discharge from electrostatically charged devices or individuals, there is a risk of an explosion in the explosion-risk area. Clean the device surface by gently wiping it with a damp or antistatic cloth only.

Electrical Data (Type 06xx):

• Nominal voltage: 24...240 V AC/DC
• Temperature class: T4 (064x) / T5 (065x)
• Ambient temperature (Individual assembly): -40...+60 °C (T4) / -40...+50 °C (T5)
• Electrical connection: Electron beam cross-linked polyolefin copolymer cable, halogen-free.