The Burkert Type 2961 control valve consists of a manual actuator and a globe valve body with exchangeable seats made of high-quality stainless steel. Each globe valve body can be equipped with up to 8 valve seat sizes and reaches the desired flow characteristic curve in interaction with parabolic cones. The precise spindle guide enables control, even under demanding operating conditions. A soft PTFE or PEEK seal guarantees reliable sealing.

The actuator is made of high-quality plastic and is suitable for use in demanding environments. It possesses a visual position indicator and can be optionally equipped with stroke limitation and locking. The packing gland uses tried-and-tested V-seals and possesses spring compensation, which means that it does not need to be pulled back manually.

Product Features

• Excellent control accuracy
• Exchangeable valve seats enable perfect coordination under the most demanding operating conditions
• Robust actuator with optional stroke limitation and locking
• Stainless steel valve body with flange, socket, clamp or welded connection

Technical Data

Product properties
Design	Globe control valve
Nominal diameter	DN 10...DN 100, NPS 3/8...NPS 4
Flow direction	Flow to open (below seat)
Performance data
Operating pressure	0 bar(g)...25 bar(g)
Nominal pressure	PN 25 (DIN EN 1333), Class 150 (DIN EN 1759)
Seat leakage	Leakage class II (metal), Leakage class VI for PTFE and PEEK
Operating characteristic	Equal percentage
Medium data
Operating medium	Steam, water, neutral gases, alcohols, oils, fuels, hydraulic fluids, salt solutions, alkalis, organic solvents
Medium temperature	-40 °C...+ 230 °C
Viscosity	Max. 600 mm²/s

Materials

No.	Element	Material
1	Cover	Polyamide (PA)
2	Screw	Stainless steel 1.4301
3	Locking device	Stainless steel 1.4305
4	Handwheel	Polyphenylene sulphide (PPS)
5	Visual position indicator with scale	Polyamide (PA)
6	Packing gland	PTFE V-rings (filled), with spring compensation
7	Stem	Stainless steel 1.4401 or 1.4404
8	Spindle guide	Stainless steel 1.4404 (316L), PTFE filled
9	Housing seal	Graphite
10	Control cone	1.4571 (optionally hardened)
11	Seat seal (optional)	PTFE or PEEK
12	Valve seat with O-ring	Stainless steel 1.4571, EPDM
13	Valve body	Stainless steel 316L/CF3M

Function and Operation

By manually overriding the handwheel, the force is transmitted via a spindle and the valve is opened or closed. Turning the handwheel anticlockwise opens the valve, turning it clockwise closes it.

Position Indicator

When turning the handwheel anticlockwise, the reproducible stroke scale becomes visible between the position indicator and the handwheel. The scale on the handwheel determines the rotation position of the handwheel (50 positions). The reproducible stroke scale shows, depending on the bottom edge of the handwheel, the relative position of the valve (valve opening) and acts as a fixation point for determining the rotation position.

Flow Direction

The valve seat is always closed against the medium flow. The flow direction should therefore be set such that the valve reaches the flow beneath the valve seat.

Flow Characteristic

• Cone of equal per cent for valve seat sizes 8 to 100
• Flow characteristic as per DIN EN 60534-2-4
• Theoretical rangeability (Kvs/Kvo): 50:1 for valve seat size 8 to 100

Operating Limits for Seat Seal

Tight sealing required	Leakage class (DIN EN 60534 - 4)	Medium temperature	Seat seal
No	II (metal seals)	-40 °C...+230 °C	Stainless steel
Yes	VI (soft seals)	-40 °C...+130 °C (recommended for ≤ +130 °C)	PTFE
Yes	VI (soft seals)	-10 °C...+230 °C (recommended for > +130 °C)	PEEK

Explosion Protection (ATEX)

For devices with Ex approval (e.g., ATEX II 2G Ex h IIC T4...T2 Gb / II 2D Ex h IIIC T135°C...T300°C Db):

• Danger of explosion due to electrostatic charge! Take appropriate measures to ensure that no electrostatic charge can build up in the potentially explosive area.
• Only wipe the surface of the device gently with a damp or antistatic cloth.
• Ground the actuator and valve body. If using a plastic valve body, ground the actuator separately.
• Only use cleaning agents approved for explosive atmospheres.