BURKERT 20111077 (Type 2961) is a manually operated 2-way globe control valve designed for demanding industrial flow control applications. The valve assembly pairs a manual rotary actuator with a stainless steel 316L/CF3M globe valve body equipped with DN 15 flanged connections according to DIN EN 1092-1 PN 25. Featuring a 15 mm replaceable seat orifice and an equal-percentage parabolic control cone, it achieves a nominal flow coefficient Kvs of 4.3 m³/h (Cv 5 gal/min) with a 50:1 theoretical rangeability. A soft PEEK seat seal ensures bubble-tight shut-off meeting DIN EN 60534-4 Leakage Class VI across operating pressures up to 25 bar(g) and media temperatures from -10 °C to +230 °C.

The manual actuator features a 45 mm polyphenylene sulphide (PPS) handwheel (Size S) and a spindle interface D10, incorporating a visual indicator system with a 50-division handwheel rotation dial and an exposed linear stroke scale for repeatable manual flow adjustments. The internal stem assembly is guided by a PTFE-filled stainless steel bush and sealed with a maintenance-free, spring-loaded PTFE V-ring gland packing. Certified under ATEX and IECEx for equipment category 2 (Zones 1/21 and 2/22), BURKERT 20111077 is rated for steam, water, neutral gases, oils, fuels, hydraulic fluids, alkalis, and organic solvents.

Technical Specifications

Parameter	Specification
Valve Type	Manually operated 2-way globe control valve
Burkert Type / Article No.	Type 2961 / 20111077
Nominal Diameter	DN 15 (1/2")
Port Connection	Flange according to DIN EN 1092-1 PN 25 (Face-to-face length FTF 1 per DIN EN 558-1)
Flow Direction	Flow to open (below seat)
Valve Body Material	Stainless steel 316L / CF3M
Seat Orifice Size	15 mm (9/16")
Nominal Flow Coefficient	Kvs = 4.3 m³/h (Cv = 5 gal/min)
Flow Characteristic	Equal percentage, theoretical rangeability 50:1
Operating Pressure Range	0 bar(g) to 25 bar(g)
Nominal Pressure Class	PN 25 (DIN EN 1333), Class 150 (DIN EN 1759)
Seat Seal Material	PEEK (Polyetheretherketone)
Seat Leakage	Leakage Class VI according to DIN EN 60534-4:2006
Medium Temperature Range	-10 °C to +230 °C
Ambient Temperature Range	-10 °C to +60 °C
Maximum Fluid Viscosity	600 mm²/s
Gland Packing	Spring-compensated PTFE V-rings (filled)
Stem Diameter / Interface	Spindle D10
Handwheel Size / Material	Size S (Ø 45 mm) / Polyphenylene sulphide (PPS)
Stroke Nominal Value	19 mm (slope per revolution 1.25 mm)
Operating Media	Steam, water, neutral gases, alcohols, oils, fuels, hydraulic fluids, salt solutions, alkalis, organic solvents
Certification	ATEX / IECEx: II 2 G Ex h IIC T4...T2 Gb, II 2 D Ex h IIIC T135°C...T300°C Db

Materials and Construction

Item	Component	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	Stainless steel 1.4571
11	Seat seal	PEEK
12	Valve seat with O-ring	Stainless steel 1.4571, EPDM
13	Valve body	Stainless steel 316L / CF3M

Dimensions

Flanged Body Dimensions (DIN EN 1092-1 PN 25)

Dimensions are stated in mm in accordance with face-to-face series FTF 1 (DIN EN 558-1):

DN	Outer Flange ∅ DF	Face-to-Face Length LF	Pitch Circle ∅ BF	Flange Thickness AF	Bolt Hole ∅ D	Bolt Pattern A x α	Neck Diameter ∅ MF
15	95 mm	130 mm	65 mm	16 mm	14 mm	4 × 90°	18.1 mm

Actuator Dimensions

For pipe size DN 15 (Handwheel Size S):

• Handwheel diameter: 45 mm
• Total height H1: 217 mm
• Total height with locking mechanism H2: 224 mm
• Full valve nominal stroke: 19 mm (slope per revolution: 1.25 mm)

Flow Characteristics and Fluidic Data

The Type 2961 valve follows an equal-percentage control characteristic conforming to DIN EN 60534-2-4. The theoretical rangeability (Kvs / Kv0) is 50:1. The smallest flow coefficient meeting the tilt tolerance ($K_{vR}$) is defined at 5% of stroke for orifices larger than 10 mm.

Intermediate Kv Values at Stroke Steps (DN 15 / Seat Orifice 15 mm)

• Measured with water according to DIN EN 60534-2-4:

Stroke (%)	Kv Value (m³/h)
5%	0.14
10%	0.17
20%	0.22
30%	0.35
40%	0.52
50%	0.80
60%	1.20
70%	1.80
80%	2.70
90%	3.70
100% (Kvs)	4.30

Operating Limits and Pressure Derating

The permissible operating pressure is bounded by the valve body rating according to DIN EN 12516-1 (PN 25) across the medium temperature spectrum:

Temperature (°C)	Maximum Permissible Operating Pressure (bar)
-10 °C to +50 °C	25.0 bar
100 °C	24.5 bar
150 °C	22.4 bar
200 °C	20.3 bar
230 °C	19.0 bar

Seat Sealing Performance

PEEK soft-sealing inserts yield DIN EN 60534-4 Leakage Class VI (bubble-tight closure), eliminating the necessity of an upstream isolation valve in standard service. PEEK is recommended for applications operating above +130 °C up to +230 °C.

Installation and Commissioning

1. Installation Orientation: The valve can be installed in any orientation, preferably with the actuator upright.
2. Flow Direction: Flow must enter beneath the valve seat (flow-to-open direction indicated by the cast body arrow).
3. Body Connection: Clean connecting pipelines thoroughly before mounting. Align pipe flanges to prevent bending stress.
4. Actuator Torque: When reinstalling the actuator into the DN 15 valve body, lubricate the external threads using Klüberpaste UH1 96-402 and tighten to 45 Nm (±3 Nm).
5. Flow Rate Adjustment: Turning the handwheel counterclockwise exposes the reproducible stroke scale between the bonnet attachment and the handwheel. The dial provides 50 graduations per revolution, allowing repeatable setting against the stroke scale.

Actuator Locking and Stroke Limitation

Optional configurations of the Type 2961 actuator allow stroke adjustment and position locking. Handwheel size S features 12 locking intervals per revolution (each 30° indexing equals 0.10 mm stroke travel), securable via a Ø 3.8 mm hole using an industrial padlock.

Safety Precaution

Depressurize and drain process lines completely before performing any disassembly or maintenance work on the valve assembly.

Maintenance and Troubleshooting

The manual actuator mechanism is maintenance-free under normal operating conditions. Inspect the valve externally and verify relief bore integrity once per year. Abrasive or contaminated media require shorter inspection intervals.

Fault Symptom	Root Cause	Remedial Action
Valve does not seal tightly	Debris trapped between seal and seat	Clean seating surfaces; install an upstream strainer
Valve does not seal tightly	PEEK seat seal worn or damaged	Replace the plug/seal closure member
Valve does not seal tightly	Flow direction reversed	Reinstall valve adhering to body flow arrow
Valve does not seal tightly	Operating pressure exceeds limits	Verify process pressure against rating curve
Leakage at relief bore	Spindle gland packing worn	Replace gland packing assembly

Explosion Protection Conditions (ATEX / IECEx)

BURKERT 20111077 complies with mechanical explosion protection code PX51 (EPS 18 ATEX 2 008 X / IECEx EPS 18.0007 X) as Category 2 mechanical equipment suitable for Zone 1/21 and Zone 2/22:

• Gas certification: II 2 G Ex h IIC T4...T2 Gb
• Dust certification: II 2 D Ex h IIIC T135 °C...T300 °C Db

Temperature Class	Maximum Permissible Surface Temperature	Ambient Temperature Range	Maximum Medium Temperature
T4	+135 °C	-40 °C to +100 °C	+125 °C
T3	+200 °C	-40 °C to +130 °C	+185 °C
T2	+300 °C	-40 °C to +130 °C	+285 °C

Potential Electrostatic Charging Hazard

Clean the device only with a damp or anti-static cloth to avoid electrostatic sparking. The metallic valve body must be grounded to the pipeline system to ensure continuous equipotential bonding.