BURKERT 20135264 (Type 2961) is a manually operated 2-way globe control valve designed for accurate continuous flow adjustment of liquids, steam, and gases. Built with a cast stainless steel 316L/CF3M globe valve body and welded pipe ends according to SMS 3008 (DN 25, 25.0 x 1.2 mm), the valve pairs with an ergonomic plastic manual actuator made from polyphenylene sulphide (PPS). The valve incorporates a 10 mm (3/8") replaceable seat orifice and an equal percentage parabolic control plug, delivering a rated flow coefficient Kv of 2.8 m³/h (Cv 3.2 gpm) with a 50:1 theoretical control rangeability.

Equipped with a soft PTFE seat seal, BURKERT 20135264 achieves bubble-tight shut-off meeting Leakage Class VI in accordance with DIN EN 60534-4. The valve stem assembly relies on a self-adjusting PTFE V-ring packing gland with integrated spring compensation, preventing external leakage without necessitating manual packing adjustments during routine operation. Medium-contacting materials comply with FDA regulations and Regulation (EC) 1935/2004, making this configuration suitable for sanitary processing, pure steam, hot water, and aggressive media across operating pressures up to 25 bar(g).

Design and Operating Principle

BURKERT 20135264 controls media flow through manual rotation of the PPS handwheel. Rotary movement transfers through a stainless steel spindle (spindle diameter D10) to reposition the parabolic plug relative to the replaceable orifice seat. Flow direction is strictly directed below the seat (flow-to-open), ensuring positive shut-off against media pressure and minimizing pressure-induced vibration.

• Manual Actuation: Size S PPS handwheel (diameter 45 mm) produces a spindle pitch travel of 1.25 mm per 360° revolution.
• Precision Spindle Guidance: Guided via 1.4404 (316L) stainless steel with PTFE filler, stabilizing the parabolic trim throughout travel.
• Spring-Compensated Packing: PTFE chevron V-rings are loaded by internal Belleville springs to maintain live sealing under thermal cycling.
• Optical Position Indication: A scale on the handwheel rim features 50 graduation divisions, working in conjunction with a linear stroke scale revealed as the valve opens.

Position Indicator Reading

The outer rim of the handwheel provides 50 division steps per revolution. Turning the handwheel counter-clockwise exposes the reproducible stroke scale between the bonnet attachment and the handwheel. This dual-scale combination allows operators to record and repeat exact throttling points.

Technical Specifications

Parameter	Technical Value
Article Number	20135264
Type Family	2961
Valve Configuration	2/2-way globe control valve
Nominal Port Diameter	DN 25 (NPS 1)
Pipe Connection Standard	Welded to SMS 3008 (Tube 25.0 x 1.2 mm)
Pressure Rating	PN 25 (DIN EN 1333) / Class 150 (DIN EN 1759)
Operating Pressure Range	0 bar(g) to 25 bar(g)
Nominal Seat Diameter	10 mm (3/8")
Water Flow Coefficient Kv	2.8 m³/h
Flow Coefficient Cv	3.2 gpm
Seat Leakage Rate	Class VI (DIN EN 60534-4)
Flow Characteristic	Equal percentage (theoretical rangeability 50:1)
Flow Direction	Below seat (flow-to-open)
Medium Temperature Range	-10 °C to +130 °C (PTFE seat limit)
Ambient Temperature Range	-10 °C to +60 °C
Maximum Medium Viscosity	Up to 600 mm²/s
Permissible Fluid Media	Steam, water, neutral gases, alcohols, oils, fuels, salt solutions, alkalis, organic solvents
Food & Hygienic Compliance	FDA (Code of Federal Regulations), Regulation (EC) 1935/2004

Materials of Construction

Item	Component	Material Specification
1	Actuator Cover	Polyamide (PA)
2	Fastening Screw	Stainless steel 1.4301
3	Locking Mechanism (optional)	Stainless steel 1.4305
4	Handwheel	Polyphenylene sulphide (PPS)
5	Position Indicator with Scale	Polyamide (PA)
6	Packing Gland	Filled PTFE V-rings with spring compensation
7	Stem (Spindle)	Stainless steel 1.4401 or 1.4404
8	Spindle Guide Bushing	Stainless steel 1.4404 (316L), PTFE-filled
9	Body Seal	Graphite
10	Control Cone (Plug)	Stainless steel 1.4571
11	Seat Seal	PTFE (soft seal, Article 20135264)
12	Valve Seat Orifice with O-ring	Stainless steel 1.4571 with EPDM O-ring
13	Valve Body	Cast stainless steel 316L / CF3M

Dimensions

Actuator Dimensions

BURKERT 20135264 utilizes manual actuator size S with a 45 mm handwheel diameter. For nominal pipe size DN 25, the vertical envelope dimensions are detailed below:

Pipe Connection Size	Handwheel Size	Handwheel Diameter ∅	Height H1 (Standard)	Height H2 (with Locking)
DN 15 (NPS 1/2)	S	45 mm	217 mm	224 mm
DN 20 (NPS 3/4)	S	45 mm	224 mm	230 mm
DN 25 (NPS 1)	S	45 mm	228 mm	234 mm
DN 32 (NPS 1 1/4)	M	110 mm	296 mm	303 mm
DN 40 (NPS 1 1/2)	M	110 mm	301 mm	307 mm
DN 50 (NPS 2)	M	110 mm	307 mm	313 mm
DN 65 (NPS 2 1/2)	L	160 mm	361 mm	368 mm
DN 80 (NPS 3)	L	160 mm	369 mm	375 mm
DN 100 (NPS 4)	L	160 mm	379 mm	385 mm

Welded Connection Body Dimensions

BURKERT 20135264 features welded tube dimensions of 25.0 x 1.2 mm according to SMS 3008. For standard butt-weld series, the body length LS and insertion depth ES are configured as follows:

Port Size DN	ES [mm]	LS [mm]	DIN EN ISO 1127 ∅ DS x WS	DIN 11850-2 ∅ DS x WS	SMS 3008 Tube Size
DN 10	20	90	17.2 x 1.6 mm	13.0 x 1.5 mm	-
DN 15	20	90	21.3 x 1.6 mm	19.0 x 1.5 mm	-
DN 20	20	100	26.9 x 1.6 mm	23.0 x 1.5 mm	-
DN 25	26	130	33.7 x 2.0 mm	29.0 x 1.5 mm	25.0 x 1.2 mm
DN 32	26	140	42.4 x 2.0 mm	35.0 x 1.5 mm	-
DN 40	26	150	48.3 x 2.0 mm	41.0 x 1.5 mm	-
DN 50	26	175	60.3 x 2.0 mm	53.0 x 1.5 mm	-

Fluidic Performance and Flow Characteristics

Type 2961 valves follow an equal percentage flow profile in compliance with DIN EN 60534-2-4. For seat sizes equal to or smaller than 10 mm, the minimum controlled flow value KvR is established at 10% of stroke to maintain tolerance compliance.

Intermediate Kv Values Across Stroke Travel (DN 25, Seat 10 mm)

For article 20135264, the nominal stroke travel is 19 mm. The table below lists water Kv values [m³/h] across opening stroke increments from 5% to 100%:

Parameter	Operating Value
Valve Pipe Size	DN 25 (NPS 1)
Seat Orifice Diameter	10 mm
Handwheel Diameter	45 mm (Size S)
Maximum Differential Pressure CF A (PTFE)	25 bar(g) (Leakage Class VI)
Theoretical Rangeability	50:1
Stroke 5%	0.10 m³/h
Stroke 10%	0.12 m³/h
Stroke 20%	0.15 m³/h
Stroke 30%	0.19 m³/h
Stroke 40%	0.30 m³/h
Stroke 50%	0.46 m³/h
Stroke 60%	0.67 m³/h
Stroke 70%	1.0 m³/h
Stroke 80%	1.5 m³/h
Stroke 90%	2.1 m³/h
Stroke 100% (Kvs)	2.8 m³/h

Pressure and Temperature Operating Limits

The permissible operating pressure of the stainless steel valve body is determined by pressure derating curves conforming to DIN EN 12516-1 (PN 25 rating):

Medium Temperature [°C]	Maximum Permissible Operating Pressure [bar]
-10 °C to +50 °C	25.0 bar
+100 °C	24.5 bar
+130 °C (PTFE seat limit)	23.2 bar
+150 °C	22.4 bar
+200 °C	20.3 bar
+230 °C	19.0 bar

Temperature Limit for Soft Seat

BURKERT 20135264 is fitted with a virgin PTFE seat seal, restricting continuous media temperature to a range of -10 °C to +130 °C. For processes exceeding +130 °C up to +230 °C, PEEK or metallic stainless steel seat trims are required.

Installation and Welding Procedures

Line Depressurization

Relieve all pipeline pressure and fully drain process lines before handling or installing the valve. Trapped pressurized media can cause severe physical injury.

Actuator Removal Prior to Welding

To prevent thermal damage to the internal graphite seal, PTFE seat seal, and plastic actuator during pipe welding, the actuator must be disassembled from the body:

1. Rotate the handwheel counter-clockwise approximately two turns to lift the plug away from the seat orifice.
2. Engage an open-ended wrench onto the body hex flats.
3. Unscrew and separate the manual actuator assembly from the stainless steel valve body.
4. Weld the bare valve body into the SMS 3008 pipeline system using appropriate sanitary welding techniques.

Actuator Reassembly and Tightening Torques

1. Inspect the body interface seal. Replace the graphite seal if deformed or contaminated, verifying that no debris remains inside the valve chamber.
2. Apply an approved lubricant (such as Klüberpaste UH1 96-402) to the body connection male threads.
3. Thread the actuator into the valve body by hand.
4. Tighten the connection to the specified torque using a calibrated torque wrench.

Valve Body Nominal Diameter	Tightening Torque [Nm]	Tolerance [Nm]
DN 10 / DN 15	45 Nm	±3 Nm
DN 20	50 Nm	±3 Nm
DN 25 (Article 20135264)	60 Nm	±3 Nm
DN 32 / DN 40	65 Nm	±3 Nm
DN 50	70 Nm	±3 Nm
DN 65	100 Nm	±3 Nm
DN 80	120 Nm	±5 Nm
DN 100	150 Nm	±5 Nm

Pipeline Stress and Vibration Check

In systems subject to intense line vibration or sustained temperatures exceeding 140 °C, inspect the body-to-actuator joint torque periodically to prevent screw connection loosening.

Handwheel Operation, Stroke Limitation, and Locking

• Manual Throttling: Turning the handwheel counter-clockwise lifts the parabolic plug and opens flow; turning clockwise closes the valve.
• Stroke Limit Adjustment (Optional): The minimum and maximum valve openings can be mechanically constrained by removing the handwheel and repositioning the internal adjustment sleeve.
• Locking Mechanism (Optional): On actuators equipped with a locking mechanism, handwheel size S offers 12 discrete lock positions per revolution (one position every 30°, corresponding to 0.10 mm of stroke). The locking pin incorporates a Ø3.8 mm bore accommodating a padlock to restrict unauthorized adjustments.

Maintenance and Troubleshooting

Under regular industrial operation conforming to operating limits, the PPS manual actuator is maintenance-free. Perform a visual inspection of external surfaces and seal junctions at least once per year.

Relief Bore Monitoring

The bonnet housing includes an inspection relief bore located between the primary process seal and the actuator head. Periodically inspect this bore. Escaping medium from the relief bore signifies wear of the internal spindle packing gland V-rings.

Fault Symptom	Probable Cause	Corrective Action
Valve does not seal tightly in closed position	Foreign particles trapped between plug seal and seat orifice	Clean internal seat cavity; install upstream pipeline strainer
	PTFE seat seal worn or mechanically deformed	Replace the control plug / seat sealing member
	Reverse flow orientation	Reorient valve so flow enters beneath the seat (arrow on body)
	Operating pressure exceeds rating	Verify process pressure against PN25 nameplate ratings
Fluid leaks from actuator relief bore	Spindle packing gland V-rings worn or degraded	Replace the spindle packing gland set using original spare kit