BURKERT 20120984 Type 2961 is a manually operated 2-way globe control valve engineered for precision fluid throttling and tight shut-off in demanding industrial applications. The assembly consists of a manual actuator crafted from polyphenylene sulphide (PPS) and a stainless steel 316L/CF3M globe body with an exchangeable seat. Configured under article number 20120984, the valve features a 3/4" NPT female threaded connection (DN 20), a 10 mm (3/8") orifice seat, and an equal percentage parabolic plug yielding a rated flow coefficient Kv of 2.8 m³/h (Cv 3.2 gal/min) with a theoretical rangeability of 50:1.

Fluid flows below the seat to ensure smooth opening control across differential pressures up to 25 bar. Tight zero-leakage shut-off corresponds to Leakage Class VI per DIN EN 60534-4 through a soft PTFE seat seal. The stem seal utilizes spring-compensated, filled PTFE V-rings that automatically compensate for wear without requiring manual repacking. The manual actuator integrates a 45 mm handwheel (Size S) with 50 division marks and an optical position indicator revealing a reproducible stroke scale for repeatable manual flow adjustments.

Technical Specifications and Operating Limits

BURKERT 20120984 operates across liquid, gas, and steam media including demineralized water, alcohols, fuels, hydraulic oils, saline solutions, lyes, and organic solvents up to a kinematic viscosity of 600 mm²/s.

Parameter	Specification
Valve Type	2-way globe control valve (Type 2961)
Article Number (SKU)	20120984
Nominal Port Size	DN 20 (NPS 3/4")
Port Connection Type	Internal thread, NPT (ASME B1.20.1)
Nominal Seat Diameter	10 mm (3/8")
Flow Direction	Flow to open (under seat)
Operating Pressure Range	0 bar(g) to 25 bar(g)
Nominal Pressure Class	PN 25 (DIN EN 1333), Class 150 (DIN EN 1759)
Seat Leakage Class	Class VI (PTFE soft seal, DIN EN 60534-4:2006)
Medium Temperature Range	-10 °C to +130 °C (PTFE seat seal)
Ambient Temperature Range	-10 °C to +60 °C
Storage Temperature	-20 °C to +65 °C
Actuator Interface	Spindle D10
Flow Characteristic	Equal percentage, 50:1 rangeability

Pressure-Temperature Derating

Operating pressure limits are subject to thermal derating according to the respective piping standards.

Temperature [°C]	DIN EN 12516-1 / PN25 [bar]	ASME B16.34 Cl. 150 [bar]	JIS B 2220 10K [bar]
-10 to +38 / +50	25.0	19.0	14.0
100	24.5	16.2	14.0
130 (PTFE limit)	~23.2	~15.4	~13.7
150	22.4	14.8	13.4
200	20.3	13.7	12.4
230	19.0	12.7	11.7

Seat Seal Temperature Capabilities

Seat Seal Material	Leakage Class	Medium Temperature	Operational Note
PTFE (Configured on 20120984)	Class VI	-40 °C to +130 °C	Soft seal for bubble-tight shut-off; recommended for temperatures ≤ +130 °C
PEEK (Optional)	Class VI	-10 °C to +230 °C	Soft seal for tight shut-off; recommended for operating temperatures > +130 °C
Stainless Steel 1.4571 (Optional)	Class II	-40 °C to +230 °C	Metallic seal allows 0.5% nominal leakage; wear may accelerate under manual spindle rotation

Flow Characteristics and Fluidic Data

Fluid reaches the underside of the plug so the valve opens against media pressure, preventing pressure surges and chatter during low-flow throttling.

The parabolic trim geometry provides an equal percentage characteristic per DIN EN 60534-2-4. For seat sizes > 10 mm, the KvR limit is evaluated at 5% stroke; for seat sizes ≤ 10 mm, it is evaluated at 10% stroke.

Intermediate Flow Rates at Stroke Increments (DN 20 / NPS 3/4")

Seat Size [mm]	Handwheel [mm]	Max Pressure [bar]	Rangeability	5%	10%	20%	30%	40%	50%	60%	70%	80%	90%	100%	Kvs [m³/h]
10 (SKU 20120984)	45 (S)	25 (VI)	50:1	0.10	0.12	0.15	0.19	0.30	0.46	0.67	1.0	1.5	2.1	2.8	2.8
15	45 (S)	25 (VI)	50:1	0.13	0.17	0.21	0.32	0.48	0.71	1.0	1.5	2.3	3.4	4.4	4.4
20	45 (S)	25 (VI)	50:1	0.19	0.24	0.29	0.42	0.64	0.97	1.4	2.0	2.9	4.2	5.9	5.9

Materials of Construction

All wetted parts are built from corrosion-resistant austenitic stainless steels and inert polymer seals.

Item	Component	Material
1	Cover	Polyamide (PA)
2	Screw	Stainless steel 1.4301
3	Locking device (optional)	Stainless steel 1.4305
4	Handwheel	Polyphenylene sulphide (PPS)
5	Position indicator with scale	Polyamide (PA)
6	Packing gland	Filled PTFE V-rings, spring-compensated
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 (optionally hardened)
11	Seat seal	PTFE (PEEK optional)
12	Valve seat with O-ring	Stainless steel 1.4571, EPDM
13	Valve body	Stainless steel 316L / CF3M

Dimensions

Actuator Dimensions by Body Size

Pipe Size DN	Pipe Size NPS	Handwheel Diameter [mm]	H1 [mm]	H2 with Locking [mm]
15	1/2	45 (S)	217	224
20 (SKU 20120984)	3/4	45 (S)	224	230
25	1	45 (S)	228	234
32	1 1/4	110 (M)	296	303
40	1 1/2	110 (M)	301	307
50	2	110 (M)	307	313
65	2 1/2	160 (L)	361	368
80	3	160 (L)	369	375
100	4	160 (L)	379	385

Threaded Body Dimensions (G, NPT, Rc)

All dimensions are stated in millimeters.

DN	NPS	E [G]	E [NPT]	E [Rc]	LM	AF (Wrench Flat)
10	3/8	12.0	10.3	10.1	65	27
15	1/2	14.0	13.7	13.2	65	27
20	3/4	16.0	14.0	14.5	75	34
25	1	18.0	16.8	16.8	90	41
32	1 1/4	20.0	17.3	19.1	110	50
40	1 1/2	22.0	17.3	19.1	120	55
50	2	24.0	17.6	23.4	150	70
65	2 1/2	26.0	23.7	26.7	185	85
80	3	28.0	30.5	29.8	205	100
100	4	32.0	33.0	35.8	240	125

Actuator Function and Position Setting

Turning the handwheel counterclockwise lifts the spindle and opens the valve. Turning clockwise drives the plug down onto the seat. For Handwheel Size S (45 mm diameter), spindle lead is 1.25 mm per complete turn, and total rated stroke for DN 20 is 19 mm.

Position Indicator and Stroke Scale

• Handwheel Scale: Features 50 rotational graduations.
• Reproducible Stroke Scale: Extends between the actuator attachment and the bottom edge of the handwheel as the valve opens, providing a precise vertical reference.
• Setting Flow: Combine the vertical scale mark with the rotation mark to replicate documented setpoints derived from the Kv flow curves.

INFO

The visibility of the stroke scale is not directly tied to the absolute seated closure. Depending on valve tolerances, the scale lines may remain slightly visible when fully seated, or become hidden before full travel.

Stroke Limitation and Locking Options

• Stroke Limit Adjustment: An optional internal adjusting sleeve allows users to calibrate mechanical stops for minimum and maximum valve openings. Removing the handwheel screw (2 mm hexagon socket) exposes the sleeve for adjustment.
• Handwheel Locking: Size S handwheels can incorporate an optional locking mechanism offering 12 positions per rotation (every 30° represents 0.10 mm of axial stroke). The locking pin features a 3.8 mm bore to accommodate an OSHA nylon lockout padlock (such as BURKERT article no. 93719475).

WARNING

Do not rely on the handwheel locking pin in the closed position to ensure specified leakage tightness under fluctuating thermal or pressure loads. Close the valve firmly by hand before engaging locking pins.

Installation and Assembly Guidelines

1. Pipeline Preparation: Flush all lines thoroughly to eliminate weld spatter, metal chips, and sealing residue. Install dirt strainers upstream where media contain particulates.
2. Orientation: The valve mounts in any orientation, though upright actuator positioning is preferred to reduce lateral stem guide wear.
3. Flow Direction: Align the fluid flow with the arrow cast on the valve body and indicated on the rating plate (flow below seat).
4. Body Thread Screwing Torques: When reinstalling actuators or assembling bodies, tighten the actuator union into the body following specific torque values.

Valve Body Nominal Size DN	Tightening Torque [Nm]	Tolerance [Nm]
10 / 15	45	±3
20 (SKU 20120984)	50	±3
25	60	±3
32 / 40	65	±3
50	70	±3
65	100	±3
80	120	±5
100	150	±5

High Pressure Hazard

Depressurize and drain pipelines completely before unscrewing the actuator or removing the valve body from the pipe network.

Body Connection Loosening

In systems subjected to severe pipeline vibration or medium temperatures above 140 °C, the threaded body joint may relax. Inspect and verify union tightness at regular maintenance intervals.

Maintenance and Troubleshooting

Under normal operating parameters, the PPS manual actuator is completely maintenance-free. Perform an annual visual inspection across the external envelope.

• Relief Bore Check: Inspect the relief hole in the actuator bonnet. Fluid discharge indicates packing gland seal wear.
• Stem Cleaning: Clean the exterior using water-dampened cloths. Ensure cleaning chemicals are compatible with PPS, PA, and 316L stainless steel.

Troubleshooting Guide

Symptom	Probable Cause	Corrective Action
Valve does not seal tightly	Dirt/debris trapped between seal and seat	Clean seating surface; install upstream strainer
Valve does not seal tightly	PTFE seat seal worn or damaged	Replace closure member / seat seal kit
Valve does not seal tightly	Reversed flow direction	Reinstall valve matching cast flow arrow
Valve does not seal tightly	Differential pressure exceeds rated limit	Verify system pressure against rating label (25 bar max)
Fluid leaks from relief bore	Packing gland V-rings worn	Replace stem packing gland assembly

Explosion Protection (ATEX and IECEx)

When ordered with variable code PX51, BURKERT Type 2961 is certified as non-electrical mechanical equipment (constructional safety) suitable for Zone 1/21 and Zone 2/22:

• ATEX: EPS 18 ATEX 2 008 X, II 2G Ex h IIC T4...T2 Gb / II 2D Ex h IIIC T135 °C...T300 °C Db
• IECEx: IECEx EPS 18.0007X, Ex h IIC T4...T2 Gb / Ex h IIIC T135 °C...T300 °C Db

Temperature Classes in Potentially Explosive Atmospheres

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

Electrostatic Discharge Hazard

Electrostatic charge accumulation presents an explosion hazard. The valve body must be grounded to the piping installation. Ground all conductive parts using an approved grounding strap or terminal clip. Clean the polymer actuator housing exclusively with a damp or antistatic cloth.

Low-Conductivity Media Restrictions

For fluids with electrical conductivity ≤ 100 pS/m, maintain flow velocity ≤ 1 m/s and ensure lines remain completely flooded to avoid static generation inside the valve body.