Burkert 20051681 Type 2000 is an externally piloted 2/2-way angle seat valve engineered for shut-off operations in industrial process automation. Configured with a DN 25 nominal orifice, DIN 11850 Series 2 / DIN 11866 Series A welded pipe connections (29 mm outer diameter × 1.5 mm wall thickness), and an investment-cast CF3M stainless steel body, the valve delivers a water Kv flow coefficient of 19 m³/h. A size 80 mm (F) polyamide (PA) pneumatic piston actuator drives the internal spindle, providing control function A (normally closed in rest position by internal spring force). Burkert 20051681 is rated for fluid operating pressures from 0 to 25 bar(g), medium temperatures from -40 °C to +185 °C, and pilot air pressures from 5.0 to 10.0 bar(g).

With CIP and SIP cleaning capability, IP67 enclosure protection, and a maintenance-free, self-adjusting PTFE V-ring spindle packing gland with spring compensation, Burkert 20051681 controls liquid and gaseous media including steam, water, alcohols, oils, fuels, hydraulic fluids, saline solutions, lyes, organic solvents, and neutral gases. The flow path enters below the valve seat, utilizing fluid pressure to assist opening while eliminating water hammer surges during closing.

Design and Material Construction

Burkert Type 2000 angle seat valves feature a flow-optimized 2-way body design combined with a linear piston actuator. The materials of construction for the CF3M stainless steel welded body variant with PA actuator are summarized below:

Item No.	Element	Material (CF3M Stainless Steel Body with PA Actuator)
1	Transparent Cover	Polycarbonate (PC)
2	Pilot Air Ports	Stainless steel 1.4305
3	Actuator Housing	Polyamide (PA)
4	Piston Seal	Nitrile butadiene rubber (NBR)
5	Packing Gland	Filled PTFE V-rings with spring compensation
6	Springs	Stainless steel 1.4310
7	Tube	Stainless steel CF3M
8	Wiper	Filled PTFE
9	Body Seal	Graphite (PTFE optional)
10	Spindle	Stainless steel 1.4401 / 1.4404
11	Pin	Stainless steel 1.4401 / 1.4404
12	Seat Seal	Polytetrafluoroethylene (PTFE)
13	Valve Body	Cast stainless steel CF3M (316L equivalent)
14	Swivel Plate	Stainless steel CF3M / 1.4401 / 1.4404

Working Principle and Control Function

Burkert 20051681 operates under Control Function A (CF A): 2/2-way, normally closed in rest position by spring force.

• Closing action: The internal spring package exerts continuous force down the spindle to seat the PTFE seal against the CF3M body orifice.
• Opening action: Compressed pilot air at 5.0 to 10.0 bar(g) is applied to the lower pilot air port (connection 10), pressurizing the underside of the actuator piston and compressing the spring pack to raise the swivel plate.
• Flow direction below seat: The process fluid flows from under the valve seat against the closing direction. Process pressure supports valve opening, preventing pressure spikes or hydraulic shock (water hammer) in liquid piping installations.

Operating Limits and Pressure-Temperature Ratings

Burkert 20051681 conforms to pressure equipment standard DIN EN 12516-1 PN25 and ASME B16.34 Class 150. Maximum permissible operating pressure decreases with increasing fluid temperature as defined by DIN EN 12516-1:

Temperature [°C]	Permissible Working Pressure PN25 [bar(g)]	Class 150 Limit [bar(g)]
-10 to +50	25.0	18.4
100	24.5	16.2
150	22.4	14.8
185 (Max. for PA actuator)	~21.0	~14.0
200	20.3	13.7
230	19.0	12.7

Ambient Temperature Limits for Polyamide (PA) Actuators

For actuator sizes 40, 50, and 63 with PA housings, ambient temperature is limited to +60 °C at fluid temperatures up to +185 °C. For the size 80 (F) actuator, continuous ambient temperature must remain between -40 °C and +60 °C. Storage temperature is rated from -20 °C to +65 °C.

Fluidic Technical Data for Welded Ports

Fluid parameters for Type 2000 valves with welded connections according to DIN 11850 Series 2 / DIN 11866 Series A / DIN EN 10357 Series A under flow direction below the seat (CF A, normally closed):

Port Size DN	Seat Size [mm]	Actuator Size Ø [mm]	Water Kv [m³/h]	Min. Pilot Pressure [bar(g)]	Max. Operating Pressure PTFE [bar(g)]	Max. Operating Pressure PEEK [bar(g)]
10	15	40 (C)	2.5	4.0	15.0	—
10	15	50 (D)	2.5	4.1	16.0	—
10	15	63 (E)	2.5	4.5	25.0	25.0
15	15	40 (C)	4.7	4.0	15.0	—
15	15	50 (D)	5.0	4.1	16.0	—
15	15	63 (E)	5.4	4.5	25.0	25.0
20	20	40 (C)	8.4	4.0	6.5	—
20	20	50 (D)	10.0	4.1	11.0	—
20	20	63 (E)	11.0	4.5	20.0	16.0
20	20	80 (F)	11.0	5.0	25.0	25.0
25 (20051681)	25	80 (F)	19.0	5.0	25.0	21.0
25	25	50 (D)	14.0	4.1	5.2	—
25	25	63 (E)	19.0	4.5	11.0	—
32	32	63 (E)	26.0	4.5	6.0	—
32	32	80 (F)	26.0	5.0	14.0	11.5
32	32	100 (G)	30.0	4.4	16.0	—
32	32	125 (H)	30.0	4.1	25.0	25.0
40	40	63 (E)	33.0	4.5	4.0	—
40	40	80 (F)	35.0	5.0	9.0	—
40	40	100 (G)	41.0	4.4	12.5	—
40	40	125 (H)	40.0	4.1	25.0	25.0
50	50	63 (E)	44.0	4.5	2.5	—
50	50	80 (F)	49.0	5.0	6.0	—
50	50	100 (G)	60.0	4.4	7.2	—
50	50	125 (H)	60.0	5.7	24.0	19.0
65	65	80 (F)	74.0	5.0	3.5	—
65	65	125 (H)	91.0	5.7	12.0	10.0
80	80	125 (H)	140.0	5.7	7.5	—

Dimensions and Connection Geometry

Actuator Dimensions

Port Size DN	Actuator Size Ø	Ø A [mm]	B / H [mm]	K / M [mm]	Pilot Port P	BS / HS [mm]
20	80 (F)	101	195	171	G 1/4	259
25 (20051681)	80 (F)	101	195	171	G 1/4	259
25	50 (D)	64	152	136	G 1/4	223
25	63 (E)	80	178	159	G 1/4	242
32	80 (F)	101	209	185	G 1/4	273
40	80 (F)	101	213	188	G 1/4	277

Note: Dimensions B, H, K, M, HS, and BS represent maximum values and may be reduced by up to 6 mm depending on port standard.

Welded Body Dimensions (DIN 11850 Series 2 / DIN 11866 Series A)

Port DN	ES [mm]	CS [mm]	LS [mm]	Ø DS [mm]	WS [mm]
10	30	46	135	13.0	1.5
15	19	34	100	19.0	1.5
20	20	39	115	23.0	1.5
25 (20051681)	26	43	130	29.0	1.5
32	26	45	145	35.0	1.5
40	26	49	160	41.0	1.5
50	26	50	175	53.0	1.5
65	26	50	210	70.0	2.0
80	26	88.5	266	85.0	2.0

Installation and Welding Procedures

Dismount Actuator Prior to Welding

When installing valves with welded spigots, the actuator must be completely removed from the valve body before welding into the pipeline. Direct heat transfer from orbital or manual welding will destroy internal seals and the PTFE seat disc.

Actuator Removal Procedure

1. Secure the valve body in an appropriate vice or clamping fixture.
2. For Control Function A (normally closed), apply compressed air (5.0 bar) to the lower pilot port (10) to lift the PTFE disc off the seating contour.
3. Position an open-end wrench on the body connection hexagon flats (8).
4. Unscrew and remove the actuator assembly from the valve body.

Pipeline Welding and Reassembly

1. Weld the bare valve body into the pipeline system ensuring correct flow orientation (arrow on body indicates direction below seat).
2. Allow the body to cool completely.
3. Verify the condition of the graphite body seal and replace if worn or damaged.
4. Grease the connection threads on the body neck using Klüberpaste UH1 96-402.
5. Pressurize the lower pilot air port of the actuator with 5.0 bar compressed air to retract the swivel plate.
6. Screw the actuator into the valve body and tighten with an open-end wrench to the specified torque:

Valve Size DN	Actuator Size	Tightening Torque [Nm]	Tolerance [Nm]
15	40 (C), 50 (D), 63 (E)	45	+10 / -5
20	40 (C), 50 (D), 63 (E), 80 (F)	50	+10 / -5
25 (20051681)	50 (D), 63 (E), 80 (F)	60	+10 / -5
32	63 (E), 80 (F), 100 (G)	65	+10 / -5
40	63 (E), 80 (F), 100 (G), 125 (H)	65	+10 / -5
50	63 (E), 80 (F), 100 (G), 125 (H)	70	+10 / -5
65	80 (F), 100 (G), 125 (H)	70	+10 / -5

Pneumatic Connection and 360° Actuator Rotation

The pilot air interface features a G 1/4 internal thread. For Control Function A, connect the control air line directly to the lower pilot port. The upper port remains vented to atmosphere. In aggressive or washdown atmospheres, route a pneumatic line from the upper port to an inert area.

To align the pneumatic connections with plant pipe runs, the actuator can be continuously rotated through 360°:

1. Clamp the valve body firmly.
2. Apply 5.0 bar compressed air to the lower pilot air connection to lift the seal disc off the seat.
3. Engage an open-end wrench on the hexagon flats of the actuator neck and an open-end wrench on the body interface flats.
4. Rotate the actuator in the direction indicated by manufacturer instructions until the pilot port reaches the desired angle.

Commissioning Guidelines

Avoid Sudden Media Release

Before introducing pressurized media into the pipeline, ensure the pneumatic control line is active and operating pressure limits (max. 25 bar for DN 25) match system conditions. Start-up sequence must follow:

1. Energize pneumatic air supply (5.0 to 10.0 bar).
2. Charge piping with process fluid.

If acoustic emission exceeds 70 dB(A) under specific operating pressures and cycling frequencies, hearing protection must be utilized by nearby personnel.

Maintenance, Inspection, and Troubleshooting

Burkert Type 2000 actuators are maintenance-free under normal operating conditions. Regular visual inspections should check for leakage across four critical zones:

Inspection Point	Inspection Detail	Remedial Measure
Media Connection	Pipe weld seam tightness	Re-weld or dress process connection
Relief Bore	Fluid escaping from actuator weep hole	Replace spindle packing gland seal set or actuator
Swivel Plate / Seat	Internal seat leakage across valve	Replace valve set (swivel plate and PTFE disc)
Body Joint	Leakage at body-to-actuator joint	Replace graphite seal ring and re-torque to 60 Nm

Troubleshooting Guide

Fault Condition	Possible Cause	Corrective Action
Actuator fails to stroke	Pilot line connected to upper instead of lower port	Connect pilot air to lower port for Function A
	Pilot pressure below 5.0 bar	Increase pilot air pressure to rating (5.0–10.0 bar)
	Process pressure exceeds 25 bar	Verify system pressure against rating plate
	Flow direction reversed	Align body arrow to match pipeline flow direction
Seat leakage across closed valve	Foreign particles trapped on valve seat	Install upstream strainer (1 mm mesh or finer)
	Worn or scored PTFE seat seal	Install replacement swivel plate set
	Insufficient spring closing force	Verify supply is fully exhausted during closed state
Fluid escaping from relief bore	Worn spindle packing V-rings	Replace spindle packing gland using assembly tools

Product Accessories and Combinations

Burkert 20051681 integrates with modular CLASSIC series accessories for automated process control:

• Electrical Position Feedback (Type 8697): Compact feedback head featuring mechanical or inductive limit switches and integrated LED position indication, conforming to IP65/IP67 and NEMA 4X for hygienic environments.
• Direct-Mounting Pilot Solenoid Valves: Type 6014 (banjo connection G 1/4, 8 W) and Type 7012 (banjo connection G 1/8, 4 W) provide localized pneumatic piloting via standard DIN EN 175301-803 cable plugs.
• Stroke Limiters: Type 2XXX mechanical limiters for restricting maximum flow opening or minimum bypass positions.
• Position Feedback Adapters: Modular single and dual inductive proximity switch mounting brackets.
• Valve Systems on/off CLASSIC (Type 8801-YA): Pre-assembled and tested factory assemblies pairing Type 2000 with Type 8697 automation heads.