BURKERT 20061740 is a pneumatically operated 2/2-way angle seat valve from the CLASSIC Type 2000 family, designed for high-cycle on/off control of neutral gases, steam, water, alcohols, fuels, hydraulic fluids, and chemical solutions. This specific configuration features a DN25 (1", 25 mm orifice) flow path with pipe weld spigots measuring 29.0 × 1.5 mm in accordance with DIN 11850 series 2, DIN 11866 series A, and DIN EN 10357 series A. It is driven by a 50 mm diameter (size D) polyamide (PA) piston actuator featuring a stainless steel threaded bushing at the G 1/4 pilot port and an internal return spring fabricated from 1.4310 stainless steel.

Configured in Control Function A (normally closed by spring force), the valve directs flow beneath the seat (flow-to-open). This flow configuration eliminates water hammer in liquid systems when the valve closes against the process line. Burkert 20061740 achieves a flow coefficient (Kv) of 14 m³/h at a water test pressure drop of 1 bar. It operates against media pressures up to 5.2 bar(g) with a minimum pilot supply pressure of 4.1 bar(g) (maximum 10 bar(g)), across an operational process temperature envelope of -10 °C to +185 °C and an ambient range of -10 °C to +40 °C (capable of reaching +60 °C with media temperature derating).

Construction and Material Specifications

Type 2000 valves combine an investment cast stainless steel body with an impact-resistant polymer actuator. Spindle sealing is maintained by a self-adjusting PTFE V-ring gland preloaded by an internal spring pack, minimizing fugitive emissions and eliminating manual packing adjustments.

Item No.	Component	Material Specification (Article 20061740)
1	Transparent Cover / Position Indicator	Polycarbonate (PC)
2	Pilot Air Port Bushing	Stainless steel 1.4305 (G 1/4)
3	Actuator Housing	Polyamide (PA, size 50 mm / Code D)
4	Piston Seal	Nitrile butadiene rubber (NBR)
5	Spindle Packing Gland	PTFE V-rings (filled), with spring compensation
6	Return Spring	Stainless steel 1.4310
7	Guiding Tube	Stainless steel CF3M
8	Wiper Seal	PTFE (filled)
9	Body Seal	Graphite (PTFE optional)
10	Valve Spindle	Stainless steel 1.4401 / 1.4404
11	Retaining Pin	Stainless steel 1.4401 / 1.4404
12	Seat Seal	Polytetrafluoroethylene (PTFE)
13	Valve Body	Cast stainless steel CF3M (equivalent to 316L)
14	Swivel Plate / Disc	Stainless steel CF3M / 1.4401 / 1.4404

Operating Principle and Flow Direction

Burkert 20061740 utilizes Control Function A (normally closed, CFA). In the unpressurized rest position, the preloaded internal spring forces the actuator piston downward. The spindle transfers this closing thrust onto the swivel plate, compressing the PTFE seat disc against the CF3M body seat.

When pilot air enters the lower control port (port 1) at a minimum of 4.1 bar, pressure acts against the underside of the actuator piston, overcoming the 1.4310 spring pack. The spindle retracts, lifting the swivel plate off the seat to fully open the flow passage. In this flow-under-seat configuration, the incoming process medium assists in lifting the valve disc during opening and cushions the final closure against the flow direction, preventing destructive pressure spikes (water hammer).

Flow Direction Restriction

Flow beneath the valve seat is suitable for both liquid media and compressible gases or steam. Valves configured for flow over the seat must never be used with liquid media due to the extreme danger of hydraulic shock.

Technical Specifications and Operating Limits

Specification Parameter	Technical Value
Nominal Diameter (DN)	DN 25 (1")
Orifice Size	25 mm
Flow Capacity (Kv, water)	14 m³/h (16.2 US gpm)
Seat Leakage Class	Leakage rate A according to DIN EN 12266-1 (PTFE seal, air test)
Maximum Operating Pressure	5.2 bar(g) (against flow under seat)
Minimum Pilot Air Pressure	4.1 bar(g)
Maximum Pilot Air Pressure	10.0 bar(g)
Pilot Port Size	G 1/4 internal thread with stainless steel insert
Process Temperature Range	-10 °C to +185 °C
Permissible Ambient Temperature	-10 °C to +40 °C (nominal SKU specification; up to +60 °C at reduced medium temp)
Storage Temperature	-20 °C to +65 °C
Operating Viscosity	Max. 600 mm²/s
Maximum Installation Altitude	2,000 m above sea level
Acoustic Emission	< 70 dB(A)
Enclosure Rating	IP67 (EN 60529 / IEC 60529)

Pressure and Temperature Derating

Process pressure retention follows DIN EN 12516-1 PN25 flange and body ratings. For CF3M stainless steel bodies:

Process Temperature	Permissible Body Pressure (PN25 Rating)
-10 °C to +50 °C	25.0 bar
+100 °C	24.5 bar
+150 °C	22.4 bar
+185 °C	21.0 bar
+200 °C	20.3 bar

Operating Pressure Limit for Size 50 Actuator

Although the CF3M valve body is rated for PN25, the 50 mm (D) actuator with Control Function A generates sufficient spring force to seal against a maximum line pressure of 5.2 bar(g) in DN25 flow-under-seat service. Operating line pressures exceeding 5.2 bar(g) can overcome the spring force and cause seat leakage.

Dimensional Data

Actuator Dimension	Parameter Value (Actuator Size 50 mm / D, DN25)
Actuator Outer Diameter (∅ A)	64 mm
Centerline to Top of Actuator (B / H)	152 mm (max.)
Centerline to Pilot Connection (K / M)	136 mm (max.)
Pilot Air Connection Thread (P)	G 1/4
Total Height from Pipe Base (BS / HS)	223 mm (max.)

Welded End Dimension	DIN 11850 Series 2 / DIN 11866 Series A / DIN EN 10357 Series A
Pipe External Diameter (∅ DS)	29.0 mm
Wall Thickness (WS)	1.5 mm
Face-to-Face Body Length (LS)	130 mm
Centerline to Port End (CS)	43 mm
Straight Weld Extension (ES)	26 mm
Hexagon Nut Across Flats (WAF)	41 mm

Installation and Body Welding Procedures

Burkert 20061740 can be installed in any orientation, though positioning the actuator upright is recommended to avoid particulate settling within the neck bushing.

Dismount Actuator Prior to Welding

Before welding the CF3M body into the process line, the pneumatic actuator assembly must be detached from the valve body. Applying welding heat to a fully assembled valve will permanently distort the PA housing, damage internal NBR piston seals, and destroy the PTFE spindle packings.

Actuator Dismounting and Reassembly Steps

1. Secure the valve body in a vice or pipe clamp with protective soft jaws.
2. Apply 5.0 bar to 5.5 bar of compressed air to the lower pilot port (port 1) to pneumatically lift the swivel disc off the valve seat. Unthreading the actuator while the valve seat is pressed shut will tear or score the PTFE seal disc.
3. While maintaining pilot air pressure, engage an open-end wrench on the hexagon flats of the body interface bushing (do not use a pipe wrench).
4. Unscrew the actuator assembly from the valve body.
5. Weld the valve body into the pipe network, maintaining proper pipe alignment and avoiding internal slag or debris.
6. Inspect the graphite body seal on the neck interface. Replace if compressed, scratched, or deteriorated.
7. Apply a thin layer of Klüberpaste UH1 96-402 (or equivalent certified lubricating paste) to the neck connection threads.
8. Re-apply 5.0 bar to 5.5 bar pilot pressure to lift the disc, insert the actuator into the body, and thread until seated.
9. Torque the body connection to 60 Nm (+10 / -5 Nm) using a calibrated torque wrench.

Aligning Pilot Air Ports

The pilot connection housing can be rotated steplessly through 360° to accommodate pipe routing. To reposition:

1. Apply 5.0 bar pilot pressure to the lower pilot air port to lift the disc.
2. Place an open-end wrench on the actuator connection hexagon and another wrench on the body connection hexagon.
3. Rotate the actuator assembly clockwise to the desired angle. Do not rotate counter-clockwise to avoid loosening the body thread.

Pneumatic Connection and Commissioning

Connect the pilot medium (instrument-grade compressed air or dry neutral gas) to the lower pilot port on the actuator cylinder base. In corrosive wash-down environments, connect a pneumatic vent hose to the upper exhaust port to vent into a non-aggressive zone.

Port Identification	Connection Assignment (Control Function A)
Port 1 (Lower Actuator Port)	Pilot air supply inlet (G 1/4)
Port 2 (Upper Actuator Port)	Atmosphere exhaust / breathing filter vent

Verify that the supply line delivers a steady pressure between 4.1 bar and 10 bar. Cycle the valve several times under dry conditions before admitting process media. Check the optical position indicator on top of the actuator transparent bonnet: the red indicator stem rises when the valve strokes open.

Maintenance, Inspection, and Spare Parts

Under clean media conditions, the Type 2000 valve mechanism operates maintenance-free. Periodic visual inspections should verify system tightness during plant maintenance shutdowns.

Inspection Checkpoint	Potential Failure Mode	Corrective Action
Process Pipeline Joint (1)	Pipe connection leakage	Check weld joints or flange/clamp seals
Actuator Relief Bore (2)	Spindle packing leakage	Replace packing gland seal set or actuator
Valve Seat / Swivel Plate (3)	Internal cross-seat leakage	Replace valve disc set (swivel plate & PTFE seal)
Body Joint Sealing Plane	Body seal leakage	Replace graphite body gasket; check 60 Nm torque

Recommended Service Kits and Tools

• Valve Set (Swivel Plate & Seat Kit): Consists of pre-assembled seal holder, PTFE seat seal disc, centering screw, and graphite body gasket.
• Spindle Packing Kit: Comprises spring-compensated PTFE V-ring sets, washers, and spindle wipers.
• Actuator Cap Service Tool (Size 50 D): Wrench socket for actuator bonnet disassembly (Order No. 639175).
• Packing Gland Assembly Sleeve (Size 50 D, ∅8 mm spindle): Tool sleeve for gland seal insertion (Order No. 639166).
• Centering Screw Tightening: When replacing the PTFE disc on the spindle tip, apply Loctite 640 to the threads and torque to exactly 0.6 Nm using a 5.5 mm open-end wrench.

Troubleshooting

Fault Condition	Probable Cause	Corrective Remedial Action
Actuator fails to stroke	Pilot pressure below 4.1 bar	Increase pilot air supply pressure to 4.1–10.0 bar
	Pilot line routed to upper port	Reconnect pilot air supply to lower port (Port 1)
	Process pressure exceeds 5.2 bar	Lower medium pressure to within 5.2 bar rating
	Pipeline flow reversed	Verify flow enters beneath seat per body arrow
Internal seat leakage when closed	Debris trapped in valve seat	Flush pipework; install an upstream Y-strainer
	PTFE seat disc worn or scored	Replace swivel plate valve set
	Pilot air venting sluggish	Check pilot solenoid valve exhaust port for blockage
External leakage at relief bore	PTFE packing gland worn	Replace spindle packing gland set using tool 639166