BURKERT 344484 (Type 2000) is an externally piloted 2/2-way angle seat valve designed for discrete process automation and fluid shut-off duties. The assembly consists of a pneumatically actuated polyamide (PA) piston actuator and an investment-cast stainless steel CF3M (316L) angle seat valve body. Process connection 1 is engineered as a welded connection conforming to ISO 4200, DIN EN ISO 1127, and DIN 11866 Series B, with a nominal diameter of DN 25, an outer pipe diameter of 33.7 mm, and a 2.0 mm wall thickness. Configured with double-acting Control Function I, the valve utilizes compressed air or neutral gas across two control air ports to actively drive the valve disc open and closed, eliminating spring dependency and providing defined actuation in both travel directions.

Operating with flow direction below the valve seat, BURKERT 344484 delivers a water flow coefficient (Kv) of 15 m³/h with an orifice seat size of 25 mm. The valve body accommodates working pressures from 0 to 16 bar(g) and fluid temperatures from -10 °C to +185 °C under nominal pressure classes PN 25 (DIN EN 1333) and Class 150 (DIN EN 1759). Tight shut-off is ensured by a virgin PTFE seat seal meeting leakage rate A in accordance with DIN EN 12266-1. Spindle sealing is achieved through a self-adjusting packing gland equipped with spring-compensated PTFE V-rings, protecting process integrity across liquid, gas, and steam duties.

Valve Structure and Operating Principle

BURKERT 344484 features an integrated construction comprising the actuator head, internal spindle transmission, and flow-diverting body. Closing and opening forces generated by the piston are transmitted directly to the swivel plate disc via a solid 1.4401/1.4404 stainless steel spindle. An integrated relief bore on the actuator neck provides atmospheric venting between the actuator chamber and the fluid packing gland, serving as an external indicator port in the event of packing wear.

Item	Description	Item	Description
1	Transparent cover with visual position indicator	7	Valve body (CF3M stainless steel)
2	Actuator cover (PA)	8	Body connection mechanism with wrench flats
3	Actuator housing (PA)	9	Wiper seal and intermediate packing
4	Atmospheric relief/bleed bore	10	Lower control air port (G 1/4)
5	Welded pipe connection (ISO 4200 / DIN 11866 B)	11	Upper control air port (G 1/4)
6	Flow direction arrow mark

Control Function I (Double-Acting)

Control Function I (SFI / DA) operates without an internal return spring. Both switching operations require positive pneumatic pressure:

• Pressure applied to the lower control air port (port 10) directs pilot air beneath the actuator piston, retracting the spindle to lift the swivel plate off the seat (opening the valve).
• Pressure applied to the upper control air port (port 11) directs pilot air above the actuator piston, extending the spindle to press the PTFE seat seal against the body orifice (closing the valve).
• In the absence of control air pressure, the valve remains in an undefined position.

Operating Safety under Control Function I

Because Control Function I does not have a spring-driven mechanical fail-safe position, an unexpected loss of supply air causes the valve to remain in its last travel state. Prior to servicing or system restart, depressurize the pipe lines, restore pilot air pressure to establish a controlled state, and then admit process fluid.

Flow Direction Below Valve Seat

BURKERT 344484 is configured exclusively for flow entering below the seat. In this arrangement, line medium enters beneath the swivel plate so that system line pressure assists the pneumatic opening stroke. Flowing against the seat face prevents water hammer surges when handling liquids, neutral media, or condensable vapors.

Restriction Against Flow Above Seat for Liquids

Valves directing flow above the seat must never be used with liquid media due to hydraulic shock waves (water hammer) that burst piping and valve housings. Flow below the seat is the specified orientation for all liquid, steam, and neutral gas duties on article 344484.

Material Specifications

All wetted parts and structural casing elements are manufactured from corrosion-resistant materials certified for industrial and sanitary utilities, supporting CIP and SIP chemical cleaning.

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

Technical Data and Operating Limits

BURKERT 344484 operates within specified fluidic and thermodynamic boundaries defined by the combination of a polyamide actuator and a stainless steel body.

Parameter	Technical Value
Medium Compatibility	Water, alcohols, oils, fuels, hydraulic fluids, saline solutions, lyes, organic solvents, steam, neutral gases
Operating Pressure Range	0 to 16 bar(g) (vacuum down to -0.9 bar(g) available on vacuum variants)
Nominal Pressure Class	PN 25 (DIN EN 1333) / Class 150 (ASME B16.5 / B16.34)
Pilot Pressure Range	2.0 to 10.0 bar(g)
Pilot Air Connection	G 1/4 female thread
Medium Temperature Range	-10 °C to +185 °C
Ambient Temperature Range	-10 °C to +40 °C (derating applies at elevated medium temperatures)
Storage Temperature	-20 °C to +65 °C
Environmental Protection	IP67 (EN 60529 / IEC 60529)
Acoustic Noise Emission	< 70 dB(A) under standardized testing
Maximum Fluid Viscosity	600 mm²/s

Pressure Derating According to Standards

The maximum permissible working pressure of the CF3M stainless steel body decreases at elevated temperatures in accordance with DIN EN 12516-1 and ASME B16.34:

Medium Temperature (°C)	DIN EN 12516-1 PN25 Maximum Pressure (bar)	ASME B16.34 Class 150 Maximum Pressure (bar)
-10 to +38 / +50	25.0	19.0
100	24.5	16.2
150	22.4	14.8
185 / 200	20.3	13.7
230	19.0	12.7

Actuator Thermal Limits

For PA actuators (size 50 / D), when medium temperatures reach the maximum rating of +185 °C, ambient temperature must not exceed +40 °C. If ambient temperature reaches +60 °C, the continuous medium temperature must be maintained below +140 °C.

Dimensions and Installation Geometry

Process port 1 features orbital butt-weld ends conforming to DIN EN ISO 1127, ISO 4200, and DIN 11866 Series B for DN 25 process piping.

Welded Body Dimensions (ISO 4200 / DIN EN ISO 1127 / DIN 11866 Series B)

Size	Pipe OD ø DS (mm)	Wall Thickness WS (mm)	Inner Diameter (mm)	Face-to-Face Length LS (mm)	End Length ES (mm)	Centerline Height CS (mm)
DN 25	33.7	2.0	29.7	130	26	43

Actuator Dimensions (Size 50 / D, ø 64 mm Housing)

Dimension Code	Metric Value (mm)	Dimension Reference Description
ø A	64	Outer diameter of PA actuator cover/casing
B / H	152	Centerline to top of actuator body
K / M	136	Centerline to lower pilot port center
P	G 1/4	Pilot air female threaded port size
BS / HS	223	Total clearance height from bottom of valve body to indicator dome

Mechanical Assembly and Pipeline Welding

Installation can occur in any mounting orientation, though an upright actuator position is recommended to reduce particulate settling in the packing gland area.

Actuator Removal Prior to Pipeline Welding

Welded Connection Procedure

When installing valves with welded connections, the actuator assembly must be detached from the valve body before welding. Thermal radiation from orbital or manual welding will destroy the internal PTFE seat seal, spindle packing V-rings, and actuator polymer housing.

Follow these sequential mechanical instructions:

1. Clamp the valve body securely in a vice equipped with soft jaws.
2. Apply 5.0 bar of compressed air to the lower control air port (port 10) to lift the swivel plate disc clear of the seat contour.
3. Position an open-ended wrench onto the wrench flats of the body connection mechanism (item 8). Never use pipe wrenches.
4. Unscrew and withdraw the complete actuator assembly vertically from the body.
5. Weld the bare CF3M body into the flushed, stress-free pipe system.
6. After cooling, inspect the graphite body seal ring (item 8 in material breakdown) and replace if deformed.
7. Reapply 5.0 bar compressed air to the lower pilot port, lubricate body threads with Klüberpaste UH1 96-402, and thread the actuator back into the body.
8. Tighten the connection mechanism to a torque of 60 Nm (+10 / -5 Nm).

360° Continuous Actuator Rotation

Control air supply lines can be routed cleanly by rotating the actuator head 360° relative to the body.

1. Pressurize the lower pilot port with 5.0 bar compressed air to hold the disc in the open position.
2. Fix an open-end wrench on the body connection hexagon flats.
3. Fit a second open-end wrench onto the hexagonal actuator connector.
4. Rotate the actuator exclusively in the direction indicated by the alignment markings until the pilot ports face the desired direction. Turning in the opposite direction risks loosening the body connection joint.

Pneumatic Setup and Commissioning

Use clean, dry instrument air or neutral gas meeting process standards. Hoses must withstand operating pressures up to 10 bar and surrounding thermal conditions.

• Lower Control Port (marked 2 / bottom): connect signal air to open the valve.
• Upper Control Port (marked 1 / top): connect signal air to close the valve.
• In corrosive atmospheres, route exhaust ports or unassigned lines into non-aggressive environments.

Commissioning Protocol

To achieve controlled, water-hammer-free initial operation, apply pilot air pressure to confirm actuator travel before introducing pressurized pipeline media. Verify that line pressure never exceeds 16 bar and that medium temperature stays within the limits of the rating plate.

Maintenance and Inspection Checklist

The actuator mechanism is maintenance-free under normal operating conditions. Regular maintenance schedules should inspect sealing interfaces for process leakage.

Inspection Point	Visual Condition	Corrective Maintenance Action
Media Connection (1)	Fluid seepage at weld joints	Repair weld joint or pipe alignment
Relief Bore (2)	Medium or pilot air weeping	Replace spindle packing gland kit or replace actuator
Swivel Disc (3)	Scratches, grooves, or seat bypass	Replace valve set (swivel plate and PTFE seal)
Body Joint Seal	External seepage above hexagon	Replace graphite body seal ring

Troubleshooting Guide

Malfunction	Probable Cause	Corrective Action
Actuator fails to stroke	Pilot lines reversed	Connect opening pilot line to lower port; closing line to upper port
	Pilot pressure below minimum limit	Increase control air pressure to minimum 2 to 4 bar
	Line pressure exceeds 16 bar limit	Regulate system operating pressure within rating limits
Internal seat leakage	Debris trapped between plug and seat	Flush pipeline; install upstream strainer (< 1 mm mesh)
	PTFE seat seal worn or mechanically cut	Install replacement valve set (swivel plate disc)
	Reverse flow orientation	Ensure pipe flow aligns with valve body arrow (flow under seat)
Leakage at relief bore	Spindle V-ring packing gland worn	Install replacement packing gland seal kit using assembly tools

Spare Parts and Service Accessories

Only genuine Bürkert spare kits should be employed to preserve type approvals and pressure integrity.

• Process Valve Packing Gland Kit: contains replacement filled-PTFE V-rings, wiper, pre-stress springs, and secondary O-rings.
• Process Valve Seat Set: includes replacement CF3M swivel plate, virgin PTFE seal disc, retention pin, and graphite body seal ring.
• Spindle Packing Assembly Sleeve: ordering tool 639166 (for 8 mm spindle / size 50 actuator).
• Actuator Cover Assembly Wrench: ordering tool 639175 (ø 40/50 mm actuator casing).