PN25
BURKERT 368999 (Type 2100) is a pneumatically operated 2/2-way ELEMENT angle seat valve engineered for decentralized process automation in steam and gaseous media applications. The valve features a cast stainless steel CF3M body with DN 40 SMS 3008 weld connections (tube outer diameter 38 mm x 1.2 mm wall thickness), providing an installation face-to-face length of 182 mm and a water flow factor Kv of 35 m³/h. Designed in Control Function A (normally closed by spring force), this valve variant directs media flow above the seat, where process pressure assists tight shut-off up to 16 bar(g). Stem sealing is maintained by a self-adjusting PTFE V-ring packing gland with stainless steel spring compensation, rated for vacuum conditions down to -0.9 bar(g) and media temperatures from -10 °C to +185 °C.
Operating Principle and Flow Direction Above Seat
BURKERT 368999 operates under Control Function A (CF A). In the unpressurized rest position, internal actuator return springs hold the stainless steel swivel plate firmly against the PTFE valve seat. Actuating air fed to pilot air port 1 lifts the piston and spindle assembly to open the flow path. Because this specific configuration directs media above the seat (flow-to-close), line pressure works in the closing direction, reinforcing shut-off tightness against the valve orifice.
DANGER: Bursting Lines from Liquid Media Water Hammer
Valves configured with flow direction above the seat must only be used for steam, gases, and vapours. In liquid media service, closing against the flow stream creates severe water hammer (hydraulic pressure shocks) that can burst pipelines, valve bodies, and connected process equipment. Do not use this valve configuration on liquid media under any operational circumstances.
Technical Specifications and Operating Limits
Nominal performance data for BURKERT 368999 aligns with international pressure equipment standards PN 25 (DIN EN 1333) and Class 150 (DIN EN 1759 / ASME B16.34).
| Specification Parameter | Value |
|---|---|
| Valve Type | 2100 ELEMENT |
| Article Number | 368999 |
| Circuit Function | 2/2-way, Control Function A (normally closed, NC) |
| Flow Direction | Above the seat (flow to close) |
| Port Size / Orifice | DN 40 (nominal seat diameter 40 mm) |
| Process Connection | SMS 3008 weld end (38.0 mm OD x 1.2 mm wall thickness x 35.6 mm ID) |
| Face-to-Face Installation Length | 182 mm |
| Flow Coefficient Kv (Water, +20 °C, 1 bar Δp) | 35 m³/h |
| Maximum Operating Pressure | 16 bar(g) |
| Vacuum Capability | Down to -0.9 bar(g) |
| Pilot Pressure Range | 2.7 bar(g) to 10 bar(g) |
| Control Medium | Neutral gases, air |
| Pilot Air Connection | Push-in connector, OD 6 mm (1/4 inch) |
| Permissible Operating Media | Steam, neutral gases, gaseous solvents, and vapours |
| Fluid Temperature Range | -10 °C to +185 °C |
| Ambient Temperature Range | -10 °C to +60 °C (push-in pneumatic connector) |
| Sound Pressure Level | < 70 dB(A) |
| Seat Leakage Class | Leakage rate A according to DIN EN 12266-1 |
| Degree of Protection | IP65 / IP67 according to EN 60529, NEMA Type 4X |
| Hygiene Conformity | Food (EC) 1935/2004 compliant wetted materials, CIP / SIP capable |
Pressure Derating with Elevated Media Temperature
Operating pressure limits decrease with higher process media temperatures in accordance with DIN EN 12516-1 (PN 25) and ASME B16.34 (Class 150):
- DIN EN 12516-1 (PN 25): 25.0 bar from -10 °C to +50 °C; 24.5 bar at 100 °C; 22.4 bar at 150 °C; 20.3 bar at 200 °C; 19.0 bar at 230 °C.
- ASME B16.34 Class 150: 19.0 bar from -29 °C to +38 °C; 18.4 bar at 50 °C; 16.2 bar at 100 °C; 14.8 bar at 150 °C; 13.7 bar at 200 °C.
Material Specifications
Wetted and non-wetted materials are selected for chemical compatibility and durability in industrial process environments. Packing gland and actuator lubricants comply with classification NSF H1.
| Item No. | Component Part | Material Specification |
|---|---|---|
| 1 | Ground terminal | Stainless steel 1.4301 / 1.4305 (supplied on ATEX options) |
| 2 | Optical position indicator | Polysulfone (PSU) transparent cap |
| 3 | Pilot air ports | Polypropylene (PP) push-in connector (6 mm / 1/4") |
| 4 | Actuator cover | Polyphenylene sulphide (PPS) |
| 5 | Actuator casing | Stainless steel 1.4561 (316Ti) |
| 6 | Piston seal | FKM |
| 7 | Spring assembly | Stainless steel 1.4310 |
| 8 | Spindle guide pipe | Stainless steel 1.4401 (316) / 1.4404 (316L) |
| 9 | Packing gland | Filled PTFE V-rings with stainless steel spring compensation |
| 10 | Spindle (stem) | Stainless steel 1.4401 (316) / 1.4404 (316L) |
| 11 | Spindle guide bushing | PEEK |
| 12 | Body seal | Graphite (PTFE optional) |
| 13 | Swivel plate | Stainless steel 1.4401 (316) / 1.4404 (316L) |
| 14 | Seat seal | PTFE |
| 15 | Valve body | Cast stainless steel CF3M (316L equivalent) |
Installation and Pipeline Welding
BURKERT 368999 can be installed in any orientation, with the actuator in the upright vertical position preferred. Flow must enter above the seat in accordance with the cast body direction arrow.
WARNING: Dismantle Actuator Before Welding
Before welding the CF3M valve body into the pipeline, dismantle the pneumatic actuator from the body. Welding heat conducts through the metal structure and destroys internal actuator components, piston seals, and spindle packing.
Actuator Dismantling and Reassembly Sequence
- For Control Function A valves, open the valve before loosening the body connection: apply 5 bar compressed air to pilot air port 1 to lift the swivel plate off the seat.
- Clamp the valve body in a holding fixture.
- Fit an open-end wrench across the wrench flat of the body connection hexagon and unscrew the actuator assembly.
- Weld the valve body into the SMS 3008 pipeline.
- Inspect the body connection seal for cleanliness and integrity. Grease the body thread using Klüber paste UH1 96-402.
- Pressurize pilot air port 1 with 5 bar air to open the swivel plate, screw the actuator back into the body, and torque to specification.
| Valve Size | Actuator Size | Tightening Torque [Nm] | Tolerance [Nm] |
|---|---|---|---|
| DN 15 | 40 (C), 50 (D), 63 (E) | 45 | +10 / -5 |
| DN 20 | 40 (C), 50 (D), 63 (E), 80 (F) | 50 | +10 / -5 |
| DN 25 | 50 (D), 63 (E), 80 (F) | 60 | +10 / -5 |
| DN 32 | 63 (E), 80 (F), 100 (G) | 65 | +10 / -5 |
| DN 40 | 63 (E), 80 (F), 100 (G), 125 (H) | 65 | +10 / -5 |
| DN 50 | 63 (E), 70 (M), 80 (F), 90 (N), 100 (G), 125 (H) | 70 | +10 / -5 |
| DN 65 | 80 (F), 100 (G), 125 (H) | 70 | +10 / -5 |
| DN 80 | 125 (H), 130 (P) | 120 | +10 / -5 |
Actuator Alignment Rotation
The pilot air connections can be positioned continuously through 360° to accommodate pipe layout constraints.
CAUTION: Observe Rotation Direction
Pressurize pilot air port 1 with 5 bar air to open the valve before turning. Apply an open-end wrench to the drive connection hexagon while holding the body connection hexagon with a second wrench. Turn only in the counterclockwise direction indicated on the actuator casing to avoid loosening the body thread connection.
Decentralized Automation and Accessories
The ELEMENT design enables direct mounting of automated top-mounted control units without external tubing, creating complete valve systems (such as Type 8801-YE):
- Type 8691 / Type 8695 Control Heads: contact-free inductive position sensor with integrated teach-in function for end position registration, high-visibility colored LED status indication, integrated pilot valve, and communication via AS-Interface, IO-Link, or büS.
- Type 8690 / Type 8697 Pneumatic Control Units: compact modular feedback units with mechanical or inductive limit switches and integrated pilot valve.
Maintenance, Inspection, and Troubleshooting
Routine inspection protects system integrity and prevents unplanned downtime. The visual inspection points indicated below must be checked periodically.
| Inspection Point | Observed Condition | Required Maintenance Action |
|---|---|---|
| Media connectors (1) | Medium leaking at weld joints or pipeline interface | Re-align and repair pipeline connections |
| Relief bore (2) | Medium or pilot air leaking from actuator relief bore | Replace spindle packing gland or actuator assembly |
| Swivel plate seat (3) | Media leaking downstream past closed valve seat | Replace valve swivel plate seat seal set |
Troubleshooting Guide
- Actuator does not switch: verify pilot air is connected to port 1; confirm pilot pressure is between 2.7 bar and 10 bar; ensure operating pressure does not exceed 16 bar.
- Valve leaks through seat: check for minimum pilot pressure; check for particulates between seat and PTFE disc; replace worn swivel plate.
- Leakage from relief bore: stem packing V-rings are worn; replace packing gland using the dedicated socket wrench (DN 32 to DN 80 with 14 mm spindle: width across flats 21 mm, part no. 683223; DN 15 to DN 50 with 10 mm spindle: width across flats 19 mm, part no. 683221).
- External cleaning: use commercially available neutral cleaning agents verified for compatibility with PPS, stainless steel, and FKM seals.
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