BURKERT 359949 (Type 2104) is an externally controlled pneumatic 3/2-way T-diaphragm valve designed for decentralised process automation in hygienic, sterile, and aggressive media applications. Built with an ASME BPE / DIN 11866 Series C DN 25 welded block body, this configuration operates under control function A (normally closed by internal spring pack). The valve assembly features a stainless steel envelope over a PPS actuator piston core, providing ingress protection to IP65/IP67 and NEMA Type 4X. Internal fluid contact surfaces are sealed with a GYLON® diaphragm laminated to an EPDM backing cushion, certified to FDA, USP Class VI, and EC 1935/2004 standards.

Operating pressure spans 0 to 10 bar (PN 16 rating, ASME Class 150), actuated by pneumatic pilot air at 5.5 to 7 bar via an integrated 6 mm push-in ELEMENT interface. The zero-deadleg T-body design is self-draining when mounted in recommended orientations, maintaining full CIP (clean-in-place) and SIP (sterilisation-in-place) compliance up to +140 °C for 60 minutes.

Technical Specifications and Operating Limits

Article 359949 operates within defined pneumatic, thermal, and mechanical parameters:

Technical Parameter	Specification
Article Number / Type	359949 / Type 2104
Fluidic Configuration	3 ports, 2 switching positions (3/2-way T-valve)
Control Function	Control function A (CF A, normally closed by spring force)
Nominal Diameter (DN)	DN 25 (1 inch, 25.4 mm outer diameter)
Pipe Specification	ASME BPE / DIN 11866 Series C (25.4 x 1.65 mm, ID 22.1 mm)
Nominal Pressure Range	0 bar to 10 bar (PN 16 according to DIN EN 1333 / Class 150 to DIN EN 1759)
Pilot Pressure Range	5.5 bar to 7 bar (maximum pilot pressure 10 bar)
Medium Temperature	-5 °C to +130 °C (steam sterilisation to +140 °C for max. 60 min)
Ambient Temperature	-5 °C to +55 °C
Diaphragm Material	GYLON® laminated with EPDM support membrane (ER material code)
Valve Body Material	Stainless steel block material 1.4435 (316L)
Actuator Housing Material	Polyphenylene sulphide (PPS) with 1.4561 (316Ti) stainless steel casing
Pilot Air Connection	Push-in connector for 6 mm OD tubing (Interface ELEMENT)
Certifications Enclosed	EN 10204 3.1 inspection certificate, factory certification 2.1 diaphragm

Component Design and Material Construction

Type 2104 separates the operating pilot air from the ambient environment via integrated internal air ducts, preventing intake of aggressive process atmospheres. The bonnet features an inspection relief bore that immediately indicates any diaphragm leakage.

Item	Component	Material
1	Ground terminal	Stainless steel 1.4301 / 1.4305 (on ATEX/IECEx variants)
2	Transparent cap	Polysulfone (PSU) with optical position indicator
3	Pilot air ports	Push-in connector PP (6 mm OD) / G 1/8 stainless steel 1.4305
4	Actuator housing	Polyphenylene sulphide (PPS)
5	Actuator casing	Stainless steel 1.4561 (316Ti)
6	Piston seal	FKM
7	Diaphragm	GYLON® laminated with EPDM support membrane (ER)
8	Diaphragm bonnet	Stainless steel CF3M
9	Valve body	Stainless steel block material 1.4435 / 316L
10	Body fasteners	Stainless steel hex screws

Steam Sterilisation Parameters

The GYLON®/EPDM laminated diaphragm accommodates saturated steam cycles up to +140 °C for a duration of 60 minutes. Extending steam cycles beyond this limit accelerates polymer fatigue and requires shortened inspection intervals.

Dimensional Data for ASME BPE DN 25 Weld Ends

Dimensions for article 359949 correspond to diaphragm size 25 with ASME BPE / DIN 11866 Series C welded branch geometry:

Parameter	Dimension (mm)	Description
Port 1 – Port 2 DN	25...25	Main line and branch diameter DN 25 (1 inch)
∅D1 x s1	25.40 x 1.65	Main run tube outside diameter and wall thickness
∅D2 x s2	25.40 x 1.65	Branch tube outside diameter and wall thickness
A	124.5	Overall body length
B	25.0	Weld end tangent length
C	74.8	Centreline to weir sealing face distance
E	25.0	Branch port tangent length
F	95.0	Total height from lower port edge to branch end
G	42.0	Distance from main centreline to body shoulder
H	26.0	Internal weir centre offset
I	6.0	Deadleg depth to weir seal seat
Product Key	SODF-SODF	Port connection configuration key

For diaphragm size 25 with actuator size 70 (M, ∅92 mm cover) or size 90 (N, ∅120 mm cover), total valve height to the manual indicator cap (H+M) is 172 mm (actuator 70) or 205 mm (actuator 90). When fitted with a Type 8691 control head, height extends to 268 mm (actuator 70) or 301 mm (actuator 90).

Pipeline Welding and Actuator Mounting

Damage to Actuator and Diaphragm during Welding

Direct welding with the actuator installed transfers destructive heat into the PPS housing, piston seals, and GYLON® diaphragm. Disassemble the actuator and diaphragm prior to welding the valve body into the line.

Disassembly and Welding Steps

1. Clamp the uninstalled valve body in a soft-jaw vice.
2. Apply pneumatic pilot pressure to pilot port 1 (5.5 bar minimum). This lifts the compressor off the weir seat to prevent tearing the diaphragm during bonnet removal.
3. Unscrew the body screws crosswise and withdraw the actuator assembly together with the diaphragm.
4. Weld the bare 1.4435 stainless steel body into the piping following ASME BPE orbital or manual welding procedures.
5. Sand and smooth inner and outer weld seams if necessary, then clean all debris, chips, and flux from the body chamber.

Reassembly and Fastener Torquing

1. Ensure the compressor guide is positioned correctly in the actuator spindle.
2. Connect pilot air to port 1 to open the actuator stroke.
3. Position the actuator with the diaphragm onto the cleaned body.
4. Thread the body screws crosswise until hand-tight, ensuring the diaphragm perimeter seats flat between body flanges.
5. Cycle the actuator twice pneumatically to allow the diaphragm to center itself.
6. Vent and disconnect the pilot air supply.
7. Tighten the four body screws without air pressure in three progressive crosswise steps: 1/3 torque (2.0 Nm), 2/3 torque (4.0 Nm), and full torque of 6.0 Nm (+10% tolerance) for GYLON® diaphragm size 25.

Leakage Detection Alignment

During horizontal or tilted pipeline installation, orient the valve body so that at least one relief bore in the diaphragm bonnet sits at the lowest downward point. This ensures immediate gravity drainage and detection should any medium leak past the primary seal.

Actuator 360-Degree Alignment

On valves with a stainless steel diaphragm bonnet, the actuator housing can be rotated continuously through 360° to optimize pilot air and electrical cable entry:

1. Place a hook wrench conforming to DIN 1810 form A (size A 68...75 for actuator sizes 70 to 130) on the actuator connection ring.
2. Turn the actuator only as far as necessary to align ports.
3. Do not loosen body screws while rotating the actuator.

Automation and Accessory Combinations

Type 2104 forms modular automated assemblies without external piping using the ELEMENT interface:

• Valve System Type 8801-TB-H: Combines Type 2104 with Type 8691 control head. Features contactless inductive position sensing, multi-colour optical status LEDs, manual pilot override, and integrated AS-Interface or IO-Link communications.
• Valve System Type 8801-TB-K: Combines Type 2104 with Type 8690 pneumatic control unit with mechanical or inductive end switches.
• Valve System Type 8802-TB-I / 8802-TB-J: Combines Type 2104 with Type 8694 positioner or Type 8693 process controller for modulating loop control, equipped with backlit graphic displays and autotune commissioning routines.

Maintenance and Diaphragm Service Life

The pneumatic piston actuator is maintenance-free under specified service conditions. The GYLON® diaphragm and FKM piston O-rings are natural wearing components requiring scheduled inspection:

• Initial Commissioning: Re-check and retighten body screws crosswise to 6.0 Nm after the first steam sterilisation cycle to compensate for thermal relaxation.
• Routine Inspection: Inspect the diaphragm for deformation or wear at least every 100,000 switching cycles, or earlier when operating with abrasive or heavily cycling media.
• Diaphragm Replacement (DS 25): The GYLON®/PTFE diaphragm size 25 attaches to the compressor via a bayonet connection. To remove, rotate the diaphragm 90° and lift off. If converting to an EPDM diaphragm, install the threaded insert into the compressor.

Diaphragm Storage Recommendations

Elastomeric and polymer spare parts should be kept in airtight protective bags between +5 °C and +25 °C with relative humidity below 65%. Store diaphragms in an uncompressed state away from direct sunlight, UV fixtures, and ozone-generating electrical equipment.