BURKERT 20084885 (Type 2104) is a pneumatically operated 3/2-way T-diaphragm valve designed for decentralized hygienic automation. The valve assembly integrates a stainless-steel-encased ELEMENT piston actuator, a zero-deadleg T-valve body machined from 1.4435 / 316L block material, and a PTFE/EPDM dual-layer diaphragm. Operating under Control Function A (normally closed by spring force), the valve controls ultra-pure, sterile, aggressive, or abrasive fluids at medium operating pressures from 0 bar to 10 bar. Process connections are weld ends engineered to ASME BPE and DIN 11866 Series C standards at DN 50 (outer diameter 50.8 mm / 2 inch with 1.65 mm wall thickness).

The Type 2104 architecture features internal pilot air routing to eliminate ambient air intake into the spring chamber. With an IP65/IP67 and NEMA 4X enclosure rating, the assembly withstands direct external washdown protocols and CIP/SIP inline steam sterilisation cycles. The fluid contact zone meets pharmaceutical standards, including FDA 21 CFR 177.1550/177.2600, USP Class VI compliance, and EC Regulation 1935/2004.

Technical Attributes (Article 20084885)

Attribute	Source Specification
Article Number	20084885
Type Family	Type 2104 ELEMENT
Construction	Complete valve assembly
Control Function	A (Normally closed, NC by spring force)
Fluidic Ports	3 ports, 2 switching positions (3/2-way T-valve)
Port 1 Connection Type	Weld end
Port 1 Pipe Standard	ASME BPE / DIN 11866 Series C
Nominal Diameter	DN 50 (2 inch)
Pipe Dimensions	Outer diameter 50.8 mm (2.000 in), wall thickness 1.65 mm (0.065 in), inner diameter 47.5 mm
Valve Body Material	Stainless steel block material 1.4435 / 316L
Diaphragm Material	PTFE with EPDM backing membrane (code EA)
Actuator Size	130 mm diameter (Code P)
Actuator Envelope	Stainless steel 1.4561 (316Ti)
Actuator Internal Body	Polyphenylene sulphide (PPS)
Nominal Pressure Range	0 bar to 10 bar (PN 16 / Class 150)
Pilot Pressure Range	5.5 bar to 7.0 bar
Medium Temperature	-10 °C to +130 °C (Steam sterilisation max. +140 °C for 60 min)
Ambient Temperature	-10 °C to +55 °C
Pilot Air Interface	ELEMENT interface, push-in connector for 6 mm tubing
Cleaning Capabilities	Full CIP (Clean-in-Place) and SIP (Sterilise-in-Place) capability
Manual Override	None
Position Indicator	Without electrical indicator (optical cap standard)
Documentation Enclosed	Manufacturer test certificate 3.1, Diaphragm declaration 2.1

Construction and Material Specifications

The ELEMENT drive housing combines a PPS core with an external 1.4561 (316Ti) stainless steel protective casing. This construction shields internal mechanical and pneumatic components from corrosive cleanroom detergents, atmospheric chemicals, and thermal shock.

Item No.	Component	Material
1	Ground terminal	Stainless steel 1.4301 / 1.4305 (included on ATEX/IECEx variants)
2	Optical position cap	Polysulfone (PSU)
3	Pilot air ports	PP push-in connector standard (6 mm / 1/4 in); optional G 1/8 stainless steel 1.4305
4	Actuator body	Polyphenylene sulphide (PPS)
5	Actuator cover	Stainless steel 1.4561 (316Ti)
6	Piston seal	Fluorocarbon elastomer (FKM)
7	Diaphragm	PTFE/EPDM dual-layer (EA), EPDM (AD), Advanced PTFE (EU), GYLON laminate (ER)
8	Valve body	Stainless steel block material 1.4435 (DIN EN 10088) / 316L (ASTM A479 / ASME BPE)

Wetted interior body surfaces are finished to controlled hygienic criteria: mechanically polished to Ra ≤ 0.5 µm (ASME BPE SF1) or electropolished to Ra ≤ 0.38 µm (ASME BPE SF4 / DIN HE4). External surfaces maintain Ra ≤ 1.6 µm.

Operating Conditions and Pressure Ratings

Under Control Function A, closing force is produced by an internal spring pack that drives the compressor and pushes the diaphragm against the internal weir. For diaphragm size 50 mounted to a 130 mm (P) actuator, the pilot pressure requirements and media sealing capabilities are strictly defined:

• Operating Medium Pressure: 0 bar to 10 bar static across the weir.
• Dynamic Operating Pressure: Tight sealing up to 7 bar with flowing medium when closing against line backpressure.
• Required Pilot Pressure: 5.0 bar to 7.0 bar (nominal operational window 5.5 bar to 7.0 bar).
• Tightness Criteria: Static tightness ensures zero leakage across the seat at maximum operating pressure when closed. Dynamic tightness ensures zero seat leakage when shutting against an active process stream.

Operating Pressure and Thermal Limits

Do not use the diaphragm as a permanent steam shut-off valve. Steam sterilisation is rated to a maximum of +140 °C for up to 60 minutes with the PTFE/EPDM diaphragm. Prolonged exposure beyond recommended time and temperature thresholds accelerates elastomer degradation and necessitates reduced inspection intervals.

Dimensions for ASME BPE Welded T-Body

Type 2104 T-bodies machined from block material integrate the main run and branch into a single piece to prevent dead legs and flow stagnation.

ASME BPE / DIN 11866 Series C Dimensions (Diaphragm Size 50)

• Port 1 – Port 2 Size: DN 50 – DN 50 (Product Key: SODI-SODI)
• Tube Dimensions: Outer diameter ∅D1 = 50.80 mm, wall thickness s1 = 1.65 mm; branch outer diameter ∅D2 = 50.80 mm, branch wall s2 = 1.65 mm
• Face-to-Face Dimension (A): 188.0 mm
• Weld End Tangent Length (B): 30.0 mm
• Centerline to Seat Face (C): 115.8 mm
• Port Centerline to Base (E): 30.0 mm
• Overall Actuator Center Height (F): 145.0 mm
• Body Width (G): 71.0 mm
• Port Centerline Offset (H): 42.0 mm
• Internal Weir Drain Offset (I): 6.5 mm
• Actuator Cover Outer Diameter (∅ A): 159 mm
• Actuator Height (H+M): 282 mm (without automation units); 346 mm with 8690/8697 control units; 379 mm with 8691 control head

Automation Integration and Decentralised Control

The pneumatic actuator interface can be rotated 360° relative to the body to permit unobstructed positioning of pilot air lines and electrical conduits. The valve can be combined directly with decentralised automation heads:

• Electrical Position Indicators: Type 8691 (for actuator Ø 70/90/130/225 mm) with contactless inductive position sensing and colored status LEDs.
• Pneumatic Control Units: Type 8690 incorporating mechanical or inductive limit switches with integrated pilot valves.
• Electropneumatic Positioners: Type 8692 (TopControl) and Type 8694 (TopControl BASIC) for continuous flow control with zero internal air bleed in the steady state.
• Process Controllers: Type 8693 with integrated PID processing algorithms and bus communications including PROFINET, EtherNet/IP, Modbus TCP, PROFIBUS DPV1, and büS.

Pipeline Installation Guidelines

Avoid Thermal Damage During Welding

Do not weld the valve body into the pipeline while the actuator and diaphragm are mounted. Heat conducted through the stainless steel block will destroy the diaphragm and warp the actuator guides. Always unbolt and remove the actuator and diaphragm prior to welding.

Installation Sequence

1. Disassemble Actuator: Apply compressed air (5.5 bar to 7.0 bar) to pilot air port 1 to retract the diaphragm from the body seat. Unscrew the body bolts crosswise and lift the actuator and diaphragm off the body.
2. Weld Body: Align and weld the 1.4435 block body into the pipeline system according to ASME BPE pipe slope standards to guarantee self-drainage. Smooth any internal weld beads and remove all chips and slag.
3. Position Leakage Detection: Re-mount the bonnet assembly ensuring that one of the relief bores is situated at the lowest gravitational point for optical leakage monitoring.

4. Align Actuator: Use a hook wrench (DIN 1810 size A 68...75 for actuator size 130) on the actuator base to rotate the actuator into the desired orientation.

Actuator Assembly and Fastening Torques

When reinstalling the actuator on the valve body for Control Function A:

1. Check that the compressor guide pins align correctly in the actuator guide tracks. An incorrectly positioned compressor will deform upon pressurisation.

2. Pressurise pilot air port 1 with compressed air to pull the compressor up.
3. Place the actuator and diaphragm assembly onto the valve body.
4. Lightly tighten the body screws crosswise until the diaphragm is held loosely between body and actuator.
5. Cycle the pilot pressure twice to center the diaphragm against the body contour.
6. Exhaust the pilot pressure so the valve returns to the closed position.
7. Tighten the body screws crosswise without pilot pressure in three progressive stages (approx. 1/3, 2/3, and final torque).

Body Connection Tightening Torques (Tolerance +10%)

Diaphragm Size	EPDM / FKM Diaphragms	PTFE / Advanced PTFE / GYLON® Diaphragms
8	2.0 Nm	2.5 Nm
15	3.5 Nm	4.0 Nm
20	4.0 Nm	4.5 Nm
25	5.0 Nm	6.0 Nm
40	8.0 Nm	10.0 Nm
50 (Article 20084885)	12.0 Nm	15.0 Nm
65	20.0 Nm	30.0 Nm
80	30.0 Nm	40.0 Nm
100	40.0 Nm	50.0 Nm

Maintenance and Diaphragm Replacement

Diaphragms are subject to mechanical flexure and thermal wear. After the initial inline steam sterilisation cycle, check and retighten the body screws crosswise to compensate for elastomer settling. Conduct visual inspections at the relief bore regularly; any fluid emergence indicates diaphragm leakage and mandates immediate replacement.

Fastening Mechanisms by Diaphragm Size

• Size ≤ 8: Button connection.
• Sizes 15 and 20: Bayonet catch (engage/disengage via 90° rotation).
• Sizes ≥ 25 (including Size 50): Bayonet catch for PTFE and Advanced PTFE diaphragms; threaded pin connection with brass/stainless insert for EPDM, FKM, and GYLON diaphragms.

Converting Between Diaphragm Materials

When switching from a PTFE diaphragm (bayonet) to an EPDM diaphragm (threaded) on size 50, place the threaded insert into the compressor pocket before screwing in the EPDM diaphragm hand-tight, then back off 1/2 turn anticlockwise. When switching back from EPDM to PTFE, remove the threaded insert completely. Leaving the insert installed with a bayonet diaphragm will crush the diaphragm and cause severe valve damage.

Storage of Elastomer Spares

Store spare diaphragms in compliance with DIN 7716 and ISO 2230 standards between +5 °C and +25 °C in dry (<65% relative humidity), UV-shielded, airtight containers away from ozone-generating equipment and solvents. Under optimal conditions, EPDM diaphragms have a maximum shelf life of 7 years (3 years operating life), and PTFE diaphragms have a maximum shelf life of 10 years (3 years operating life).