BURKERT 321061 (Type 2103) is an externally controlled 2/2-way diaphragm valve engineered for decentralised process automation in hygienic, sterile, and demanding liquid or gaseous media applications. The valve assembly combines a flow-efficient stainless steel body with a compact ELEMENT design pneumatic piston actuator. Configured in Control Function A, the valve is closed by spring force in its rest position and opens when pilot air pressure is applied. Article 321061 is specified with a nominal diameter of DN 20 and features butt-weld ends conforming to DIN EN ISO 1127, ISO 4200, and DIN 11866 Series B dimensions (outer diameter 26.9 mm, wall thickness 1.6 mm, inner diameter 23.7 mm). Process sealing is provided by a high-temperature EPDM diaphragm capable of handling continuous media temperatures from -10 °C to +143 °C, with steam sterilisation ratings up to +150 °C for durations up to 60 minutes.

The pneumatic piston actuator has an outer diameter of 91 mm (size 70 mm / M) and utilizes a polyphenylene sulphide (PPS) structural core enveloped in a stainless steel 1.4561 (316Ti) cover, providing resistance against harsh cleaning chemicals and atmospheric washdowns. Pilot air pressure between 4.8 bar and 10 bar drives the internal actuator piston via integrated pilot air channels without drawing in ambient air. Article 321061 provides a nominal water flow coefficient (Kv) of 10.7 m³/h and maintains tight bidirectional shut-off up to a maximum operating pressure of 10 bar (PN 16 / Class 150). The valve is certified clean-in-place (CIP) and sterilisation-in-place (SIP) capable and supports full self-draining when mounted at the designated installation angle.

Technical Specifications

Parameter	Specification
Article Number	321061
Valve Type	2103 (ELEMENT series)
Valve Construction	Complete assembled valve
Circuit Function	2/2-way, Control Function A (normally closed, spring return)
Nominal Diameter	DN 20 (20 mm)
Diaphragm Size	20
Flow Value Kv (Water)	10.7 m³/h
Nominal Pressure Rating	PN 16 (DIN EN 1333) / Class 150 (DIN EN 1759)
Medium Operating Pressure	0.00...10.00 bar
Required Pilot Pressure	4.8...10.0 bar
Pilot Air Connection	Push-in connector for 6 mm (1/4 in) outer diameter tube
Process Connection Type	Weld end (DIN EN ISO 1127 / ISO 4200 / DIN 11866 Series B)
Pipe Connection Dimensions	26.9 mm outer diameter × 1.6 mm wall thickness (23.7 mm inner diameter)
Product Key Connection Code	SA43
Medium Temperature Range	-10...+143 °C
Steam Sterilisation Limit	Max. +150 °C for 60 min
Ambient Temperature Range	-10...+60 °C (standard push-in connector)
Body Material	Stainless steel (1.4435 / 316L)
Diaphragm Material	EPDM high-temperature (code AD)
Diaphragm Attachment	Bayonet catch
Manual Override	None
CIP / SIP Capability	Yes
Ingress Protection Rating	IP65 / IP67, NEMA Type 4X

Actuator Design and Construction Materials

The ELEMENT pneumatic actuator size 70 mm (M) uses an integrated pilot duct design that routes control air without external tubing between automation modules. An optical position indicator is visible through the transparent polysulfone cap at the top of the actuator cover.

Item No.	Element	Material
1	Ground terminal	Stainless steel 1.4301 / 1.4305 (only on ATEX/IECEx variants)
2	Transparent cap	Polysulfone (PSU)
3	Pilot air ports	Push-in connector PP (standard), G 1/8 thread stainless steel 1.4305
4	Actuator	Polyphenylene sulphide (PPS)
5	Cover	Stainless steel 1.4561 (316Ti)
6	Piston seal	Fluoroelastomer (FKM)
7	Interface	Polyphenylene sulphide (PPS standard, stainless steel 1.4308 optional)
8	Diaphragm	EPDM high-temperature (AD)
9	Valve body	Stainless steel 1.4435 / 316L

Operating Parameters and Pressure Limits

For Control Function A actuators of size 70 mm (M) paired with diaphragm size 20, the closing force is produced by an internal spring pack. The static and dynamic operating pressure limits depend on the supplied pilot pressure:

• Medium Operating Pressure: 0 to 10 bar against static seat shut-off and dynamic flow conditions.
• Minimum Pilot Pressure: 4.8 bar is required to fully overcome the spring pack and achieve 100% stroke open position.
• Maximum Pilot Pressure: 10.0 bar for standard PPS actuator construction.
• Tightness Definition: Static tightness corresponds to zero seat leakage when the valve is closed and pressurized upstream. Dynamic tightness corresponds to bubble-tight shut-off during media flow against downstream restriction.

Medium Temperature Limits for Diaphragm

The EPDM (AD) diaphragm is rated for continuous liquid and gas media exposure between -10 °C and +143 °C. Steam sterilisation is permissible up to +150 °C for a duration of 60 minutes. Diaphragms must not be used as permanent steam shut-off valves.

Installation and Pipeline Welding Guidelines

The valve can be mounted in any spatial orientation, though installation with the actuator positioned vertically upright is preferred. For applications requiring complete fluid evacuation, proper line inclination and self-draining body orientation must be verified:

1. Self-Draining Angle (α): For connection code SA43 (pipe dimensions 26.9 mm × 1.6 mm, diaphragm size 20), the specified self-draining angle is 17°.
2. Marking Alignment: The self-draining angle marking on the weld connection must face upwards.
3. Bonnet Leak Detection: One of the relief bores located in the diaphragm bonnet must face directly downward to ensure early drainage and visibility in the event of diaphragm wear.

Disassembly Required Before Welding

Thermal conduction during pipeline welding will destroy the EPDM diaphragm and actuator seals. The actuator and diaphragm must be unbolted and removed from the valve body before welding the body into the piping system. Once welding and surface finishing are complete, clean the valve body cavity thoroughly before reassembling the actuator.

Actuator Assembly and Diaphragm Replacement

For Control Function A, the actuator stem is retracted using compressed air before removing or reinstalling the valve body bolts:

1. Connect compressed air (minimum 4.8 bar) to pilot air port 1 to open the valve and pull the compressor off the weir seat.
2. Loosen the four body screws crosswise and withdraw the actuator and diaphragm assembly from the body.
3. Disengage the diaphragm from the compressor: diaphragm size 20 uses a bayonet catch. Rotate the diaphragm 90° to detach it from the spindle compressor.
4. Fit the replacement EPDM diaphragm by inserting its bayonet pin into the compressor slot and rotating 90°. Align the diaphragm identification tab perpendicular to the pipeline flow direction.
5. Mount the actuator and diaphragm onto the body. Hand-tighten the body screws crosswise.
6. Cycle the actuator twice with pilot pressure to center the diaphragm properly.
7. Vent the pilot air pressure from port 1 so the valve moves to the closed position.
8. Without applying pilot pressure, tighten the body screws crosswise in three uniform stages (1/3, 2/3, and full torque) to 4.0 Nm (+10% tolerance).

Inspection Intervals

Check the diaphragm for mechanical wear after a maximum of 100,000 switching cycles, or shorten the interval when operating with abrasive media. Retighten the valve body screws crosswise following the initial steam sterilisation cycle.

Automation Units and Accessories

The 70 mm (M) ELEMENT actuator interface allows integrated mechanical and pneumatic coupling with decentralised Burkert automation modules:

• Type 8691 Control Head: Optical status display using coloured high-power LEDs, non-contact inductive valve position sensor, integrated pilot valve, and AS-Interface or IO-Link.
• Type 8690 Pneumatic Control Unit: Mechanical or inductive limit switches for end-position detection with an integrated pilot valve.
• Type 8692 Electropneumatic Positioner: Digital positioner with graphic display, touch keypad, automatic TUNE initialisation, and bus interfaces including PROFIBUS, PROFINET, Modbus TCP, and büS.
• Type 8694 Positioner TopControl BASIC: Compact digital electropneumatic positioner with DIP switch and push-button commissioning.
• Type 8693 Process Controller: Integrated PID controller with valve diagnostics and digital communication for process control loops.