BURKERT 348414 (Type 2031) is an externally piloted 2/2-way diaphragm valve engineered for ultra-pure, sterile, aggressive, and abrasive fluid duties in pharmaceutical, biotechnical, and hygienic process lines. Operating under control function B (CF B), the valve is held open in its unpressurised rest state by internal spring tension and closes upon pneumatic pressurisation through the upper pilot air connection. The valve body is constructed from forged stainless steel alloy 1.4435 (316L, conforming to ASME BPE / BN2 DIN EN 10222-5) and features 1 1/2" ASME BPE sanitary clamp ends (clamp outer diameter 50.5 mm, tube outer diameter 38.1 mm, wall thickness 1.65 mm). Zero-dead-leg geometry and flow-optimised contouring yield a water Kv coefficient of 37.5 m³/h.

The process interface is sealed by a two-piece PTFE/EPDM diaphragm (order code EA) mounted via a twist-and-lock bayonet mechanism, isolating operating fluids from the mechanical drive components. Drive actuation is managed by an autoclavable polyphenylene sulphide (PPS) piston actuator equipped with an integrated optical stem position indicator, fluor rubber (FKM) piston seals, and G 1/4" female pilot air ports. The valve handles operating pressures from 0 to 10 bar, working temperatures from -10 °C to +130 °C, and steam sterilization cycles up to +140 °C for 60 minutes. Standard delivery includes a manufacturer 3.1 inspection certificate and a 2.1 diaphragm declaration.

Technical Specifications

Specification Parameter	Technical Value / Detail
Model Number / Resource SKU	348414 (Type 2031 CLASSIC series)
Valve Type	Pneumatically operated 2/2-way diaphragm valve, complete assembly
Switching Positions / Ports	2 switching positions / 2 fluidic ports
Control Function	Function B (CF B / SFB): Bidirectional, normally open by spring force
Nominal Diameter (DN)	DN 40 (1 1/2" / 1.5 Inch)
Diaphragm Size	Diaphragm size 40
Body Port Connection	ASME BPE Clamp (DIN 11866 series C)
Port 1 Outer Diameter (OD)	38.1 mm (1 1/2")
Port 1 Inner Diameter (ID)	34.8 mm
Port 1 Wall Thickness (s)	1.65 mm (0.065")
Clamp Flange Outer Diameter	50.5 mm (1.984")
Nominal Pressure Rating	PN 16 (DIN EN 1333) / Class 150 (DIN EN 1759)
Operating Medium Pressure	0.00 bar to 10.00 bar (gauge pressure)
Pilot Control Pressure Range	2.0 bar to 7.0 bar (pilot medium: neutral gases, dry instrument air)
Flow Coefficient Kv (Water)	37.5 m³/h (+20 °C, 4 bar inlet, 3 bar outlet)
Medium Temperature Limits	-10 °C to +130 °C (steam sterilisation: +140 °C for 60 min)
Ambient Temperature Limits	+5 °C to +90 °C (short-term exposure up to +140 °C)
Valve Body Material	Forged stainless steel 1.4435 / 316L (BN2 / ASME BPE)
Internal Surface Roughness	Ra ≤ 0.38 µm (ASME BPE SF4 electropolished) / Ra ≤ 0.5 µm (SF1 mechanical)
Actuator Housing Material	Polyphenylene sulphide (PPS)
Diaphragm Material	PTFE with EPDM backing membrane (EA)
Piston Seal Material	FKM (Fluor rubber)
Pilot Air Connection	G 1/4" internal thread (stainless steel 1.4305 port insert)
Manual Override	None
Cleaning Capabilities	Full CIP (Clean-in-Place) and SIP (Steam-in-Place) capable
Compliance & Certificates	3.1 Inspection Certificate, 2.1 Membrane Certificate, FDA, USP Class VI, EC 1935/2004

Valve Construction and Material Specifications

BURKERT 348414 is composed of a forged stainless steel 2-way body, a hygienic diaphragm seal, and a compact piston actuator. Internal fluid-contacting surfaces are finished to sanitary roughness grades to eliminate bacterial accumulation and cross-contamination risks.

Item No.	Valve Element	Material Specification
1	Transparent Cap / Position Visualisation	Polysulfone (PSU)
2	Actuator Cover	Polyphenylene sulphide (PPS) standard (PA available on request)
3	Pilot Air Ports	Stainless steel 1.4305 (G 1/4" female)
4	Piston Seal	Fluor rubber (FKM)
5	Socket / Guiding Element	Sinter metal
6	Interface / Actuator Base	Polyphenylene sulphide (PPS) standard (1.4404 on request)
7	Process Diaphragm	PTFE with EPDM backing cushion (code EA)
8	Valve Body	Forged stainless steel 1.4435 / 316L (BN2, ASME BPE)

Hygienic Process Diaphragm

The diaphragm on BURKERT 348414 uses an inert PTFE process contact shield supported by a vulcanised EPDM backing cushion. The compound complies with FDA 21 CFR 177.1550 and 177.2600, passes USP Class VI biocompatibility testing, and adheres to European Regulation EC 1935/2004 for food contact materials.

Control Function and Operating Dynamics

BURKERT 348414 is configured with Control Function B (CF B / SFB). The actuator contains internal compression springs configured to drive the piston and spindle upward in the absence of control air, holding the valve fully open.

• De-energised / Rest Position (Open): Spring force holds the compressor and diaphragm off the valve body weir. Medium flows unrestricted across both directions.
• Energised Position (Closed): Applying pilot air (2.0 to 7.0 bar) into the upper pilot air port pressurises the piston chamber above the piston, overcoming spring force to drive the compressor down and seat the diaphragm against the forged body weir.
• Exhausting: Releasing pilot air from the upper port allows the compression spring to return the valve to its open position.

Pneumatic Port Selection

Never apply pilot air to the lower port on a CF B valve during operational switching. The lower port vents air from beneath the piston. Connecting pilot pressure to the incorrect port prevents closing and causes process disruption.

Dimensional Data and Clamp Standards

The forged valve body conforms to ASME BPE hygienic clamp dimensions, featuring standardized end-to-end lengths and clamp face geometry.

Dimension Designation	Symbol	Dimension [mm]	Dimension [Inch]
Nominal Port Diameter	DN	40 mm	1 1/2" (1.5")
Diaphragm Size	DS	40 mm	—
Tube Outer Diameter	∅ D1	38.10 mm	1.500"
Tube Wall Thickness	s	1.65 mm	0.065"
Tube Inner Diameter	ID	34.80 mm	1.370"
Clamp Flange Outer Diameter	∅ D2	50.50 mm	1.984"
Face-to-Face Body Length (TG05 standard)	L	140 mm	5.512"
Face-to-Face Body Length (TG05 + AF34 long version)	L	159 mm	6.260"
Weir Height to Port Axis	h	27.60 mm	1.087"
Body Centerline to Actuator Interface	H	52.40 mm	2.063"

Actuator Boundary Dimensions

For diaphragm size 40, Type 2031 utilises actuator size 100 (G) or 125 (H) with G 1/4" pilot air connections:

Actuator Size	Outer Diameter ∅ A [mm]	Height C [mm]	Air Port K	Total Actuator Height H [mm]	Height with MT85 Block [mm]	Total Height with Type 8697 [mm]
100 (G)	127	73	G 1/4"	205	246	298 (HM) / 339 (HM+MT85)
125 (H)	158	86	G 1/4"	243	284	336 (HM) / 377 (HM+MT85)

Performance and Pressure Limits

Flow rate data is established in accordance with DIN EN 60534 standards at +20 °C fluid temperature, with 4 bar at the valve inlet and 3 bar at the outlet (Δp = 1 bar).

Diaphragm Size	Connection Standard	Pipe Size	Water Kv Value (Elastomer)	Water Kv Value (PTFE/EPDM)
40	ASME BPE (DIN 11866 C)	1 1/2" (38.1 x 1.65 mm)	37.0 to 40.0 m³/h	37.5 m³/h
40	DIN EN ISO 1127 (B)	DN 32 / DN 40	41.0 m³/h	40.0 m³/h
40	DIN 11850 Series 2 (A)	DN 40 (41.0 x 1.5 mm)	40.0 m³/h	40.0 m³/h
40	SMS 3008	DN 40 (38.0 x 1.2 mm)	38.0 m³/h	38.0 m³/h

Medium Operating Pressure Ratings for Control Function B

Under control function B, the valve achieves bidirectional shut-off up to 10.0 bar static line pressure when pilot air is supplied within the allowable 2.0 to 7.0 bar range. To maximize diaphragm service life, the pilot pressure supplied to the upper port should not exceed the level necessary to reliably close the process medium pressure.

Installation and Self-Draining Alignment

BURKERT 348414 can be installed in any orientation; positioning the actuator vertically upright is recommended. When installed horizontally, the valve must be angled around the pipe axis to ensure gravity self-draining without pooling behind the weir.

Self-Draining Installation Requirements

1. Pipeline Slope (β): The pipeline should maintain a continuous downward slope between 1° and 5° in accordance with ASME BPE guidelines.
2. Valve Self-Draining Angle (α): For forged body size DN 40 (ASME BPE 1 1/2", pipe dimensions 38.1 x 1.65 mm, product code SODH / TG05), the precise self-draining angle is α = 24°.
3. Orientation Guide: The forged valve body features an etched alignment mark on the port end, which must face directly upward (12 o'clock). The exact angle α must be confirmed with an inclinometer.
4. Leakage Monitoring Relief Bore: The bonnet contains a relief bore designed to detect fluid migration in case of diaphragm wear. This bore must be positioned at the lowest physical orientation to discharge freely.

Maintenance and Diaphragm Replacement

The PPS actuator is maintenance-free under normal operating conditions. Regular maintenance requires periodic visual inspection of the leakage bore and inspection of the PTFE/EPDM diaphragm every 100,000 cycles, or sooner if handling abrasive fluids.

Stored Energy and Depressurisation Hazard

Before loosening body screws or clamp connections, isolate the pipeline, depressurise both fluid and pneumatic lines, and allow the system to drain and cool. Valves with Control Function B contain preloaded compression springs beneath the piston. Do not attempt to dismantle the actuator cylinder housing without an authorized fixture.

Diaphragm Replacement Procedure (CF B)

1. Disassembly: Loosen the 4 body screws crosswise and withdraw the actuator and diaphragm assembly from the body. Diaphragm size 40 utilizes a bayonet catch connection.
2. Removal: Rotate the diaphragm 90° relative to the compressor to disengage the bayonet lock, then slide it out.
3. Inspection: Check compressor positioning and spindle freedom of motion.
4. Installation of New Diaphragm: Insert the new PTFE/EPDM bayonet diaphragm into the compressor slot and turn 90° until locked. Ensure the tab orientation is positioned perpendicular to the fluid flow line.
5. Reassembly: Place the actuator and diaphragm onto the body. Lightly hand-tighten the body screws crosswise.
6. Cycle Alignment: Apply pilot air to the upper port (G 1/4") to cycle the valve closed and open twice to seat the elastomer evenly.
7. Final Torquing: With pilot air applied to keep the valve closed, tighten the body screws crosswise in three gradual steps (approx. 1/3, 2/3, and 3/3 of final torque) using a calibrated torque wrench.

Diaphragm Size	Port DN	Valve Body Type	Tightening Torque (PTFE/EPDM)	Tightening Torque (EPDM/FKM)
40	DN 40 (1 1/2")	Forged Body (VS)	10.0 Nm (+10% tolerance)	8.0 Nm (+10% tolerance)

Troubleshooting Guide

Symptom / Malfunction	Root Cause	Corrective Action
Actuator fails to open	Upper pilot port remained pressurized; pilot air supply exhausted	Vent upper pilot air port; check compression spring integrity
Actuator fails to close	Pilot air connected to lower port instead of upper port	Reconnect pilot line to upper port (SFB closes via upper port)
Valve leaks past seat	Pilot pressure too low to overcome line pressure; line pressure exceeds 10 bar	Increase pilot pressure within 2.0–7.0 bar range; verify line pressure
External leakage at body flange	Body screws untorqued after steam cycle; diaphragm cold-flowed	Re-torque body screws crosswise to 10.0 Nm in pressurized state
Fluid leaks from bonnet relief hole	Worn or ruptured PTFE/EPDM diaphragm	Immediately replace diaphragm (Order number 20093073)
Flow rate significantly reduced	Distorted or bulging PTFE diaphragm from overheating or vacuum	Replace diaphragm; avoid using diaphragm as primary steam stop

Spare Parts and Conversion Kits

Original BURKERT spare parts maintain technical conformity and hygiene certifications:

Component Description	Type / Size Detail	Order Article Number
Replacement Diaphragm PTFE/EPDM (EA)	Diaphragm Size 40 (EPDM E04 / PTFE P05 bayonet)	20093073
Replacement Diaphragm EPDM (AD)	Diaphragm Size 40 (EPDM E04 threaded with insert)	688426
Replacement Diaphragm GYLON® (ER)	Diaphragm Size 40 (PTFE L08 laminate)	693180
Actuator Seal Set (PPS Actuator)	Actuator Size 100 (G), Diaphragm Size 40	012127
Actuator Seal Set (PPS Actuator)	Actuator Size 125 (H), Diaphragm Size 40	011494
Actuator Cover Installation Wrench	Tool for Actuator Cover ∅ 100 mm / 125 mm	639172 / 639173
Control Function Conversion Kit (CF A → CF B)	Actuator Size 100 (G) / Actuator Size 125 (H)	011710 / 011715
Integrated Position Feedback Module	Type 8697 (Inductive or mechanical limit switches)	Consult Bürkert Type 8697
Integrated Process Automation Head	Type 8690 (Decentralised pilot valve / feedback)	Consult Bürkert Type 8690