BURKERT 20050340 (Type 2933) is a 2/2-way manually operated diaphragm valve actuator designed for hygienic, sterile, and aggressive process environments. Part of the Type 2933 Basic series, this configuration corresponds to diaphragm size 20 and handwheel size S (Ø45 mm). It features a precision-cast stainless steel 1.4308 diaphragm bonnet paired with a PPS (polyphenylene sulphide) handwheel, enabling continuous service in ambient temperatures from -10 °C to +130 °C (short-term tolerance up to +150 °C) and full autoclave sterilization.

Article 20050340 is delivered as a dedicated actuator assembly module without a pre-assembled valve body or diaphragm seal. It is factory-equipped with an integrated optical position indicator showing a yellow marker with a 30-position rotation scale, a single minimum stroke limiter that acts as an adjustable closing limiter to prevent diaphragm over-compression, and two threaded M5x0.5 bores to mount optional inductive proximity sensors for electrical open/closed position feedback.

Technical Data and Actuator Dimensions

Specification Parameter	Technical Value / Execution
Valve Type / Function	Type 2933 Basic / 2/2-way shut-off
Bürkert Part Number (MPN)	20050340
Diaphragm Size	20
Handwheel Size / Diameter (Ø B)	Size S / 45 mm
Handwheel Elevation per Rotation	1.75 mm
Height in Open Position (H1)	95 mm
Height in Closed Position (H2)	86 mm
Bonnet Material	Stainless steel 1.4308
Handwheel Material	Polyphenylene sulphide (PPS)
Valve Spindle Material	Stainless steel 1.4305
Position Indicator Construction	Optical indicator with stroke scale (PA / 1.4305)
End Position Detection	Prepared with 2x M5x0.5 threaded bores
Actuator Ambient Temperature	-10 °C to +130 °C (short-term up to +150 °C, autoclavable)
Permissible Static Medium Pressure	Up to 10 bar
Identification	Data matrix code on product label

Material Specifications and Valve Construction

Item No.	Component	Material Specification in Article 20050340
1	Handwheel	Polyphenylene sulphide (PPS)
2	Visual Position Indicator	Polyamide (PA) / Stainless steel 1.4305
3	Valve Spindle	Stainless steel 1.4305
4	Diaphragm Bonnet	Stainless steel 1.4308
5	Diaphragm (compatible options)	EPDM (AD), PTFE/EPDM (EA), advanced PTFE/EPDM (EU), GYLON®/EPDM (ER), FKM (FF)
6	Valve Body (compatible options)	Forged stainless steel (VS), tube body (VP), cast stainless steel (VG), plastic (PP, PVDF, PVC-U, PVC-C)

Compatible Diaphragm Size 20 Valve Bodies

Actuator 20050340 combines with any Bürkert size 20 2-way valve body. The connection geometry and length depend on the selected body manufacturing method and pipe standard:

Forged Stainless Steel Bodies (VS) – 1.4435 BN2 / 316L

Connection Standard	Port DN	Pipe Ext. Ø D1 [mm]	Wall s [mm]	Length L [mm]	h [mm]	H [mm]	Product Key
DIN EN ISO 1127 / ISO 4200 (Series B)	DN 15	21.3	1.6	119	16.0	30.3	SA42
DIN EN ISO 1127 / ISO 4200 (Series B)	DN 20	26.9	1.6	119	16.0	30.3	SA43
DIN 11850 Series 2 / DIN 11866 Series A	DN 20	23.0	1.5	119	16.0	30.3	SD43
ASME BPE / DIN 11866 Series C	3/4"	19.05	1.65	117	16.0	30.3	SA93
BS 4825	DN 20	19.05	1.20	117	16.0	30.3	SODE
Clamp DIN 32676 Series B (ISO pipe)	DN 20	26.9	1.6	114 (D2=50.5)	16.0	30.3	TC43
Clamp DIN 32676 Series A (DIN pipe)	DN 20	23.0	1.5	119 (D2=34.0)	16.0	30.3	TD43
Clamp ASME BPE	3/4"	19.05	1.65	102 (D2=25.0)	16.0	30.3	TG03
Clamp ASME BPE (with variable AF34)	3/4"	19.05	1.65	117 (D2=25.0)	16.0	30.3	TG03 + AF34

Tube Valve Bodies (VP) – 1.4435-BN2 / 316L

Connection Type / Standard	Nominal Port	Pipe Dimensions	Length L [mm]	h [mm]	H [mm]	Product Key
Welded DIN EN ISO 1127 (Series B)	DN 20	Ø 26.9 × 1.6 mm	119	17.15	30.45	SA43
Welded ASME BPE (Series C)	1"	Ø 25.4 × 1.65 mm	127	16.40	41.65	SODF
Clamp DIN 32676 Series B (ISO pipe)	DN 20	Ø 26.9 × 1.6 mm	119 (D2=50.5)	17.15	42.40	TC43
Threaded G Connection	G 3/4	Thread depth 12 mm	118 (SW 32)	17.15	30.45	GM85
Threaded NPT Connection	NPT 3/4	Thread depth 14 mm	118 (SW 32)	17.15	30.45	NM85
Threaded Rc Connection	Rc 3/4	Thread depth 14.5 mm	118 (SW 32)	17.15	30.45	RC85
Flanged DIN EN 1092-1	DN 20	Flange Ø 105 mm	150 (L3)	18.0	2.0	FD23
Flanged ANSI B16.5	3/4" (DN 20)	Flange Ø 99 mm	150 (L3)	12.7	1.6	FA03
Flanged JIS 10K	DN 20	Flange Ø 100 mm	150 (L3)	14.0	1.0	FJ02

Precision Cast Stainless Steel Bodies (VG) – 1.4435 / 316L

Connection Type / Standard	Port Size	Pipe Ext. Ø D1 [mm]	Length L [mm]	h [mm]	H [mm]	Product Key
Welded DIN EN ISO 1127 (Series B)	DN 20	26.9	119	18.0	32.7	SA43
Welded DIN 11850 Series 2	DN 20	23.0	119	18.0	32.8	SD43
Welded ASME BPE	3/4"	19.05	119	18.0	32.8	SA93
Welded ASME BPE	1"	25.4	119	18.0	32.7	SODF
Clamp DIN 32676 Series A	DN 20	23.0	119 (D2=34.0)	18.0	32.8	TD43
Clamp ASME BPE	3/4"	19.05	117 (D2=25.0)	18.0	25.0	TG03

Plastic Valve Bodies (PP, PVDF, PVC-U, PVC-C)

Body Material	Connection Style	Nominal Port	Fitting Dimension Ø d	Face-to-Face L1 [mm]	h [mm]	H [mm]	Product Key
PP (PP)	Spigot connection	DN 20	Ø 25 mm	144	17.0	42.0	SS26
PVDF (PD)	Spigot connection	DN 20	Ø 25 mm	144	17.0	36.0	SS26
PVC-U (PV)	Spigot connection	DN 20	Ø 25 mm	144	17.0	36.0	KS26
PP (PP)	True union socket	DN 20	Ø 24.2 mm	146 (L3=108)	17.0	42.0	SM26
PVDF (PD)	True union socket	DN 20	Ø 24.2 mm	146 (L3=108)	17.0	36.0	SM26
PVC-U (PV)	True union socket	DN 20	Ø 25.0 mm	152 (L3=108)	17.0	36.0	KM26
PP / PVDF / PVC-U	Flanged connection	DN 20	Flange 4×14 PCD 75	154 (L)	17.0	42 / 36	FL25

Flow Rates (Kv Values for Diaphragm Size 20)

Flow rate data represents water flow in m³/h at +20 °C with 4 bar at the valve inlet and 3 bar at the valve outlet:

• Forged Steel Body (VS): DIN EN ISO 1127 DN 20: 12.5 m³/h; DIN 11850 Series 2 DN 20: 12.4 m³/h; ASME BPE 3/4": 8.4 m³/h; BS 4825: 8.9 m³/h.
• Tube Valve Body (VP): DIN EN ISO 1127 DN 20: 13.5 m³/h; ASME BPE 1": 12.8 m³/h.
• Cast Valve Body (VG): DN 20 (3/4"): 10.7 m³/h.
• Plastic Valve Body: DN 20 (3/4") with EPDM diaphragm: 14.1 m³/h; with PTFE/EPDM diaphragm: 13.1 m³/h.

Operating Pressures and Tightening Torques

For diaphragm size 20, the maximum static operating pressure is 10 bar across plastic, forged stainless steel, cast stainless steel, and tube bodies. Adhere to the following handwheel and body bolting torque specifications (+10% tolerance):

Operating Parameter	Diaphragm: EPDM / FKM	Diaphragm: PTFE / Advanced PTFE / GYLON®
Max. Permissible Medium Pressure	10 bar	10 bar
Handwheel Torque for Static Tightness	0.9 Nm	3.0 Nm
Handwheel Torque for Dynamic Tightness	2.0 Nm	4.5 Nm
Body Fastening Screws (VS, VG, Plastic bodies)	4.0 Nm	4.5 Nm
Body Fastening Screws (Tube body VP)	4.0 Nm	4.5 Nm
Handwheel Retaining Screw Torque	0.9 Nm	0.9 Nm

Tightening Torque Limits

Tightening the handwheel beyond the specified torques reduces diaphragm operating life without improving seal performance. Always tighten the handwheel manually without lever tools.

Diaphragm Selection and Bayonet Mounting

All size 20 diaphragms utilize a bayonet catch for attachment to the actuator spindle compressor:

Diaphragm Material	Material Code	Bürkert Article Number	Temperature Range	Steam Sterilization Limit
EPDM (AD)	EPDM E04	693 166	-10 °C to +143 °C	Max. +150 °C for 60 min
FKM (FF)	FKM F01	693 167	0 °C to +130 °C	Dry heat up to +150 °C (no steam)
PTFE / EPDM (EA)	EPDM E04 / PTFE P05	20093070	-10 °C to +130 °C	Max. +140 °C for 60 min
Advanced PTFE / EPDM (EU)	EPDM E04 / PTFE P06	20093080	-5 °C to +143 °C	Max. +150 °C for 60 min
GYLON® / EPDM Laminate (ER)	PTFE L08	693 177	-5 °C to +130 °C	Max. +140 °C for 60 min

Diaphragm Replacement Procedure

1. Rotate the handwheel counterclockwise until it reaches the mechanical stop (OPEN position).
2. Loosen the four body fastening screws crosswise and detach the actuator assembly from the valve body.
3. Turn the handwheel clockwise to the CLOSED position to extend the spindle compressor.
4. Rotate the old bayonet diaphragm by 90° to disengage it from the compressor socket.
5. Insert the bayonet pin of the replacement diaphragm into the compressor slot and lock it by rotating 90°.
6. Return the handwheel to the fully OPEN position.
7. Align the diaphragm so that its identification tab is oriented at a 90° angle relative to the pipeline flow axis.
8. Place the actuator with the mounted diaphragm onto the valve body. For PP bodies, install the external body reinforcement bracket.
9. Tighten the body screws crosswise in three gradual steps (1/3, 2/3, and 3/3 of final torque: 4.0 Nm for EPDM/FKM; 4.5 Nm for PTFE).

Stroke Limitation and Handwheel Configuration

Type 2933 actuator 20050340 includes an adjustable internal minimum stroke limiter implemented via an internal hexagon nut beneath the handwheel:

1. Turn the handwheel clockwise until the valve reaches the fully closed position.
2. Loosen the handwheel set screw (size 2 hexagon socket) and lift the handwheel off the spindle.
3. Turn the internal hexagon nut down until it contacts the mechanical stop.
4. Reinstall the handwheel, ensuring the spindle square and the internal nut hexagon align with the handwheel interior.
5. Tighten the handwheel set screw to 0.9 Nm. If required by severe vibration, apply threadlocker.

Adjustment Range

The minimum stroke limiter must be positioned strictly within the 0% to 25% opening stroke range. Do not thread the hexagon nut onto the square portion of the drive spindle.

Position Indicator and Sensor Integration

The actuator includes an optical position indicator located below the handwheel. When turning the handwheel counterclockwise to open the valve, a yellow sleeve with an axial millimeter stroke scale emerges. The perimeter of the handwheel carries 30 divisions, allowing fine verification of valve opening stroke.

The stainless steel bonnet of article 20050340 contains two M5x0.5 threaded bores for direct mounting of inductive proximity switches:

• Standard Inductive Proximity Switch M5: Part number 550412
• ATEX-Certified Inductive Proximity Switch M5: Part number 904779

To configure electrical feedback, screw the inductive sensor into the respective port (upper port for OPEN, lower port for CLOSED) until it detects the internal metallic compressor plate, then secure the sensor locknut.

Installation and Maintenance Rules

Self-Draining Alignment

Mount the valve assembly with the actuator oriented upright or angled according to the self-draining angle marked on forged (VS) or tube (VP) bodies. Ensure the leak detection relief bore on the diaphragm bonnet points toward the lowest elevation.

• Welding or Solvent Cementing: Dismantle the actuator and diaphragm completely from the valve body before welding stainless steel bodies or cementing plastic bodies into the pipeline. Heat and chemical fumes damage the elastomer and internal guide components.
• Plastic Body Reinforcement: For PP valve bodies in diaphragm size 20, always mount the external metal reinforcement brackets before tightening body screws.
• Routine Inspection: Check the diaphragm bonnet relief bore periodically for liquid or gas discharge. Re-torque body bolts crosswise after the initial steam sterilization cycle.

Explosion Protection Compliance (Variable PX51)

When combined with ATEX/IECEx certified assemblies under variable code PX51 (EPS 18 ATEX 2 008 X / IECEx EPS 18.0007X), the actuator qualifies as Category 2 mechanical equipment for Zones 1/21 and 2/22 (Ex h IIC T4...T2 Gb / Ex h IIIC T135 °C...T300 °C Db). Ground the valve body to the piping system. If installed on a non-conductive plastic body, connect the actuator bonnet to earth via a dedicated grounding strap. Clean external surfaces only with a damp or anti-static cloth to prevent electrostatic charge generation.