BURKERT 20108541 (Type 2933) is a manually operated 2/2-way diaphragm valve engineered for zero deadleg shut-off duties in hygienic, sterile, and corrosive chemical processes. Built with a Hastelloy C22 (material 2.4602) valve body, this model features welded line connections conforming to ASME BPE and DIN 11866 Series C with port dimensions of 12.7 x 1.65 mm (DN 15, NPS 1/2). Fluid isolation is achieved with a diaphragm size 8 seal comprised of PTFE with an EPDM backing diaphragm, ensuring non-contaminating operation across a static medium pressure range from 0 to 10 bar (PN 10, Class 150). The valve operates continuously across medium temperatures from -10 °C to +130 °C and tolerates steam sterilisation up to +140 °C for 60 minutes.

Equipped with a compact manual actuator, the valve utilizes a stainless steel diaphragm bonnet and a 35 mm diameter polyphenylene sulphide (PPS) handwheel (size T, 1.5 mm spindle pitch per rotation). The manual assembly incorporates an integrated optical visual position indicator located beneath the handwheel and an adjustable mechanical minimum stroke limiter that protects the PTFE diaphragm against overcompression during closing. Both CIP and SIP cleaning procedures are fully supported. All wetted polymer elements meet USP Class VI, FDA Code of Federal Regulations, and EC Regulation 1935/2004 requirements, backed by manufacturer test certificate EN 10204 3.1 and factory certification EN 10204 2.1.

Technical Specifications

Attribute	Source-Supported Specification
Valve Type	2933 (Basic 2/2-way manually operated shut-off valve)
Article Number	20108541
Diaphragm Size	8
Port Nominal Size	DN 15 (NPS 1/2)
Port Outer Diameter x Wall Thickness	12.7 x 1.65 mm
Connection Standard	Welded connection to ASME BPE / DIN 11866 Series C
Body Material	Hastelloy C22 (2.4602)
Bonnet Material	Stainless steel
Handwheel Material	PPS (polyphenylene sulphide)
Diaphragm Material	PTFE with EPDM backing diaphragm (code EA)
Operating Pressure Range	0 bar to 10 bar (static)
Pressure Ratings	PN 10 (DIN EN 1333), Class 150 (DIN EN 1759)
Medium Temperature Range	-10 °C to +130 °C (steam sterilisation max. +140 °C for 60 min)
Ambient Temperature Range	-10 °C to +130 °C (short-term up to +150 °C), autoclavable
Flow Coefficient (Kv)	1.9 m³/h (water at +20 °C, inlet 4 bar, outlet 3 bar)
Surface Roughness	Ra ≤ 0.38 µm to Ra ≤ 1.6 µm
Stroke Limitation	Single min-stroke limiter (closing limiter via internal nut)
Position Feedback	End position feedback sensor without (optional M5 sensor port)
Cleaning Capabilities	CIP capable: Yes; SIP capable: Yes
Product Identification	Data matrix code, physical laser etching

Material Specifications

Item No.	Component	Source Material
1	Handwheel	Polyphenylene sulphide (PPS) (optional 1.4308 stainless steel)
2	Visual position indicator	Polyamide (PA), Stainless steel 1.4305
3	Valve spindle	Stainless steel 1.4305
4	Diaphragm bonnet	Stainless steel 1.4308 (optional PPS)
5	Diaphragm	PTFE with EPDM backing (EA) (alternatives: EPDM AD, Advanced PTFE EU, GYLON/EPDM ER)
6	Valve body	Hastelloy C22 (2.4602) for article 20108541

INFO

Chemical compatibility across aggressive process media can be cross-referenced via the Bürkert resistApp database prior to deploying alternative materials.

Actuator Dimensions and Stroke Limitation

Manual actuator dimensions correspond to diaphragm size 8 (handwheel size T):

Diaphragm Size	Handwheel Size Code	Handwheel Designation	Handwheel Diameter ∅ B [mm]	Open Height H1 [mm]	Closed Height H2 [mm]	Spindle Pitch [mm/rev]
8	T	Tiny	35	54	49	1.5

Rotating the PPS handwheel counterclockwise draws the internal spindle upward, opening the flow passage and gradually revealing the yellow visual position indicator positioned on the diaphragm bonnet. Turning the handwheel clockwise closes the valve orifice.

Setting the Minimum Stroke Limit (Closing Limiter)

The Type 2933 manual actuator contains an internal stroke limiter that prevents excessive compression force on the diaphragm seal:

1. Rotate the handwheel clockwise until the valve reaches the fully closed position.
2. Loosen the retaining screw located on the handwheel using an AF 2 hexagon socket wrench and pull the handwheel off the spindle.
3. Screw down the internal hexagon nut until it makes solid contact. The minimum stroke limit is now defined.
4. Align the square profile of the spindle and the hexagon nut with the mating geometry inside the handwheel.
5. Reinstall the handwheel and tighten the central retaining screw to 0.9 Nm.

WARNING

Do not thread the hexagon nut across the square spindle profile. The minimum stroke limiter is designed solely for setting within the 0% to 25% valve stroke opening range.

Operating Pressures and Tightening Torques

Manual operation requires specific handwheel torques to establish tight shut-off without shortening diaphragm operating life. A tolerance of +10% applies to all source torque ratings.

| Diaphragm Size | Medium Pressure [bar] | Static Tightening Torque [Nm] | Dynamic Tightening Torque [Nm] | | :--- | :--- | :--- | :--- | :--- | | 8 | 10 | 1.1 (PTFE) / 0.6 (EPDM) | 1.2 (PTFE) / 0.9 (EPDM) |

Static tightness defines zero seat leakage with the valve closed and pressure applied to one port. Dynamic tightness defines closure against media flowing through the open orifice until the designated shut-off torque is reached.

Installation and Self-Draining Guidelines

Installation position is universal, though orientation with the actuator facing upright is preferred. When installed for self-draining performance, the valve body must be positioned according to the drain angle specified for DN 15 ASME BPE welded bodies (12.7 x 1.65 mm):

• Diaphragm size 8 port body dimensions: Face-to-face length L = 89 mm, body weir height h = 9.3 mm, total body center height H = 18.8 mm.
• The orientation marking on the pipe connection port must point vertically upward.
• One of the relief inspection bores located on the diaphragm bonnet must face the lowest physical position to detect diaphragm leakage immediately.

DANGER

Depressurize and completely drain or vent the piping system prior to beginning any mechanical installation or dismantling.

Welding Procedure

To prevent permanent thermal damage to internal elastomers:

1. Open the handwheel completely (counterclockwise rotation until internal stop).
2. Loosen the four bonnet fastening bolts crosswise and detach the manual actuator and diaphragm assembly from the Hastelloy body.
3. Weld the valve body into the pipeline adhering to ASME BPE alignment and inclination standards.
4. Thoroughly clean the interior cavity of the valve body after welding.
5. Reassemble the actuator and diaphragm onto the body, threading the bolts crosswise in 3 gradual stages (approx. 1/3, 2/3, and 3/3 of total torque).

Diaphragm Size	Body Material Type	EPDM / FKM Fastening Torque [Nm]	PTFE / Advanced PTFE Fastening Torque [Nm]
8	VS (Hastelloy / Forged), VG, Plastics	2.0	2.5

Diaphragm Maintenance and Replacement

Diaphragm inspection intervals depend on media temperature, abrasiveness, and switching frequency. Check the bonnet relief bore regularly for escaping fluid. After the initial in-line steam sterilisation cycle, retighten the four body fastening bolts crosswise to 2.5 Nm.

Diaphragm Fastening Mechanism for Size 8

Diaphragm size 8 utilizes a buttoned connection method on both PTFE and elastomeric diaphragms:

1. Shift the valve into the fully OPEN position by turning the handwheel counterclockwise.
2. Remove the fastening bolts crosswise and separate the actuator from the body.
3. Move the actuator into the CLOSED position by turning the handwheel clockwise.
4. Unbutton the worn diaphragm from the compressor pin.
5. Button the new replacement diaphragm securely into the compressor socket.
6. Return the actuator to the OPEN position.
7. Align the diaphragm tab exactly perpendicular (90 degrees) to the fluid flow direction.
8. Remount the assembly onto the body, lightly tension the bolts, cycle the valve twice between open and closed, set to approximately 20% open, and tighten crosswise in three stages to 2.5 Nm.

Diaphragm Size	Diaphragm Material	Bürkert Article Number	Material Identification Tab Code
8	PTFE/EPDM (EA)	20093068	PTFE L11
8	Advanced PTFE/EPDM (EU)	20093078	PTFE L12
8	EPDM (AD)	688421	EPDM E04
8	FKM (FF)	677684	FKM F01
8	GYLON/EPDM laminate (ER)	693175	PTFE L08

Conformity, Certifications, and Explosion Protection

All contact polymers used in article 20108541 comply with major international hygienic directives:

• FDA Code of Federal Regulations title 21 compliance.
• USP Class VI test certification.
• European Regulation (EC) 1935/2004 for materials contacting food and beverages.
• DIN EN 10204 3.1 inspection certificate and 2.1 diaphragm certificate provided.

Explosion Protection (ATEX / IECEx Option Code PX51)

When equipped under variable code PX51, the manual actuator is certified as a non-electrical Category 2 mechanical device for explosive gas and dust atmospheres (Zone 1/21 and Zone 2/22):

• ATEX marking: EPS 18 ATEX 2 008 X, II 2G Ex h IIC T4...T2 Gb, II 2D Ex h IIIC T135 °C...T300 °C Db.
• IECEx marking: IECEx EPS 18.0007X, Ex h IIC T4...T2 Gb, Ex h IIIC T135 °C...T300 °C Db.

Temperature Class	Maximum Surface Temperature	Permissible Ambient Temperature	Maximum Medium Temperature
T4	+135 °C	-40 °C to +100 °C	+125 °C
T3	+200 °C	-40 °C to +130 °C	+185 °C
T2	+300 °C	-40 °C to +130 °C	+285 °C

TIP

Conductive grounding of both the Hastelloy body and the actuator is mandatory when deploying in hazardous areas to prevent static discharge.