BURKERT 20094791 (Type 2933) is a manually operated 2/2-way diaphragm valve designed for shut-off control in ultra-pure, hygienic, and sterile process lines. Built with a flow-optimised tube valve body (VP) made of stainless steel pipe 1.4435 BN2 / 316L, the unit features zero deadleg geometry to ensure high flow rates and complete media recovery. The fluid port connection is configured as a DN 25 clamp according to DIN 32676 Series A (matching DIN 11850 Series 2 pipe dimensions of 29.0 x 1.5 mm with a 50.5 mm clamp collar).

This valve configuration incorporates a diaphragm size 20 sealing element made of GYLON® laminated with an EPDM backing (material code ER), attached via a positive bayonet catch. The manual actuator features an autoclavable polyphenylene sulphide (PPS) handwheel, a stainless steel bonnet (1.4308), an integrated visual position indicator with a 30-position rotation scale, and an adjustable closing limiter to prevent diaphragm damage from overtorquing. The bonnet includes two M5 x 0.5 threaded holes to accept inductive limit switches for electrical position feedback.

Construction and Material Specifications

The Type 2933 manual diaphragm valve assembly consists of six functional mechanical elements engineered for aggressive and sanitary working environments:

Item	Element	Material Configuration for Article 20094791
1	Handwheel	Polyphenylene sulphide (PPS), size S (∅ 45 mm)
2	Visual position indicator	Polyamide (PA), stainless steel 1.4305
3	Valve spindle	Stainless steel 1.4305
4	Diaphragm bonnet	Stainless steel 1.4308 (with 2x M5x0.5 feedback ports)
5	Diaphragm	GYLON® laminated with EPDM backing (ER), size 20
6	Valve body	Stainless steel pipe 1.4435-BN2 / 316L (VP tube body)

Hygienic Material Conformity

The GYLON® and EPDM laminated diaphragm meets US FDA Code of Federal Regulations, passes USP Class VI biological reactivity testing, and complies with European Regulation (EC) 1935/2004 for food contact materials. Deliveries include an EN 10204 3.1 manufacturer test certificate and a 2.1 diaphragm certificate.

Technical Data and Operating Limits

Technical Parameter	Specification Value
Operating medium	Neutral gases, liquids, sterile, highly purified, aggressive or abrasive media
Nominal pressure rating	PN 10 (DIN EN 1333) / Class 150 (DIN EN 1759)
Permitted medium pressure	0.00 bar to 10.00 bar
Medium temperature (GYLON® / EPDM)	-5 °C to +130 °C (steam sterilisation up to +140 °C for max. 60 min)
Ambient temperature (actuator)	-10 °C to +130 °C (short-term exposure up to +150 °C), autoclavable
Flow coefficient Kv (water, 20 °C)	13.7 m³/h (Cv = 16 gal/min)
Handwheel diameter (Size S)	45 mm (slope per spindle rotation: 1.75 mm)
Closing torque for handwheel (static)	3.0 Nm (diaphragm size 20, PTFE / GYLON® at 10 bar static, +10% tolerance)
Dynamic tightening torque	4.5 Nm (+10% tolerance)
Fastening screw torque (bonnet to body)	4.5 Nm (VP tube body, diaphragm size 20, +10% tolerance)
Cleaning capability	CIP (Cleaning in Place) and SIP (Sterilisation in Place) compatible
Product identification	Data matrix code on body / type label

Dimensions

Manual Actuator Dimensions

Dimensions for manual actuators across diaphragm sizes 6 through 25 are specified in millimeters:

Diaphragm Size	Handwheel Size	H1 (Open) [mm]	H2 (Closed) [mm]	∅ B (Handwheel) [mm]
6	T	49	42	35
8	T	54	49	35
15	S	84	78	45
20 (Article 20094791)	S	95	86	45
25	S	101	90	45

Tube Valve Body (VP) with Clamp Connection

Dimensions for stainless steel tube valve bodies (VP) with clamp connection according to DIN 32676 Series A (DIN pipe) are listed below in millimeters:

Diaphragm Size	Port Connection DN	∅ D1 [mm]	s [mm]	∅ D2 [mm]	L [mm]	h [mm]	H [mm]	Product Key
8	10	13.0	1.5	34.0	89	9.85	26.85	TD41
15	15	19.0	1.5	34.0	110	13.20	30.20	TD42
15	20	23.0	1.5	34.0	119	15.20	32.20	TD43
20 (Article 20094791)	25	29.0	1.5	50.5	129	18.20	43.45	TD44
25	32	35.0	1.5	50.5	148	21.20	46.45	TD45
32	40	41.0	1.5	50.5	161	24.40	49.65	TD46
40	50	53.0	1.5	64.0	192	31.70	63.70	TD47

Function and Manual Operation

Turning the handwheel counterclockwise lifts the compressor spindle to open the valve passage; turning clockwise depresses the compressor and presses the diaphragm onto the body weir to close flow.

Position Indicator and Stroke Scale

On diaphragm sizes 15 to 50, rotating the handwheel counterclockwise reveals a yellow visual position indicator sleeve and an etched stroke scale located below the handwheel. The collar markings permit 30 discrete rotary positions to set reproducible throttling points.

Manual Closing Force

Turn the handwheel only until the valve seat seals tightly. Applying excessive torque beyond the specified static closing torque of 3.0 Nm damages the diaphragm face and reduces service life.

Adjusting the Minimum Stroke Limit (Closing Limiter)

The Type 2933 actuator includes an adjustable minimum stroke limit that functions as a mechanical closing limiter:

1. Move the valve into the fully closed position by rotating the handwheel clockwise.
2. Loosen the set screw on the handwheel (AF 2 mm hexagon socket) and lift off the handwheel.
3. Screw down the hexagon nut onto the spindle until it contacts the stop.
4. Reinstall the handwheel, ensuring the spindle square and nut flats align with the internal broach of the handwheel.
5. Tighten the handwheel retaining screw to 0.9 Nm.

Installation and Self-Draining Alignment

To ensure complete gravity draining in clean utility and biopharmaceutical applications, observe the following mounting guidelines:

• The installation position is unrestricted, but orienting the manual actuator vertically upright is preferred.
• The self-draining angle α etched onto the tube body must be aligned with the pipeline axis using a digital inclinometer.
• The marking stamped on the port connection must face vertically upward.

Leakage Detection and Relief Bore Orientation

The diaphragm bonnet incorporates relief bores designed to vent fluid and reveal leakage if the diaphragm ruptures. When mounting the valve assembly, ensure at least one relief bore points directly toward the lowest gravitational position to prevent trapped media.

Fastening Screws Tightening Sequence

When bolting the actuator to the tube valve body, follow a three-stage crosswise sequence:

1. Rotate the handwheel counterclockwise into the OPEN position before positioning the bonnet over the diaphragm.
2. Engage the fastening screws and hand-tighten them evenly.
3. Cycle the valve twice between open and closed to centre the diaphragm on the body weir.
4. Open the valve to approximately 20% stroke.
5. Tighten the four bonnet screws diagonally in stages (approx. 1/3, 2/3, and full torque of 4.5 Nm for size 20 VP body).

Maintenance and Diaphragm Replacement

Under clean operational conditions, the manual actuator is maintenance-free. Inspect the bonnet relief bore regularly for signs of leakage.

• Re-torque bonnet fastening screws diagonally after the initial steam sterilisation cycle.
• Inspect the diaphragm for mechanical wear or cold flow after a maximum of 100,000 switching operations (or shorter intervals for abrasive fluids).

Diaphragm Replacement Procedure

1. Depressurise and vent the pipeline completely. Drain residual media.
2. Turn the handwheel counterclockwise into the fully OPEN position.
3. Loosen the four body fastening screws crosswise and withdraw the actuator and diaphragm assembly from the body.
4. Rotate the handwheel clockwise to the CLOSED position to extend the compressor.
5. Disengage the bayonet catch by turning the GYLON®/EPDM diaphragm 90° relative to the compressor.
6. Insert the new size 20 diaphragm bayonet lug into the compressor slot and rotate 90° until locked.
7. Rotate the handwheel back to the fully OPEN position.
8. Align the diaphragm tab at a 90° angle to the pipe flow direction and re-assemble onto the body following the three-stage torque procedure.

Spare Parts and Ordering Numbers

Accessory / Spare Part Description	Article Number
Size 20 replacement diaphragm: GYLON® / EPDM (ER) bayonet, material code PTFE L08	693 177
Inductive proximity switch (initiator) M5 x 0.5	550412
Inductive proximity switch M5 x 0.5 ATEX certified	904779
4-fold nylon locking mechanism with 3 mm bracket	93719475