BURKERT 20135668 (Type 2933) is a manually operated 2/2-way diaphragm valve designed for shut-off applications in hygienic, aseptic, and aggressive fluid handling processes. Configured with a nominal diameter of DN 50 (NPS 2) and diaphragm size 50, this unit features a fabricated tube valve body (VP) in 316L stainless steel (1.4435-BN2) and sanitary clamp connections compliant with DIN 32676 Series B (ISO 4200 pipe). The sealing diaphragm consists of a chemically resistant GYLON® laminate with an EPDM elastomer backing, offering high integrity under continuous operating pressures from 0 to 10 bar (PN 10) and medium temperatures between -5 °C and +130 °C. The valve provides full CIP and SIP capability, supporting steam sterilisation up to +140 °C for 60 minutes. Actuation is performed manually via a 110 mm diameter PPS handwheel mounted on a stainless steel diaphragm bonnet, incorporating an integrated optical position indicator with stroke scale and an adjustable single minimum-stroke closing limiter.

Design and Component Materials

BURKERT Type 2933 utilizes a flow-optimized 2-way valve body with zero dead leg to provide high flow coefficients while preventing media stagnation. The manual actuator transmits thrust via an internal spindle mechanism: turning the handwheel counterclockwise lifts the compressor to open the line, while clockwise rotation depresses the diaphragm against the body weir to close flow.

Item	Component	Material Specification
1	Handwheel	Polyphenylene sulphide (PPS), ∅ 110 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
5	Diaphragm	GYLON® laminated with EPDM backing (ER code)
6	Valve body	Stainless steel tube 1.4435-BN2 / UNS S31603 (316L)

Actuator Protection and Autoclavability

The actuator assembly features a compact, autoclavable design rated for ambient temperatures up to +130 °C (short periods up to +150 °C). The bonnet includes built-in relief bores configured to vent any leakage immediately if diaphragm integrity is compromised.

Technical Specifications and Operating Parameters

Specification Parameter	Technical Value
Fluidic port connection quantity	2
Switch positions	2 (shut-off valve)
Nominal port size	DN 50 (NPS 2)
Diaphragm size	50
Body port configuration	Tube valve body (VP) with clamp connection
Port connection standard	DIN 32676 Series B (ISO pipe ISO 4200)
Pipe dimensions / Clamp outer diameter	60.3 x 2.0 mm / Clamp ∅ 77.5 mm (Product key TC47)
Pressure rating	0 bar to 10 bar (PN 10 / Class 150)
Medium temperature range	-5 °C to +130 °C
Steam sterilisation limit	Up to +140 °C for max. 60 minutes
Ambient operating temperature	-10 °C to +130 °C (temporary +150 °C)
Flow coefficient Kv (water, Δp = 1 bar)	70 m³/h (Cv 81.6 gal/min; VP nominal water curve: 69.7 m³/h)
Handwheel dimensions	∅ 110 mm (Medium designation M)
Spindle lead / slope per rotation	2.0 mm
CIP / SIP capability	Yes
Product identification	Data matrix code on product label

Dimensional Data

Actuator dimensions and body layout conform to standardized hygienic dimensional standards. For diaphragm size 50, manual actuator dimensions are summarized below.

Diaphragm Size	Handwheel Designation	H1 (Open) [mm]	H2 (Closed) [mm]	Handwheel ∅ B [mm]
32	M	129	115	110
40	M	134	116	110
50	M	149	125	110

Tube Valve Body (VP) Clamp Dimensions (DIN 32676 Series B ISO Pipe)

Diaphragm Size	Port DN	∅D1 [mm]	s [mm]	∅D2 [mm]	L [mm]	h [mm]	H [mm]	Product Key
8	8	13.5	1.6	25.0	89	9.85	22.35	TC40
8	10	17.2	1.6	25.0	89	11.70	24.20	TC53
15	15	21.3	1.6	50.5	110	14.35	39.60	TC52
20	20	26.9	1.6	50.5	119	17.15	42.40	TC43
25	25	33.7	2.0	50.5	129	20.55	45.80	TC44
32	32	42.4	2.0	64.0	148	25.10	57.10	TC55
40	40	48.3	2.0	64.0	161	29.35	61.35	TC46
50	50	60.3	2.0	77.5	192	35.35	74.10	TC47

Position Indication and Stroke Limitation

Actuators for diaphragm sizes 15 to 50 are equipped with a high-visibility yellow optical position indicator and marked stroke scale. As the handwheel is turned counterclockwise, the yellow indicator emerges from beneath the handwheel collar.

• The rotational scale on the handwheel provides 30 indexing positions per complete revolution.
• The vertical stroke scale indicates the relative opening height of the diaphragm compressor.
• Visibility of the yellow indicator does not directly establish shut-off sealing; seal engagement must be verified by tactile seating.

Setting the Minimum Stroke Limit (Closing Limiter)

Type 2933 incorporates an adjustable minimum stroke limiter that protects the GYLON®/EPDM diaphragm from excessive compressive strain.

1. Turn the handwheel clockwise until the valve reaches the fully closed seat position.
2. Loosen the handwheel fastening screw using a 2 mm hex key and remove the handwheel.
3. Screw down the internal hexagon nut until it makes positive contact. The minimum stroke limit is now defined.
4. Align the square spindle and the nut hexagon head with the internal geometry of the handwheel, then refit the handwheel.
5. Fasten the handwheel screw to a tightening torque of 0.9 Nm.

Stroke Limiter Operating Limits

Do not screw the hexagon nut onto the square portion of the spindle. The minimum stroke limit adjustment is strictly intended for the 0% to 25% opening stroke range.

Installation and Self-Draining Requirements

Type 2933 can be mounted in any orientation, although positioning the actuator vertically upward is preferred.

1. Leakage Monitoring: One relief bore on the stainless steel diaphragm bonnet must be situated at the lowest gravitational point to permit immediate leak detection.
2. Self-Draining Alignment: To guarantee gravity drainage without liquid entrapment, align the pipeline pitch with ASME BPE slope recommendations. The orientation marking stamped on the tube port connection must point vertically upwards.
3. Welding or Bonding Caution: The actuator and diaphragm assembly must be dismantled from the body prior to executing pipe welding or chemical bonding on adjacent lines.

Operating Closure Force

Tighten the handwheel only until tactile shut-off resistance is achieved. Applying excessive manual torque damages the diaphragm and accelerates fatigue without improving seal integrity.

Torques and Tightening Guidelines

Assembly screws must be torqued evenly in a crosswise pattern in 3 successive stages (approximately 1/3, 2/3, and full torque).

Body Fastening Screw Torques (Table 3)

Diaphragm Size	Cast / Forged / Plastic Bodies [Nm]	Tube Valve Body (VP) [Nm]
8	2.5	2.5
15	4	4
20	4.5	4.5
25	6	8
32	8	10
40	10	15
50 (GYLON® / PTFE)	15	20
65	30	30
80	40	40
100	40	—

A torque tolerance of +10% applies to all specified values.

Handwheel Operating Tightening Torques at 10 bar Media Pressure

• Static Tightness (pressurised on one side of seat while closed): 11 Nm for diaphragm size 50 with PTFE / GYLON® laminate.
• Dynamic Tightness (closing against ongoing process flow): 20 Nm for diaphragm size 50 with PTFE / GYLON® laminate.

Maintenance and Diaphragm Replacement

The manual actuator requires no lubrication or periodic internal overhaul under normal operation. The diaphragm should be examined at intervals not exceeding 100,000 switching cycles, or sooner when conveying abrasive slurries.

1. Rotate the handwheel counterclockwise to the fully open position.
2. Loosen the body screws crosswise and lift the actuator and diaphragm off the tube body.
3. Turn the handwheel clockwise to the closed position to expose the diaphragm mounting connection.
4. Unscrew the threaded pin of the GYLON®/EPDM diaphragm from the compressor.
5. Thread the replacement diaphragm hand-tight into the compressor, then back it off counterclockwise by 180° (one half-turn) to prevent pinning stress.
6. Rotate the handwheel to the fully open position. Align the diaphragm identification tab at exactly 90° relative to the flow axis.
7. Position the actuator onto the valve body and hand-tighten screws crosswise. Cycle the handwheel open and closed twice to seat the elastomer, reopen approximately 20%, and torque screws crosswise to 20 Nm in three stages.

Ordering Data and Accessories

Factory Replacement Diaphragm

Diaphragm Size	Diaphragm Material	Bürkert Material Code	Fastening Type	Article Number
50	GYLON® laminated with EPDM (ER)	PTFE L08	Threaded connection	693 181

Optional System Accessories

Accessory Description	Article Number
4-fold nylon locking mechanism with 3 mm bracket	93719475
Inductive proximity switch (initiator) M5	550412
Inductive proximity switch (initiator) M5 ATEX	904779
Inductive proximity switch (initiator) M8	902475
Inductive proximity switch (initiator) M12	902473

Inductive Proximity Feedback

Feedback for upper or lower travel limits can be installed if the diaphragm bonnet is ordered with dual M5 x 0.5 threaded sensor ports. Proximity switches sense compressor travel directly rather than the diaphragm sealing face.

Certifications and Standards

BURKERT 20135668 complies with relevant European harmonisation directives and hygienic standards:

• Food Contact: Regulation (EC) 1935/2004 compliance declaration
• FDA: Diaphragm materials comply with 21 CFR standards
• Pharma Testing: Diaphragms tested according to USP Class VI protocols
• Documentation: Manufacturer test certificate EN 10204 3.1 and factory certification 2.1 enclosed with delivery