BURKERT 347724 is an externally controlled 2/2-way diaphragm valve from the CLASSIC Type 2031 series, designed for hygienic, sterile, and demanding process fluids. It incorporates a pneumatic piston actuator, a zero-deadleg stainless steel 2-way body, and a PTFE/EPDM backing diaphragm. Operating under Control Function A, the valve is held normally closed (NC) by spring force when no control pressure is applied. Compressed air introduced into the lower pilot air port overcomes the spring pack to raise the diaphragm off the valve seat, clearing an unobstructed flow passage.

The fluid path features a welded connection conforming to ASME BPE and DIN 11866 Series C in nominal diameter DN 40 (1 1/2"). Engineered for high-purity and abrasive media, the flow-optimised stainless steel body delivers a nominal flow rate of 30 m³/h (water). The valve is fully CIP/SIP capable, handling process temperatures from -10 °C to +100 °C under operating pressures up to 9 bar.

Technical Specifications and Process Conditions

BURKERT 347724 meets rigorous hygienic design criteria and mechanical ratings according to DIN EN 1333 (PN 16) and DIN EN 1759 (Class 150).

Parameter	Specification
Valve Type	Type 2031 (CLASSIC)
Article Number	347724
Control Function	CF A: 2/2-way, normally closed by spring force
Port Size / Tube Standard	DN 40 (1 1/2") ASME BPE / DIN 11866 Series C
Pipe External Diameter (OD)	38.1 mm (1.5")
Pipe Internal Diameter (ID)	34.8 mm
Wall Thickness	1.65 mm (0.065")
Valve Body Material	Stainless steel 1.4435 / 316L
Actuator Material	Polyamide (PA)
Actuator Size	Ø 100 mm (Size G)
Diaphragm Material	PTFE with EPDM backing membrane (EA)
Piston Seal Material	NBR / FKM
Operating Pressure Range	0.00 to 9.00 bar
Pilot Air Pressure Range	5.5 to 10.0 bar
Pressure Rating	PN 16 / Class 150
Flow Rate Kv (Water)	30 m³/h (nominal catalog flow 37 m³/h)
Medium Temperature Range	-10 °C to +100 °C
Ambient Temperature Range	-10 °C to +60 °C
Pilot Air Port	G 1/4" internal thread
Cleaning Compatibility	CIP / SIP capable

Medium Temperature Limitation

The polyamide (PA) actuator limits the permissible medium temperature to +100 °C. For processes requiring higher steam sterilisation cycles (up to +140 °C or +150 °C for 60 min), a polyphenylene sulphide (PPS) actuator variant is required.

Materials of Construction

BURKERT 347724 uses materials tested for chemical compatibility and hygienic compliance across food, beverage, biotechnology, and pharmaceutical applications.

Item	Component	Material
1	Transparent Position Cap	Polysulfone (PSU)
2	Actuator Cover	Polyamide (PA)
3	Pilot Air Port	Stainless steel 1.4305
4	Piston Seal	FKM / NBR
5	Socket	Sinter metal
6	Interface / Adapter	Polyamide (PA)
7	Diaphragm	PTFE with EPDM backing (EA)
8	Valve Body	Forged/fabricated stainless steel 1.4435 / 316L

The PTFE/EPDM composite diaphragm complies with the FDA 21 CFR Code of Federal Regulations, EC Regulation 1935/2004, and has been tested in accordance with USP Class VI requirements.

Dimensions

Dimensions correspond to the CLASSIC actuator size 100 mm (G) paired with a DN 40 ASME BPE welded body.

Diaphragm Size	Actuator Size Ø	Ø A [mm]	C [mm]	Pilot Port K	Actuator Height H [mm]
40	100 (G)	127	73	G 1/4"	205
40 (with MT85 Block Mount)	100 (G)	127	73	G 1/4"	246
40 (with Type 8697)	100 (G)	127	73	G 1/4"	298 (HM) / 339 (HM + MT85)

Diaphragm Size	Port Connection DN	External Ø D1 [mm]	Wall s [mm]	Body Length L [mm]	Weir Height h [mm]	Centerline Height H [mm]	Product Key
40	1 1/2" (ASME BPE)	38.1	1.65	159	27.6	52.4	SODH

Pilot Pressure and Media Pressure Ratings

For Control Function A (normally closed), the maximum static operating pressure depends on the actuator diameter and diaphragm material combination:

Diaphragm Size [mm]	Actuator Size Ø [mm]	Pilot Air Pressure [bar]	Max Static Media Pressure (EPDM) [bar]	Max Static Media Pressure (PTFE/EPDM) [bar]
40	100 (G)	5.5 to 7.0	10	9
40	125 (H)	5.5 to 7.0	10	10

Operating Pressure Limits

For DN 40 diaphragm size with actuator size 100 (G), BURKERT 347724 provides tight shut-off up to 9 bar static working pressure when equipped with a PTFE/EPDM diaphragm. Minimum pilot pressure to open against 0 bar is 5.5 bar, and 4.0 bar when operating at maximum line pressure.

Installation and Pipeline Welding

Proper piping alignment, leak-detection drainage, and self-draining inclination are required during system integration.

Dismantle Actuator Before Welding

Do not weld the valve body into the pipeline while the actuator and diaphragm are mounted. Heat conducted through the stainless steel body destroys the PTFE/EPDM diaphragm and degrades internal actuator seals. Follow the three-step sequence:

1. Disassemble the actuator and diaphragm from the valve body.
2. Weld the body into the pipeline and flush/clean thoroughly.
3. Reassemble the diaphragm and actuator, torquing to specification.

Mounting Orientation

• The preferred installation position is with the actuator pointing vertically upright.
• Ensure the leakage indicator hole in the diaphragm bonnet is situated at the lowest point to allow immediate detection of media escape.
• Maintain a piping slope between 1° and 5° to ensure complete self-draining of the valve interior.

Maintenance and Diaphragm Replacement

Natural wear is concentrated on the diaphragm and internal piston seals. Periodic inspections should check the bonnet overflow hole for medium leakage. PTFE diaphragms are attached via a bayonet connection for DN 40 size.

Diaphragm Replacement Procedure for Control Function A

1. Pressurise the lower pilot air port with compressed air (5.5 bar). This retracts the spindle and pulls the diaphragm free from the valve weir to prevent tearing.
2. Loosen the body fasteners crosswise and lift the actuator and diaphragm assembly away from the valve body.
3. Rotate the worn PTFE diaphragm by 90° to disengage the bayonet lock.
4. Align and engage the new PTFE/EPDM diaphragm into the bayonet socket, orienting the identification tab perpendicular to the pipeline direction.
5. Mount the actuator back onto the valve body.
6. Hand-tighten the body screws crosswise until the diaphragm seats lightly between body and bonnet.
7. Cycle the valve twice with pilot air to seat the membrane correctly.
8. Exhaust the pilot air. Tighten the body bolts crosswise in three stages (approximately 1/3, 2/3, and full torque) to the value specified below.

Nominal Diameter DN	Diaphragm Size	EPDM / FKM [Nm]	PTFE / Advanced PTFE / Laminate [Nm]
8	8	2.0	2.5
15	15	3.5	4.0
20	20	4.0	4.5
25	25	5.0	6.0
32	32	6.0	8.0
40	40	8.0	10.0
50	50	12.0	15.0
65	65	20.0	30.0

Tightening Torque

For BURKERT 347724 (DN 40, PTFE/EPDM diaphragm on a forged stainless body), the specified final bolt tightening torque is 10.0 Nm. The permissible torque tolerance is +10%.

Accessories and System Combination

BURKERT 347724 supports direct mounting of discrete automation units on the CLASSIC actuator top interface.

• Type 8697 Position Feedback: Designed for integrated mounting on actuator sizes Ø 40 to 225 mm. Provides mechanical or inductive limit switches for valve end-position sensing, LED status indication, and an IP65/IP67 enclosure.
• Valve System Type 8801-DB: The combination of Type 2031 with Type 8697 constitutes the factory-tested, automated valve system Type 8801-DB.

Spare Parts

Only genuine Bürkert spare parts ensure tightness and process integrity.

Item	Description	Order Number
Seal Set	PA Actuator size G (DN 32 / DN 40)	012 125
Diaphragm	PTFE (EA), DN 40 (Bayonet mounting)	584 378
Diaphragm	Advanced PTFE (EU), DN 40 (Bayonet mounting)	584 379
Diaphragm	EPDM (AD), DN 40	688 426