BURKERT 558627 (Type 2031) is an externally controlled 2/2-way diaphragm valve designed for shut-off control of neutral, ultrapure, sterile, and chemically aggressive liquid or gaseous media. As part of the CLASSIC series, it combines a compact, autoclavable polyphenylene sulphide (PPS) pneumatic piston actuator with a forged stainless steel valve body (1.4435 / 316L). The valve is configured with Control Function A (normally closed by spring force), a nominal diameter of 8 mm (diaphragm size 8), and welded port connections conforming to the BS 4825 standard for 1/2" tubing (12.7 mm outer diameter, 1.2 mm wall thickness). Sealing is provided by a two-piece PTFE diaphragm backed by an EPDM cushion, achieving bubble-tight shut-off across an operating pressure span of 0.00 bar to 10.00 bar.

Technical Specifications & Operating Parameters

Burkert 558627 is engineered to meet sterile process requirements, offering full Clean-in-Place (CIP) and Steam-in-Place (SIP) capability. The fluidic channel features a flow-optimised weir design that minimizes internal dead volume, delivering a flow rate coefficient (Kv) of 1.5 m³/h measured with water at +20 °C.

Technical Attribute	Specification Value
Product Identification	Article 558627 / Type 2031
Valve Design	2/2-way weir-type diaphragm valve
Operating Mode / Control Function	Control Function A (normally closed, NC)
Fluidic Port Standard	BS 4825 welded spigot connection
Port Nominal Size	DN 15 (tube OD 12.7 mm / 1/2", ID 10.3 mm)
Tube Wall Thickness	1.2 mm (0.047")
Orifice Size (Nominal Diameter)	8 mm (diaphragm size 8)
Flow Rate Coefficient (Kv)	1.5 m³/h (water at +20 °C)
Operating Pressure Range	0.00 bar to 10.00 bar (gauge pressure)
Pilot Pressure Range	5.0 bar to 7.0 bar
Pilot Air Connection	G 1/8" internal thread
Medium Temperature Range	-10 °C to +130 °C (steam sterilisation up to +140 °C for 60 min)
Permissible Ambient Temperature	+5 °C to +140 °C (PPS actuator size ≤ 80 mm)
Pressure Rating	PN 16 (DIN EN 1333) / Class 150 (DIN EN 1759)
Installation Altitude	Up to 2,000 m above sea level

Materials of Construction

Actuator size 40 (C) is constructed from chemically resistant, autoclavable polyphenylene sulphide (PPS) as standard. An optical position indicator located inside a transparent polysulfone (PSU) cap provides direct visual feedback of the open/closed valve status.

Item No.	Element	Material
1	Transparent cap	Polysulfone (PSU)
2	Actuator cover	Polyphenylene sulphide (PPS)
3	Pilot air ports	Stainless steel 1.4305
4	Piston seal	FKM (fluororubber)
5	Socket	Sinter metal
6	Interface	Polyphenylene sulphide (PPS)
7	Diaphragm	PTFE with EPDM backing diaphragm (EA)
8	Valve body	Forged stainless steel 1.4435 / 316L (BN2 / ASME BPE)

Operating Principle and Control Function

Burkert 558627 operates under Control Function A (normally closed, CF A). In the rest position, mechanical compression springs positioned inside the PPS actuator push the piston down. The connected valve spindle transmits this closing force directly to the compressor, which presses the PTFE/EPDM diaphragm against the weir of the stainless steel valve body, ensuring tight shut-off against medium pressures up to 10 bar.

When pilot air at 5.0 bar to 7.0 bar is introduced into the lower pilot air port (G 1/8"), the pneumatic force overcomes the spring pack, lifting the piston, spindle, and diaphragm away from the weir to open the fluid passage. Releasing pilot pressure vents the lower chamber and allows the compression springs to immediately return the diaphragm to its closed position.

Dimensions and Process Connection

Burkert 558627 features welded spigots conforming to BS 4825. Actuator dimensions correspond to size 40 (C) with a pilot air port located at the lower cylinder base.

Parameter	Dimension / Value
Diaphragm Size	8
Nominal Diameter (DN)	15 mm (1/2" BS 4825)
Pipe Outer Diameter (∅ D1)	12.7 mm
Pipe Wall Thickness (s)	1.20 mm
Body Face-to-Face Length (L)	89 mm (cast VG) / 108 mm (forged VS)
Port Centreline Height (h)	9.6 mm (VG) / 8.15 mm (VS)
Body Height Under Flange (H)	18.6 mm (VG) / 19.85 mm (VS)
Actuator Outer Diameter (∅ A)	53 mm
Actuator Air Port Offset (C)	34 mm
Pilot Air Connection Thread (K)	G 1/8"
Actuator Height (H)	89 mm (standard CLASSIC size 40)
Overall Height with Type 8697 (HM)	185 mm

Installation, Welding and Self-Draining

Burkert 558627 can be installed in any orientation, though upright positioning with the actuator facing vertically upward is recommended. To monitor potential seal degradation, one of the leakage relief bores in the diaphragm bonnet must be oriented at the lowest physical point.

Dismount Actuator Before Welding

Thermal conduction during orbital or manual welding will destroy the PTFE/EPDM diaphragm and internal actuator seals. The actuator and diaphragm must be completely unbolted and removed from the valve body prior to welding the body into the pipeline.

Welding Procedure

1. For Control Function A, apply 5.0 bar to 7.0 bar pilot pressure to the lower pilot air port (G 1/8") to retract the diaphragm from the body seat.
2. Loosen the body screws crosswise and lift the actuator and diaphragm assembly off the valve body.
3. Weld the valve body into the pipeline according to sanitary welding standards. Smooth internal weld seams if required and thoroughly flush out chips or debris.
4. Re-pressurise the lower actuator air port to retract the diaphragm, place the actuator back onto the valve body, and tighten the body screws lightly crosswise.
5. Actuate the valve twice under pilot pressure to seat the diaphragm correctly.
6. Vent the pilot pressure and tighten the body screws in three crosswise stages (1/3, 2/3, and full torque).

Self-Draining Alignment

For complete drainage of liquid media without residue, the valve body must be installed at a specific angle relative to the pipeline axis:

• Pipe inclination (β): Set according to ASME BPE pipeline gradient recommendations.
• Self-draining angle (α): For BS 4825 DN 15 with diaphragm size 8, the required angle is 24° (forged body KB04) or 23° (cast body). The alignment mark on the port spigot must point directly upward.

Body Screw Tightening Torques

For diaphragm size 8 with PTFE, advanced PTFE, or GYLON® diaphragm materials, the final tightening torque for the body screws is 2.5 Nm (+10% tolerance).

Explosion Protection and Standards Compliance

Burkert 558627 carries official explosion protection certifications for hazardous areas under ATEX and IECEx standards:

• ATEX Certificate: EPS 18 ATEX 2 008 X
• IECEx Certificate: IECEx EPS 18.0007X
• Classification: II 2G Ex h IIC T4…T2 Gb / II 2D Ex h IIIC T135 °C…T300 °C Db
• Temperature Class Limits: At T4, maximum surface temperature is +135 °C, ambient temperature is -40 °C to +100 °C, and medium temperature is limited to +125 °C.

Media-wetted diaphragm materials comply with regulatory hygiene frameworks:

• FDA: Code of Federal Regulations 21 CFR 177.1550 (PTFE) and 21 CFR 177.2600 (EPDM).
• USP: Tested in accordance with USP Class VI.
• EC Regulation 1935/2004: Formulation compliant for materials in contact with food and beverages.

Maintenance and Spare Parts

Under normal operating conditions with clean control air, the PPS pneumatic actuator is completely maintenance-free. Wearing parts (diaphragms and internal actuator seals) must be inspected at defined intervals:

• Inspection Interval: Re-tighten body screws crosswise after the first steam sterilisation cycle. Inspect the diaphragm for wear at least every 100,000 switching cycles (more frequently for abrasive or scaling media).
• Fastening Method: For diaphragm size 8, the PTFE/EPDM diaphragm is secured to the compressor using an integrated rubber button. Press the button into the compressor socket using a slight rotational motion. Ensure the identification tab is positioned perpendicular to the media flow direction.

Service Part Numbers

• Replacement Diaphragm (Size 8, PTFE/EPDM EA): Order number 20093068 (Material code PTFE L11).
• Actuator Seal Set (Size 40 C, PPS housing): Order number 011465 (contains piston seal, lip seal, and O-rings).
• Cover Assembly Wrench: Order number 639175 (diameter 40/50 mm).

Compatible Accessories and Automation

Burkert 558627 can be retrofitted with decentralized automation heads and position indicators designed for the CLASSIC series.

• Type 8697 Position Feedback Indicator: Integrates mechanically or inductively with actuator size 40 (C). Features an IP65/IP67 chemically resistant enclosure, bright LED status indication, and an overall combined assembly height of 185 mm.
• Type 8801-DB Valve System: Pre-assembled factory combination of Type 2031 diaphragm valve and Type 8697 control head for rapid commissioning.