BURKERT 56632 (Type 0256) is a direct-acting, normally closed 2/2-way plunger solenoid valve designed for shut-off, dosing, and control of neutral fluids, gases, and technical vacuum. Constructed with an AF12 brass body featuring a 56 mm face-to-face length and G 3/8 internal threaded ports, this complete valve integrates a 4.0 mm orifice (DN 4.0) delivering a water flow factor Kv of 0.5 m³/h and a gas nominal flow rate QNn of 540 l/min. Actuation is driven by an epoxy-encapsulated Class H coil rated for 120 V AC, supporting 100% continuous duty rating (100% ED). The valve operates from 0 bar differential pressure up to 12 bar on liquids and 16 bar on gases, utilizing NBR seat seals across a medium temperature span of -10 °C to +90 °C and ambient temperatures up to +55 °C.

Circuit Function and Operating Principle

Circuit Function A (CF A)

Type 0256 in circuit function A is a direct-acting 2/2-way valve that remains closed when de-energized. Pressure is admitted above the seat at port 1 (P/NC). Energizing the coil lifts the plunger core directly against the return spring, opening the seat orifice without requiring differential pilot pressure.

• Fluid port count: 2 ports, 2 switching positions (on/off)
• Media separation: Non-media-separated plunger design
• Flow direction: Above seat (inlet at port 1 P/NC)
• Vacuum capability: Suitable for technical vacuum down to 0 bar absolute
• Media suitability: Neutral media including compressed air, water, hydraulic oils, and oils without additives

Technical Specifications

Technical Parameter	Specification Value
Valve Type	0256
Article Number (SKU)	56632
Circuit Function	Circuit function A (WW A / CF A), normally closed
Orifice Size	4.0 mm (5/32")
Port Connection 1 & 2	G 3/8 internal thread
Installation Length	56 mm (short housing AF12)
Operating Pressure Range (AC Liquids)	0.00 bar to 12.00 bar
Operating Pressure Range (AC Gases)	0.00 bar to 16.00 bar
Flow Factor Kv (Water, +20 °C, 1 bar Δp)	0.5 m³/h
Nominal Flow QNn (Gas)	540 l/min
Nominal Operating Voltage	120 V AC (50/60 Hz)
Voltage Tolerance	±10%
Coil Duty Cycle	100% ED continuous rating
AC Switching Time (Opening)	10 ms to 20 ms (measured at +20 °C, 6 bar inlet pressure)
AC Switching Time (Closing)	20 ms to 30 ms (measured at +20 °C, 6 bar inlet pressure)
Maximum Fluid Viscosity	21 mm²/s (21 cSt)
Permissible Medium Temperature	-10 °C to +90 °C
Maximum Ambient Temperature	+55 °C
Storage Temperature	-40 °C to +80 °C
Degree of Protection	IP65 (with cable plug attached)
Electrical Connection Standard	Form A plug according to DIN EN 175301-803
Coil Thermal Insulation Class	Class H (epoxy encapsulated)
Valve Body Material	Brass
Seat Seal Material	NBR (Nitrile rubber)
External Seal Material	NBR

Materials of Construction

Item No.	Component	Material Specification
1	Solenoid Coil	Epoxy (insulation class H)
2	Return Spring	Stainless steel 1.4310
3	Plunger Core	Stainless steel 1.4105
4	Seals (Seat and External)	NBR (Nitrile rubber)
5	Valve Body	Brass

Dimensions and Installation Footprint

Body Material	Thread Connection D	Thread Depth F [mm]	Total Height H [mm]	Face-to-Face Length L [mm]	Wrench Size SW [mm]
Brass (56632 AF12)	G 3/8	12	92	56	22
Brass (AF12 alternative)	G 1/4	12	92	56	22
Brass (standard body)	G 1/4	12	91	74.5	22
Brass (standard body)	G 3/8	12	91	74.5	22
Brass (standard body)	G 1/2	14	94	74.5	27

Installation and Electrical Connection

Pressure and High Voltage Hazards

• Before loosening lines or valves, switch off the operating pressure and vent pipelines completely.
• Before touching or wiring the device, switch off electrical power and secure against inadvertent reactivation.
• Observe all local accident prevention and safety regulations for electrical apparatus.

Pipeline Mounting

• Mounting position is arbitrary, but an upright actuator position with the coil facing upward is recommended.
• Clean process pipelines thoroughly prior to installation to clear pipe chips, scale, or sealing residue.
• Install a dirt trap or strainer with mesh size ≤ 500 µm upstream of the valve inlet port.
• Do not use the coil as a lever arm. Tighten the valve into piping exclusively by gripping the wrench flats on the body (SW 22).
• Observe fluid flow direction: an arrow cast or engraved on the valve housing indicates the mandatory flow direction.

Electrical Wiring with Cable Plug

Protective Conductor and AC Solenoids

• Always connect the protective conductor (PE) terminal and check electrical continuity between the coil core assembly and the metal housing.
• When operating AC solenoids, ensure the armature core moves freely. A seized or blocked core prevents magnetic circuit closure, causing excessive inrush current that will overheat and destroy the coil.

1. Insert the flat seal (Item 1) between the solenoid terminal base and the cable plug (Item 2).
2. Mount the DIN EN 175301-803 Form A cable plug (Bürkert Type 2518 or equivalent).
3. Tighten the central fastening screw to a maximum torque of 1 Nm to maintain the IP65 seal.
4. Verify that nominal voltage and frequency match the 120 V AC rating indicated on the type label.

Operating Parameters and Service Life

• Operating mode: Solenoid actuator is rated for continuous operation (100% ED).
• Permissible ambient temperature: -10 °C to +55 °C.
• Duty cycle and cycle frequency: High switching frequency combined with high operating pressure accelerates mechanical wear.

Operational Readiness Recommendation

During prolonged system downtime under continuous energization or extended standby, actuate at least 1 to 2 switching cycles per day to prevent the plunger core and seal from sticking.

Maintenance, Troubleshooting, and Spare Parts

Authorized Maintenance Only

Maintenance work must be conducted exclusively by authorized technical personnel using appropriate tools. Ensure complete de-energization and depressurization before opening the valve body.

Troubleshooting Checklist

• Valve does not switch open:
  • Verify electrical voltage supply and confirm operating voltage matches 120 V AC.
  • Check coil winding for electrical continuity or short-circuit.
  • Inspect operating pressure: verify line pressure does not exceed 12 bar (liquids) or 16 bar (gases).
  • Disassemble and clean core guide tube if debris or particle deposits inhibit plunger travel.
• Valve does not close tightly:
  • Inspect valve seat and NBR seal disc for particulate contamination or foreign matter.
  • Check return spring for mechanical damage or fatigue.

Spare Parts Overview

Spare part sets for Burkert Type 0256:

• Item 1: Coil Set (complete replacement solenoid module)
• Item 2: Wearing Part Set (plunger core, return spring, and NBR seals)
• When ordering spare parts, quote the part position number and the 56632 device identification number.

Compatible Accessories

Accessory Description	Specification / Details	Article Number
Mounting Set for Brass Body	Mounting clamp with 2 cheese head screws M5×35 (37 mm threaded hole spacing, 48 mm clamp bore spacing)	151287
Cable Plug Type 2518 Form A	Without circuitry, 0–250 V AC/DC	314802
Cable Plug Type 2518 Form A	With LED, 12–24 V AC/DC	314812
Cable Plug Type 2518 Form A	With LED and varistor, 12–24 V AC/DC	314820
Plug-in Timer Type 1087 Form A	Analogue timer, 24–240 V AC/DC	348829
Plug-in Timer Type 1087 Form A	Digital timer, 110–240 V AC/DC	348831