BURKERT 322549 Type 6281 is a servo-assisted 2/2-way diaphragm solenoid valve configured with Circuit Function B (normally open, NO). Engineered with an investment cast stainless steel 1.4408 (CF8M) valve body, G 1/4 internal thread ports, and FKM elastomeric seals, the valve controls neutral and aggressive liquids and gases that do not chemically attack the wetted materials. An operating differential pressure of at least 0.2 bar is required for reliable switching, handling working pressures up to 16 bar with a nominal flow factor Kv of 1.5 m³/h (QNn 1,600 l/min for gases).

Equipped with a Class H epoxy-encapsulated solenoid coil rated for 230 V AC (50 Hz), article number 322549 withstands medium operating temperatures from 0 °C to +120 °C at ambient temperatures up to +55 °C. The valve features a vibration-resistant, centrally fastened coil system and a damped internal geometry designed for smooth, quiet closure. The electrical interface conforms to DIN EN 175301-803 Form A, achieving IP65 ingress protection when paired with a matching cable plug connector.

Operating Principle and Circuit Function

Type 6281 operates via pilot diaphragm control. In de-energized mode (rest position), Circuit Function B remains open: fluid pressure acts on the top of the diaphragm through a pilot passage, but venting through the pilot orifice relieves the upper control chamber, holding the main seal off its seat. When electrical power is applied to the 230 V AC coil, the magnetic plunger pulls down to close the pilot seat. Pressure builds above the diaphragm, pressing it down against the valve seat to shut off main flow.

Minimum Pressure Differential Required

Type 6281 requires an active pressure differential between inlet port 1 and outlet port 2. The minimum differential pressure is 0.2 bar. Full seat opening cross-section is achieved at a pressure difference of 0.5 bar. If differential pressure drops below 0.2 bar, the valve will not switch reliably.

Technical Specifications

Parameter	Specification
Product Type	Servo-assisted 2/2-way diaphragm solenoid valve
Type / Generation	6281 / EV
Article Number	322549
Circuit Function	B (2/2-way, normally open)
Port Connection	G 1/4 internal thread (DIN ISO 228)
Nominal Diameter (DN)	10 mm (3/8")
Pilot Control Orifice	1.2 mm
Flow Coefficient Kv (Water, +20 °C)	1.5 m³/h
Flow Rate QNn (Gas)	1,600 l/min
Operating Pressure Range	0.2 to 16 bar (differential pressure)
Nominal Pressure Rating	PN 16
Operating Voltage	230 V AC (50 Hz)
Voltage Tolerance	±10%
Duty Cycle	100% ED continuous operation
Switching Time (Opening)	0.1 to 1.5 s
Switching Time (Closing)	0.2 to 4.0 s
Permissible Medium Temperature	0 °C to +120 °C
Maximum Ambient Temperature	+55 °C
Enclosure Rating	IP65 acc. to DIN EN 60529 (with plug connector)
Unit Net Weight	0.43 kg

Materials of Construction

Item	Element	Material
1	Solenoid Coil	Epoxy (Class H insulation, code NA38)
2	Stopper	Stainless steel 1.4113
3	Shading Ring	Silver (Ag, stainless steel valve version)
4	Magnetic Core / Plunger	Stainless steel 1.4113
5	O-Ring	FKM (Fluor rubber)
6	Core Seal	FKM (Fluor rubber)
7	Plunger Return Spring	Stainless steel 1.4310
8	O-Ring	FKM (Fluor rubber)
9	Main Diaphragm	FKM (Fluor rubber)
10	Diaphragm Holder	Polyphenylene sulfide glass-filled (PPS-GF40)
11	Valve Body	Cast stainless steel 1.4408 (CF8M)

Dimensions and Mounting Footprint

Dimension Parameter	Value (DN 10 G 1/4 Stainless Steel)
Overall Length L	50 mm
Centerline to Top of Coil A	83.6 mm
Overall Height B	94.6 mm
Coil Width C	32 mm
Solenoid Length D	44 mm
Centerline to Fluid Port Base E	22 mm
Thread Depth F1 (G thread)	12 mm
Fluid Thread Specification G1	G 1/4
Wrench Flat Width SW	22 mm
Solenoid Size (Width H)	32 mm
Solenoid Plug Offset J	20.5 mm
Solenoid Height K	45 mm
Solenoid Plug Length M	41 mm
Solenoid Nut Overhang O	3.4 mm

Ordering Reference and Compatible Variants

Article 322549 belongs to the Type 6281 standard stainless steel series with Circuit Function B and FKM seals (0 °C to +120 °C):

Article No.	Circuit Function	Port Connection	DN [mm]	Kv (Water) [m³/h]	Pressure [bar]	Coil Voltage / Frequency	Body Material	Weight [kg]
322549	B (NO)	G 1/4	10	1.5	0.2 to 16	230 V / 50 Hz	Stainless steel	0.43
322547	B (NO)	G 1/4	10	1.5	0.2 to 16	24 V / DC	Stainless steel	0.43
322548	B (NO)	G 1/4	10	1.5	0.2 to 16	24 V / 50 Hz	Stainless steel	0.43
322550	B (NO)	G 3/8	10	1.9	0.2 to 16	24 V / DC	Stainless steel	0.40
322551	B (NO)	G 3/8	10	1.9	0.2 to 16	24 V / 50 Hz	Stainless steel	0.40
322552	B (NO)	G 3/8	10	1.9	0.2 to 16	230 V / 50 Hz	Stainless steel	0.40

Cable Plug Selection

The cable plug is not included in the standard delivery scope of article 322549 and must be ordered separately. For standard industrial use, Bürkert Type 2518 (Form A, article 314802 without wiring, 0-250 V AC/DC) or Type 2509 (Form A, article 137943) is recommended.

Installation and Piping Guidelines

Pre-Installation Pipeline Cleaning

Before connecting Type 6281, flush all process lines thoroughly to remove burrs, slag, and pipe sealant residues. Install a dirt trap or inline strainer with a mesh size of ≤ 500 µm upstream of the valve inlet to prevent particle accumulation in the pilot diaphragm bores.

1. Ensure the piping system is completely depressurized and vented.
2. Verify flow direction matches the cast arrow on the stainless steel valve body (flow direction is above seat, inlet port 1 to outlet port 2).
3. Apply an open-end wrench (SW 22) exclusively to the body flats when tightening pipe connections. Never apply torque to the solenoid coil housing or use the coil as a lever arm.
4. Mount in any orientation; positioning the valve with the solenoid actuator upright is recommended for maximum reliability.

Electrical Connection

Type 6281 utilizes a standard 3-pin Form A terminal configuration complying with DIN EN 175301-803:

• Connect power leads to pins 1 and 2 according to the specified 230 V AC operating voltage.
• Always connect the protective earth (PE) lead to the earth ground terminal.
• Ensure the flat elastomer gasket is properly aligned between the coil base and the plug housing.
• Fasten the central plug securing screw to a maximum tightening torque of 1.0 Nm to maintain IP65 sealing.

Coil Assembly, Maintenance and Spare Parts

When servicing the valve or replacing the solenoid coil:

1. Slide the coil body over the stainless steel core guide tube.
2. Verify the anti-twist mechanism and O-ring are correctly seated against the valve cover.
3. Fasten the central fixing nut using an open-end wrench, applying the specified torque shown below.

Solenoid Type	Solenoid Width	Fastening Torque
AC10	32 mm or 40 mm	5 Nm
AC19	42 mm	10 Nm

Prevent Coil Overheating

Never energize the solenoid coil while it is removed from the valve guide tube. Activating the coil without the magnetic iron path of the assembled valve will cause immediate overheating and thermal destruction.

Troubleshooting Checklist

• Valve fails to open: Verify that supply pressure provides at least 0.2 bar differential; check line voltage against nominal 230 V AC rating; inspect coil continuity for short circuits or open windings.
• Valve fails to close: Confirm manual override (if present on specialized sub-models) is disengaged; check whether the small pilot control bore in the diaphragm is clogged with media particulates; inspect core guide tube for foreign particle buildup.

Spare Parts Identification

Original replacement parts are supplied in pre-assembled factory packages. When ordering replacement sets, specify SET 1, SET 3, or SET 7 along with the valve article number 322549.