BURKERT 8640 (article 20138859) is a modular 3-bank pneumatic valve block configured with a total width of 33 mm (11 mm width per station) designed for DIN-rail mounting according to EN 50022 (35 x 7.5 mm or 35 x 15 mm). Configured without internal bus communication modules for individual discrete single wiring, this valve assembly integrates a G 1/2 main supply connection (port 1/P) and G 1/4 working service ports (ports 2/A and 4/B) situated opposite the supply side. The block operates within a pressure range of 3.0 to 10.0 bar and handles compressed air or neutral gases from 0 °C to +50 °C under ambient operating temperatures between 0 °C and +55 °C, offering IP20 ingress protection.

Technical Data and Article 20138859 Configuration

Article 20138859 defines a specific modular pneumatic block configuration within the Type 8640 family. The technical parameters reflect factory specifications for discrete control cabinet integration.

Specification Parameter	Value
Product Type	Type 8640 valve block
Article Number	20138859
Configuration	3-bank (3 valve slots)
Width per Station / Total Width	11 mm per station / 33 mm total assembly width
Supply Connection	G 1/2 (port 1/P)
Working Connection (Service Ports)	G 1/4 (ports 2/A and 4/B)
Working Port Orientation	Opposite of supply side
Nominal Operating Pressure	3.0 bar to 10.0 bar (0.3 MPa to 1.0 MPa)
Medium Temperature	0 °C to +50 °C
Ambient Operating Temperature	0 °C to +55 °C
Digital Inputs	0 PCE
Intermediate Feed Modules	0 PCE
Modular Bus Variant	Without (due to single wiring)
Internal Bus Communication	Without (due to single wiring)
Manual / Automatic Switching	No
Integrated Check Valves in Port 3 (R) / 5 (S)	No
Pneumatic HotSwap in Port 1 (P)	No
Mounting Style	Standard DIN-rail (EN 50022 35 x 7.5 mm or 35 x 15 mm)
Ingress Protection Rating	IP20

Modular Valve Island Architecture and Base Assembly

Type 8640 pneumatic valve blocks utilize high-grade polyamide (PA) base bodies and connection modules joined via integrated mechanical snap connectors and latch hooks. O-rings provide sealing across common pneumatic galleries, including supply channel 1 (P) and exhaust channels 3 (R) and 5 (S).

Item Number	Component Designation
1	Pneumatic connection module, left
2	Basic pneumatic modules (11 mm station width)
3	Pneumatic connection module, right
4	Pilot solenoid valves (e.g. Type 6524, Type 6525, or Type 0460)

Assembly Procedure

1. Begin module latching from the left pneumatic connection module.
2. Verify that two O-rings are present in the designated seal seats between adjacent modules. Apply a light coat of grease or oil to each O-ring before mechanical joining.
3. Engage the lower latch hooks of the succeeding pneumatic module into the matching latch grooves of the preceding unit, confirming that O-rings remain properly seated.
4. Pivot the module slightly upward until the upper latch hook engages fully with an audible snap.
5. Fit 3 O-rings into the rear recess of each pilot valve body prior to positioning on the sub-base.
6. Fasten each valve to the pneumatic base module using 2 fastening screws, tightening to a torque of 0.6 ±0.1 Nm.

Sealing Integrity

Pinched, displaced, or missing O-rings and profile seals between modular sub-bases result in internal cross-channel leakage or external pressure drops. Verify complete seal seating prior to latch engagement.

Compatible Pilot Solenoid Valves (11 mm Station Width)

Type 8640 valve blocks with 11 mm station widths host several Bürkert pilot solenoid valve variants:

• Type 6524: 3/2-way and 2 x 3/2-way flipper solenoid valve combining a Type 6144 pilot flipper actuator with a pneumatic seat valve body. Power consumption is 0.8 W per single valve or 2 x 0.8 W (with integrated power reduction) for double valves. Flow rate $Q_{Nn}$ is 300 l/min.
• Type 6525: 5/2-way flipper solenoid valve with seat valve mechanism. Power consumption is 0.8 W, delivering a flow rate $Q_{Nn}$ of 300 l/min.
• Type 0460: 5/2-way impulse or 5/3-way bistable solenoid valve built with an aluminium valve body and double coil pilot system. Power consumption is 0.5 W (impulse) to 1.0 W, with a nominal air flow rate $Q_{Nn}$ of 200 l/min.

Flange Pattern Revisions (REV2 vs REV3)

Pilot valves Type 6524 and 6525 utilize standardized flange interfaces: FM14 or FM20 on REV1/REV2 systems, and FM20 or FM24 on REV3 platforms. Unused valve slots must be sealed with a dedicated pneumatic cover plate (e.g. article 661092) to maintain pneumatic pressure integrity.

Mechanical Installation and Mounting

BURKERT Type 8640 valve blocks are designed for direct mounting inside standard electrical control cabinets, securing either to standard DIN rails or flat vertical mounting plates.

Item Number	Functional Element
1	Electrical interface (single wired or modular)
2	Wall mounting bracket surface
3	Standard DIN rail (EN 50022 35 x 7.5 mm or 35 x 15 mm)
4	Pneumatic connection module

DIN Rail Mounting Steps

1. Hook the upper locating groove of the Type 8640 valve block over the top edge of the EN 50022 DIN rail.
2. Swivel the block downward until the lower clamping elements snap onto the bottom rail edge.
3. Secure the clamping screws firmly against the rail surface.
4. Alternatively, screw the block directly to a wall or mounting plate using M4 fasteners.

Pneumatic Tubing and Operating Precautions

Pneumatic lines must be clean, deburred, and cut square at 90° before insertion into push-in fittings or threaded ports. In accordance with ISO 14743:2020, use hoses with outer diameters conforming to standard tolerances (polyamide PA: 3–10 mm ±0.08 mm, 12–16 mm ±0.1 mm; polyurethane PU: 3–8 mm ±0.1 mm, 10–16 mm ±0.15 mm).

Port Thread Size	Function / Marking	Recommended Torque	Maximum Tightening Torque
G 1/4	P, R/S Supply / Exhaust connections	4.0 to 7.0 Nm	20 Nm
G 1/8	Service ports A/B, P, R/S connections	3.0 to 6.0 Nm	7 Nm

Pipeline Protection

Do not use solenoid coils as a lever arm when tightening threaded fittings into the connection modules. Install an upstream particulate filter (≤ 5 µm rating) to prevent debris from reaching valve pilot seats.

Maintenance and Troubleshooting

Fault Condition	Probable Cause	Corrective Action
Valves fail to switch	Absence of operating voltage or supply voltage below tolerance	Verify 24 V DC supply across individual conductors; ensure ±10% voltage tolerance.
	Manual override locked in engaged position	Rotate manual override 90° counterclockwise to return it to the zero position.
	Supply pressure below required threshold	Ensure main supply pressure is at least 3.0 bar (pilot operation requires minimum 2.0–3.0 bar).
Delayed switching or exhaust blow-off	System energized before pressure buildup	Apply pneumatic pressure to the manifold before triggering electrical switching commands.
	Excessive back pressure in exhaust channels	Clean clogged silencers on ports 3 and 5, or install larger expansion exhaust conduits.
External leakage between blocks	Displaced, missing, or crushed internal O-rings	Disassemble sub-modules and install new pre-lubricated seals (e.g. Type MP16 seal set).