BURKERT 20085620 Type 8640 is a modular pneumatic valve island configured with a mixed valve population and 11 mm station width, designed for controlling neutral media and compressed air in industrial automation systems. Operating under revision 3 engineering standards, this valve block variant utilizes single wiring without internal bus communication and provides an ingress protection rating of IP20. Pneumatic supply is delivered through G 1/4 ports, with working connections routed out the bottom of the pneumatic module via D6 push-in connectors. The assembly supports an operating pressure range between 2.5 bar and 10 bar across a medium temperature span of 0 °C to 50 °C and an ambient temperature span of 0 °C to 55 °C.

Technical Specifications

Specification Parameter	Value / Detail
Model Article Number	20085620
Valve Type Family	Type 8640 (utilizing Type 5470 valves with Type 6106 pilot valves)
Hardware Generation	Revision 3
Valve Population Type	Mixed valve population (3/2-way and 4/2-way functions)
Station Width	11.00 mm
Supply Connection	G 1/4
Working Port Size & Position	D6 push-in connectors, located at bottom of pneumatic module
Nominal Pressure Range	2.50 bar to 10.00 bar
Medium Temperature Range	0 °C to +50 °C
Ambient Temperature Range	0 °C to +55 °C
Operating Fluid	Filtered compressed air (particle size max. 10 μm, lubricated or unlubricated), neutral gases (5 μm filtering)
Pilot Operating Pressure	2 to 10 bar (at least 70% of operating pressure)
Pressure Difference Requirement	Minimum 2 bar difference between port 1 and port 3
Ingress Protection Rating	IP20 (max. with suitable connection)
Control Variant	Single wiring (without internal bus communication, 0 digital inputs)
Mounting Standard	DIN-rail installation (EN 50022 35 x 15 or 35 x 7.5)

Valve Structure and Operating Mechanisms

Type 8640 valve islands integrate solenoid valves constructed from a 3/2-way Type 6106 pilot valve, a main valve body equipped with diaphragm seals, seat seals, and A/B connection plates. Individual stations assemble onto pneumatic base modules to form a rigid manifold block.

Item	Designation
1	Pilot valve Type 6106
2	Exhaust port 3
3	Pressure port 1
4	Working port 4
5	Working port 2
6	Manual override
7	Cable plug Type 2506 / Type 2516

Manual Override

Manual override allows actuation of each valve during setup and testing without requiring electrical signals.

• To actuate the valve manually, press the manual override down and turn it 90° clockwise until it stops. The manual override remains locked in this energized position and will not reset automatically.
• Only actuate the manual override when electrical power to the station is disconnected.
• For electrical operation during routine service, verify that the manual override is returned to its unlocked zero position.

Circuit Functions and 4/2 to 3/2-Way Conversion

Type 8640 accommodates several switching configurations. Port connections are numbered according to standard pneumatic designations: port 1 indicates the pressure supply, ports 2 and 4 serve as working outlets, and port 3 serves as the exhaust channel.

• Circuit Function C (3/2-way valve, NC): In rest position, pressure port 1 (P/NC) is closed, and working port 2 (A/OUT) vents to exhaust port 3 (R/NO).
• Circuit Function D (3/2-way valve, NO): In rest position, pressure port 1 (P/NO) communicates with working port 2 (B/OUT), while port 3 (R/NC) is closed.
• Circuit Function G (4/2-way valve): In rest position, pressure port 1 (P) connects to working port 2 (A), and working port 4 (B) vents to port 3 (R).

A 4/2-way valve can be converted into a 3/2-way valve by plugging one of the working outlets with a dedicated stopper:

Port 2	Port 4	Resulting Circuit Function
Closed	Open	Function C (Normally Closed 3/2-way)
Open	Closed	Function D (Normally Open 3/2-way)

Mechanical Assembly and Installation

Valves mount onto modular pneumatic base rails (such as Type MP05 modules). Standard operating orientation permits any installation position, with vertical mounting (solenoid actuator on top) preferred.

Item	Designation
1	Left connection module
2	Latch tab
3	Latch hook
4	Base modules 3-fold
5	Right connection module
6	Base modules 2-fold
7	Exhaust channel 3(R)
8	Supply channel 1(P)
9	O-ring

Multi-Block Assembly Procedure

1. Begin block assembly at the left connection module.
2. Confirm each module has 2 O-rings properly seated; apply a thin layer of oil or grease to all O-rings prior to engagement.
3. Hook the lower latch hooks of the adjoining module into the latch grooves of the preceding module.
4. Push the module upward slightly and engage the upper latch hook until locked.
5. Fit 3 O-rings into the rear recess of each valve body, verifying flat, uncrushed seating to eliminate internal block leakage.
6. Secure each valve body to the base module using 2 fastening screws tightened to a torque of 0.6 ±0.1 Nm.

Pilot Solenoid Rotation

If space constraints require an alternative cable exit, the solenoid operator can be rotated 180°. Remove the M2 screw, lift the coil from the valve body, rotate it 180°, reseat it, and retighten in two stages: first increment to 0.1 ±0.05 Nm, followed by a final tightening to 0.2 ±0.05 Nm.

Valve Island Mounting Methods

Item	Component Description
1	Electrical connection (rotatable by 180°)
2	Wall mounting bracket
3	Standard rail 35 x 15 or 35 x 7.5 EN 50022
4	Connection module

• Standard Rail Installation: Hook the top groove of the valve block over the DIN rail (EN 50022 35 x 15 or 35 x 7.5), snap the lower clamping brackets into position, and tighten the bracket clamping screws.
• Wall Mounting: Secure the valve assembly directly to the mounting panel using M4 screws.

Connection Port Tightening Torques

When threading fittings into port blocks, adhere strictly to the following torque limits:

Port Size	Port Identification	Recommended Torque [Nm]	Maximum Torque [Nm]
G 1/4 / NPT 1/4	P (Supply), R/S (Exhaust)	4 to 7	20
G 1/8 / NPT 1/8	P, R/S, and A/B outlets	3 to 6	7

Pneumatic Piping and Push-In Fitting Requirements

Tubing lines must meet strict dimensional and material criteria to prevent pull-out and leakage under pressure:

• Hardness: Minimum 40 Shore D according to DIN 53505 or ISO 868.
• Diameter: Outer dimensions compliant with DIN 73378 (permissible tolerance within ±0.1 mm of nominal).
• Preparation: Tube ends must be cut square, burr-free, and free of outer surface scoring or kinks.

ISO 14743:2020 Tubing Outer Diameter Tolerances

Tubing Material	Outer Diameter (OD) [mm]	Permitted OD Deviation [mm]
Polyamide (PA)	3 to 10	±0.08
Polyamide (PA)	12 to 16	±0.10
Polyurethane (PU)	3 to 8	±0.10
Polyurethane (PU)	10 to 16	±0.15

ISO 14743:2020 Tensile Retention Limits

Every inserted tube must satisfy the tensile test holding capacity defined by DIN ISO 14743:2020:

Metric Tube OD [mm]	Imperial Equiv. [in (mm)]	PA Minimum Tensile Force [N]	PU Minimum Tensile Force [N]
3	1/8 (3.17)	60	25
4	5/32 (4.00)	70	50
6	1/4 (6.35)	120	100
8	5/16 (8.00)	170	150
10	3/8 (9.52)	250	200
12	1/2 (12.70)	300	200
14	—	300	250
16	5/8 (16.00)	350	300

Soft Tubing Retention

When utilizing flexible polyurethane (PU) tubing, install support sleeves (ID 20099400) inside the hose end to maximize retention stability and prevent sealing deformation within the push-in gripping claws.

Electrical Installation

BURKERT 20085620 features single-wired connections. For cable connection, use approved cable plugs conforming to DIN EN 175301-803 Form C (such as Type 2516).

Item	Description
1	Flat gasket seal
2	Cable plug (Type 2516 or compliant DIN EN 175301-803 Form C)

• Position the flat seal correctly between the coil interface and the cable plug to maintain sealing integrity.
• Tighten the cable plug fastening screw to a maximum torque of 0.3 Nm (coil plug fastening torque is 1 Nm).
• Ensure protective ground continuity between the coil body and grounding conductor.

Parameter	Protective Conductor Test Specification
Maximum Resistance	0.1 Ω
Test Voltage	12 V
Test Current	1 A

Impulse Coil Control Requirements

When equipped with impulse coils, strict electrical polarity must be maintained according to the coil label. Control signals require a minimum pulse duration of 50 ms.

Plug Terminal Polarity	Pilot Valve State	Pneumatic Channel Effect
(+) on pin 2 / (-) on pin 1	Pilot valve opened	1 connects to 4 (Function C) / 1-3, 2-3 (Function G)
(+) on pin 1 / (-) on pin 2	Pilot valve closed	4 vents to 3 (Function C) / 1-2, 4-3 (Function G)

Maintenance and Troubleshooting

Depressurize Before Servicing

Prior to performing maintenance, isolate pneumatic supply lines, vent all trapped pressure from the manifold, and disconnect electrical power. Secure the system against accidental restart.

Operational Fault	Probable Cause	Corrective Action
Valves fail to switch	Missing or insufficient electrical supply voltage	Verify supply wiring; ensure voltage conforms to coil type label.
Valves fail to switch	Manual override engaged in locked position	Reset manual override mechanism back to zero position.
Valves fail to switch	Insufficient pressure supply	Establish larger-capacity air supply; verify minimum operating pressure is ≥ 2 bar.
Delayed switching or continuous venting at exhaust ports	Supply air pressure too low	Ensure operating supply is ≥ 2 bar; check upstream regulators and filters.
Delayed switching or continuous venting at exhaust ports	System pressurized while valves were in energized state	Ensure valves are in de-energized rest position before applying air pressure.
Delayed switching or continuous venting at exhaust ports	Silencers undersized, clogged, or generating backpressure	Clean dirty exhaust silencers or install larger silencer/expansion chambers.
Delayed switching or continuous venting at exhaust ports	Particulate contamination inside pilot or main valve seat	Apply pulsed air bursts through exhaust lines to clear debris, or replace valve capsule.
External leakage across valve block	Missing, damaged, or pinched O-rings between modules	Disassemble sub-blocks and replace missing or pinched inter-module O-rings.
External leakage across valve block	Missing or misaligned flat gasket seal between valve body and base plate	Inspect base seal interface; install new flat gasket seated in proper orientation.

Disassembly, Storage, and Disposal

• Manifold Disassembly: Loosen DIN rail clamping screws approximately 4 turns and lift the assembly upward from the standard rail. To separate base modules, insert a flat-blade screwdriver into the release notch on the front edge to unhook the upper latch hook, then pull the sub-block sideways.
• Tubing Removal: Press the push-in connector release ring inward firmly while extracting the pneumatic tube.
• Storage Limits: Store in a dry, dust-free environment at temperatures between -40 °C and +55 °C. Keep protective shipping caps on pneumatic ports and electrical pins.
• Disposal: Dispose of electronic sub-assemblies and metal components through certified technical recycling channels in accordance with national environmental regulations.