BURKERT 20062748 Type 8640 is a modular pneumatic valve island built with an 11 mm per-station module width and mixed 3/2-way valve functionality. Engineered for controlling neutral gases and filtered compressed air, the island operates within a nominal pressure range of 2.5 to 10.0 bar and an ambient temperature range of 0 °C to +55 °C. The unit integrates a 25-pin Sub-D multi-pole electrical connection with internal Bürkert bus communication, bottom-oriented D1/4 pneumatic working connections, and a D3/8 main supply port. The complete assembly is configured for DIN-rail installation with an IP20 ingress protection rating.

Valve Island Structure and Solenoid Valve Design

The Type 8640 pneumatic valve island utilizes modular base modules combined with integrated solenoid pilot valves (Type 5470 with Type 6106 pilot stage). The assembly incorporates dedicated pressure supply, exhaust, and working ports arranged along the manifold.

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 connection interface

Pneumatic Port Identification

Ports are identified by molded numbers to ensure correct piping:

• Port 1: Main pressure supply channel (P)
• Ports 2 and 4: Working outlets (B and A) positioned at the bottom of the pneumatic module
• Port 3: Exhaust channel (R)

Manual Override Operation

Each valve station is equipped with a mechanical manual override for commissioning and testing without electrical actuation.

To operate the valve manually, press the manual override down and turn it 90° clockwise until it hits the mechanical stop. In this position, the manual override remains mechanically locked and does not automatically reset. To restore electrical control, rotate the override 90° counter-clockwise back to the neutral position.

Manual Override Safety

Operate the manual override only when the valve station is de-energized. Before placing the system into regular electrical operation, confirm that all manual overrides across the island are rotated back to their zero position.

Circuit Functions and Valve Configuration

The 20062748 configuration provides 3/2-way valve operations within the manifold assembly:

• Function C (3/2-way NC): In the de-energized rest position, pressure port 1 (P) is closed, while working port 2 (A) exhausts through port 3 (R).
• Function D (3/2-way NO): In the de-energized rest position, pressure port 1 (P) connects directly to working port 2 (B), while exhaust port 3 (R) remains closed.
• Function G (4/2-way base architecture): In rest position, pressure port 1 feeds working port 2, while working port 4 exhausts through port 3. Ports 2 or 4 can be sealed with a dedicated plug to configure Function C or Function D operation.

Technical Specifications

Parameter	Specification Value
Type Series	Type 8640 (Generation revision 3)
Identification Article Number	20062748
Station Pitch / Add-on Dimension	11 mm
Operating Pressure Range	2.5 to 10.0 bar (minimum pressure difference 1 to 3: 2 bar)
Pilot Pressure Requirement	2 to 10 bar (at least 70% of operating pressure)
Operating Medium	Filtered compressed air (particle size max. 10 μm), neutral gases (5 μm filtering)
Lubrication Condition	Preferably unlubricated; operation with lubricated air is permitted
Seal Material	NBR
Medium Temperature Range	0 °C to +50 °C (restricted to dried air below 0 °C)
Ambient Temperature Range	0 °C to +55 °C
Storage Temperature Range	-40 °C to +55 °C
Electrical Interface Hardware	Sub D 25-pin connector
Modular Version / Protocol	Multi-pole control with internal Bürkert bus
Degree of Protection	IP20 (overall valve island assembly)
Mounting Standard	DIN rail 35 x 15 mm or 35 x 7.5 mm (EN 50022)

Modular Assembly and Mechanical Installation

Type 8640 multi-blocks consist of modular interlocking segments mounted between left and right connection modules.

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

Assembly Sequence

1. Begin block assembly from the left connection module.
2. Confirm that each module contains two clean, undamaged O-rings in the pneumatic supply and exhaust duct recesses.
3. Apply a light film of oil or grease to all O-rings before mating.
4. Hook the lower latch hooks of the adjacent module into the lower receiving grooves of the installed block, verifying seal positioning.
5. Press the module slightly upward and snap the upper latch hook securely into place.
6. Seat three O-rings into the rear recess of each valve body before fastening it to the base module.
7. Tighten the two mounting screws per valve with a torque of 0.6 ±0.1 Nm.

Seal Integrity

Crushed or misaligned O-rings and profile seals cause pressure loss across pneumatic ducts. Do not pinch seals during module latching.

Mounting to DIN Rail and Walls

The valve island is factory-configured for DIN-rail mounting and can alternatively be installed directly against a flat mounting surface.

• DIN-Rail Installation (EN 50022 35 x 15 / 35 x 7.5): Hook the upper groove of the valve block brackets over the top of the rail. Snap the lower clamping pieces over the rail and tighten the clamping screws.
• Wall Installation: Fasten the connection modules directly to a flat mounting surface using M4 screws.
• Port Tightening Torques: Adhere to specified thread tightening limits:
  • G1/4 and NPT1/4 supply/exhaust ports: 4 to 7 Nm (maximum 20 Nm)
  • G1/8 and NPT1/8 ports: 3 to 6 Nm (maximum 7 Nm)

Pneumatic Hose and Push-in Connector Requirements

Pneumatic connections must meet dimensional and hardness tolerances to maintain mechanical retention and airtight sealing under pressure.

• Hose Hardness: Minimum 40 Shore D according to DIN 53505 or ISO 868.
• Hose Tolerances: Outer diameter according to DIN 73378 (maximum permissible deviation ±0.1 mm from nominal dimension).
• Cut Preparation: Hoses must be cut square, burr-free, and undamaged across the outer circumference. Diagonal cuts reduce mechanical gripping strength and cause seal failure.

Push-in Connector Tolerances (ISO 14743:2020)

Hose Material	Hose Outer Diameter (OD) [mm]	Permitted 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

Minimum Tensile Holding Force (ISO 14743:2020)

Hose OD [mm]	3	4	6	8	10	12	14	16
Hose OD [in]	1/8 (3.17)	5/32 (4.0)	1/4 (6.35)	5/16 (8.0)	3/8 (9.52)	1/2 (12.7)	—	5/8 (16.0)
Minimum Tensile Force PA [N]	60	70	120	170	250	300	300	350
Minimum Tensile Force PU [N]	25	50	100	150	200	200	250	300

Tube Support Sleeves

When using flexible tubing such as polyurethane (PU), support sleeves (ID 20099400) can be inserted inside the hose end to reinforce holding capacity and prevent tube collapse under lateral tension.

Electrical Installation and Multi-Pole Interface

Model 20062748 uses a 25-pin Sub-D connector interface to route control signals across the multi-pole block. When individual pilot coils are detached or serviced, ensure proper protective earthing continuity.

Test Parameter	Test Condition / Value
Maximum Protective Earth Resistance	0.1 Ω
Test Voltage	12 V
Test Current	1 A

For pulse-driven pilot coils, adhere to polarity markings on the coil surface and maintain a control pulse duration of at least 50 ms.

Electrical Shock Hazard

Disconnect power supplies before disassembling or rewiring modules. Secure electrical systems against accidental reactivation. For external cable plugs (such as Type 2516), tighten mounting screws to 0.3 Nm and verify gasket alignment to maintain enclosure isolation.

Start-up and Commissioning Checklist

1. Confirm supply voltage matches the ratings specified on the module type labels.
2. Verify that supply pressure to port 1 is within 2.5 to 10.0 bar and that pilot pressure is at least 70% of operating pressure.
3. Check that pressure supply line 1 and exhaust line 3 are correctly routed and not transposed.
4. Rotate all manual overrides counter-clockwise back to their zero position prior to electrical actuation.
5. For continuous-operation installations subject to prolonged downtime, actuate each valve station 1 to 2 times daily to ensure ongoing operational readiness.

Troubleshooting

Fault	Possible Cause	Corrective Action
Valve does not switch	Missing or insufficient supply voltage	Verify power supply and electrical pinout against label specifications.
Valve does not switch	Manual override engaged in locked position	Reset manual override 90° counter-clockwise to zero position.
Valve does not switch	Inadequate operating pressure	Ensure pressure supply delivers at least 2.0 bar minimum differential pressure.
Delayed switching or blow-off at exhaust port	Supply pressure drops during switching	Install larger volume supply lines or buffer reservoirs upstream.
Delayed switching or blow-off at exhaust port	Valves energized prior to pneumatic pressurization	Apply pneumatic pressure to the island before triggering electrical switching.
Delayed switching or blow-off at exhaust port	Restricted exhaust flow or clogged silencers	Clean contaminated silencers or install higher-flow exhaust units.
Delayed switching or blow-off at exhaust port	Contamination inside pilot or main valve seat	Cycle pressure pulses through exhaust ducts or replace the valve insert.
External leakage between modules	Pinched, damaged, or missing O-rings	Disassemble block segment, inspect seal grooves, and replace damaged O-rings.
Leakage under valve body	Damaged or misaligned base plate gasket	Check valve seating face and re-torque mounting screws to 0.6 Nm.

Disassembly and Decommissioning

1. Disconnect electrical power to the 25-pin Sub-D interface and discharge all residual line pressure.
2. To release push-in fittings, depress the outer release collar squarely into the fitting body and pull the hose straight out.
3. To unmount the valve block from the DIN rail, loosen the lower clamping screws by approximately 4 turns and lift the assembly upward from the top rail edge.
4. To separate individual multi-block modules, insert a flat screwdriver into the disassembly notch on the front edge to release the upper latch hook, then unhook the lower latch.

Modular Right Connection Options

The right connection module can be adapted in modular systems to serve as an auxiliary feed point for high-flow installations, or as an intermediate separator to establish distinct pressure stages across a single contiguous block assembly. Internal separating walls at ports 1 and 3 can be opened when continuous through-feeding is required.

Transportation, Storage, and Disposal

Store the valve island in a dry, dust-free enclosure within a temperature range of -40 °C to +55 °C. Retain protective shipping plugs on pneumatic connections and electrical pin covers until mechanical installation. Dispose of decommissioned electronic and pneumatic sub-assemblies through authorized electronic waste (WEEE) collection facilities in compliance with national regulations.