The BURKERT 20026311 Type 8640 is a modular valve island designed for pneumatics, featuring a 19 mm width per station and a 2-bank configuration. The system is constructed to solve diverse control problems through its systematic modular design. The bodies and connection modules are manufactured from polyamide (PA) and are assembled using built-in snap connectors. This specific model operates within a pressure range of 2 to 8 bar and supports medium temperatures from 0 °C to 50 °C. It utilizes a G 1/8 pressure port and a D6 working port, providing a flow rate of 300 l/min (measured at +20 °C, 6 bar pressure at valve inlet, and 1 bar differential pressure).

Structure and Description

The 19 mm width per station variant of the Type 8640 valve island utilizes the Type 5470 solenoid valve. The valve consists of a pneumatic valve body fitted with a Type 6106 rocker pilot valve. An armature with a tilting bearing tilts within the body of the pilot valve to switch the valve. The minimal tilting movement of the rocker is non-wearing, and basic lubrication is unnecessary.

Design Components

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

Manual Override

To operate the valve manually, press the manual override and turn it 90° clockwise until it stops. The manual override is locked and does not reset automatically. Only operate the manual override when the power is off.

Circuit Functions

The Type 5470 valves support the following circuit functions:

• C (CF C): 3/2-way valve. In rest position, pressure port 1 (P/NC) is closed, working port 2 (A/OUT) is open after port 3 (R/NO).
• D (CF D): 3/2-way valve. In rest position, pressure port 1 (P/NO) is open after working port 2 (B/OUT), port 3 (R/NC) is closed.
• G (CF G): 4/2-way valve. In rest position, pressure port 1 (P) is open after working port 2 (A), working port 4 (B) is open after port 3 (R).

Conversion of 4/2 to a 3/2-way Valve

To convert the 4/2-way valve to a 3/2-way valve, close port 2 or port 4 with a stopper depending on the desired circuit function.

Port 2	Port 4	Circuit function
closed	open	C
open	closed	D

Operating Conditions

INFO

Pilot pressure for the pneumatic control unit depends on the pressure of the flow medium; it must be between 2 and 10 bar (at least 70% of operating pressure).

WARNING

A pressure difference between port 1 and 3 of at least 2 bar is required. When temperatures are below 0 °C, operation is restricted to dried air.

• Medium: Filtered compressed air (particle size max. 10 μm), preferably unlubricated (operation with lubricated air is possible), or neutral gases (5 μm filtering).
• Operating pressure range: 2 to 10 bar (SKU 20026311 is rated for 2 to 8 bar).

Installation

Rotating the Solenoid

Valves are delivered fully assembled. If the location of the solenoid of the pilot valve is not suitable for installation, the solenoid can be rotated 180°.

1. Loosen screw M2 and remove the coil from the valve body.
2. Rotate the coil, place it back onto the valve body, and screw it back into position in stages with M2 screws.
3. Observe the tightening torque: Increment of 0.1 Nm (±0.05 Nm), then Increment of 0.2 Nm (±0.05 Nm).

Installing Multiple Blocks

1. Begin installation with the connection module on the left.
2. Check modules for complete installation with 2 O-rings each. Lightly oil or grease all O-rings before engaging.
3. Engage the lower latch hooks of the module to be attached in the latch grooves of the preceding module. Make sure that the O-rings are properly seated.
4. Press the module to be locked upwards slightly and engage the upper latch hook.
5. Insert 3 O-rings into the recess on the back of the valve and ensure that the seal is properly fitted.

WARNING

Crushed O-rings and profile seals lead to leaky blocks.

Fasten each valve to the base module with 2 screws. The recommended tightening torque is 0.6 ±0.1 Nm.

Valve Block Installation

Standard rail installation:

1. Hook the valve block with the upper groove into the standard rail (35 x 15 or 35 x 7.5 EN 50022).
2. Snap the lower clamping pieces into the standard rail.
3. Tighten the screws on the clamping pieces.

Wall installation: Fasten the valve block directly to the wall with M4 screws.

Tightening Torques for Port Connections

Port size	Marking/function	Recommended tightening torque [Nm]	Maximum tightening torque [Nm]
G1/4, NPT1/4	P, R/S connection	4...7	20
G1/8, NPT1/8	P, R/S connection, A/B valve outlets	3...6	7

Maintenance and Troubleshooting

TIP

If continuous operation is interrupted, a minimum activity of 1-2 switching operations per day is recommended for the duration of the downtime to ensure functional reliability.

Fault	Possible cause	Remedy
Valves do not switch	No operating voltage or operating voltage too low	Check electrical connection. Ensure operating voltage according to type label.
	Manual override not in zero position	Bring manual override to zero position.
	Pressure supply insufficient or not available	Set up large-volume pressure supply. Minimum operating pressure ≥ 2 bar.
Valves switch with a delay or blow off at the exhaust ports	Insufficient ventilation of the exhaust air ducts due to too small or dirty silencers	Use suitably sized silencers or expansion vessels. Clean the dirty silencers.
	Impurities or foreign matter in the pilot or pneumatic valve	Apply pulsed pressure to the exhaust air ducts to blow out the impurities. Install a new pilot or pneumatic valve.
Leaky valve blocks	Missing or crushed O-rings between the modules	Identify leak or missing seals.
	Missing or incorrectly positioned flat seals between valve and base plate	Insert missing seals or replace damaged seals.