The BURKERT 702523 Type 8640 valve unit system is designed to solve diverse and complex control problems due to its systematic modular construction and combination of pneumatic and electrical interfaces. This specific model features a 19 mm width per station, a 12-bank configuration, G 1/4 pressure ports, and a collective socket module. By putting together a row of pneumatic modules, multiple valve functionalities can be realized on one valve unit. The valves allow different applications to be covered, controlling neutral media and compressed air reliably.

Structure and Description

The valves consist of a 3/2-way pilot valve (Type 6106) with different electrical connection variants, a valve body with diaphragm, seat seals, and A/B connection plates. The working ports 2 (B) / 4 (A) as well as the supply connection and exhaust port 1 (P) / 3 (R) are available with internal threads, plug-in couplings, or pointed hose nipples. A manual override is included for manual activation of the valve.

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

The valves can be mounted on the modular, pneumatic type MP05 base rails to form valve blocks. Any installation position is possible, preferably with the solenoid actuator on top.

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.

WARNING

Only operate the manual override when the power is off.

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

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

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

Technical Data

Operating Conditions

INFO

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

INFO

Pressure difference between port 1 and 3 must be at least 2 bar. When temperatures are below 0 °C, operation is restricted to dried air.

Parameter	Value
Ambient temperature	-10 ... +55 °C
Medium temperature	-10 ... +50 °C
Medium	Filtered compressed air (particle size max. 10 μm), preferably unlubricated; neutral gases (5 μm filtering)
Seal material	NBR
Operating pressure range	2 ... 10 bar

Electrical Data

Parameter	Value
Electrical connection	Cable plug Type 2516 on the plug contacts of the coil (torque for fastening: 1 Nm).
Voltage tolerance	±10%
Degree of protection	IP65 (only in conjunction with cable plug Type 2516)
Cable plug	Can be mounted offset by 180° for the cable outlet selected.

TIP

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

Installation

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

Observe the following tightening torques when screwing into the port connections. The specified tightening torque may vary depending on the sealing system.

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

Pneumatic Installation

DANGER

Risk of injury due to high pressure and escaping medium. Switch off the pressure before working on the device or system. Vent or drain the pipes.

Before connection:

• Check the hose lines for contamination and clean them.
• If necessary, install dirt traps upstream of the valve inlet (≤ 5 µm).

Pneumatic connection: Push the hose lines into the push-in connections of the solenoid valves until they come to a stop. Use PTFE tape or elastomer seal for sealing the threaded connection. Align hose lines and connect the supply and working lines to the valve block.

Electrical Installation

DANGER

Risk of injury due to electric shock. Switch off voltage before working on the device or system. Secure against reactivation. When screwing in the solenoid with the cable plug, make sure that the seal is properly seated.

Screw on the cable plug observing the maximum tightening torque of 0.3 Nm. Check that the seal is correctly fitted. Connect the protective conductor and check electrical continuity between the coil and housing.

Maintenance and Troubleshooting

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	Pressure supply insufficient or not available	Set up large-volume pressure supply. Minimum operating pressure ≥ 2 bar.
	Valves are not in the home position (de-energised) during pressure build-up	Apply pressure to the valve block before the valves are switched.
	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.