Burkert Type 8644 - Manual (Page 56)

52 - 8644/Rockwell
S
YSTEM
D
ESCRIPTION
Basic pneumatic module with integral pressure shut-off
General description
For the basic pneumatic module MP 11 in the 2-way and 8-way versions, an integral pressure shut-off is
available as an option. With this option, a faulty valve may be exchanged under pressure without relieving
the pressure in the entire valve island or system. On exchange of the valve, the open cross section is
reduced by a mechanism until only a very small leak remains.
Feature and limitations
Through the use of a pressure shut-off, some limitations arise in respect of the operating data of the overall
system:
• The flow though valve types 6524/25 is reduced to ca. 60%.
• The operating pressure range possible lies between 5 and 7 bar.
• When using valves with external auxiliary control air, the pressure supply for the pilot valves is not shut
off. Hence pressure shut-off may be used only in connection with valves with internal auxiliary control air
within the limited pressure range.
• Pressure shut-off may be combined with the integral non-return valves.
ATTENTION!
• Only one valve may be removed at a time.
• On disassembly, note that in each case only the pressure channel is shut off!
This means that any pressure applied to the service ports A or B is relieved on rem-
oval of the valve. Consequently, an actuator connected thereto will also become
pressureless and a movement may be triggered.
• If the volume on the actuator side is large, install a device by which the service ports
can be shut off to prevent movement of the actuator.
On removal of a valve, for functional reasons, a relatively large amount of air is initially blown off to
ambient, since the pressure shut-off can close only when the required presure difference is reached.
Automatic shut-off, however, significantly reduces the air loss, so that only a small leak remains after
closure.
On assembly of the valve, make sure the seal is inserted correctly.
Assemble the valve with the tightening torques stated in the operating instructions.
On assembly of the valve, may sure the service ports are also pressurized in the corresponding rest
position of the valve up to the time it is switched. Any actuator connected may execute a movement
because of the pressurization.
Make sure that such movements of the actuator do not cause damage or undesired actions in the
system.
NOTE Before exchanging a valve, we recommend bringing the system electrically into a safe
basic condition.
Procedure on exchange of a valve
NOTE When using basic modules with pressure shut-off, take care that the pressure supply for
the valve islands is executed with a suitably large volume
(minimum hose diameter: 8/6 mm).