IFM Electronic Efector 500 PS7570 Notice D'utilisation page 34

Technical information (pneumatic system)
Supply pressure
Series connection
Recommendation for
the backpressure
nozzles
Harsh operating
conditions
Page 34
During the measurement of the backpressure fast primary pressure
fluctuations (< 1 Hz) should be avoided.
Damping of the basic signal in the sensor (→ menu point dAP, page
31) can compensate for fast pressure fluctuations. However this can
slightly change the response time.
So please note:
• Ensure a sufficient air supply (primary pressure). Recommendation:
Cross-section of the tubes 6 mm or higher.
• Use a pressure regulator which should not be followed by any addi-
tional devices.
Set the pressure regulator to a pressure < 1.5 bar (150 kPa / 22 PSI) befo-
re you install the control unit.
You can couple several blocks in series to detect several backpressure
nozzles at the same workpiece.
If you detect several workpieces using coupled pneumatic blocks, there
should be a time interval between each detection to ensure stable
pressure conditions in the primary pressure tube during the signal
detection.
• Outlet of the nozzle bore hole should have a sharp edge.
• Ratio of the length to diameter of the nozzle bore hole: 1.5 to 1.
• Expanding the access bore hole to an angle of 120°.
• Ratio of the diameter of the access bore hole to the diameter of the
nozzle bore hole: 2.5 to 1.
Make sure that the coolant does not clog the backpressure nozzles. For
the different mounting conditions please note the following:
• Vertical arrangement of the backpressure nozzles, from the top into
the machine section (figure 1). This arrangement is best to prevent
the ingress of coolant into the backpressure nozzles even if the air
supply is interrupted (unless the coolant is forced into the gap bet-
ween the detection surface and the workpiece at a high pressure).
• Horizontal arrangement of the backpressure nozzles, from the side
into the machine section; the pipes should be inclined (figure 2) the-
refore allowing any ingress of coolant to drain from the nozzles when
the air supply is interrupted. Attention: Do not allow the pipes to form
a collection point for coolant (figure 2).
• Vertical arrangement of the backpressure nozzles, from the bottom
into the machine section (figure 3). Coolant may ingress into the
backpressure nozzles when the air supply is interrupted and it may
not be fully removed by the normal airflow.
As an option, the connection of purging air to the backpressure
nozzles is possible. While the contact surface is absent the back-
pressure nozzles are supplied with a higher air quantity (and possi-
bly higher pressure).
Attention: The purging air connected to the backpressure nozzles
should not flow through the measuring block (the orifices of the
measuring block are bypassed)! Ensure an automatic changeover in