Page 128 - Parker - Vacuum products

Catalog 0802-E Vacuum Generators
Glossary

__A__ __L__
Air consumption Last output state
The amount of air in (measured in SCFM) consumed to achieve During an emergency stop or power loss event, emergency
the maximum rated vacuum level of the venturi. stop circuits from Parker can maintain the current state of
operation. This is referred to as maintaining the last output
Air-economizing function state from the system controls.
Integrated vacuum generators have the capacity to minimize
air consumption by utilizing the built in check valve. Once a __P__
predetermined vacuum level has been achieved (with a non- Part present signal
B porous application) , the check valve can maintain the vacuum Each sensor has an available NPN / PNP output and can be
level within the system. The hysteresis feature of the vacuum
sensor can maintain the vacuum level of the system indefinitely used for numerous purposes. One of them is a part present
when properly wired to the vacuum solenoid pilot valve. signal that usually signifies that a preset output for a vacuum
level has been achieved and it is safe to proceed. The
accuracy and repeatability of this signal can be critical to high
__B__ speed applications. False or dropped signals can interrupt
Blow-off needle the systems operations. Therefore, stable vacuum levels and
This is a flow adjustment supplied on integrated units to control output settings near the “part-off” vacuum level are critical.
Selection
the flow rate of the blow-off release.
Generator
“Part-on” / “Part-off” vacuum differential
Blow-off time You must determine the highs and lows of the vacuum system
CV-CK
The amount of time required to break the vacuum and release in order to properly set the sensor outputs. Typically with
MCA, CV,
the product in a pick and place application. This is signal venturi systems at fixed operating pressures, the maximum
vacuum level is known. The “Part-off” vacuum level of the
controlled by the PLC or by the MVS-201 sensor.
system must be determined by operating the system “open”
CHF
while the sensor displays the level of vacuum in the system.
Blow-off release master valve This is known as the “Part/on” / “Part-off” differential in
This is a shuttle valve that works by differential forces which is vacuum levels. Once this window of vacuum is known, the
MC22
piloted by a 2-3 valve. This valve is always configured normally part present signal could be set in the middle between these
closed. vacuum levels. Ideally, it would be best if this window was
a big as possible to avoid any issues with the sensors. Yet,
sometimes by design or necessity, this window is very small
MC72
__E__ or insignificant due to a high speed operation. To maximize
Emergency stop the speed of the machinery, reduce the response time of the
Emergency stop conditions for factory automation; this is sensor output by setting the output around 1 inHg above the
CEK
an external override condition that is usually activated by open vacuum level. The system response time is minimized
the machine operator to temporarily shut the equipment and thus the “Part-on” / “Part-off” window is insignificant.
down. The relevance to vacuum is the ability of the vacuum -30
equipment to maintain the last output state of the control inHg “Part-On”
CVXCEK
circuit. This feature would prevent part loss during this event Vacuum Level
as a normally closed system could maintain the current Upper Limit
vacuum state without the presence of power. Output Range
MPS-23
Lower Limit
__F__
“Part-Off”
Filtration Vacuum Level
MVS-201
Filtration between the pad and generator is recommended.
Regular maintenance of filters maintains the efficiency of the 0 100 200
system. Output Response Time (msec)
Generator
Accessories
__I__
Integrated vacuum generator
A vacuum venturi with integrated vacuum and blow-off release Power loss
Glossary
pilot valves built on the unit to minimize response times of the This refers to loss of electrical power supply to the system.
system. The unit may also incorporate filters, silencers, blow- Unlike other pneumatic components with safety features, loss
off flow controls , and optional sensors. of electrical power to a normally closed vacuum circuit could
be catastrophic; possibly resulting in dropping the product. To
prevent this situation, consider an E-stop circuit or a normally
open vacuum circuit.

B58 Parker Hannifin Corporation
Pneumatic Division
Richland, Michigan
www.parker.com/pneumatics