Datasheet
Selection of Vacuum Ejector and Vacuum Switching Valve
3
Leakage Volume during Work Adsorption
4
ZH07BS, ZH07DS
Exhaust Characteristics
Flow-rate Characteristics
Supply pressure {0.45 MPa}
Vacuum pressure (kPa)
Supply pressure (MPa)
Suction flow rate (L/min (ANR))
Suction flow rate
Suction flow rate
Vacuum pressure
Vacuum p
ressure
Air consumption
Air consum
pt
ion
Suction flow rate
Vacuum pressure
Air consumption
Suction flow rate (L/min (ANR))
Air consumption (L/min (ANR))
Vacuum pressure (kPa)
Calculating Vacuum Ejector and Switching Valve Size with the Formula
Average suction flow rate for achieving adsorption response time
Max. suction flow rate
Qmax = (2 to 3) x Q L/min (ANR)
<Selection Procedure>
• Ejector
Select the ejector with the greater maximum suction flow rate from the Qmax indicated above.
• Direct operation valve
∗ Select a valve (solenoid valve) having a conductance that is greater than that of the conductance C formula given above from
the related equipment (page 1278 in Best Pneumatics No. 4).
Q : Average suction flow rate L/min (ANR)
V : Piping capacity (L)
T1 : Arrival time to stable Pv 63% after adsorption (sec)
T2 : Arrival time to stable Pv 95% after adsorption (sec)
QL : Leakage volume during work adsorption L/min (ANR)
Note 1)
Q = ——— + QL
T2 = 3 x T1
V x 60
T
1
Conductance C =
————
[dm
3
/(s·bar)]
Qmax
5 x 11.1
Note 1) QL: 0 when no leakage occurs during adsorbing a workpiece.
If there is leakage during adsorbing a workpiece, find the leakage volume based on “4. Leakage Volume during Work Adsorption.”
Note 2) Tube piping capacity can be found in “8. Data: Piping Capacity by Tube I.D. (Selection Graph (2)).”
Leakage Volume from Conductance of Work
Leakage Volume from Adsorption Test
Air could be drawn in depending on the type of workpiece. As a result,
the vacuum pressure in the pad becomes reduced and the amount of
vacuum that is necessary for adsorption cannot be attained.
When this type of workpiece must be handled, it is necessary to select
the proper size of the ejector and the vacuum switching valve by taking
into consideration the amount of air that could leak through the
workpiece.
Leakage volume Q
L = 11.1 x 5 x CL
QL: Leakage volume L/min (ANR)
C
L: Conductance between work and pad, and work opening area [dm
3
/(s·bar)]
As described in the illustration below, pick up the workpiece with the ejector, using an ejector, pad and a vacuum gauge.
At this time, read vacuum pressure P
1
, obtain the suction flow rate from the flow-rate characteristics graph for the ejector that is being used,
and render this amount as the leakage of the workpiece.
Pad
Pad
Ventilation work Rough work surface
Pad
Vacuum pressure: P
1
Work
Exercise: Using a supply pressure of 0.45 MPa, when the ejector
(ZH07S) picks up a workpiece that leaks air, the vacuum gauge
indicated a pressure of –53 kPa. Calculate the leakage volume
from the workpiece.
<Selection Procedure>
When obtaining the suction flow rate at a vacuum pressure of
–53 kPa from the ZH07DS flow-rate characteristics graph, the
suction flow rate is 5 L/min (ANR).
Leakage volume Suction flow rate 5 L/min (ANR)
Model Selection
Front matter 17