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Auto-Off Safety Vent Valves (KF flanged)

Our automatic foreline shut-off valve is a safety valve that protects the vacuum system upon power failure by isolating the vacuum system and venting the mechanical pump.


Features

  • Eliminate time consuming and costly cleanup of dirty vacuum lines, caused by oil backstreaming from the pump
  • Small orifice in the shut-off valves vents the mechanical pump to atmospheric pressure for easy restart when power resumes
  • Even when the mechanical pump is equipped with an anti-suckback valve, these valves are recommended because the pump’s integral valve will not vent the pump
  • Available in a variety of ISO-KF flange sizes, solenoid voltages, and frequencies

How it all works

The automatic foreline shut-off valves (anti suck-back vent valves) are connected in parallel with the mechanical pump’s electrical supply, either at its source or at the pump’s switch. When the electrical power is on, the solenoid valve is held closed, enabling the pump to keep both the shut-off valve’s body and the vacuum system evacuated. Interruption of electrical power to the mechanical pump causes the solenoid valve to open, admitting air into the shut-off valve, causing it to close. The pressure differential between the outside atmosphere and the vacuum system provides the necessary force to maintain the valve in its closed position without the aid of electrical or pneumatic power. With the vacuum system isolated, a series of small orifices admits air into the inlet port of the mechanical pump until it has risen to atmospheric pressure. When the power comes back on, the solenoid closes the pump. The mechanical pump is then restarted, and evacuates the area above the piston until the pressure is lowered to approximately that of the vacuum system. The automatic foreline shut-off valve then reopens, enabling the vacuum system to be pumped at the full speed of the mechanical pump.

Additional features and benefits

  • Protects vacuum system from oil backstreaming in the event of power failure (to the pump)
  • Enables quick system restarts
  • Operates up to 100,000 cycles
  • No external pressurized gas source required for actuation
  • Available in a variety of sizes for use with the most common mechanical pumps

Specifications Table

Temperature (°C) Valve: 0° to 100° C
Solenoid: 0° to 55° C
Material Body: AL 6061-T6
Piston: AL 2024
Seals: Fluorocarbon
Guide Pin: Fluorocarbon
Leak Rate (cc/sec) Body: < 1x10-9 std cc/sec. He
Seal: < 1x10-9 std cc/sec. He
Power 7W @ 115 VAC
Closing Time 30 ms
Venting Time 10 sec./Liter of vented volume
Weight 4 lbs. (1.8 kg) (for KF40 size)

Dimensional Drawings


Contact Us
To speak with someone directly, please call 1-412-387-9200 or email international@lesker.com.
Got VacuCADSM?
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Ordering Table

(Click column headers to sort data)

Flange
Size
Solenoid
Voltage
Manual PartNo Price Add Item
VacuCADSM
Flange
Size
Solenoid
Voltage
Manual PartNo Price Add Item
VacuCADSM
KF25 100 VAC/50 Hz
Download PDF
ASVQF25-100A
P.O.R.
N/A
KF25 120 VAC/60 Hz
Download PDF
ASVQF25-120A
P.O.R.
N/A
KF25 208 VAC/60 Hz
Download PDF
ASVQF25-208A
P.O.R.
N/A
KF25 220 VAC/50–60 Hz
Download PDF
ASVQF25-220A
P.O.R.
N/A
KF25 24 VAC/50–60 Hz
Download PDF
ASVQF25-24AC
P.O.R.
N/A
KF25 24 VDC
Download PDF
ASVQF25-24DC
P.O.R.
N/A
KF40 100 VAC/50 Hz
Download PDF
ASVQF40-100A
P.O.R.
N/A
KF40 120 VAC/60Hz
Download PDF
ASVQF40-120A
P.O.R.
N/A
KF40 208 VAC/60 Hz
Download PDF
ASVQF40-208A
P.O.R.
N/A
KF40 220 VAC/50–60 Hz
Download PDF
ASVQF40-220A
P.O.R.
N/A
KF40 24 VAC/50–60 Hz
Download PDF
ASVQF40-24AC
P.O.R.
N/A
KF40 24 VDC
Download PDF
ASVQF40-24DC
P.O.R.
N/A
KF50 100 VAC/50 Hz
Download PDF
ASVQF50-100A
P.O.R.
N/A
KF50 120 VAC/60 Hz
Download PDF
ASVQF50-120A
P.O.R.
N/A
KF50 208 VAC/60 Hz
Download PDF
ASVQF50-208A
P.O.R.
N/A
KF50 220 VAC/50–60 Hz
Download PDF
ASVQF50-220A
P.O.R.
N/A
KF50 24 VAC/50–60 Hz
Download PDF
ASVQF50-24AC
P.O.R.
N/A
KF50 24 VDC
Download PDF
ASVQF50-24DC
P.O.R.
N/A

Accessories Table

Type Description Manual PartNo Price Add
Item
Type Description Manual PartNo Price Add
Item
Clamp
For KF25 Flange
--
QF25-100-C
P.O.R.
Clamp
For KF40 Flange
--
QF40-150-C
P.O.R.
Clamp
For KF50 Flange
--
QF50-200-C
P.O.R.
Fluorocarbon Centering Ring
For KF25 Flange
--
QF25-100-ARV
$7.00
Fluorocarbon Centering Ring
For KF40 Flange
--
QF40-150-ARV
$9.60
Fluorocarbon Centering Ring
For KF50 Flange
--
QF50-200-ARV
$11.80

 

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