KF Style ISO Flange Specifications
Appendix A: Product Specifications
36
KF Style ISO Flange Specifications
Valve Type Number
253B-
20-40-1
253B-
20-40-2
253B-
1-40-1
253B-
1-40-2
253B-
2-50-1
253B-
2-50-2
Inside Diameter (A)*
Inches
(mm)
0.779
(19.8)
0.779
(19.8)
1.270
(32.3)
1.270
(32.3)
1.888
(48.0)
2.000
(50.8)
Mounting Flange
KF-40
KF-40
KF-40
KF-40
KF-50
KF-50
Outside Diameter (B)*
Unheated
Inches
(mm)
With heater option
Inches
(mm)
2.75
(69.9)
3.00
(76.2)
2.75
(69.9)
3.00
(76.2)
2.75
(69.9)
3.00
(76.2)
2.75
(69.9)
3.00
(76.2)
3.25
(82.6)
3.50
(88.9)
3.25
(82.6)
3.50
(88.9)
Controllable
Conductance (l/sec)
min
max
0.07
24
0.25
31
0.20
50
0.40
55
0.35
300
0.70
300
Closed Leakage
(Torr l/sec)
<10
-7
N/A
<10
-7
N/A
<10
-7
N/A
Flapper Seal**
Viton
None
Viton
None
Viton
None
Thickness (C)*
Inches
(mm)
2.25
(57.2)
2.25
(57.2)
2.25
(57.2)
2.25
(57.2)
2.00
(50.8)
2.00
(50.8)
Overall Height
Unheated
Inches
(mm)
With heater option
Inches
(mm)
8.64
(219.5)
8.81
(223.8)
8.64
(219.5)
8.81
(223.8)
8.64
(219.5)
8.81
(223.8)
8.64
(219.5)
8.81
(223.8)
9.14
(232.2)
9.31
(236.5)
9.14
(232.2)
9.31
(236.5)
No. of Bolt Holes
N/A
N/A
N/A
N/A
N/A
N/A
Bolt Hole Diameter (D)
N/A
N/A
N/A
N/A
N/A
N/A
Bolt Circle Diameter
N/A
N/A
N/A
N/A
N/A
N/A
Flange O-ring groove
ID
N/A
N/A
N/A
N/A
N/A
N/A
* Refer to Figure 2, page 24.
** Where Viton is used, other materials are available; consult factory.
Summary of Contents for 253B-1-2CF-1
Page 3: ...118843 P1 Rev C 2 99 MKS Type 253B Exhaust Throttle Valve...
Page 8: ...List of Figures and Tables vi...
Page 40: ...Maintenance Chapter Four Maintenance 32 This page intentionally left blank...
Page 52: ...Model Code Appendix B Model Code Explanation 44 This page intentionally left blank...
