MKS 253B-2-2-2 - Page 47

Appendix A: Product Specifications CF Flan
g
e S
p
ecifications
39
CF Flange Specifications ( Continued )
Valve Type Number 253B
2-3CF-2
253B
2-4CF-1
253B
2-4CF-2
253B
3-6CF-2
253B
4-6CF-2
Inside Diameter (A)*
Inches
(mm)
2.000
(50.8)
1.888
(48.0)
2.000
(50.8)
3.000
(76.2)
3.875
(98.4)
Mounting Flange
2¾” CF 4½” CF 4½” CF 6” CF 6” CF
Outside Diameter (B)*
Inches
(mm)
3.25
(82.6)
4.47
(113.5)
4.47
(113.5)
7.40
(188.0)
7.40
(188.0)
Controllable
Conductance (l/sec)
min
max
0.70
300
TBD
TBD
0.70
300
1.00
500
1.50
900
Closed Leakage
(Torr l/sec)
<10
-7
<10
-7
N/A N/A N/A
Flapper Seal**
Viton Viton None None None
Thickness (C)*
Inches
(mm)
1.25
(31.8)
1.00
(25.4)
1.00
(25.4)
0.81
(20.6)
0.94
(23.9)
Overall Height***
Inches
(mm)
1.06
(26.9)
1.00
(25.4)
1.00
(25.4)
0.81
(20.6)
0.94
(23.9)
No. of Bolt Holes
6 8 8 16 16
Bolt Hole
Diameter (D)*
Inches
(mm)
0.33
(8.38)
0.33
(8.38)
0.33
(8.38)
0.33
(8.38)
0.33
(8.38)
Bolt Circle Diameter
Inches
(mm)
2.859
(72.6)
3.628
(92.2)
3.628
(92.2)
5.128
(130.3)
5.128
(130.3)
Flange O-ring groove
ID
N/A N/A N/A N/A N/A
* Refer to Figure 4, page 25.
** Where Viton is used, other materials are available; consult factory.