EVAC Hardware and Accessories
The uncoated chain clamps can be used with Ebara or other manufacturers? KF flanges with a radius of approximately .060 of an inch on the outer edge of the non-sealing side. Most manufacturers? KF flanges have this feature. If the flanges to be sealed have a sharp edge, the Teflon coated chain clamps are required to ensure adequate sealing force for aluminum metal seals. Both versions use a single, hex head nut for closure. Stainless steel chain clamps and low cost composite chain clamps are available for elastomer KF connections. Chain clamps for KF-63 flanges are similar to the KF-16 to 50 sizes. The style to use with KF-63 elastomer seals has a single knob for tightening. The clamp used for sealing aluminum metal seals has a single hex head nut. Both have uncoated aluminum links, although Teflon coated aluminum versions are available. Chain clamps for 80 to 100mm tapered flanges are stocked in two styles: one with a single knob for elastomer seals and another with two allen head bolts for aluminum metal seals. Although chain clamps are bakeable to 150°C, the knobs should not be baked above 60°C. Chain clamps for tube sizes up to 28 inch OD can be supplied on request.
EVAC aluminum seals locate on the centering ring groove (inner centering) or outside edge of the flange (outer centering) depending on the size. (Inner and outer centering versions are available for all NW flange sizes.) Aluminum knife-edges are compressed by the sealing surfaces of the mating flanges when the chain clamp or ISO claw clamp is tightened. The resultant seal has a helium leak rate of less than 1x10-11 standard cc/sec. and can be baked repeatedly to 150°C. Proper sealing occurs even if the flanges are slightly scratched or misaligned. The aluminum alloy is soft enough to make a good seal with reasonable force but will not flow at moderate temperatures. EVAC seals will even work with aluminum flanges. Normally the seals are for one-time use, however, by sealing the first time with a low torque and increasing the torque each time thereafter, they can be reused up to five times. If the seal is going to be baked or subject to vibration or pressure, it should be tightened to the recommended torque initially.