Supaflex CA Expansion Bellows with 25mm axial movement at 6.9 bar working pressure (100 psi) were designed a number of years ago to fill a gap in the market. Cupric-based material was used. i.e. a phosphor bronze bellows element welded on to swaged BS2871 table X copper tube. This eliminated the problems encountered with residual flux, normally chloride based, attacking stainless steel units. All units are 100% helium mass spectrometer leak tested. Available in sizes 22mm, 28mm and 35mm (15mm being covered using the 22mm unit with reducing sets in the compression couplings or capillary reducers). They can also be used with ‘push fit’ connections due to the low ‘spring rate.’ All sizes are set to an installed length of 150mm and do not require ‘cold draw.’
Designers and installers should not be fooled by some of the units, which have appeared on the market over the years, claiming to be a cheaper alternative to bellows. They are normally a simple form of ‘slip joint’ containing ‘O’ rings, offering small axial movements and obviously, cycle life will be poor. A much greater number of units have to be installed and the failure rate and resultant labour costs to replace them turn it into an uneconomical solution. Life cycle tests at the development of Supaflex CA Bellows in the early 1980s proved a minimum of 4000 complete reversals at maximum movement/pressure. Supaflex CA Bellows are likely to last as long as the entire system.
With a proven history over many years in the perimeter heating market, they can also be used for radiator schemes piped in copper and secondary HWS installations, where natural flexibility cannot be gained on the pipe supports
