Heating expansion vessels are round with a compact flat design to meet the needs of boiler and heat interface unit manufacturers. Expansion vessels for heating systems are manufactured to meet the requirements of PED 97/23/EC Directive and BS EN 13831:2007 ‘Closed expansion vessels with built in diaphragm for installation in water’. Design The vessels are fabricated by clamping the two sections together which results in a very reliable structure suitable for internal pressures up to 3 bar. The tanks are designed with no corners to trap sediment. Epoxy coated in red - RAL 3013. Suitable for temperatures up to 90˚C, resistant to ethylene or propylene glycol mixtures. Altecnic expansion vessels are all tested according to the Pressure Systems Directive.