INOX-PRO: The expansion tanks in this line are entirely made of stainless steel.  They are especially used for systems that produce sanitary hot water produced by a boiler or from plate heat exchangers.  They are excellent choices for situations that requires high hygienic standards and a product life time that is practically limitless. The membrane is absolutely non-toxic and is drinking and food grade.  This model of tanks, also for their reduced volumes, are particularly useful for anti-water hammer effect in water systems, preventing vibrations or noises.  They can also be used with reduced flow pumps. Available volumes range from 0.16 to 18 litres (0.3 to 4  UK gallons).