钠离子交换器是用于降低水中的硬度，生水由上而下通过交换器进行软化，水中含有的镁、钙、阳离子与水交换剂的钠离子互相交换；生水被软化成为含极少的钙、镁、盐水的水(称为软水)，可用于锅炉给水及一些工业用水。由于钠离子在水中有很大的溶解性。不会在锅炉内部结成影垢，并且容易排出，经过钠离子交换器的水，应该澄清过滤出来，基本少含有悬浮物。经交换器软化后，其剩余硬度不超过0.03毫克当量/升。

The exchanging device is for reducing hardness of hard water. Raw water goes through the exchanger from top to bottom, to be softened by the sodium ion exchanger inside the device. Magnesium and calcium that contained by water are exchanged with that of sodium. Then the raw water becomes soft water containing very few ions of magnesium and calcium. The soft water can be used for feeding water of boiler and for some industrial uses. Due to its high dissolving ability in water, sodium ions will not form hard sediment in the boiler and can be easily removed. Raw water shall be filtered and settled with less suspended solids before coming into the exchanging device. After being softened in the device, the water?s hardness shall be less than 0.03mg equivalent.