离子交换的压降与颗粒大小分布、床深、离子交换物质的空隙体积、水流流速、进水粘度（温度）有关。任何影响上述因素，如水中细粒（或悬浮物）被树脂床过滤造成树脂不正常的压实，或床层分散不均匀，都将增加压降而产生严重后果。
The pressure drop of ion exchange is related to particle size distribution, bed depth, void volume of ion exchange material, flow velocity and inlet viscosity (temperature). Any factors affecting the above, such as the abnormal compaction of resin caused by the filtration of fine particles (or suspended solids) in water by resin bed, or the uneven dispersion of bed layer, will increase the pressure drop and have serious consequences.
运行流速一般在10~30床体积/小时。
The operating flow rate is generally 10-30 bed volume / hour.
在向上反洗时，树脂应膨胀50~70%，以除去床内气泡和杂物。并将树脂粗细分层越彻底越好，使水流阻力降至最低值。
When backwashing upward, the resin should expand 50-70% to remove bubbles and sundries in the bed. And the more thorough the resin layer, the better, so that the flow resistance to the lowest value.
床体积膨胀随流速的增大而增大，随温度增长而降低，这适用于未用过的树脂，因为树脂是不再生的，因此就不需要在失效后反洗。反洗时须注意避免树脂床过度膨胀而使树脂损失。
The volume expansion of the bed increases with the increase of flow rate and decreases with the increase of temperature, which is applicable to the unused resin, because the resin is not regenerated, so it is not necessary to backwash after failure. When backwashing, pay attention to avoid excessive expansion of resin bed and resin loss.