儲罐的容量與其幾何尺寸有關。按鋼材耗量最小的原則，對大型的立式儲罐，當公稱容量在1000～2000mm³時，取高度約等于直徑；對3000mm³以上的儲罐取高度等于3/8～3/4的直徑較為合理。儲罐的公稱容量是指按幾何尺寸計算所得的容量，向上或向下圓整后以整數表示的容量。

  由于罐(guan)內介質的溫度、壓(ya)力(li)變化等原因，儲(chu)罐(guan)不(bu)能完全裝(zhuang)滿，應留(liu)有一(yi)定的空間，而且液體儲(chu)罐(guan)工(gong)(gong)作(zuo)時(shi)液面允許(xu)有一(yi)個上下波動(dong)的范圍。這(zhe)一(yi)上下波動(dong)范圍內的容(rong)(rong)量(liang)(liang)(liang)(liang)稱(cheng)為(wei)工(gong)(gong)作(zuo)容(rong)(rong)量(liang)(liang)(liang)(liang)，儲(chu)罐(guan)實(shi)際允許(xu)儲(chu)存(cun)的最(zui)大容(rong)(rong)量(liang)(liang)(liang)(liang)稱(cheng)為(wei)儲(chu)存(cun)容(rong)(rong)量(liang)(liang)(liang)(liang)，所(suo)以，儲(chu)罐(guan)公稱(cheng)容(rong)(rong)量(liang)(liang)(liang)(liang)最(zui)大，工(gong)(gong)作(zuo)容(rong)(rong)量(liang)(liang)(liang)(liang)最(zui)小，儲(chu)存(cun)容(rong)(rong)量(liang)(liang)(liang)(liang)居中(zhong)。立式儲(chu)罐(guan)容(rong)(rong)量(liang)(liang)(liang)(liang)示意(yi)見(jian)圖12.3。液體儲(chu)罐(guan)工(gong)(gong)作(zuo)時(shi)，其(qi)實(shi)際存(cun)量(liang)(liang)(liang)(liang)不(bu)得(de)大于儲(chu)存(cun)容(rong)(rong)量(liang)(liang)(liang)(liang)，也不(bu)得(de)小于儲(chu)存(cun)容(rong)(rong)量(liang)(liang)(liang)(liang)減去工(gong)(gong)作(zuo)容(rong)(rong)量(liang)(liang)(liang)(liang)之差。