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(yu)(yu)罐(guan)(guan)內介質的(de)溫度、壓(ya)力變化等原因，儲(chu)(chu)(chu)(chu)(chu)罐(guan)(guan)不能完(wan)全裝滿，應留有一定的(de)空間，而(er)且液體(ti)儲(chu)(chu)(chu)(chu)(chu)罐(guan)(guan)工(gong)(gong)(gong)作(zuo)時液面(mian)允(yun)許有一個上下(xia)波動(dong)的(de)范(fan)(fan)圍。這一上下(xia)波動(dong)范(fan)(fan)圍內的(de)容(rong)(rong)量(liang)(liang)(liang)稱為(wei)工(gong)(gong)(gong)作(zuo)容(rong)(rong)量(liang)(liang)(liang)，儲(chu)(chu)(chu)(chu)(chu)罐(guan)(guan)實際允(yun)許儲(chu)(chu)(chu)(chu)(chu)存的(de)最大容(rong)(rong)量(liang)(liang)(liang)稱為(wei)儲(chu)(chu)(chu)(chu)(chu)存容(rong)(rong)量(liang)(liang)(liang)，所以，儲(chu)(chu)(chu)(chu)(chu)罐(guan)(guan)公稱容(rong)(rong)量(liang)(liang)(liang)最大，工(gong)(gong)(gong)作(zuo)容(rong)(rong)量(liang)(liang)(liang)最小(xiao)，儲(chu)(chu)(chu)(chu)(chu)存容(rong)(rong)量(liang)(liang)(liang)居中。立式儲(chu)(chu)(chu)(chu)(chu)罐(guan)(guan)容(rong)(rong)量(liang)(liang)(liang)示意見圖12.3。液體(ti)儲(chu)(chu)(chu)(chu)(chu)罐(guan)(guan)工(gong)(gong)(gong)作(zuo)時，其實際存量(liang)(liang)(liang)不得大于(yu)(yu)儲(chu)(chu)(chu)(chu)(chu)存容(rong)(rong)量(liang)(liang)(liang)，也不得小(xiao)于(yu)(yu)儲(chu)(chu)(chu)(chu)(chu)存容(rong)(rong)量(liang)(liang)(liang)減去(qu)工(gong)(gong)(gong)作(zuo)容(rong)(rong)量(liang)(liang)(liang)之差。