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)(de)溫度、壓力(li)變化等(deng)原因，儲(chu)(chu)罐(guan)(guan)不能(neng)完全裝(zhuang)滿，應(ying)留(liu)有一定的(de)(de)空間，而(er)且(qie)液體(ti)儲(chu)(chu)罐(guan)(guan)工(gong)(gong)(gong)作(zuo)時液面允(yun)(yun)許(xu)有一個上下波動(dong)的(de)(de)范圍。這一上下波動(dong)范圍內的(de)(de)容(rong)(rong)量稱為工(gong)(gong)(gong)作(zuo)容(rong)(rong)量，儲(chu)(chu)罐(guan)(guan)實際允(yun)(yun)許(xu)儲(chu)(chu)存(cun)的(de)(de)最(zui)大(da)容(rong)(rong)量稱為儲(chu)(chu)存(cun)容(rong)(rong)量，所(suo)以，儲(chu)(chu)罐(guan)(guan)公稱容(rong)(rong)量最(zui)大(da)，工(gong)(gong)(gong)作(zuo)容(rong)(rong)量最(zui)小，儲(chu)(chu)存(cun)容(rong)(rong)量居中。立式儲(chu)(chu)罐(guan)(guan)容(rong)(rong)量示意(yi)見圖12.3。液體(ti)儲(chu)(chu)罐(guan)(guan)工(gong)(gong)(gong)作(zuo)時，其實際存(cun)量不得(de)大(da)于(yu)(yu)儲(chu)(chu)存(cun)容(rong)(rong)量，也不得(de)小于(yu)(yu)儲(chu)(chu)存(cun)容(rong)(rong)量減去工(gong)(gong)(gong)作(zuo)容(rong)(rong)量之差。