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)罐(guan)內介(jie)質(zhi)的溫度、壓力變化(hua)等原因，儲(chu)(chu)(chu)罐(guan)不能完全裝滿，應留有(you)一(yi)定的空間，而(er)且液(ye)體儲(chu)(chu)(chu)罐(guan)工(gong)作時(shi)液(ye)面允許有(you)一(yi)個(ge)上(shang)下(xia)波(bo)動的范(fan)圍。這一(yi)上(shang)下(xia)波(bo)動范(fan)圍內的容(rong)(rong)量(liang)(liang)(liang)稱為工(gong)作容(rong)(rong)量(liang)(liang)(liang)，儲(chu)(chu)(chu)罐(guan)實際允許儲(chu)(chu)(chu)存(cun)的最大(da)容(rong)(rong)量(liang)(liang)(liang)稱為儲(chu)(chu)(chu)存(cun)容(rong)(rong)量(liang)(liang)(liang)，所以，儲(chu)(chu)(chu)罐(guan)公稱容(rong)(rong)量(liang)(liang)(liang)最大(da)，工(gong)作容(rong)(rong)量(liang)(liang)(liang)最小，儲(chu)(chu)(chu)存(cun)容(rong)(rong)量(liang)(liang)(liang)居中。立式(shi)儲(chu)(chu)(chu)罐(guan)容(rong)(rong)量(liang)(liang)(liang)示意見圖12.3。液(ye)體儲(chu)(chu)(chu)罐(guan)工(gong)作時(shi)，其實際存(cun)量(liang)(liang)(liang)不得(de)大(da)于(yu)儲(chu)(chu)(chu)存(cun)容(rong)(rong)量(liang)(liang)(liang)，也不得(de)小于(yu)儲(chu)(chu)(chu)存(cun)容(rong)(rong)量(liang)(liang)(liang)減去(qu)工(gong)作容(rong)(rong)量(liang)(liang)(liang)之差。