此儀器(qi)含(han)有兩(liang)個(ge)凹槽(cao)，一(yi)(yi)個(ge)用于10～20升(sheng)的桶(tong)(tong)(tong)，一(yi)(yi)個(ge)用于1～10升(sheng)的桶(tong)(tong)(tong)，將塑料(liao)桶(tong)(tong)(tong)置于凹槽(cao)上，然后(hou)套(tao)上套(tao)索，打(da)開空壓(ya)(ya)機(ji)，調節好(hao)壓(ya)(ya)力(li)(li)，在壓(ya)(ya)力(li)(li)的驅動下，測(ce)量箱(xiang)開始收(shou)縮(suo)，當空壓(ya)(ya)機(ji)關閉后(hou)，儀器(qi)會顯示(shi)壓(ya)(ya)縮(suo)的尺(chi)(chi)寸(cun)（以(yi)mm顯示(shi)。此時操(cao)作(zuo)者會得(de)到兩(liang)個(ge)數值，A和(he)B，分別顯示(shi)不同(tong)尺(chi)(chi)寸(cun)的桶(tong)(tong)(tong)，反方向松開套(tao)索，桶(tong)(tong)(tong)箱(xiang)回復到原(yuan)來的位置，取下塑料(liao)桶(tong)(tong)(tong)。