準確確定蒸氣的在線密度是確保蒸氣流量測量精度的最重要的條件之一。

    A.飽和蒸氣的密度

    水shui經jing過guo加jia熱re蒸zheng發fa變bian成cheng蒸zheng汽qi，這zhe就jiu是shi飽bao和he蒸zheng汽qi。飽bao和he蒸zheng汽qi的de溫wen度du與yu壓ya力li之zhi間jian有you著zhe嚴yan格ge的de一yi一yi對dui應ying關guan係xi。飽bao和he蒸zheng汽qi的de密mi度du可ke以yi是shi其qi溫wen度du或huo者zhe是shi其qi壓ya力li的de單dan一yi函han數shu。根gen據ju飽bao和he蒸zheng汽qi的de溫wen度du值zhi或huo者zhe是shi壓ya力li值zhi的de大da小xiao，將jiang其qi代dai入ru飽bao和he蒸zheng汽qi密mi度du計ji算suan公gong式shi就jiu可ke以yi計ji算suan出chu準zhun確que的de飽bao和he蒸zheng氣qi的de密mi度du值zhi。

    B.過熱蒸氣的密度

    guorezhengqishijiangbaohezhengqijinxingzaijiarehouhuodedeyizhongjuyouteshupinzhidezhengqi。tadapolebaohezhengqisuoguyoudewenduyuyaliyangeyiyiduiyingdeguanxi。yejiushishuo，zaigudingdezhengqiyalitiaojianxia
，fanshiwenduchaoguoduiyingyalitiaojianxiabaohewendudezhengqidoubeichengweiguorezhengqi。youyuguorezhengqijuyouguoredu
，yincizaishusongheliuliangceliangguochengzhongyibanburongyifashengxingzhibianyi（不容易產生冷凝水析出），在流量測量過程中可以將過熱蒸汽作為單一介質看待。

    guorezhengqidemidushiqiwenduheyalidezonghehanshu，miduzhikeyigenjuguorezhengqidewenduzhiheyalizhitongguoguorezhengqimidujisuangongshizhunquejisuanhuode。tianchenzhengqiliuliangjicaiyongzaixianwendu、yalimidubuchangdefangfakeyihuodezhunquedeguorezhengqimidu

，keyibaozhengzaiguorezhengqiliuliangceliangguochengzhongbuhuiyinweimidudewentidailaiewaideceliangwucha，baozhengceliangdejingdu。