電熱真空幹燥箱先抽真空再升溫加熱的原因 

1）如ru果guo按an先xian升sheng溫wen加jia熱re再zai抽chou真zhen空kong的de程cheng序xu操cao作zuo
，加jia熱re的de空kong氣qi被bei真zhen空kong泵beng抽chou出chu去qu的de時shi候hou，熱re量liang必bi然ran會hui被bei帶dai到dao真zhen空kong泵beng上shang去qu
，從cong而er導dao致zhi真zhen空kong泵beng溫wen升sheng過guo高gao
，有you可ke能neng使shi真zhen空kong泵beng效xiao率lv下xia降jiang。 

2）加jia熱re後hou的de氣qi體ti被bei導dao向xiang真zhen空kong壓ya力li表biao，真zhen空kong壓ya力li表biao就jiu會hui產chan生sheng溫wen升sheng。如ru果guo溫wen升sheng超chao過guo了le真zhen空kong壓ya力li表biao規gui定ding的de使shi用yong溫wen度du範fan圍wei，就jiu可ke能neng使shi真zhen空kong壓ya力li表biao產chan生sheng示shi值zhi誤wu差cha。 

正zheng確que的de使shi用yong方fang法fa應ying該gai先xian抽chou真zhen空kong再zai升sheng溫wen加jia熱re。待dai達da到dao了le額e定ding溫wen度du後hou如ru發fa現xian真zhen空kong度du有you所suo下xia降jiang時shi再zai適shi當dang加jia抽chou一yi下xia。這zhe樣yang做zuo對dui於yu延yan長chang設she備bei的de使shi用yong壽shou命ming是shi有you利li的de。 

3）工gong件jian放fang入ru真zhen空kong箱xiang裏li抽chou真zhen空kong是shi為wei了le抽chou去qu工gong件jian材cai質zhi中zhong可ke以yi抽chou去qu的de氣qi體ti成cheng分fen。如ru果guo先xian加jia熱re工gong件jian，氣qi體ti遇yu熱re就jiu會hui膨peng脹zhang。由you於yu真zhen空kong箱xiang的de密mi封feng性xing非fei常chang好hao，膨peng脹zhang氣qi體ti所suo產chan生sheng的de巨ju大da壓ya力li有you可ke能neng使shi觀guan察cha窗chuang鋼gang化hua玻bo璃li爆bao裂lie。這zhe是shi一yi個ge潛qian在zai的de危wei險xian。按an先xian抽chou真zhen空kong再zai升sheng溫wen加jia熱re的de程cheng序xu操cao作zuo

，就jiu可ke以yi避bi免mian這zhe種zhong危wei險xian。

    電熱真空幹燥箱不設溫度均勻度參數的原因 

一般的電熱（鼓風）幹燥箱均設有溫度均勻度參數：自然對流式的幹燥箱為工作溫度上限乘3%
，強製對流式的幹燥箱為工作溫度上限乘2.5%。惟wei獨du電dian熱re真zhen空kong幹gan燥zao箱xiang不bu設she溫wen度du均jun勻yun度du參can數shu，這zhe是shi為wei什shen麼me？真zhen空kong幹gan燥zao箱xiang內nei依yi靠kao氣qi體ti分fen子zi運yun動dong使shi工gong作zuo室shi溫wen度du達da到dao均jun勻yun的de可ke能neng性xing幾ji乎hu已yi經jing沒mei有you了le。因yin此ci

，從cong概gai念nian上shang我wo們men就jiu不bu能neng再zai把ba通tong常chang電dian熱re（鼓風）幹(gan)燥(zao)箱(xiang)所(suo)規(gui)定(ding)的(de)溫(wen)度(du)均(jun)勻(yun)度(du)定(ding)義(yi)用(yong)到(dao)真(zhen)空(kong)幹(gan)燥(zao)箱(xiang)上(shang)來(lai)。在(zai)真(zhen)空(kong)狀(zhuang)態(tai)下(xia)設(she)這(zhe)個(ge)指(zhi)標(biao)也(ye)是(shi)沒(mei)有(you)意(yi)義(yi)的(de)。熱(re)輻(fu)射(she)的(de)量(liang)與(yu)距(ju)離(li)的(de)平(ping)方(fang)成(cheng)反(fan)比(bi)。同(tong)一(yi)個(ge)物(wu)體(ti)，距(ju)離(li)加(jia)熱(re)壁(bi)20cm處所接受的輻射熱隻是距離加熱壁10cm處的1/4。chayihenda。zhezhongxianxiangyudongtianshaitaiyangshi，shaidaotaiyangdeyimianhennuanhe，shaibudaotaiyangdeyimianbijiaolengshiyigedaoli。youyuzhenkongganzaoxiangzaijiegoushanghennanzuodaoshigongzuoshisanweikongjianneidegedianfusheredejunyunyizhi
，tongshiyequefaquanweidepinggufangfa
，zheyoukenengshidianrezhenkongganzaoxiangbiaozhunzhongbushewendujunyunducanshudeyuanyin。