來源:上海滬升實驗儀器廠發布(bu)時間:2015-07-13
1、環境(jing)條件的再現性
在(zai)試驗室內(nei)完整而(er)精確地(di)再現自然界(jie)存在(zai)的(de)(de)(de)(de)環(huan)境(jing)(jing)條件(jian)是(shi)可望而(er)不可及的(de)(de)(de)(de)事情。但是(shi),在(zai)一定(ding)的(de)(de)(de)(de)容(rong)差范(fan)圍之內(nei),人們完全可以正(zheng)確而(er)近似地(di)模擬工(gong)程產品在(zai)使用(yong)、貯存、運輸等(deng)過程中所(suo)經受的(de)(de)(de)(de)外(wai)界(jie)環(huan)境(jing)(jing)條件(jian)。這段話用(yong)工(gong)程的(de)(de)(de)(de)語言概括,就(jiu)是(shi)“試驗設備所(suo)創造的(de)(de)(de)(de)圍繞被試產品周邊(bian)的(de)(de)(de)(de)環(huan)境(jing)(jing)條件(jian)(含平臺環(huan)境(jing)(jing))應該(gai)滿足產品試驗規范(fan)所(suo)規定(ding)的(de)(de)(de)(de)環(huan)境(jing)(jing)條件(jian)及其容(rong)差的(de)(de)(de)(de)要(yao)求”。如用(yong)于軍(jun)工(gong)產品試驗的(de)(de)(de)(de)溫(wen)度(du)箱不僅要(yao)滿足國軍(jun)標GJB150.3-86、GJB150.4-86中根據不同的(de)(de)(de)(de)均勻性(xing)和溫(wen)度(du)控制(zhi)精度(du)的(de)(de)(de)(de)要(yao)求。只(zhi)有這樣(yang),才能保證在(zai)環(huan)境(jing)(jing)試驗中環(huan)境(jing)(jing)條件(jian)的(de)(de)(de)(de)再現性(xing)。
2、環境條件的可重復性(xing)
一(yi)臺(tai)(tai)環(huan)境(jing)試(shi)(shi)(shi)(shi)(shi)驗設備可(ke)(ke)能用(yong)于同(tong)一(yi)類型產(chan)品(pin)的(de)(de)(de)(de)(de)(de)多次(ci)試(shi)(shi)(shi)(shi)(shi)驗,而一(yi)臺(tai)(tai)被(bei)試(shi)(shi)(shi)(shi)(shi)的(de)(de)(de)(de)(de)(de)工程(cheng)產(chan)品(pin)也(ye)可(ke)(ke)能在(zai)不(bu)同(tong)的(de)(de)(de)(de)(de)(de)環(huan)境(jing)試(shi)(shi)(shi)(shi)(shi)驗設備中(zhong)(zhong)進行(xing)試(shi)(shi)(shi)(shi)(shi)驗,為了保證同(tong)一(yi)臺(tai)(tai)產(chan)品(pin)在(zai)同(tong)一(yi)試(shi)(shi)(shi)(shi)(shi)驗規(gui)范所規(gui)定(ding)(ding)(ding)的(de)(de)(de)(de)(de)(de)環(huan)境(jing)試(shi)(shi)(shi)(shi)(shi)驗條件(jian)下所得試(shi)(shi)(shi)(shi)(shi)驗結果的(de)(de)(de)(de)(de)(de)可(ke)(ke)比較性,必(bi)然要(yao)求(qiu)(qiu)環(huan)境(jing)試(shi)(shi)(shi)(shi)(shi)驗設備所提供(gong)(gong)的(de)(de)(de)(de)(de)(de)環(huan)境(jing)條件(jian)具有可(ke)(ke)重復(fu)性。這(zhe)也(ye)就是說(shuo),環(huan)境(jing)試(shi)(shi)(shi)(shi)(shi)驗設備施用(yong)于被(bei)試(shi)(shi)(shi)(shi)(shi)驗產(chan)品(pin)的(de)(de)(de)(de)(de)(de)應力(li)水平(如熱應力(li)、振(zhen)(zhen)動(dong)(dong)應力(li)、電(dian)應力(li)等(deng))對于同(tong)一(yi)試(shi)(shi)(shi)(shi)(shi)驗規(gui)范的(de)(de)(de)(de)(de)(de)要(yao)求(qiu)(qiu)是一(yi)致(zhi)的(de)(de)(de)(de)(de)(de)。環(huan)境(jing)試(shi)(shi)(shi)(shi)(shi)驗設備所提供(gong)(gong)環(huan)境(jing)條件(jian)的(de)(de)(de)(de)(de)(de)可(ke)(ke)重復(fu)性是由國家計量檢(jian)定(ding)(ding)(ding)部門(men)依據國家技術監督機(ji)構(gou)所制定(ding)(ding)(ding)的(de)(de)(de)(de)(de)(de)檢(jian)定(ding)(ding)(ding)規(gui)程(cheng)檢(jian)定(ding)(ding)(ding)合格后提供(gong)(gong)保證。為此,必(bi)須要(yao)求(qiu)(qiu)環(huan)境(jing)試(shi)(shi)(shi)(shi)(shi)驗設備能滿足檢(jian)定(ding)(ding)(ding)規(gui)程(cheng)中(zhong)(zhong)的(de)(de)(de)(de)(de)(de)各(ge)項技術指(zhi)標(biao)及精(jing)度(du)指(zhi)標(biao)的(de)(de)(de)(de)(de)(de)要(yao)求(qiu)(qiu),并且(qie)在(zai)使(shi)用(yong)時間上不(bu)超(chao)過(guo)檢(jian)定(ding)(ding)(ding)周期所規(gui)定(ding)(ding)(ding)的(de)(de)(de)(de)(de)(de)時限。如使(shi)用(yong)非常(chang)普(pu)遍的(de)(de)(de)(de)(de)(de)電(dian)動(dong)(dong)振(zhen)(zhen)動(dong)(dong)臺(tai)(tai)除滿足激振(zhen)(zhen)力(li)、頻率范圍、負載能力(li)等(deng)技術指(zhi)標(biao)外,還必(bi)須滿足檢(jian)定(ding)(ding)(ding)規(gui)程(cheng)中(zhong)(zhong)規(gui)定(ding)(ding)(ding)的(de)(de)(de)(de)(de)(de)橫(heng)向振(zhen)(zhen)動(dong)(dong)比、臺(tai)(tai)面(mian)加速(su)度(du)均(jun)勻性、諧波(bo)失真度(du)等(deng)精(jing)度(du)指(zhi)標(biao)的(de)(de)(de)(de)(de)(de)要(yao)求(qiu)(qiu),而且(qie)每(mei)次(ci)檢(jian)定(ding)(ding)(ding)后的(de)(de)(de)(de)(de)(de)使(shi)用(yong)周期為二(er)年,超(chao)過(guo)二(er)年必(bi)須重新檢(jian)定(ding)(ding)(ding)合格后才能投入使(shi)用(yong)。
3、環境條件參數的可(ke)測(ce)控性(xing)
任何(he)一臺環(huan)(huan)(huan)境試(shi)驗(yan)(yan)設備所提供的環(huan)(huan)(huan)境條件(jian)必(bi)須是可觀測的和可控制的,這不(bu)僅是為(wei)了使環(huan)(huan)(huan)境參數限制在一定的容差(cha)范圍之(zhi)內,保證試(shi)驗(yan)(yan)條件(jian)的再(zai)現(xian)性和重復性的要(yao)求(qiu)(qiu),而且從產(chan)品試(shi)驗(yan)(yan)的安全出發(fa)也(ye)是必(bi)須的,以便防止環(huan)(huan)(huan)境條件(jian)失控導致被試(shi)產(chan)品的損(sun)壞,帶來不(bu)必(bi)要(yao)的損(sun)失。目前各種試(shi)驗(yan)(yan)規范中大體要(yao)求(qiu)(qiu)參數測試(shi)的精度不(bu)應低于試(shi)驗(yan)(yan)條件(jian)允許的誤差(cha)的三分之(zhi)一。
4、環(huan)境試(shi)驗條件的(de)排它(ta)性(xing)
每一次(ci)進行環境或(huo)可(ke)靠性試(shi)(shi)驗(yan)(yan),對環境因素的(de)(de)(de)類別(bie)、量值及(ji)容差(cha)都有(you)嚴格的(de)(de)(de)規定(ding)(ding),并(bing)排除非(fei)試(shi)(shi)驗(yan)(yan)所(suo)需的(de)(de)(de)環境因素滲透其中,以便在試(shi)(shi)驗(yan)(yan)中或(huo)試(shi)(shi)驗(yan)(yan)結束后判斷(duan)和分析產(chan)品失效與(yu)故障(zhang)模(mo)式時,提(ti)(ti)供確切的(de)(de)(de)依據,故要求環境試(shi)(shi)驗(yan)(yan)設備除提(ti)(ti)供所(suo)規定(ding)(ding)的(de)(de)(de)環境條(tiao)件外,不允(yun)許對被(bei)試(shi)(shi)產(chan)品附加(jia)(jia)其它的(de)(de)(de)環境應力干擾。如電動振(zhen)動臺檢(jian)(jian)定(ding)(ding)規程中所(suo)限定(ding)(ding)的(de)(de)(de)臺面漏(lou)磁,加(jia)(jia)速(su)度(du)(du)信(xin)噪比(bi)、帶內帶外加(jia)(jia)速(su)度(du)(du)總均方根值比(bi)。隨機(ji)信(xin)號的(de)(de)(de)檢(jian)(jian)驗(yan)(yan)、諧(xie)波失真度(du)(du)等(deng)精度(du)(du)指標都是為了保證(zheng)環境試(shi)(shi)驗(yan)(yan)條(tiao)件的(de)(de)(de)唯一性而制定(ding)(ding)的(de)(de)(de)檢(jian)(jian)定(ding)(ding)項目(mu)。
5、試(shi)驗設備的安全可靠性
環境(jing)(jing)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan),特別是可(ke)(ke)靠性(xing)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan),試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)周期長,試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)的(de)對象有(you)時是價值很(hen)高的(de)軍(jun)工產品,試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)過程中(zhong),試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)人(ren)員經常(chang)要在現場(chang)周圍操作(zuo)巡(xun)視或測(ce)試(shi)(shi)(shi)(shi)(shi)工作(zuo),因此要求環境(jing)(jing)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)設備(bei)必須具有(you)運(yun)行安全(quan)、操作(zuo)方便、使用可(ke)(ke)靠、工作(zuo)壽(shou)命長等特點,以(yi)確保(bao)試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)本(ben)身的(de)正常(chang)進行。試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)設備(bei)的(de)各種保(bao)護、告警措(cuo)施及安全(quan)連鎖裝置應(ying)該完(wan)善可(ke)(ke)靠,以(yi)保(bao)證試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)人(ren)員、被(bei)試(shi)(shi)(shi)(shi)(shi)產品和試(shi)(shi)(shi)(shi)(shi)驗(yan)(yan)設備(bei)本(ben)身的(de)安全(quan)可(ke)(ke)靠性(xing)。
溫濕(shi)度箱(xiang)的選(xuan)擇
1、容積的選擇
將被試產品(元器件、組件、部件或整機)置入氣候環境箱進行試驗時,為了保證被試產品周圍氣氛能滿足試驗規范所規定的環境試驗條件,氣候箱工作尺寸與被試產品外廓尺寸之間應遵循以下幾點規定:
a)被試產品的體積(W×D×H)不得超過試驗箱有效工作空間的(20~35)%(推薦選用20%)。對于在試驗中發熱的產品推薦選用不大于10%。
b) 被試產品的迎風斷面積與該斷面上試驗箱工作室總面積之比不大于(35~50)%(推薦選用35%)。
c) 被試產品外廓表面距試驗箱壁的距離至少保持100~150mm,(推薦選用150mm)。
上(shang)述三點規定實際上(shang)是(shi)相(xiang)互依存和統一的(de)。以1立(li)方米正方體箱子為(wei)(wei)例,面積比(bi)為(wei)(wei)1:(0.35~0.5)相(xiang)當(dang)于(yu)體積之(zhi)比(bi)為(wei)(wei)1:(0.207~0.354)。距(ju)箱壁100~150mm相(xiang)當(dang)于(yu)體積之(zhi)比(bi)為(wei)(wei)1:(0.343~0.512)。
總括上述三點(dian)規定(ding),氣候環(huan)境試(shi)驗(yan)箱的(de)工作(zuo)腔容積至少應是被試(shi)產品(pin)外廓體積的(de)3~5倍。作(zuo)出(chu)這種規定(ding)的(de)理由有(you)以(yi)下幾(ji)點(dian):
(1)被(bei)試(shi)(shi)驗(yan)(yan)(yan)件置入箱體后擠占了流(liu)暢的(de)(de)(de)通道,通道變窄將導致氣流(liu)流(liu)速的(de)(de)(de)增加(jia)。加(jia)速氣流(liu)與(yu)被(bei)試(shi)(shi)驗(yan)(yan)(yan)件之間(jian)的(de)(de)(de)熱(re)交換(huan)。這與(yu)環境條件的(de)(de)(de)再(zai)現不(bu)(bu)符,因為在有關(guan)標(biao)準(zhun)中(zhong)對涉及溫度環境試(shi)(shi)驗(yan)(yan)(yan)都規(gui)定(ding)試(shi)(shi)驗(yan)(yan)(yan)箱內試(shi)(shi)驗(yan)(yan)(yan)樣件周(zhou)圍(wei)的(de)(de)(de)空(kong)氣流(liu)速不(bu)(bu)應超過1.7m/s,以防止試(shi)(shi)驗(yan)(yan)(yan)樣件和周(zhou)圍(wei)氣氛產生不(bu)(bu)符合實際的(de)(de)(de)熱(re)傳(chuan)導。在空(kong)載時試(shi)(shi)驗(yan)(yan)(yan)箱內平均風速為0.6~0.8m/s,不(bu)(bu)超過1m/s,滿(man)足a)、b)兩點要(yao)求所規(gui)定(ding)的(de)(de)(de)空(kong)間(jian)及面積(ji)比時,流(liu)場(chang)的(de)(de)(de)風速可能增大(da)(50~100)%,平均最(zui)(zui)高(gao)風速為(1~1.7)m/s。滿(man)足標(biao)準(zhun)規(gui)定(ding)的(de)(de)(de)要(yao)求。如(ru)果(guo)在試(shi)(shi)驗(yan)(yan)(yan)中(zhong)不(bu)(bu)加(jia)限(xian)制地加(jia)大(da)試(shi)(shi)驗(yan)(yan)(yan)件的(de)(de)(de)體積(ji)或迎風斷面積(ji),則(ze)實際試(shi)(shi)驗(yan)(yan)(yan)時氣流(liu)風速將增大(da)到(dao)超出試(shi)(shi)驗(yan)(yan)(yan)標(biao)準(zhun)所規(gui)定(ding)的(de)(de)(de)最(zui)(zui)高(gao)風速,其試(shi)(shi)驗(yan)(yan)(yan)結果(guo)的(de)(de)(de)有效性(xing)將受(shou)到(dao)懷(huai)疑。
(2)氣(qi)候箱工作(zuo)(zuo)腔內環境(jing)(jing)參(can)(can)數〔如溫度(du)、濕(shi)度(du)、鹽霧沉降率等〕的精(jing)度(du)指(zhi)標都(dou)是在空(kong)載狀態(tai)下(xia)檢測(ce)(ce)的結果,一旦置入被試(shi)驗(yan)(yan)件后,對試(shi)驗(yan)(yan)箱工作(zuo)(zuo)腔內環境(jing)(jing)參(can)(can)數的均勻性(xing)將產生影響(xiang),試(shi)驗(yan)(yan)件占(zhan)有的空(kong)間越大,這種影響(xiang)也就越嚴重(zhong)。實測(ce)(ce)試(shi)驗(yan)(yan)數據(ju)表(biao)明,流場中迎風面(mian)與背風面(mian)的溫差可(ke)達(da)到(dao)3~8℃,嚴重(zhong)時可(ke)大到(dao)10℃以上。因(yin)此,必須(xu)盡量滿(man)足a〕、b〕兩項(xiang)要(yao)求,以保證(zheng)被試(shi)產品周(zhou)圍環境(jing)(jing)參(can)(can)數的均勻性(xing)。
(3)根據熱傳導的(de)原(yuan)理(li),箱(xiang)壁(bi)附(fu)(fu)近(jin)氣流的(de)溫(wen)(wen)(wen)度(du)通(tong)常與(yu)(yu)流場中心溫(wen)(wen)(wen)度(du)相差2~3℃,在高(gao)低(di)溫(wen)(wen)(wen)的(de)上下限(xian)時,還可能達到5℃。箱(xiang)壁(bi)的(de)溫(wen)(wen)(wen)度(du)與(yu)(yu)箱(xiang)壁(bi)附(fu)(fu)近(jin)流場的(de)溫(wen)(wen)(wen)度(du)又相差2~3℃(視(shi)箱(xiang)壁(bi)的(de)結(jie)構和材料而定)試(shi)驗溫(wen)(wen)(wen)度(du)與(yu)(yu)外(wai)界(jie)大(da)氣環(huan)境(jing)相差越(yue)大(da),上述溫(wen)(wen)(wen)差也越(yue)大(da),因(yin)此,距(ju)箱(xiang)壁(bi)(100~150mm)距(ju)離內的(de)空(kong)間(jian)是不(bu)可利(li)用(yong)空(kong)間(jian)。
2、溫度范圍的選擇
目前,國(guo)外溫(wen)(wen)度試(shi)驗箱(xiang)的(de)(de)范圍(wei)大(da)體(ti)上(shang)為(wei)(wei)-73~+177℃,或-70~+180℃。國(guo)內(nei)多數(shu)廠家一(yi)般為(wei)(wei)-80~+130℃,-60~+130℃,-40~+130℃,也(ye)(ye)有(you)高(gao)(gao)溫(wen)(wen)到150℃。這些溫(wen)(wen)度范圍(wei)通常可(ke)以滿足國(guo)內(nei)絕大(da)多數(shu)軍用(yong)、民用(yong)產品(pin)溫(wen)(wen)度試(shi)驗的(de)(de)需(xu)要,除非(fei)確有(you)特殊(shu)需(xu)要,如安裝位(wei)置(zhi)靠近發動機等熱(re)(re)源(yuan)的(de)(de)產品(pin)外,不可(ke)盲目提高(gao)(gao)溫(wen)(wen)度上(shang)限(xian)。因為(wei)(wei)上(shang)限(xian)溫(wen)(wen)度越高(gao)(gao),箱(xiang)體(ti)內(nei)外的(de)(de)溫(wen)(wen)差(cha)(cha)越大(da),箱(xiang)體(ti)內(nei)部流場的(de)(de)均勻性(xing)也(ye)(ye)越差(cha)(cha)。可(ke)利用(yong)的(de)(de)工(gong)作(zuo)室體(ti)積也(ye)(ye)就越小。另一(yi)方面,上(shang)限(xian)溫(wen)(wen)度值越高(gao)(gao),對箱(xiang)壁夾(jia)層中保溫(wen)(wen)材料(如玻璃棉(mian)等)的(de)(de)耐熱(re)(re)性(xing)要求(qiu)越高(gao)(gao)。箱(xiang)體(ti)密(mi)封性(xing)的(de)(de)要求(qiu)也(ye)(ye)越高(gao)(gao),使箱(xiang)體(ti)的(de)(de)制(zhi)作(zuo)成本增加。
3、濕度范圍的選擇
國內(nei)外環境(jing)試(shi)驗(yan)(yan)箱給出(chu)的(de)濕(shi)度(du)(du)指(zhi)標大都是(shi)(shi)20~98%RH或30~98%RH,如(ru)果濕(shi)熱試(shi)驗(yan)(yan)箱沒有除濕(shi)系統,則濕(shi)度(du)(du)范(fan)圍為(wei)(wei)(wei)(wei)60~98%,這(zhe)一類試(shi)驗(yan)(yan)箱只(zhi)能做高濕(shi)試(shi)驗(yan)(yan),但它(ta)的(de)價格低(di)得(de)多。值得(de)注意的(de)是(shi)(shi)在(zai)濕(shi)度(du)(du)指(zhi)標后(hou)面應該注明相(xiang)(xiang)(xiang)(xiang)應的(de)溫(wen)(wen)度(du)(du)范(fan)圍,或給出(chu)最(zui)低(di)露(lu)點溫(wen)(wen)度(du)(du)。因為(wei)(wei)(wei)(wei)相(xiang)(xiang)(xiang)(xiang)對(dui)濕(shi)度(du)(du)是(shi)(shi)與溫(wen)(wen)度(du)(du)直接(jie)相(xiang)(xiang)(xiang)(xiang)關的(de),對(dui)于同樣的(de)絕(jue)對(dui)含濕(shi)量,溫(wen)(wen)度(du)(du)越高,相(xiang)(xiang)(xiang)(xiang)對(dui)濕(shi)度(du)(du)就越小(xiao),如(ru)絕(jue)對(dui)含濕(shi)量為(wei)(wei)(wei)(wei)5g/Kg(指(zhi)1公斤干空氣中含有5克的(de)水蒸汽),當溫(wen)(wen)度(du)(du)為(wei)(wei)(wei)(wei)29℃時,相(xiang)(xiang)(xiang)(xiang)對(dui)濕(shi)度(du)(du)為(wei)(wei)(wei)(wei)20%RH,溫(wen)(wen)度(du)(du)為(wei)(wei)(wei)(wei)6℃時,相(xiang)(xiang)(xiang)(xiang)對(dui)濕(shi)度(du)(du)為(wei)(wei)(wei)(wei)90%RH,當溫(wen)(wen)度(du)(du)降至4℃以下(xia),相(xiang)(xiang)(xiang)(xiang)對(dui)濕(shi)度(du)(du)超過(guo)100%,在(zai)箱體內(nei)會出(chu)現結(jie)露(lu)現象。
實(shi)現(xian)高(gao)溫(wen)(wen)、高(gao)濕(shi)(shi)(shi)(shi)只需要(yao)往箱(xiang)體空(kong)(kong)氣(qi)(qi)(qi)(qi)中(zhong)噴水(shui)蒸汽或(huo)霧化的(de)(de)(de)水(shui)珠,進(jin)(jin)行加濕(shi)(shi)(shi)(shi)。低溫(wen)(wen)低濕(shi)(shi)(shi)(shi)則相(xiang)(xiang)對(dui)(dui)難(nan)于控(kong)制(zhi),因(yin)為此(ci)(ci)時(shi)的(de)(de)(de)絕(jue)對(dui)(dui)含(han)(han)濕(shi)(shi)(shi)(shi)量(liang)很低,有時(shi)比(bi)大(da)(da)氣(qi)(qi)(qi)(qi)中(zhong)的(de)(de)(de)絕(jue)對(dui)(dui)含(han)(han)濕(shi)(shi)(shi)(shi)量(liang)低很多,需要(yao)對(dui)(dui)箱(xiang)體內(nei)流動的(de)(de)(de)空(kong)(kong)氣(qi)(qi)(qi)(qi)除(chu)(chu)濕(shi)(shi)(shi)(shi),使(shi)空(kong)(kong)氣(qi)(qi)(qi)(qi)變得干(gan)燥。目前國內(nei)外絕(jue)大(da)(da)多數的(de)(de)(de)溫(wen)(wen)濕(shi)(shi)(shi)(shi)度(du)(du)(du)(du)(du)(du)箱(xiang)都采用(yong)制(zhi)冷(leng)除(chu)(chu)濕(shi)(shi)(shi)(shi)的(de)(de)(de)原理,是(shi)在(zai)箱(xiang)體的(de)(de)(de)空(kong)(kong)氣(qi)(qi)(qi)(qi)預(yu)調室內(nei)加一組制(zhi)冷(leng)光管(guan)(guan)。當(dang)濕(shi)(shi)(shi)(shi)空(kong)(kong)氣(qi)(qi)(qi)(qi)經過冷(leng)管(guan)(guan)時(shi),其相(xiang)(xiang)對(dui)(dui)濕(shi)(shi)(shi)(shi)度(du)(du)(du)(du)(du)(du)會達(da)(da)(da)到(dao)(dao)100%RH,因(yin)空(kong)(kong)氣(qi)(qi)(qi)(qi)飽和在(zai)光管(guan)(guan)上結露,使(shi)空(kong)(kong)氣(qi)(qi)(qi)(qi)變得更干(gan)燥。這(zhe)種除(chu)(chu)濕(shi)(shi)(shi)(shi)方式理論上可達(da)(da)(da)到(dao)(dao)零度(du)(du)(du)(du)(du)(du)以下(xia)的(de)(de)(de)露點(dian)(dian)溫(wen)(wen)度(du)(du)(du)(du)(du)(du),但是(shi)當(dang)冷(leng)點(dian)(dian)表(biao)(biao)面溫(wen)(wen)度(du)(du)(du)(du)(du)(du)到(dao)(dao)達(da)(da)(da)0℃時(shi),光管(guan)(guan)表(biao)(biao)面結露的(de)(de)(de)水(shui)滴會結冰,從而影響光管(guan)(guan)表(biao)(biao)面的(de)(de)(de)熱(re)交換,使(shi)除(chu)(chu)濕(shi)(shi)(shi)(shi)能(neng)(neng)力下(xia)降。又因(yin)為箱(xiang)體不可能(neng)(neng)絕(jue)對(dui)(dui)密封(feng),大(da)(da)氣(qi)(qi)(qi)(qi)中(zhong)的(de)(de)(de)濕(shi)(shi)(shi)(shi)空(kong)(kong)氣(qi)(qi)(qi)(qi)會滲入到(dao)(dao)箱(xiang)體內(nei),使(shi)露點(dian)(dian)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)回升。另一方面,在(zai)光管(guan)(guan)間(jian)流動的(de)(de)(de)濕(shi)(shi)(shi)(shi)空(kong)(kong)氣(qi)(qi)(qi)(qi)只是(shi)在(zai)和光管(guan)(guan)(冷(leng)點(dian)(dian))接(jie)觸的(de)(de)(de)瞬間(jian)達(da)(da)(da)到(dao)(dao)飽和狀態(tai)而析出水(shui)蒸汽,因(yin)此(ci)(ci)這(zhe)種除(chu)(chu)濕(shi)(shi)(shi)(shi)方法很難(nan)使(shi)箱(xiang)體內(nei)的(de)(de)(de)露點(dian)(dian)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)在(zai)到(dao)(dao)0℃以下(xia)。實(shi)際所達(da)(da)(da)到(dao)(dao)的(de)(de)(de)最(zui)低露點(dian)(dian)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)為5~7℃。露點(dian)(dian)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)5℃相(xiang)(xiang)當(dang)于絕(jue)對(dui)(dui)含(han)(han)濕(shi)(shi)(shi)(shi)量(liang)為0.0055g/Kg,對(dui)(dui)應相(xiang)(xiang)對(dui)(dui)濕(shi)(shi)(shi)(shi)度(du)(du)(du)(du)(du)(du)20%RH的(de)(de)(de)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)為30℃。如果(guo)要(yao)求(qiu)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)20℃進(jin)(jin)相(xiang)(xiang)對(dui)(dui)濕(shi)(shi)(shi)(shi)度(du)(du)(du)(du)(du)(du)達(da)(da)(da)到(dao)(dao)20%RH,此(ci)(ci)時(shi)的(de)(de)(de)露點(dian)(dian)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)為-3℃,采用(yong)致冷(leng)方式除(chu)(chu)濕(shi)(shi)(shi)(shi)是(shi)很困難(nan)的(de)(de)(de),必須選用(yong)空(kong)(kong)氣(qi)(qi)(qi)(qi)干(gan)燥系統才能(neng)(neng)實(shi)現(xian)。
4、控制方式的選擇
溫度、濕度試(shi)驗(yan)箱有(you)恒定試(shi)驗(yan)箱、交變試(shi)驗(yan)箱兩種情況。
普通的(de)(de)(de)(de)(de)高(gao)低(di)溫(wen)(wen)(wen)(wen)(wen)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)一般(ban)指的(de)(de)(de)(de)(de)是恒(heng)(heng)(heng)定(ding)(ding)(ding)(ding)(ding)高(gao)低(di)溫(wen)(wen)(wen)(wen)(wen)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang),其控(kong)制(zhi)(zhi)(zhi)方式(shi)為:設(she)定(ding)(ding)(ding)(ding)(ding)一個(ge)目(mu)(mu)標溫(wen)(wen)(wen)(wen)(wen)度,試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)具(ju)(ju)有自動恒(heng)(heng)(heng)溫(wen)(wen)(wen)(wen)(wen)到(dao)目(mu)(mu)標溫(wen)(wen)(wen)(wen)(wen)度點的(de)(de)(de)(de)(de)能(neng)(neng)(neng)力(li)。恒(heng)(heng)(heng)定(ding)(ding)(ding)(ding)(ding)溫(wen)(wen)(wen)(wen)(wen)濕(shi)度試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)的(de)(de)(de)(de)(de)控(kong)制(zhi)(zhi)(zhi)控(kong)制(zhi)(zhi)(zhi)方式(shi)也類似,設(she)定(ding)(ding)(ding)(ding)(ding)一個(ge)目(mu)(mu)標溫(wen)(wen)(wen)(wen)(wen)度、濕(shi)度點,試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)具(ju)(ju)有自動恒(heng)(heng)(heng)溫(wen)(wen)(wen)(wen)(wen)到(dao)目(mu)(mu)標溫(wen)(wen)(wen)(wen)(wen)度、濕(shi)度點的(de)(de)(de)(de)(de)能(neng)(neng)(neng)力(li)。高(gao)、低(di)溫(wen)(wen)(wen)(wen)(wen)交(jiao)(jiao)(jiao)變(bian)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)具(ju)(ju)有設(she)定(ding)(ding)(ding)(ding)(ding)一條或者(zhe)多條高(gao)低(di)溫(wen)(wen)(wen)(wen)(wen)變(bian)化(hua)、循(xun)環的(de)(de)(de)(de)(de)程(cheng)序(xu),試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)有能(neng)(neng)(neng)力(li)根據預(yu)置(zhi)的(de)(de)(de)(de)(de)曲(qu)線(xian)(xian)完成(cheng)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)過程(cheng),并(bing)且(qie)可以在最大升溫(wen)(wen)(wen)(wen)(wen)、降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)速率能(neng)(neng)(neng)力(li)的(de)(de)(de)(de)(de)范圍內,精(jing)確控(kong)制(zhi)(zhi)(zhi)升溫(wen)(wen)(wen)(wen)(wen)、降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)的(de)(de)(de)(de)(de)速率,即可以根據設(she)定(ding)(ding)(ding)(ding)(ding)的(de)(de)(de)(de)(de)曲(qu)線(xian)(xian)的(de)(de)(de)(de)(de)斜率控(kong)制(zhi)(zhi)(zhi)升溫(wen)(wen)(wen)(wen)(wen)、降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)速率。同樣,高(gao)低(di)溫(wen)(wen)(wen)(wen)(wen)交(jiao)(jiao)(jiao)變(bian)濕(shi)熱試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)也具(ju)(ju)有預(yu)置(zhi)溫(wen)(wen)(wen)(wen)(wen)度、濕(shi)度曲(qu)線(xian)(xian),并(bing)且(qie)根據預(yu)置(zhi)進行控(kong)制(zhi)(zhi)(zhi)的(de)(de)(de)(de)(de)能(neng)(neng)(neng)力(li)。當然(ran),交(jiao)(jiao)(jiao)變(bian)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)都具(ju)(ju)有恒(heng)(heng)(heng)定(ding)(ding)(ding)(ding)(ding)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)的(de)(de)(de)(de)(de)功(gong)能(neng)(neng)(neng),但(dan)交(jiao)(jiao)(jiao)變(bian)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)的(de)(de)(de)(de)(de)制(zhi)(zhi)(zhi)造成(cheng)本較高(gao),因(yin)(yin)為交(jiao)(jiao)(jiao)變(bian)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)需配置(zhi)有曲(qu)線(xian)(xian)自動記(ji)錄裝置(zhi)、程(cheng)序(xu)控(kong)制(zhi)(zhi)(zhi)儀,還(huan)須解決試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)在工作室內溫(wen)(wen)(wen)(wen)(wen)度較高(gao)的(de)(de)(de)(de)(de)情況下開(kai)啟(qi)制(zhi)(zhi)(zhi)冷機等(deng)問題(ti),因(yin)(yin)此(ci),交(jiao)(jiao)(jiao)變(bian)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)的(de)(de)(de)(de)(de)價格比(bi)恒(heng)(heng)(heng)定(ding)(ding)(ding)(ding)(ding)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)的(de)(de)(de)(de)(de)價格一般(ban)要(yao)高(gao)20%以上。因(yin)(yin)此(ci),我們應當實事求是的(de)(de)(de)(de)(de)以試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)方法的(de)(de)(de)(de)(de)需要(yao)為出發點,選用恒(heng)(heng)(heng)定(ding)(ding)(ding)(ding)(ding)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)或者(zhe)是交(jiao)(jiao)(jiao)變(bian)試(shi)(shi)(shi)(shi)驗(yan)(yan)(yan)(yan)(yan)(yan)(yan)箱(xiang)(xiang)(xiang)。
5、變溫速率的選擇
普通的(de)高(gao)(gao)低溫(wen)(wen)試驗(yan)箱(xiang)沒有降溫(wen)(wen)速(su)(su)度的(de)指標(biao),從(cong)環(huan)境溫(wen)(wen)度降溫(wen)(wen)到標(biao)稱的(de)最低溫(wen)(wen)度的(de)時間一般為90~120min。高(gao)(gao)低溫(wen)(wen)交(jiao)變試驗(yan)箱(xiang)、高(gao)(gao)低溫(wen)(wen)交(jiao)變濕熱試驗(yan)箱(xiang)都有變溫(wen)(wen)速(su)(su)度的(de)要(yao)求(qiu),其(qi)變溫(wen)(wen)速(su)(su)率(lv)(lv)一般要(yao)求(qiu)1℃/min,在(zai)此速(su)(su)率(lv)(lv)的(de)范圍內(nei)速(su)(su)度可調(diao)。而(er)快速(su)(su)溫(wen)(wen)度變化(hua)試驗(yan)箱(xiang)的(de)變溫(wen)(wen)速(su)(su)率(lv)(lv)較(jiao)快,升(sheng)溫(wen)(wen)、降溫(wen)(wen)速(su)(su)率(lv)(lv)可以(yi)(yi)達到3℃/min~15℃/min,在(zai)某些溫(wen)(wen)度段升(sheng)溫(wen)(wen)、降溫(wen)(wen)速(su)(su)率(lv)(lv)甚(shen)至可以(yi)(yi)達到30℃/min以(yi)(yi)上。
各種規格、速(su)度(du)的(de)快速(su)溫(wen)度(du)變(bian)化(hua)試驗(yan)箱的(de)溫(wen)度(du)范(fan)(fan)圍(wei)一般都是相同(tong)的(de),即-60~+130℃,但考核降溫(wen)速(su)度(du)的(de)變(bian)溫(wen)范(fan)(fan)圍(wei)卻(que)不盡相同(tong),根據(ju)試驗(yan)不同(tong)的(de)試驗(yan)要(yao)求(qiu),快速(su)溫(wen)度(du)變(bian)化(hua)試驗(yan)箱變(bian)溫(wen)范(fan)(fan)圍(wei)有(you)的(de)是-55~+80℃,而有(you)的(de)是-40~+80℃。
關于(yu)快(kuai)速(su)(su)(su)(su)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)變化試(shi)(shi)驗箱的(de)(de)變溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)率有兩(liang)種提(ti)法,一種是(shi)(shi)全(quan)(quan)程(cheng)平(ping)(ping)(ping)(ping)(ping)均(jun)(jun)(jun)(jun)升(sheng)(sheng)降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)度(du)(du)(du),一種是(shi)(shi)線(xian)(xian)(xian)形(xing)(xing)(xing)(xing)升(sheng)(sheng)降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)度(du)(du)(du)(實(shi)際(ji)上(shang)(shang)是(shi)(shi)每5min平(ping)(ping)(ping)(ping)(ping)均(jun)(jun)(jun)(jun)速(su)(su)(su)(su)度(du)(du)(du))。全(quan)(quan)程(cheng)平(ping)(ping)(ping)(ping)(ping)均(jun)(jun)(jun)(jun)速(su)(su)(su)(su)度(du)(du)(du)是(shi)(shi)指在試(shi)(shi)驗箱的(de)(de)變溫(wen)(wen)(wen)(wen)(wen)(wen)范圍內,最(zui)高溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)與最(zui)低溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)之(zhi)差值與時間之(zhi)比。目前(qian)國外各環(huan)境(jing)試(shi)(shi)驗設備生產(chan)廠家提(ti)供的(de)(de)變溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)率的(de)(de)技術參(can)(can)數(shu)都是(shi)(shi)指的(de)(de)全(quan)(quan)程(cheng)平(ping)(ping)(ping)(ping)(ping)均(jun)(jun)(jun)(jun)速(su)(su)(su)(su)率。線(xian)(xian)(xian)形(xing)(xing)(xing)(xing)升(sheng)(sheng)降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)度(du)(du)(du)指在任意的(de)(de)每5min時間段(duan)內,能夠保證(zheng)的(de)(de)變溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)率。而實(shi)際(ji)上(shang)(shang)對于(yu)快(kuai)速(su)(su)(su)(su)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)變化試(shi)(shi)驗箱來說,保證(zheng)線(xian)(xian)(xian)形(xing)(xing)(xing)(xing)升(sheng)(sheng)降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)度(du)(du)(du)的(de)(de)難度(du)(du)(du)最(zui)大、最(zui)關鍵的(de)(de)一段(duan)是(shi)(shi),在降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)(wen)段(duan)最(zui)后的(de)(de)一個5 min的(de)(de)時間段(duan)內,試(shi)(shi)驗箱可以達到的(de)(de)降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)率。從某(mou)種角(jiao)度(du)(du)(du)講(jiang),線(xian)(xian)(xian)形(xing)(xing)(xing)(xing)升(sheng)(sheng)降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)度(du)(du)(du)(每5 min平(ping)(ping)(ping)(ping)(ping)均(jun)(jun)(jun)(jun)速(su)(su)(su)(su)度(du)(du)(du))更科(ke)學。因此試(shi)(shi)驗設備最(zui)好具有全(quan)(quan)程(cheng)平(ping)(ping)(ping)(ping)(ping)均(jun)(jun)(jun)(jun)升(sheng)(sheng)降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)度(du)(du)(du)和線(xian)(xian)(xian)形(xing)(xing)(xing)(xing)升(sheng)(sheng)降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)度(du)(du)(du)(每5min平(ping)(ping)(ping)(ping)(ping)均(jun)(jun)(jun)(jun)速(su)(su)(su)(su)度(du)(du)(du))這兩(liang)個參(can)(can)數(shu)。一般來說,線(xian)(xian)(xian)形(xing)(xing)(xing)(xing)升(sheng)(sheng)降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)度(du)(du)(du)(每5 min平(ping)(ping)(ping)(ping)(ping)均(jun)(jun)(jun)(jun)速(su)(su)(su)(su)度(du)(du)(du))是(shi)(shi)全(quan)(quan)程(cheng)平(ping)(ping)(ping)(ping)(ping)均(jun)(jun)(jun)(jun)升(sheng)(sheng)降(jiang)(jiang)溫(wen)(wen)(wen)(wen)(wen)(wen)速(su)(su)(su)(su)度(du)(du)(du)的(de)(de)1/2。
6、風速
有(you)關標準規定,進行(xing)環(huan)境試(shi)驗(yan)(yan)時溫(wen)(wen)濕箱(xiang)內(nei)的(de)風(feng)速應小于(yu)(yu)1.7m/s,對(dui)于(yu)(yu)試(shi)驗(yan)(yan)本身來(lai)說,風(feng)速越小越好,風(feng)速過大(da)會加速試(shi)驗(yan)(yan)件(jian)表面(mian)與箱(xiang)體內(nei)流(liu)(liu)動氣流(liu)(liu)的(de)熱交(jiao)換,于(yu)(yu)試(shi)驗(yan)(yan)的(de)真實性(xing)不利(li)。但為了保證試(shi)驗(yan)(yan)箱(xiang)工作室(shi)內(nei)的(de)均勻性(xing),試(shi)驗(yan)(yan)箱(xiang)內(nei)具有(you)循(xun)環(huan)風(feng)是(shi)(shi)必需(xu)的(de)。但是(shi)(shi)快(kuai)速溫(wen)(wen)度變(bian)化試(shi)驗(yan)(yan)箱(xiang)以及(ji)溫(wen)(wen)度、濕度、振動等多因(yin)素綜合環(huan)境試(shi)驗(yan)(yan)箱(xiang),為追求(qiu)變(bian)溫(wen)(wen)速率,必須(xu)加快(kuai)箱(xiang)體內(nei)循(xun)環(huan)氣流(liu)(liu)的(de)流(liu)(liu)速,風(feng)速通常在2~3m/s。因(yin)此,對(dui)于(yu)(yu)不同的(de)使用目的(de),風(feng)速的(de)限制(zhi)是(shi)(shi)不一樣的(de)。
7、溫度波動度
溫度波(bo)動是一個比(bi)較容易實現(xian)的(de)參數,所(suo)有環境試(shi)驗(yan)設備廠家生(sheng)產的(de)多數的(de)試(shi)驗(yan)箱實際的(de)溫度波(bo)動都可以控制(zhi)在±0.3℃的(de)范圍以內。
8、溫度場均勻度
為(wei)了更正確地模擬產品(pin)(pin)在(zai)(zai)自然界所遭受的(de)(de)實際環境狀況,在(zai)(zai)環境試(shi)驗(yan)中(zhong)必須保(bao)證(zheng)被試(shi)產品(pin)(pin)的(de)(de)周邊處(chu)在(zai)(zai)同一溫度(du)(du)環境條件(jian)下,為(wei)此,必須對試(shi)驗(yan)箱內的(de)(de)溫度(du)(du)梯度(du)(du)和溫度(du)(du)的(de)(de)波(bo)動(dong)度(du)(du)加以限制。在(zai)(zai)國軍標GJB150.1-86軍用設備環境試(shi)驗(yan)方法總則中(zhong)明確規定“試(shi)驗(yan)樣品(pin)(pin)附近測量(liang)系統的(de)(de)溫度(du)(du)應在(zai)(zai)試(shi)驗(yan)溫度(du)(du)的(de)(de)±2℃以內,其溫度(du)(du)工不超過1℃/m或(huo)總的(de)(de)最大(da)值為(wei)2.2℃(試(shi)驗(yan)樣品(pin)(pin)不工作)”。
9、濕度的精度控制
環境試驗(yan)箱(xiang)(xiang)中測量濕(shi)度(du)(du)(du)多(duo)數是(shi)采用干(gan)濕(shi)球(qiu)法(fa),環境試驗(yan)設備的(de)(de)制造標準GB10586要(yao)求,相對濕(shi)度(du)(du)(du)偏差應在+2-3%RH。為(wei)滿足濕(shi)度(du)(du)(du)控(kong)制精度(du)(du)(du)的(de)(de)要(yao)求,濕(shi)度(du)(du)(du)試驗(yan)箱(xiang)(xiang)的(de)(de)溫度(du)(du)(du)控(kong)制精度(du)(du)(du)較高,溫度(du)(du)(du)波(bo)動一般小于±0.2℃。否則(ze)很難達(da)到濕(shi)度(du)(du)(du)控(kong)制精度(du)(du)(du)的(de)(de)要(yao)求。
10、冷卻方式選擇
試驗(yan)箱(xiang)如果帶有制冷系統,制冷系統需(xu)要進(jin)行冷卻。試驗(yan)箱(xiang)有風冷、水冷兩(liang)種(zhong)形式。
風冷 水冷
使用條件 設備安裝簡便,只需要接通電源即可使用。環境溫度應低于28℃,如果環境溫度高于28℃對制冷效果有一定的影響(最好配備空調) 需配置循環冷卻水系統。
換熱效果 相對于水冷方式而言是較差 穩定、良好
對使用環境的影響 會導致試驗箱周圍的空氣溫度上升。 不影響試驗箱周圍的溫度。
噪聲 較大(da)(相(xiang)對于水冷方式) 較小
結論 選擇(ze)何種冷(leng)卻方式,應結合試驗室的(de)實際情況(kuang)而定。 在(zai)條件允許的(de)情況(kuang)下,優先(xian)考(kao)慮選擇(ze)水(shui)冷(leng)方式。但如果(guo)選用的(de)試驗箱的(de)制冷(leng)系統很小,也可(ke)以優先(xian)考(kao)慮選擇(ze)水(shui)冷(leng)方式。
溫濕(shi)度試驗(yan)設備狀況分(fen)析
1〕溫濕度環境(jing)試(shi)驗(yan)設備(bei)(bei)的(de)(de)(de)(de)(de)(de)生(sheng)(sheng)產(chan)(chan)(chan)(chan)(chan)是持續了幾(ji)十年的(de)(de)(de)(de)(de)(de)機械制(zhi)(zhi)造(zao)行(xing)業(ye),其(qi)(qi)基本技術(shu)(如制(zhi)(zhi)冷,加(jia)熱)已經成熟。便是隨(sui)著工業(ye)技術(shu)的(de)(de)(de)(de)(de)(de)進(jin)步(bu)和(he)發展,很(hen)(hen)多(duo)新(xin)的(de)(de)(de)(de)(de)(de)應(ying)用(yong)技術(shu)不斷(duan)引入到環境(jing)試(shi)驗(yan)設備(bei)(bei)中(zhong),如計算機技術(shu),模糊控制(zhi)(zhi)理(li)論(lun),多(duo)箱(xiang)同(tong)(tong)步(bu)運行(xing)等,因(yin)此(ci),很(hen)(hen)難給制(zhi)(zhi)造(zao)廠(chang)家下(xia)一(yi)(yi)(yi)個(ge)孰(shu)優孰(shu)劣的(de)(de)(de)(de)(de)(de)武斷(duan)性結(jie)論(lun)。各(ge)個(ge)生(sheng)(sheng)產(chan)(chan)(chan)(chan)(chan)廠(chang)家積幾(ji)十年的(de)(de)(de)(de)(de)(de)制(zhi)(zhi)造(zao)經驗(yan)所(suo)(suo)生(sheng)(sheng)產(chan)(chan)(chan)(chan)(chan)的(de)(de)(de)(de)(de)(de)設備(bei)(bei)都(dou)是可(ke)以使(shi)用(yong)的(de)(de)(de)(de)(de)(de),其(qi)(qi)工作原理(li)、所(suo)(suo)應(ying)用(yong)的(de)(de)(de)(de)(de)(de)技術(shu),甚至結(jie)構、材料等都(dou)有很(hen)(hen)多(duo)相(xiang)似之(zhi)(zhi)處。但(dan)是由(you)于環境(jing)試(shi)驗(yan)設備(bei)(bei)“多(duo)非標、多(duo)品(pin)種(zhong)、小批量”的(de)(de)(de)(de)(de)(de)生(sheng)(sheng)產(chan)(chan)(chan)(chan)(chan)方式的(de)(de)(de)(de)(de)(de)制(zhi)(zhi)約,產(chan)(chan)(chan)(chan)(chan)品(pin)的(de)(de)(de)(de)(de)(de)可(ke)靠性始終是困繞國(guo)(guo)內、國(guo)(guo)外制(zhi)(zhi)造(zao)商的(de)(de)(de)(de)(de)(de)一(yi)(yi)(yi)個(ge)問題。關鍵在(zai)于生(sheng)(sheng)產(chan)(chan)(chan)(chan)(chan)廠(chang)家必須管理(li)精細,工藝完(wan)備(bei)(bei)、檢測手(shou)段齊全、對質量認真負(fu)責(如通過(guo)ISO9000論(lun)證(zheng))。同(tong)(tong)時,環境(jing)試(shi)驗(yan)設備(bei)(bei)是一(yi)(yi)(yi)種(zhong)耐用(yong)品(pin),一(yi)(yi)(yi)些問題和(he)設計缺(que)陷需要多(duo)年使(shi)用(yong)才能(neng)暴露出來,通過(guo)統計分析才能(neng)發現問題所(suo)(suo)在(zai)。一(yi)(yi)(yi)個(ge)成熟的(de)(de)(de)(de)(de)(de)、高可(ke)靠性的(de)(de)(de)(de)(de)(de)產(chan)(chan)(chan)(chan)(chan)品(pin)往往需要多(duo)年改進(jin)、完(wan)善。因(yin)此(ci),環境(jing)試(shi)驗(yan)設備(bei)(bei)生(sheng)(sheng)產(chan)(chan)(chan)(chan)(chan)廠(chang)家具有一(yi)(yi)(yi)定(ding)生(sheng)(sheng)產(chan)(chan)(chan)(chan)(chan)規(gui)模和(he)生(sheng)(sheng)產(chan)(chan)(chan)(chan)(chan)歷(li)史,是產(chan)(chan)(chan)(chan)(chan)品(pin)具有較高可(ke)靠性的(de)(de)(de)(de)(de)(de)必要條件(jian)之(zhi)(zhi)一(yi)(yi)(yi)。
2〕生(sheng)產(chan)過(guo)程的(de)質(zhi)量控(kong)制(zhi)(zhi)。國(guo)內(nei)生(sheng)產(chan)過(guo)程的(de)質(zhi)量控(kong)制(zhi)(zhi)有很大提高(gao)。生(sheng)產(chan)過(guo)程的(de)質(zhi)量控(kong)制(zhi)(zhi)與生(sheng)產(chan)廠(chang)家的(de)管理(li)水平、生(sheng)產(chan)習(xi)慣有關,通過(guo)ISO9000的(de)論證是生(sheng)產(chan)過(guo)程質(zhi)量控(kong)制(zhi)(zhi)走上(shang)規范化的(de)一(yi)個標志。
國(guo)內外生(sheng)產溫濕(shi)度環境試(shi)驗設(she)備(bei)的(de)(de)廠家在生(sheng)產氣候環境試(shi)驗方面都積累了豐富的(de)(de)經驗。提供的(de)(de)都是(shi)可供使用(yong)的(de)(de),在質量上(shang)都可信賴(lai)。至于(yu)究竟應(ying)該選用(yong)哪一(yi)家,哪一(yi)種型號的(de)(de)產品更符合要(yao)求(qiu),除(chu)了本文前面所述(shu)的(de)(de)一(yi)些(xie)原則和(he)具體的(de)(de)技術(shu)指(zhi)標(biao)要(yao)求(qiu)外,還有一(yi)些(xie)值得重視和(he)考慮的(de)(de)因素。
a〕性能/價格比。
在對(dui)環境試(shi)驗設備的(de)技(ji)術參數、可靠性(xing)充分考證(zheng)的(de)基(ji)礎上,性(xing)價比是應當(dang)(dang)考慮的(de)重(zhong)要(yao)因(yin)素。環境試(shi)驗設備的(de)進(jin)(jin)口(kou)無一例外(wai)都是通過(guo)代理商(shang)在國(guo)內進(jin)(jin)行銷售的(de),價格的(de)因(yin)素不(bu)僅取決于(yu)生(sheng)(sheng)產(chan)廠家(jia)的(de)成(cheng)(cheng)本(ben)和利潤,還包含著很多中間(jian)(jian)環節費用及銷售提成(cheng)(cheng)。在相(xiang)同的(de)制造成(cheng)(cheng)本(ben)下,降低中間(jian)(jian)費用是降低訂貨價格的(de)重(zhong)要(yao)因(yin)素,同一國(guo)家(jia)相(xiang)關(guan)技(ji)術指(zhi)標(biao)的(de)產(chan)品(pin),制造成(cheng)(cheng)本(ben)大體相(xiang)當(dang)(dang),不(bu)同國(guo)家(jia)(指(zhi)西方發(fa)達國(guo)家(jia))生(sheng)(sheng)產(chan)的(de)產(chan)品(pin)即使有差別也不(bu)會太大。
b〕滿足用戶需要的程度和能力。
用(yong)戶(hu)訂購一臺溫濕度環境試(shi)(shi)驗箱,其要求依產品試(shi)(shi)驗的(de)(de)(de)(de)需要而不同,如(ru)有的(de)(de)(de)(de)三綜(zong)合試(shi)(shi)驗箱常常用(yong)于產品部件(jian)或組件(jian)和環境應(ying)力篩選試(shi)(shi)驗,此時設備的(de)(de)(de)(de)強制除(chu)濕能(neng)力以及附加空氣干燥系(xi)統的(de)(de)(de)(de)可(ke)能(neng)性是用(yong)戶(hu)應(ying)該(gai)重點關心(xin)的(de)(de)(de)(de)項目,如(ru)果有的(de)(de)(de)(de)用(yong)戶(hu)想利用(yong)三綜(zong)合試(shi)(shi)驗箱作環境試(shi)(shi)驗(如(ru)濕熱試(shi)(shi)驗),則風速可(ke)調(diao)整性就(jiu)是必須考慮的(de)(de)(de)(de)因(yin)素。
c〕售后服務及設備故障的處理能力。
任何一臺設備在(zai)使(shi)(shi)用(yong)(yong)中不(bu)可能不(bu)出故障(zhang),一旦出現問題(ti)使(shi)(shi)用(yong)(yong)者能否享受到及(ji)時的(de)維(wei)(wei)修服務,或者能根據設備自身具有的(de)故障(zhang)診斷能力(li)很快(kuai)確定出故障(zhang)處理辦(ban)法,使(shi)(shi)設備盡快(kuai)恢復性能,重新投入使(shi)(shi)用(yong)(yong)。在(zai)這方(fang)面,國內(nei)外的(de)生產廠家(jia)都已經或正在(zai)做出積極的(de)努力(li),如建立快(kuai)速(su)反應(ying)的(de)維(wei)(wei)修隊伍,如在(zai)計算機控制系(xi)統中增(zeng)加診斷及(ji)故障(zhang)預警系(xi)統軟件,用(yong)(yong)戶可根據計算機提供的(de)信(xin)息,盡快(kuai)處理故障(zhang)。
生產,研發,銷售一體 設(she)備(bei):高低溫、恒溫恒濕、淋(lin)雨、砂塵、紫外、氙燈等(deng)試(shi)驗(yan)箱;振(zhen)動臺(tai)、模擬運輸臺(tai)、跌落臺(tai)、鹽霧試(shi)驗(yan)機、大(da)型(xing)步入式(shi)實驗(yan)室等(deng);可根據客(ke)戶要(yao)求定制各種(zhong)非(fei)標尺寸(cun)實驗(yan)設(she)備(bei),歡迎廣大(da)新老客(ke)戶來電(dian)咨詢洽談。
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