無錫徽科特測控技術有限公司露點儀、相對濕度和氧分析專家
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1．選(xuan)擇測量(liang)范圍
和測(ce)(ce)量(liang)重量(liang)、溫度(du)一樣(yang)，濕(shi)(shi)度(du)傳(chuan)感(gan)器(qi)選擇先(xian)要(yao)考慮測(ce)(ce)量(liang)范圍(wei)。除(chu)了氣象、科(ke)研部(bu)門外，溫、濕(shi)(shi)度(du)測(ce)(ce)控(kong)(kong)的(de)(de)(de)不(bu)(bu)需要(yao)全(quan)濕(shi)(shi)程(0-100％RH)測(ce)(ce)量(liang)。在當今的(de)(de)(de)信息時代，傳(chuan)感(gan)器(qi)技與計算機、自動控(kong)(kong)制(zhi)(zhi)技術(shu)緊密結合著。測(ce)(ce)量(liang)的(de)(de)(de)目的(de)(de)(de)在于控(kong)(kong)制(zhi)(zhi)，測(ce)(ce)量(liang)與控(kong)(kong)制(zhi)(zhi)合稱使(shi)用(yong)(yong)(yong)范圍(wei)。對于不(bu)(bu)需要(yao)做測(ce)(ce)控(kong)(kong)系統的(de)(de)(de)應(ying)用(yong)(yong)(yong)者(zhe)來說(shuo)，直接選擇通用(yong)(yong)(yong)型濕(shi)(shi)度(du)儀就可以了。例如應(ying)用(yong)(yong)(yong)領域對濕(shi)(shi)度(du)傳(chuan)感(gan)器(qi)使(shi)用(yong)(yong)(yong)溫度(du)、濕(shi)(shi)度(du)的(de)(de)(de)要(yao)求也各不(bu)(bu)相同，供使(shi)用(yong)(yong)(yong)者(zhe)參考。用(yong)(yong)(yong)戶(hu)根據需要(yao)向傳(chuan)感(gan)器(qi)生產廠(chang)提出(chu)測(ce)(ce)量(liang)范圍(wei)，生產廠(chang)優先(xian)保用(yong)(yong)(yong)戶(hu)在使(shi)用(yong)(yong)(yong)范圍(wei)內(nei)傳(chuan)感(gan)器(qi)的(de)(de)(de)性能(neng)穩定(ding)，求得合理(li)的(de)(de)(de)性能(neng)比，對雙方來講是一件相得益彰的(de)(de)(de)事情。
2、選(xuan)擇測量精度
和測量范圍一(yi)樣，測量精度(du)同是傳感器重要的(de)(de)指標。每(mei)高—個百分(fen)點．對傳感器來說就是上(shang)一(yi)個臺階，是上(shang)一(yi)個檔次。因為(wei)要達到不(bu)同的(de)(de)精度(du)，其制造(zao)成(cheng)本相差(cha)(cha)很(hen)大，售價也相差(cha)(cha)遠。例如1只廉價的(de)(de)濕度(du)傳感器只有(you)幾美元，而1只供標定用的(de)(de)全濕程濕度(du)傳感器要幾百美元，相差(cha)(cha)。所以使(shi)用者要量體裁(cai)衣(yi)，不(bu)宜盲(mang)目追求“高、精、尖”。
生產廠商往往是(shi)(shi)(shi)分段給出其濕(shi)(shi)(shi)度(du)(du)(du)傳感器的(de)(de)精度(du)(du)(du)的(de)(de)。如(ru)(ru)(ru)中、低溫(wen)(wen)(wen)(wen)段(0一80％RH)為(wei)(wei)±2％RH，而高(gao)濕(shi)(shi)(shi)段(80—100％RH)為(wei)(wei)±4％RH。而且(qie)此(ci)精度(du)(du)(du)是(shi)(shi)(shi)在某溫(wen)(wen)(wen)(wen)度(du)(du)(du)下(如(ru)(ru)(ru)25℃)的(de)(de)值。如(ru)(ru)(ru)在不(bu)同溫(wen)(wen)(wen)(wen)度(du)(du)(du)下使用濕(shi)(shi)(shi)度(du)(du)(du)傳感器．其示值還(huan)要考(kao)慮溫(wen)(wen)(wen)(wen)度(du)(du)(du)漂移的(de)(de)影(ying)響。相對濕(shi)(shi)(shi)度(du)(du)(du)是(shi)(shi)(shi)溫(wen)(wen)(wen)(wen)度(du)(du)(du)的(de)(de)函數，溫(wen)(wen)(wen)(wen)度(du)(du)(du)嚴重地影(ying)響著空間內(nei)的(de)(de)相對濕(shi)(shi)(shi)度(du)(du)(du)。溫(wen)(wen)(wen)(wen)度(du)(du)(du)每變化0.1℃。將產生0.5％RH的(de)(de)濕(shi)(shi)(shi)度(du)(du)(du)變化(誤(wu)差)。使用場(chang)合如(ru)(ru)(ru)果難做到(dao)恒(heng)溫(wen)(wen)(wen)(wen)，則(ze)提出過(guo)高(gao)的(de)(de)測濕(shi)(shi)(shi)精度(du)(du)(du)是(shi)(shi)(shi)不(bu)好的(de)(de)。因為(wei)(wei)濕(shi)(shi)(shi)度(du)(du)(du)隨(sui)著溫(wen)(wen)(wen)(wen)度(du)(du)(du)的(de)(de)變化也漂忽(hu)不(bu)定的(de)(de)話，奢談測濕(shi)(shi)(shi)精度(du)(du)(du)將失去實際意義(yi)。所以控濕(shi)(shi)(shi)先(xian)要控好溫(wen)(wen)(wen)(wen)，這就是(shi)(shi)(shi)大量應用的(de)(de)往往是(shi)(shi)(shi)溫(wen)(wen)(wen)(wen)濕(shi)(shi)(shi)度(du)(du)(du)—體化傳感器而不(bu)單純(chun)是(shi)(shi)(shi)濕(shi)(shi)(shi)度(du)(du)(du)傳感器的(de)(de)緣故(gu)。
大多(duo)數情況下，如果(guo)沒有控溫(wen)手段，或(huo)者(zhe)被(bei)測空(kong)間是非密封的，±5％RH的精度(du)(du)(du)(du)就夠了。對于要(yao)求控制恒溫(wen)、恒濕(shi)的局部空(kong)間，或(huo)者(zhe)需要(yao)記錄(lu)濕(shi)度(du)(du)(du)(du)變化的場合，再選(xuan)用±3％RH。以上精度(du)(du)(du)(du)的濕(shi)度(du)(du)(du)(du)傳(chuan)感(gan)器(qi)(qi)。與此相對應(ying)的溫(wen)度(du)(du)(du)(du)傳(chuan)感(gan)器(qi)(qi)．其測溫(wen)精度(du)(du)(du)(du)須足±0.3℃以上，起碼是±0.5℃的。而(er)精度(du)(du)(du)(du)高于±2％RH的要(yao)求恐怕連校準(zhun)(zhun)(zhun)傳(chuan)感(gan)器(qi)(qi)的標準(zhun)(zhun)(zhun)濕(shi)度(du)(du)(du)(du)發生(sheng)器(qi)(qi)也難(nan)做(zuo)到(dao)(dao)，何況傳(chuan)感(gan)器(qi)(qi)自身了。國家標準(zhun)(zhun)(zhun)物質濕(shi)度(du)(du)(du)(du)室的文章認(ren)為：“相對濕(shi)度(du)(du)(du)(du)測量儀表，即使在20—25℃下，要(yao)達到(dao)(dao)2％RH的準(zhun)(zhun)(zhun)確度(du)(du)(du)(du)仍是很(hen)困難(nan)的。”
3、考慮時(shi)漂(piao)和溫漂(piao)
傳(chuan)感器都存在(zai)時(shi)漂和溫(wen)漂。由于濕(shi)度傳(chuan)感器中(zhong)的(de)水汽相接觸，所以不能(neng)密(mi)封。這(zhe)就決(jue)定了(le)它的(de)穩定性和壽命(ming)是(shi)有(you)限的(de)。一(yi)般情況下，生產廠商會標明(ming)1次標定的(de)使用時(shi)間為1年或2年，到期負責重新(xin)標定。請使用者在(zai)選(xuan)擇傳(chuan)感器時(shi)考慮好日后(hou)重新(xin)標定的(de)渠道，不要貪圖便宜或迷信洋貨(huo)而(er)忽略(lve)了(le)售后(hou)服務問(wen)屬。
選擇濕(shi)(shi)(shi)(shi)(shi)度(du)(du)傳(chuan)(chuan)(chuan)(chuan)感(gan)(gan)器(qi)(qi)(qi)要(yao)考(kao)(kao)慮(lv)應用(yong)(yong)場(chang)合的(de)(de)(de)溫(wen)(wen)(wen)度(du)(du)變化范(fan)圍(wei)(wei)，看(kan)所(suo)選傳(chuan)(chuan)(chuan)(chuan)感(gan)(gan)器(qi)(qi)(qi)在(zai)溫(wen)(wen)(wen)度(du)(du)下能否(fou)正常(chang)工作，溫(wen)(wen)(wen)漂(piao)(piao)是否(fou)出設計指標。要(yao)提醒(xing)使(shi)用(yong)(yong)者(zhe)注意的(de)(de)(de)是：電(dian)(dian)(dian)容式(shi)濕(shi)(shi)(shi)(shi)(shi)度(du)(du)傳(chuan)(chuan)(chuan)(chuan)感(gan)(gan)器(qi)(qi)(qi)的(de)(de)(de)溫(wen)(wen)(wen)度(du)(du)系數(shu)(shu)α是個變量，它隨使(shi)用(yong)(yong)溫(wen)(wen)(wen)度(du)(du)、濕(shi)(shi)(shi)(shi)(shi)度(du)(du)范(fan)圍(wei)(wei)而(er)異。這(zhe)是因為(wei)水(shui)和高分子聚合物的(de)(de)(de)介電(dian)(dian)(dian)系數(shu)(shu)隨溫(wen)(wen)(wen)度(du)(du)的(de)(de)(de)改變是不同(tong)步的(de)(de)(de)，而(er)溫(wen)(wen)(wen)度(du)(du)系數(shu)(shu)α又主要(yao)取決于水(shui)和感(gan)(gan)濕(shi)(shi)(shi)(shi)(shi)材料的(de)(de)(de)介電(dian)(dian)(dian)系數(shu)(shu)，所(suo)以電(dian)(dian)(dian)容式(shi)濕(shi)(shi)(shi)(shi)(shi)敏(min)元件(jian)(jian)的(de)(de)(de)溫(wen)(wen)(wen)度(du)(du)系數(shu)(shu)。電(dian)(dian)(dian)容式(shi)濕(shi)(shi)(shi)(shi)(shi)度(du)(du)傳(chuan)(chuan)(chuan)(chuan)感(gan)(gan)器(qi)(qi)(qi)在(zai)常(chang)溫(wen)(wen)(wen)、中濕(shi)(shi)(shi)(shi)(shi)段的(de)(de)(de)溫(wen)(wen)(wen)度(du)(du)系數(shu)(shu)小(xiao)，5-25℃時(shi)，中低濕(shi)(shi)(shi)(shi)(shi)段的(de)(de)(de)溫(wen)(wen)(wen)漂(piao)(piao)可忽略不計。但在(zai)高溫(wen)(wen)(wen)高濕(shi)(shi)(shi)(shi)(shi)區或(huo)負溫(wen)(wen)(wen)高濕(shi)(shi)(shi)(shi)(shi)區使(shi)用(yong)(yong)時(shi)，就要(yao)考(kao)(kao)慮(lv)溫(wen)(wen)(wen)漂(piao)(piao)的(de)(de)(de)影響，進(jin)行的(de)(de)(de)補償或(huo)訂正。隨著時(shi)代的(de)(de)(de)發(fa)展，科研(yan)、農業(ye)(ye)、暖通、紡(fang)織、機房(fang)、電(dian)(dian)(dian)力等工業(ye)(ye)部門，越(yue)來越(yue)需要(yao)采用(yong)(yong)濕(shi)(shi)(shi)(shi)(shi)度(du)(du)傳(chuan)(chuan)(chuan)(chuan)感(gan)(gan)器(qi)(qi)(qi)，對產品質量的(de)(de)(de)要(yao)求越(yue)業(ye)(ye)越(yue)高，對環境(jing)溫(wen)(wen)(wen)、濕(shi)(shi)(shi)(shi)(shi)度(du)(du)的(de)(de)(de)控制以及對工業(ye)(ye)材料水(shui)份值(zhi)的(de)(de)(de)監測(ce)與分析(xi)都已成(cheng)為(wei)比較普遍的(de)(de)(de)技術條件(jian)(jian)之(zhi)一。濕(shi)(shi)(shi)(shi)(shi)度(du)(du)傳(chuan)(chuan)(chuan)(chuan)感(gan)(gan)器(qi)(qi)(qi)產品屬于90年(nian)代興(xing)起(qi)的(de)(de)(de)行業(ye)(ye)。如何(he)使(shi)用(yong)(yong)好濕(shi)(shi)(shi)(shi)(shi)度(du)(du)傳(chuan)(chuan)(chuan)(chuan)感(gan)(gan)器(qi)(qi)(qi)，如何(he)判斷濕(shi)(shi)(shi)(shi)(shi)度(du)(du)傳(chuan)(chuan)(chuan)(chuan)感(gan)(gan)器(qi)(qi)(qi)的(de)(de)(de)性能，這(zhe)對一般(ban)用(yong)(yong)戶(hu)來講，仍(reng)然是一件(jian)(jian)較為(wei)復雜(za)的(de)(de)(de)技術問(wen)題。
