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電磁(ci)流量計流體(ti)噪聲的產生原因(yin)有下面幾種情況

 1、不銹鋼電(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)的耐腐蝕是紅外碳(tan)硫儀在其表(biao)(biao)面(mian)具有一個極(ji)(ji)薄的鈍化(hua)(hua)(hua)層(ceng)，使得電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)學(xue)反(fan)應(ying)達到平(ping)衡(heng)(heng)狀態。流(liu)(liu)(liu)體(ti)中的固體(ti)物(wu)撞(zhuang)(zhuang)擊(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)，使得電(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)表(biao)(biao)面(mian)鈍化(hua)(hua)(hua)層(ceng)被破壞，失掉電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)學(xue)平(ping)衡(heng)(heng)。而金屬材料與(yu)流(liu)(liu)(liu)體(ti)介質接觸具有重新恢復生成表(biao)(biao)面(mian)鈍化(hua)(hua)(hua)層(ceng)保持電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)學(xue)平(ping)衡(heng)(heng)的能(neng)力。在達到電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)學(xue)平(ping)衡(heng)(heng)期間，金屬和流(liu)(liu)(liu)體(ti)中的游離離子在信(xin)號電(dian)(dian)(dian)(dian)(dian)(dian)(dian)場(chang)作用下不斷(duan)(duan)進行著電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)學(xue)反(fan)應(ying)。固體(ti)顆粒(li)撞(zhuang)(zhuang)擊(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)，不斷(duan)(duan)破壞保護的鈍化(hua)(hua)(hua)層(ceng)；電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)學(xue)反(fan)應(ying)又反(fan)復生成鈍化(hua)(hua)(hua)層(ceng)，于是形成了(le)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)(ji)間的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)不斷(duan)(duan)大(da)幅(fu)度(du)地變化(hua)(hua)(hua)，這種變化(hua)(hua)(hua)的電(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)造成流(liu)(liu)(liu)量(liang)信(xin)號中的流(liu)(liu)(liu)體(ti)噪(zao)聲。這種情(qing)況也(ye)即(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)磁流(liu)(liu)(liu)量(liang)計中通常(chang)講(jiang)的漿液噪(zao)聲。理論和實踐表(biao)(biao)明(ming)，影響電(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)(hua)學(xue)反(fan)應(ying)信(xin)號電(dian)(dian)(dian)(dian)(dian)(dian)(dian)場(chang)變化(hua)(hua)(hua)的頻率升(sheng)高(gao)，可使流(liu)(liu)(liu)體(ti)噪(zao)聲幅(fu)度(du)迅(xun)速下降，這就是高(gao)頻勵磁和雙頻勵磁可以(yi)解決漿液測量(liang)的原因。

2、流(liu)(liu)(liu)(liu)體摩擦襯(chen)里(li)和電(dian)極(ji)(ji)紅外碳硫儀(yi)，流(liu)(liu)(liu)(liu)體中發生的(de)(de)正(zheng)、負離(li)子(zi)從電(dian)解質(zhi)流(liu)(liu)(liu)(liu)體中分(fen)離(li)。襯(chen)里(li)和電(dian)極(ji)(ji)表(biao)(biao)面越粗糙，游離(li)的(de)(de)離(li)子(zi)濃度就(jiu)(jiu)越高。受電(dian)極(ji)(ji)信號電(dian)場(chang)的(de)(de)作用，一部(bu)分(fen)離(li)子(zi)會向(xiang)電(dian)極(ji)(ji)移動(dong)，形成噪聲(sheng)電(dian)壓，這種(zhong)噪聲(sheng)被稱為(wei)流(liu)(liu)(liu)(liu)動(dong)噪聲(sheng)。流(liu)(liu)(liu)(liu)動(dong)噪聲(sheng)在低(di)電(dian)導率(lv)測量時表(biao)(biao)現比較(jiao)突出(chu)。流(liu)(liu)(liu)(liu)動(dong)噪聲(sheng)與外電(dian)場(chang)強度有關，高流(liu)(liu)(liu)(liu)速時感應信號越大，噪聲(sheng)幅(fu)度也越大，輸出(chu)就(jiu)(jiu)會很不穩(wen)定(ding)。  

3、流體(ti)電導(dao)率(lv)和(he)pH 值(zhi)的(de)急劇變化也會形成流動噪聲，流量計(ji)上游加藥表(biao)現的(de)測量不(bu)穩定就是典型例子(zi)。原(yuan)因是不(bu)同介質在不(bu)均勻混合(he)時，流體中容易分離(li)出正、負離(li)子(zi)，受電(dian)極信號電(dian)場的(de)作用，一部(bu)分離(li)子(zi)會(hui)向電(dian)極移動，形成了流動噪聲電(dian)壓，造(zao)成輸(shu)出的(de)不(bu)穩定。  

4、由于高流速流動流體靠近襯里和電極部位的層流邊界層厚度變得很薄，襯里和電極的粗糙度高度突破了流速層流邊界層的厚度，流體撞擊這部分粗糙度高度，發生流速發散和突變。有一部分與測量管中心軸方向相同（或相反）的流速分量，受信號權重函數的作用，對電極信號產生了很大影響，形成了大的正誤差，這也就是流速噪聲污水流量計。