在測量污(wu)水、漿液等介(jie)質時，管道內壁和(he)(he)電(dian)(dian)極(ji)(ji)表面(mian)容易發生結垢和(he)(he)產生附著物(wu)。當結垢物(wu)質的電(dian)(dian)導率和(he)(he)被測介(jie)質的電(dian)(dian)導率不同(tong)時，就會帶來測量誤差。污(wu)泥、油(you)污(wu)對電(dian)(dian)極(ji)(ji)的附著，也會使儀表輸出發生擺動(dong)和(he)(he)漂移。因此，在一些情況下(xia)需要(yao)對電(dian)(dian)極(ji)(ji)進行維(wei)護處(chu)理(li)。譬(pi)如(ru)說，清洗電(dian)(dian)極(ji)(ji)和(he)(he)更換電(dian)(dian)極(ji)(ji)。 

  電極清洗常用的方法有以下(xia)幾(ji)種： 

  (l)電化學方法(fa) 

  金屬(shu)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)在(zai)(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)解(jie)質(zhi)流(liu)(liu)體(ti)中(zhong)存在(zai)(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)學(xue)現(xian)(xian)象。根據電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)學(xue)原(yuan)理，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)與流(liu)(liu)體(ti)存在(zai)(zai)(zai)界(jie)面電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)場，電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)與流(liu)(liu)體(ti)的(de)(de)(de)(de)界(jie)面電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)場是(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)流(liu)(liu)體(ti)相(xiang)間(jian)存在(zai)(zai)(zai)的(de)(de)(de)(de)雙(shuang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)層所引起的(de)(de)(de)(de)。對于電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)與流(liu)(liu)體(ti)界(jie)面電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)場的(de)(de)(de)(de)研究(jiu)發(fa)現(xian)(xian)物質(zhi)的(de)(de)(de)(de)分子(zi)(zi)(zi)、原(yuan)子(zi)(zi)(zi)或離(li)(li)子(zi)(zi)(zi)在(zai)(zai)(zai)界(jie)面具有(you)富集(ji)或貧(pin)乏的(de)(de)(de)(de)吸(xi)(xi)附現(xian)(xian)象，而(er)且(qie)發(fa)現(xian)(xian)大(da)多(duo)數無(wu)機(ji)陰(yin)(yin)離(li)(li)子(zi)(zi)(zi)是(shi)表(biao)(biao)面活性物質(zhi)，具有(you)典型的(de)(de)(de)(de)離(li)(li)子(zi)(zi)(zi)吸(xi)(xi)附規律，而(er)無(wu)機(ji)陽離(li)(li)子(zi)(zi)(zi)的(de)(de)(de)(de)表(biao)(biao)面活性很小，因此電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)學(xue)清(qing)洗(xi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)僅考(kao)慮陰(yin)(yin)離(li)(li)子(zi)(zi)(zi)吸(xi)(xi)附的(de)(de)(de)(de)情況。陰(yin)(yin)離(li)(li)子(zi)(zi)(zi)的(de)(de)(de)(de)吸(xi)(xi)附與電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)有(you)密切關(guan)系，吸(xi)(xi)附主要發(fa)生在(zai)(zai)(zai)比零(ling)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)荷(he)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)更正(zheng)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)范(fan)圍，即帶異(yi)號(hao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)荷(he)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)報表(biao)(biao)面。在(zai)(zai)(zai)同號(hao)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)荷(he)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)表(biao)(biao)面上(shang)，當剩(sheng)余電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)荷(he)密度稍大(da)時，靜電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)斥力(li)大(da)于吸(xi)(xi)附作(zuo)用力(li)，陰(yin)(yin)離(li)(li)子(zi)(zi)(zi)很快就脫附了，這(zhe)就是(shi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)化(hua)(hua)學(xue)清(qing)洗(xi)的(de)(de)(de)(de)原(yuan)理。有(you)些公司(si)通過把兩(liang)個(ge)正(zheng)向二(er)極(ji)管的(de)(de)(de)(de)壓(ya)(ya)降(jiang)加(jia)(jia)在(zai)(zai)(zai)信號(hao)回路(lu)上(shang)，然后以(yi)(yi)共(gong)模的(de)(de)(de)(de)形(xing)式(shi)將負的(de)(de)(de)(de)約1.2.1.4V的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)加(jia)(jia)到(dao)(dao)兩(liang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)。因為在(zai)(zai)(zai)兩(liang)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)上(shang)所加(jia)(jia)的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)是(shi)負的(de)(de)(de)(de)直流(liu)(liu)共(gong)模電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，不會造(zao)成放大(da)器(qi)飽和。直流(liu)(liu)共(gong)模電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)疊(die)加(jia)(jia)在(zai)(zai)(zai)微小的(de)(de)(de)(de)交(jiao)變流(liu)(liu)量(liang)信號(hao)上(shang)，由電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容將直流(liu)(liu)隔離(li)(li)，并由前(qian)置放大(da)器(qi)將共(gong)模電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)抑制，直流(liu)(liu)共(gong)模電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)不會影響(xiang)到(dao)(dao)流(liu)(liu)量(liang)的(de)(de)(de)(de)測量(liang)。加(jia)(jia)在(zai)(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)上(shang)的(de)(de)(de)(de)直流(liu)(liu)負電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)，形(xing)成負的(de)(de)(de)(de)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)場能推斥附著在(zai)(zai)(zai)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)上(shang)的(de)(de)(de)(de)物質(zhi)，達到(dao)(dao)清(qing)洗(xi)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)的(de)(de)(de)(de)日的(de)(de)(de)(de)。這(zhe)種方法(fa)在(zai)(zai)(zai)交(jiao)流(liu)(liu)勵磁中(zhong)能有(you)效地(di)、自動(dong)地(di)、連續地(di)進行電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)極(ji)消(xiao)洗(xi)。但(dan)對于低頻矩形(xing)波勵磁，由于極(ji)化(hua)(hua)電(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)壓(ya)(ya)幅度較高，作(zuo)用不一定(ding)很好，所以(yi)(yi)近來很少見到(dao)(dao)。 

  (2)機(ji)械清(qing)除法 

  機械清(qing)除(chu)法(fa)是通(tong)過在電極上安裝特殊的機械結構來實現電極清(qing)除(chu)。目前有兩種(zhong)形式(shi)： 

  一(yi)種(zhong)是采用(yong)機械(xie)刮(gua)(gua)(gua)(gua)除(chu)(chu)(chu)器。用(yong)不銹(xiu)鋼(gang)制一(yi)把帶有細軸(zhou)的刮(gua)(gua)(gua)(gua)刀，通過空心電(dian)(dian)極把刮(gua)(gua)(gua)(gua)刀引出，細軸(zhou)和(he)空心電(dian)(dian)極之間采用(yong)機械(xie)密封以防(fang)止介質外，于是紺成了機械(xie)刮(gua)(gua)(gua)(gua)除(chu)(chu)(chu)器。當從外面轉(zhuan)動細軸(zhou)時，刮(gua)(gua)(gua)(gua)刀緊貼電(dian)(dian)平面轉(zhuan)動，刮(gua)(gua)(gua)(gua)除(chu)(chu)(chu)污(wu)垢。這種(zhong)刮(gua)(gua)(gua)(gua)除(chu)(chu)(chu)器可以手(shou)動，也可以用(yong)馬達驅動細軸(zhou)自動刮(gua)(gua)(gua)(gua)除(chu)(chu)(chu)。另一(yi)種(zhong)是在管狀電(dian)(dian)極中，裝上清除(chu)(chu)(chu)污(wu)垢用(yong)的鋼(gang)絲(si)刷，軸(zhou)裹在密封的“O"形(xing)圈里，以防(fang)止流體泄漏。這種(zhong)清洗(xi)裝置需要有人經常拉動鋼(gang)絲(si)屆來清洗(xi)電(dian)(dian)極。