Water Environment Federation (WEF) Discussion ForumsWater Environment Federation (WEF) Discussion Forumshttp://www.wef.org/TechnicalDiscussions/jfuller@wef.orgFri, 21 Nov 2008 16:20:29 GMT20http://www.wef.org/TechnicalDiscussions/Topic8926-9-1.aspxHach has an ultra low method that is EPA approved and is easy to use, Hach method 10014.</P><P>We figured there would be less error between operators with this method. </P><P>MarkThu, 17 Apr 2008 17:04:49 GMTDvanthttp://www.wef.org/TechnicalDiscussions/Topic8926-9-1.aspxAmperometric titration (foreward or backward). Hach has an auto-cad 9000 that's nice but expensive (5K). Gives good repeatable results.Thu, 17 Apr 2008 16:01:53 GMTrwhitworth52http://www.wef.org/TechnicalDiscussions/Topic8926-9-1.aspxWe chlorinate (Cl2 gas) and dechlorinate (SO2) seasonally for fecal control and we have a discharge permit limit of no more than 0.05 mg/L chlorine. Currently we measure the chlorine with an ORION residual chlorine ISE probe (replaced yearly) that always gives us calibration fits. The calibration is per CFR40 part136 with 0.2, 1.0, and 5.0 mg/L chlorine standards. The calibration takes forever, slope is nearly always 30 or above. The permit limit is way outside the calibration standards. Is there a better way to measure a next-to-nothing chlorine residual in dechlorinated effluent?<P>Thanks,</P><P>GreggThu, 17 Apr 2008 15:44:38 GMT01630545