GB/T 29340-2012Analysis of water used in boil and cooling system - Determination of chloride - Ammonium thiocyanate titration method (English PDF)

1 Scope

This standard specifies the boiler water and cooling water - Determination of chloride, ammonium thiocyanate titration.

This standard applies to natural water, boiler water and chloride content of the circulating cooling water to 5mg/L ~ 100mg/L determination chloride

Content greater than 100mg/L water samples should be measured after dilution.

2 Normative references

The following documents for the application of this document is essential. For dated references, only the dated version suitable for use herein

Member. For undated references, the latest edition (including any amendments) applies to this document.

GB/T 603 chemical reagent test method Preparations of articles (GB/T 603-2002, ISO 6353-1 with. 1982,

NEQ)

GB/T 6682 analytical laboratory use specifications and test methods (GB/T 6682-2008, ISO 3696. 1987, MOD)

3 General

The reagents used in this standard, unless otherwise specified, shall use analytical reagent and in line with GB/T 6682 stipulated two of water.

In the absence of special note, according to the provisions of GB/T 603 test preparation needed preparations and products.

4 Method summary

Measured water acidified with nitric acid, and then adding an excess of standard solution of silver nitrate, and Ag generation so Cl- all silver chloride (AgCl) Shen

Lakes, excess Ag with ammonium thiocyanate (NH4SCN) back titration standard solution, choose ferric ammonium alum [NH4Fe (SO4) 2] as an indicator when it reaches

Titration end point, SCN- and Fe3 form a red complex, the solution was discolored, is the titration end point.

Cl- Ag -> AgCl -> (white)

SCN- Ag -> AgSCN -> (white)

SCN- Fe3 -> FeSCN2 (red complex)

In an excess of silver nitrate (AgNO3) standard solution volume, deduct an amount equal amounts consumed SCN-, you can calculate the water C1- content.

5 Reagents and materials