BS EN 15482:2012 pdf download – Chemicals used for treatment of water intended for human consumption — Sodium permanganate
5 Test methods
Observe the general recommendations of ISO 3165 and take account those of ISO 6206.
5.1.2 Sampling from drums and bottles
22.214.171.124.1 Mix the contents of each container to be sampled by shaking the container, by rolling it or by rocking it from side to side, taking care not to damage the container or spill any of the liquid.
126.96.36.199.2 If the design of the container is such (for example, a narrow-necked bottle) that it is impracticable to use a sampling implement, take a sample by pouring after the contents have been thoroughly mixed. Otherwise, proceed as described in 188.8.131.52.3.
184.108.40.206.3 Examine the surface of the liquid. If there are signs of surface contamination, take samples from the surface as described in 220.127.116.11. Otherwise, take samples as described in 18.104.22.168.
22.214.171.124 Surface sampling Take a sample using a suitable ladle. Lower the ladle into the liquid until the rim is just below the surface, so that the surface layer runs into it. Withdraw the ladle just before it fills completely and allow any liquid adhering to the ladle to drain off. If necessary, repeat this operation so that, when the other selected containers have been sampled in a similar manner, the total volume of sample required for subsequent analysis is obtained.
126.96.36.199 Bottom sampling Take a sample using an open sampling tube, or a bottom-valve sampling tube, suited to the size of container and the viscosity of the liquid. When using an open sampling tube, close it at the top and then lower the bottom end to the bottom of the container. Open the tube and move it rapidly so that the bottom of the tube traverses the bottom of the container before the tube is filled. Close the tube, withdraw it from the container and allow any liquid adhering to the outside of the tube to drain off. When using a bottom-valve sampling tube, close the valve before lowering the tube into the container and then proceed in a similar manner to that when using an open sampling tube.
5.1.3 Sampling from tanks and tankers From each access point, take samples as follows:
a) from the surface of the liquid, using a ladle as described in 188.8.131.52;
b) from the bottom of the tank or tanker, using a sampling tube as described in 184.108.40.206 or using a specially designed bottom-sampling apparatus;
c) from one or more positions, depending on the overall depth, between the bottom and the surface using a weighted sampling can.
5.2.1 Determination of sodium permanganate
Reduction of sodium permanganate Mn(VII) to Mn(II) with sodium oxalate under acidic conditions. The excess of sodium oxalate is titrated with a standard volumetric solution of potassium permanganate.
All reagents shall be of a recognised analytical grade and the water used shall conform to grade 3 in
accordance with EN ISO 3696.
220.127.116.11.1 Potassium permanganate.
18.104.22.168.2 Sodium oxalate.
22.214.171.124.3 Sulfuric acid solution, mass fraction 20 %.
126.96.36.199.4 Potassium permanganate standard volumetric solution c(KMnO 4 ) = 1,000 g/l.
Weigh 1,000 g of the potassium permanganate (188.8.131.52.1), transfer to a 1 l volumetric flask and make up to the volume with water. Allow to stand with occasional mixing for 15 min.
Weigh 2,120 g of the sodium oxalate (184.108.40.206.2) and transfer to a 1 l volumetric flask. Add 20 ml of H 2 SO 4 (220.127.116.11.3) to the 1 l volumetric flask containing the oxalate, dissolve and allow to stand for 5 min.
Transfer 40 ml of the sodium oxalate solution by pipette into a small conical flask, heat to 70 °C to 80 °C and titrate with the prepared potassium permanganate solution to a faint pink end-point that persists for 20 s to 30 s.