Horrock Ortho Toludine Water Sampling 4k276e

Water Practicals

HORROCKS APPARATUS

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Designed to find out the dose of bleaching powder required for disinfection of water.

CONTENTS        

6 white cups( 200ml capacity) 1 black cup with circular mark inside 2 metal spoons(2g capacity) 7 glass stirring rods 1 special pipette 2 droppers Starch– iodide indicator solution Instruction folder

PROCEDURE 

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Take 2g of bleaching powder in the black cup, make it into a thin paste with little water. Add more water to paste & make up volume up to circular mark with stirring. Fill 6 white cups with water to be tested up to 1 cm below the brim.

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With the special pippette provided add one drop of stock soln to 1st cup, 2 drops to the 2nd cup and so on.. Stir the water in each cup with separate rod. wait for half hour for the action of chlorine. Add 3 drops of starch– iodide indicator to each. Development of blue color indicates presence of free residual chlorine.

Calculations  

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Suppose 3rd cup develops blue color. Then 3 x 2 g of bleaching powder is needed to disinfect 455 l of water. Therefore the quantity needed (x) to disinfect (y) l of water will be = 6 y / 455

Orthotoludine test  

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0.1ml OT reagent to 1 ml of water. Yellow colour develops proportionate to cl concentration. Measured by chloroscope.

SAMPLING FOR PHYSICAL & CHEMICAL ASSESMENT sample collected in clean glass stoppered bottles made of neutral glass of capacity not less than 2ltrs. FOR BACTERIOLOGICAL EXAMINATION sample collected in clean sterilized bottles made of neutral glass, capacity of 250ml, with a ground glass stopper having a overlapping rim.

SAMPLE FROM TAP WATER 

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Tap opened fully, let water run to waste for 2 min. Bottle held near the base with one hand & the stopper & paper cover over it removed together & held in fingers. Bottle should be filled from a gentle stream of water from tap, avoiding splashing.

Sampling from rivers, wells etc 

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Tie additional string to the bottle string. Dip bottle with string not with hands. Face mouth of bottle towards stream Generate current in still water. Location for the sampling

Transport & storage of Samples 

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the bacteriological examination of the sample should be commenced asap after collection. Water should be kept in ice until it is taken for analysis within 48hrs of collection. Samples not preserved in this manner should be rejected.

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