Boiler water tests

Corrosion and tube failure caused by water chemistry

Recommended ranges( Co-ordinated phosphate treatment for w/t boiler )

pH	- 9.6 to 10.3
PO₄	- 4 to 20 ppm
N₂H₄	- 0.01 to 0.03 ppm
TDS	- < 150 ppm
Cond pH	- 8.6 to 9.0
Cl	- 20 ppm
O₂	- 10 ppb
Si	- 10 ppb

Measure 100ml of sample water into a casserole
Add 10 drops phenol pthalein (RE 106)
Neutralize with sulphuric acid
Add 10 drops of Potassium Chromate
Titrate Silver Nitrate untill sample just turns brick red
ppm as CaCO₃= (ml x 10) ppm

Measure 100ml of sample water into a casserole
Add 10 drops of phenolpthalein
Neutralise with TDS reagent (acetic acid)
Temperature compensate then read off scale in ppm.

Fill one 10 ml tube with distilled water
Fill one 10 ml tube with boiler water tests.
Add 0.5 ml sulphuric acid (RE 131) to each
Add 0.5 ml Ammonium Molybdnate (RE130) to each
Add 0.5 ml Aminonapthol Sulfonic acid (RE 132) to each
Stir well between each addition
Wait 3 minutes for calorimetric compaison
Alternately Vanado-molybdnate test
Place 5 ml boiler water in 10 ml tube
Place 5 ml distilled water in other 10 ml tube
Top both to 10 ml with Vanado-molybdnate reagent
Place in colour comparator and compare after 5 mins

Add 9ml distilled water to one tube
Add 9 ml boiler test water to anouther
Add 1 ml hydrazine reagent to each
Use colour comparator

Alkalinity Phenolpthalein

100 ml filtered water
Add 1 ml phenolpthalein
If pH >8.4 Solution turns pink
Add H₂SO₄ untill pink disapears
Ml 0.02N H₂SO₄ x 10 = ALk in CaCO₃ ppm
Measures hydroxides and carbonates in sample, bi-carbonates do not show up so sample should not be allowed to be exposed to the air for too long

Alkalinity Methyl orange

Take phenolpthalein sample, add 1 ml methyl orange
If yellow, bi carbonates are present
Add H2SO4 untill red
Total 0.02N H₂SO₄ x 10 = Total Alk in CaCO₃

100 ml unfiltered sealed water poured into two 50 ml glass stoppered test tubes
Add 0.2 ml pH indicator to one ( pH indicator vary's according to required measuring range)
Use colour comparator
Due to difficulty of excluding air, electronic pH meter preferred

Sulphite reserve

Exclude air at all stages
100 ml unfiltered water
Add 4 ml H₂SO₄ + 1 ml starch
Add potassium iodate-iodide untill blue colour
ml Iodate-Iodide sol x 806 / ml of sample = SO₃ reserve in ppm

Ammonia in feed

Only necessary where N₂H₄ used in blr
Pour condensate sample into two 50 ml colour comparator tubes
Add 2 ml Nessler reagent to one
Wait 10 mins
Use colour comparator