Sample Analysis; Check Levels Of Tanks; Unit Warm-Up And Cleaning - J.P. SELECTA PRO-NITRO A Instruction Manual

MANUAL DE INSTRUCCIONES
Check the reagents tanks levels befo-
re starting a batch analysis.
J
.P. SELECTA s.a.u.
CODIGO 80189 REV E

6 Sample analysis

To get good analysis' results and a good performance of the distiller it is suggested
to follow a working routine.
Before starting to analyse valuable samples do some training sessions running the
operations related on the chapter 8, until the operator will be familiar with the unit.

6.1 Check levels of tanks

Before starting a batch analysis, check the following levels:
Steam generator water tank level
Check water
Refill it with demineralised water.
level
Assure its conductivity adding about 50mg of sodium carbonate or NaCl.
The water reservoir is 6 litres capacity, enough for analysing more than 20 sam-
ples.
Level of NaOH tank
Refill with NaOH 40% from the 2 litres flask, placed inside the unit.
Get the NaOH flask from the door placed on the left hand side cover.
The NaOH solution must be free of ammonia salts, to avoid its interference on the
result.
Level of Ammonia fixative solution tank
Refill with Fixative solution (Boric acid 1% + mixed indicator 4.8) 2 litres flask. It is
placed inside the unit.
Note: See chapter 7.2 for ammonia fixative solution preparation.
Level of Titration reagent
Refill the 2 litres flask placed inside the unit with titration reagent, usually HCl or
H SO with a concentration of 0.25 N. (or 0.1N)
2 4
Note: See chapter 7 about reagents.
Note: The precision of the results are affected directly by the precision of the acid
normality used for titration. This is a common cause of error, because bottles
opened for a long time tend to increase its normality.
Priming the dispensers
The tubing for NaOH, fixative solution and titration reagent must be properly
primed, air free, to provide a good and exact dispensing.
Carry on the refill operations to avoid air entry on the tubing. See 5.1.2 and 8.1 to
know how to carry on the prime operations.

6.2 Unit warm-up and cleaning.

In order to get the best results with your Kjeldahl distiller, you have to run a warm-
up step before starting samples analysis.
To do so, just insert a sample tube with 25ml of clean water.
From the «TEST» select «DEST.» and push «ENTER» distillate for 5 minutes and
push «ESC» to stop the distillation.
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12/2020 Pag.: 47
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