TABLE 1: CHEMICAL REQUIREMENTS
OF FEED WATER AND BOILER WATER FOR LOW AND MEDIUM PRESSURE
BOILERS (Regulation
624 and 626)
|
| Sl..
No. |
CHARACTERISTIC |
REQUIREMENT FOR BOILER PRESSURE
----------------------------------------
|
METHOD OF TEST (Ref. to Cl. No. of)
--------------------------
|
| |
|
Up to 2.0
|
2.1 to 3.9
|
4.0 to 5.9
|
IS : 3550-
|
IS : 3025-_
|
| |
|
MN/m2
|
MN/m2
|
MN/m2
|
1965*
|
1964!
|
|
(1)
|
(2)
|
(3)
|
(4)
|
(5)
|
(6)
|
(7)
|
|
i)
|
Feed Water |
|
|
| |
a)
|
Total hardness
(as CaCO2 ),mg/l, Max |
10
|
1.0
|
0.5
|
--
|
16.1
|
| ----------------------------------------------------------------------------------------------------------------------- |
|
(1)
|
(2)
|
(3)
|
(4)
|
(5)
|
(6)
|
(7)
|
| |
b) |
pH
value |
8.5 to 9.5
|
8.5 to 9.5
|
8.5 to 9.5
|
--
|
8
|
| |
c) |
Dissolved Oxygen,
mg/1, Max |
0.1
|
0.02
|
0.01
|
25
|
--
|
| |
d) |
Silica (as SiO2),
mg/l, Max |
--
|
5
|
0.5
|
16
|
--
|
|
ii)
|
Boiler Water |
|
|
|
|
|
| |
a) |
Total hardness(of
filteredsample) (as CaCO3), mg/l, |
--------- Not detectable -------------
|
--
|
16.1
|
| |
b |
Total alkalinitya
(as CaCO3), mg/l,Max
|
700
|
500
|
300
|
--
|
13
|
| |
c) |
Caustic alkalinity
(as CaCO3), mg/lMax |
350
|
200
|
60
|
--
|
15
|
| |
d) |
pH value |
11.0 to 12.0
|
11.0 to 12.0
|
10.5 to 11.0
|
--
|
8
|
| |
e) |
b
Residual sodi um sulphite (asNa2SO3)
mg/l
|
30 to 50
|
20 to 30
|
--
|
--
|
21
|
| |
f) |
Residual hydrazine
(as N2H4),mg/l |
0.1 to 1
(if added)
|
0 .1 to 0.5
(if added)
|
0.05 to 0.3
|
26
|
--
|
| |
g) |
j
Ratio Na2SO4/Caustic alkalinity
(as NaOH)
or
Ratio NaNO3/ total alkalinity (as NaOH)
|
------------ above 2.5
---------------
|
--
|
20.2
and 15
|
|
------------- above 0.4
----------------
|
--
|
48
and 13
|
| |
h) |
Phosphates (asPO4),
mg/l (if added )
|
20 to 40
|
15 to 30
|
5 to 20
|
14
|
--
|
| |
i) |
Total dissoslved
solids mg/l, Max |
3500s
|
2500
|
1500
|
9
|
12
|
| |
k) |
Silica (as SiO2),
mg/l |
Less than 0.4 of caustic
alkalinity
|
15
|
16
|
30
|
| ------------------------------------------------------------------------------------------------------------------------ |
| Note 1-
Recovery Boilers - The boiler feed water used shall
be completely de-mineralized and also the boiler feed
water and boiler water shall be conditioned in accordance
with high pressure boilers working at 60 kg/cm2 and above
(see IS : 4343-1967**) |
|
Note 2 - When feed water heaters are of copper or copper
alloy constructions, the pH of the feed water shall
be maintained between 8.5 and 9.2 while when feed water
heaters are of iron constructions, the pH of the feed
may be maintained between 8.5 and 9.5.
|
|
Note 3 - Silica in Boiler Water - Lower concentration
of silica may be advisable for steam of turbines, which
generally requires less than 0.02 mg/l silica in steam.
|
| |
* Methods of test for routine control for
water used in industry.
! Methods of sampling and test (physical and chemical)
for water used in industry.
a
Total alkalinity should preferably be about 20 percent
of total dissolved solids.
b
Shall not apply if reducing agents other than sodium
sulphite are used.
j For riveted boilers only.
s
For shell type boilers depending on parameters, the
limits can be relaxed.
** Code of practice for treatment of water for high
pressure boilers (under revision).
|
