41
of the filtrate piping, close the feed water valve (V-1).
-
Take appropriate measures to prevent the
mis-operation or accidents that could cause the
chemicals to get into the product water. Check the
piping and correctly position of each valve before
starting the chemical cleaning.
(19) The standard conditions for chemical cleaning are shown in Table 5.
- The concentration, the chemical quantity and the hold time shown in Table 5
should be observed. Otherwise the element may get damaged and/or the life of
membranes may be shortened.
- The cleaning temperature should be 20 to 40 degree C.
Table 5. Standard conditions for chemical cleaning
Pollutants Chemicals
Maximum
Concentration
Hold
Time
Inorganic
Substances
Citric acid
*1
3.0 wt%
1 - 3 hr
Organic
Substances
Sodium hypochlorite
3,000 mg/L
as chlorine
(10 < pH < 12)
1 - 3 hr
*1: Besides citric acid, hydrochloric acid (with the maximum concentration of 1.0 mol/L),
oxalic acid (with the maximum concentration of 1.0 wt%), sulfuric acid (with the
maximum concentration of 0.05 mol/L) and nitric acid (with the maximum
concentration of 0.1 mol/L) are acceptable.
- In the case of cleaning with acid and with sodium
hypochlorite alternately, rinse the cleaning line and
the element with rinse water thoroughly after each
cleaning.
- Do not use any other chemicals than those indicated
above.
- Do not mix sodium hypochlorite with acid. Such
mixture generates toxic chlorine gas.
!
CAUTION
!
CAUTION
!
DANGER
!
DANGER
!
CAUTION
!
CAUTION
Summary of Contents for HSU-1515
Page 20: ...18 2 Configuration Rack Model R16 ...
Page 21: ...19 Rack Model R08 ...
