30
Operation and maintenance, Discfilter HPF2200-series PFLC
7.4.2 Chemical cleaning of filter panels
Long-term clogging of the filter media can be caused by, among other things, iron, calcium or
organic fouling. This clogging can normally be removed through chemical cleaning. Three proven
products that do not affect the life of the filter media are dilute hydrochloric acid (HCl), dilute
sodium hypochlorite (NaClO) and dilute sodium hydroxide (NaOH).
The use of other types of cleaning agents can cause damage to equipment.
The cleaning products must not be mixed. If, for example, HCl and NaClO are mixed this
produces toxic chlorine gas. HCl and NaOH are highly corrosive. For safety advice, see app-
licable local regulations.
For more detailed instructions, please contact your supplier.
Hydrotech Discfilters in the HPF2200 series as standard are prepared with a chemical ramp to
make removal of long-term clogging of the filter media possible.
The Hydrotech chemical trolley HCT (option) is connected to the chemical ramp connection (see
Figure 3.2 and Figure 3.6). The control system is prepared and programmed for connection of
a dosage system. After completing electrical and mechanical connection, chemical cleaning is
started as follows:
1. Turn the mode selector to “HAND”.
2. Select “Login” (if the user is not already logged in) and log in using your user name and
password.
3. Select “Chemical” on the operator panel, see Figure 7.11.
4. Set the number of full cleaning cycles to be completed, see Figure 7.12.
5. Select “Start” to start the chemical cleaning programme, see Figure 7.12. (Settings are found
under “Settings”, see Automatic System Manual.)
6. Once chemical cleaning has been completed, re-start operation as described in section 5.1.
Figure 7.11 Main menu in HAND operating mode.
Figure 7.12 “Chemical cleaning” window.
