2-10. BACKWASH OF MULTIMEDIA FILTER - cont.
The multimedia filter should be backwashed:
After 20 hours of ROWPU operation, or
Multimedia filter gage reading is over 10 psid, or
Multimedia filter gage reading exceeds 5 psid above log reading at startup, or
ROWPU is to be shut down for more than 24 hours.
Perform normal shutdown of ROWPU (para. 2-14).
Make sure R.O. ELEMENT CLEANING switch (4, figure 2-66) on side of control panel is down
Check brine water level in backwash tank (figure 2-62). Tank should be full.
Ensure strainer on backwash pump is not clogged (para. 3-6).
Open gate valve between backwash tank and backwash pump (figure 2-62).
To aid priming, loosen vent plug on top of backwash pump (figure 2-28). Tighten plug when a
steady stream of water flows from vent plug.
Turn BACKWASH VALVE (1, figure 2-66) handle downward to BACKWASH.
Do not hold START BACKWASH switch up for more than 5 seconds to avoid damage
to the controls.
Solid-state timer will come on immediately. BACKWASH PUMP ON lamp will come
on, pump will start and backwash water will flow through the multimedia filter and out
the WASTE water hose. The MULTIMEDIA FILTER gage needle will move to full
right. During backwash, the BACKWASH WATER FLOW rate varies automatically
from 0 to 70 to 120 gpm while washing and rinsing. Backwash operation is automatic
and lasts about 13 minutes.
Push BACKWASH switch (2) up to START position and release immediately.
When backwash is complete, BACKWASH PUMP ON (3) lamp will go off and MULTIMEDIA
FILTER gauge (6) and BACKWASH WATER FLOW gauge (5) will return to 0. When
backwash pump shuts off, turn BACKWASH VALVE (1) handle upward to NORMAL position.
Close gate valve between backwash tank and backwash pump (figure 2-62).