Purified Water System; Flush System - Dometic RO400 Service Manual

puRified wateR system

After the purified water leave the membrane pressure vessel, it pass through the
pressure regulating valve (e30). This is a safety feature, to avoid high pressure to
the distribution net in case of failure, and to protect the the product from water ham-
mer when a valve or faucet is closed on the pure water hose.
Before the purified water outlet (a7) the pure water passes a conductivity sensor
(e25), described under "
WATER qUAlITY MONITORINg",
(integrated in the purified water outlet) and pressure accumulator valve (e27). The
check valve prevents back flow to the product. The pressure accumulator valve
buffers a small quantity of water to compensate for small internal or external leak-
ages and has also a reducing effect of water hammer.
Attached to the pressure accumulator valve is the outlet pressure sensor (e26). The
outlet pressure sensor measures the pressure in the purified water outlet, and gives a
signal to the electronics to start and stop the product.
The pressure drops if a valve or faucet opens or if a connected tank needs filling;
and the pressure increase when a valve or faucet closes or if a connected tank is
filled up.
low pressure starts the product, described under "
high pressure stops the product, but before closing the inlet valve and the motor, is
a flushing performed, described under "
See Table 1 for values.

flusH system

The purpose of flushing is to fill up the system, exchange old water inside the prod-
uct or flush out an increased concentration of contaminants after a production cycle.
With the motor running and inlet valve open, is the flush valve energized to open
completely. Reject flow goes from approx 2 / 2.5 litres/minute to more than 6 l/
minute.
The flushing takes place in four different situations:
a) When the product is connected to electrical supply, does the product flush 30
seconds. This is done to fill up the system when a product is new or to manu-
ally efficiently replace the water inside the unit.
This flush cannot be interrupted by production of purified water.
b) The product flush approx. every 12 hours (starting when the product is con-
nected to electrical supply), for 30 seconds, in order to replace the water
inside. This is done to avoid biological growth. Therefore is it important that
the product is connected to electrical and water supplies.
This flush is interrupted if purified water is required.
c) After every production cycle does the product flush the system, to flush out
an increased concentration of contaminants. The flushing time is relative to
the time the product was in operation. As indication should flush be about 20
seconds after 2 minutes operation. Maximum flush time is 90 seconds.
This flush is interrupted if purified water is required.
d) Only applicable to commercial (c-) models:
When operation cycles are long, does the product make an automatic flush
for two minutes every 15 minutes operation, i.e. 15 - 2 - 15 - 2 ... The reason
is the same as for point c) above.
This flush cannot be interrupted by production of purified water.
pROduCt desCRiptiOn
a check valve (e28)
INlET WATER SYSTEM".
flUSh SYSTEM".
- 13 -
mOdel
pRessuRe
(bar)
Start level 0.5
Stop level 4.5
Table 1.
0.5 3
2 4.5