R410A DC Inverter VRF V4 Plus W Series 50Hz
MCAC-VTSM-2016-04
182 Installation
3.6.2 Double-pipe heat exchanger cleaning
Cleaning system schematic diagram of double-pipe heat exchanger
3.6.2.1 Preparation of cleaning liquor:
1) The material of water side double-pipe is red copper, and for general corrosion situation it is suggested that
use the pickle liquor with 5% oxalic acid, 1.2% buffer and 0.8%surfactant, and the temperature should be
controlled in 60°C, that will has prefect cleaning effect.
2) If use hydrochloric acid as the cleaning liquor, for avoiding to the corrosion and shorten the working life of
the heat exchanger, it should limit the concentration of the hydrochloric acid to be 3%
～
5%, and add corrosion
inhibitor with 0.2%
～
0.3% concentration. When it is cleaning, pay attention to the PH value change, when the
PH=8, then stop cleaning immediately. Then change to fresh water for cleaning.
3.6.2.2 Cleaning method:
1) Before connecting to the cleaning system, it must stop the unit operation, close the circulating water pump of
water system, and close the gate valves in inlet and outlet water return pipes.
2) Correctly connect the cleaning system as the above figure 3-7, make the cleaning liquor counter flush the
double-pipe heat exchanger (opposite the general flow direction).
3) Acid cleaning: After make sure it will not leak water, and then open the water pump to make the double-pipe
heat exchanger fill with acid liquor, and close the water pump, and then let the double-pipe heat exchanger
static state for 2h. And open the water pump continuously dynamic loop for 3
～
4h. During that every 0.5h, it is
done both side alternative cleaning. During the acid cleaning, it should timely do sampling test for acid
concentration, if the continuous twice testing concentration difference is lower than 0.2%, which means the
acid cleaning finish reaction. Put the waste liquor to the waste liquor tank.
4) Neutralization: After acid cleaning, use NaOH, Na3PO4 and soften liquid mixed accord to some proportion,
and use dynamic loop to alkali cleaning for the heat exchanger, in order to alkalis counteract acids. Drain the
waste liquor to the waste liquor tank.
5) Water cleaning: After alkali cleaning, use clean soften liquor repeatedly wash the heat exchanger for 0.5h,
thoroughly wash the heat exchanger. Then drain the waste liquor to the waste liquor tank.
6) Passivating treatment : Expose the double-pipe heat exchanger in the air for 3
～
4h, or blow for 2h with high
pressure air. Make the pipe surface form a oxidation passivating layer.
7) After cleaning, close the isolating valve, and take down the cleaning system devices and keeping properly
for backup.
8) Please contact the waste liquor treating company to treat the collected waste liquor.
9) Connect the unit water system as the state before cleaning, thoroughly check the unit and assist devices
whether work normally. Make sure there is no abnormal situation then re-operates the unit.
WARNING:
•
The cleaning liquor flow direction must be correctly connected.
•
Because different water quality and different using situations of the heat exchanger, the cleaning period and
