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Maintenance of brazed plate heat exchanger
The efficiency of the heat exchanger will decrease as the scaling accumulates. furthermore,
freezing and bursting caused by the decrease in flow may lead to damages to the product.
For these reasons, it is necessary to perform maintenance on a regular basis to prevent scale
generation.
● Check the following items prior to the heating season. (interval: once a year)
- Perform a water quality inspection to verify compliance with the standard requirements.
- Performing cleaning of the strainer.
- Check whether the water flow is appropriate.
- Check whether the operating environment is appropriate.
(pressure, water flow, leaving water temperature, etc.)
● To clean the brazed plate heat exchanger, it is necessary to comply with the following
procedures.
- Check whether a service port is mounted in the water pipe to clean using chemical solvent.
Installing a pressure sensor in the inlet and outlet pipes facilitates the identification of the degree of
cleaning by checking pressure changes.
The descaling operation includes 2 stages, a cleaning operation and a neutralization operation.
Diluted phosphoric acid or oxalic acid with a concentration of 5% is an appropriate chemical agent for
descaling.
(Do not use hydrochloric acid, sulfuric acid or nitric acid, as they are caustic.)
- Check whether the ball valve of the inlet and outlet pipes and the drain pipe valve are closed properly
when performing cleaning.
- Connect a pipe to service valve for cleaning and fill cleaning agent with a temperature of 50 to 60℃
into the brazed plate heat exchanger and circulate it for 4 to 8 hours using a pump.
Water flow more than 1.5 times of the normal flow is appropriate; reverse the direction of water flow
every 30 minutes.
Before reversing the circulation direction, flush the water through the drain valve for about 5 minutes
until no impurities are discharged.
The circulation time may vary depending on the temperature of the cleaning agent or the degree of
scaling.
For this reason, it is necessary to observe carefully the changes in color to determine the circulation
duration for descaling.
When the pressure difference between the inlet and outlet of BPHE is equal to the design value or PH
between inlet and outlet of BPHE is equal, it indicates that the cleaning has been completed.
- Drain all chemical agents inside the brazed plate heat exchange after cleaning work, fill sodium
hydroxide (NaOH) or sodium bicarbonate (NaHCO3) in the heat exchanger and circulate for 15 to 20
minutes to neutralize it.
- After the completion of neutralization, clean the inside of the heat exchanger with clean water.
You can check whether the chemical agent is properly removed by measuring the pH concentration of
the water.
- If using a different kind of chemical cleaner on sale in the market, you must check whether it causes
corrosion on stainless steel or copper in advance.
- For more information about chemical cleaners, consult with a professional in the field.
● After completing the cleaning work, operate the product to check whether it works properly.
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