CLEANING IN PLACE
There are many methods for cleaning the heat exchanger and many different
proprietary chemicals available for this purpose. All methods involve pre-rinsing,
chemical cleaning, disinfection and final rinsing.
The following is a suggested cleaning method but it is assumed that this method will
be refined by the operator as experience is gained.
1. Have a supply of 2 litres of clean potable rinse water available as the end of
the product run is approached.
2. As the last quantities of product drain from the tank, pour a small quantity of
the water into the tank and use this, with the aid of a cloth or small brush, to
clean the inside walls of the feed tank. Allow this water to drain and pour in
the rest of the rinse water.
Note: Take care not to allow slugs of air to enter the system as the feed tank
is emptying.
3. After a short time, this water will emerge from the cooling section of the heat
exchanger. Wait until this water becomes reasonably clear then re-circulate by
moving the flexible tube from the outlet back into the feed tank.
4. Set the temperature controller of the water circulator to 60°C.
5. Temperature (T1) will begin to fall. When the temperature is less than 100°C,
it is possible to release the system pressure completely by turning the back
pressure valve handle anti-clockwise. Do not release the pressure if the
temperature is above 100°C as the liquid in the heat exchanger will boil
causing possible damage.
When the pressure is released, the flow rate of the water will increase and the
feed pump motor speed can be set to maximum to give the best possible
cleaning action.
If processing has been at elevated temperatures, this operation could take
several minutes to achieve. During this time, prepare 4.0 litres of a 5% caustic
soda solution.
6. When the temperature (T1) is 60°C, empty the feed tank by simply removing
the return hose from the feed tank and guiding to drain or a separate container.
When almost all of the water has drained, put the flexible hose back to the
feed tank and pour the caustic solution into the feed tank.
7. The temperature will recover to maintain 60°C. Allow this solution to
circulate for 30 minutes.
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