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Cleaning and Passivation
Passivation
Cleaning of the leakage outlet system
The leakage chamber is cleaned via a spray nozzle in the double disk, which is
connected to a valve seat cleaning pipe. Here, only general recommendations can be
made about the number and duration of spray cleaning. Because depending on the
prevailing conditions such as type of product, temperatures, cleaning agents, cleaning
intervals, etc., longer or more frequent cleanings may be required.
It is recommended to set the cleaning conditions in the system in a test phase to save
cleaning medium. To optimize the seat cleaning is thereby determined by occasional
checks valves after cleaning, if the valve seats are clean. All attached systems for
cleaning the valves should be used regularly in order to ensure optimum results and to
prevent any damage to the valve.
The spray cleaning purifies the leakage chamber, while product can flow in the two lines,
by means of a spray nozzle, which distributes the liquid in the CIP total leakage area.
Here, however, not the sealing surfaces of the valve plate seals are purified. This type of
leakage chamber cleaning is widely used in liquid, easily flushable media which do not
remain on the sealing surfaces are liable or may crystallize.
Passivation
Before commissioning a plant, passivation is commonly carried out for long pipes and
tanks. Valve blocks are usually excluded from this.
Passivation is typically performed using nitric acid (HNO
3
) at approx. 80°C (176 °F) at a
concentration in the 3% range and a contact time of 6 to 8 hours.
