AN OVERVIEW OF CIP TECHNOLOGY
 
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Spray Device Selection and Application 

The first application of spray cleaning in the dairy industry was to wash the farm bulk milk pick-up tanker in the early 1950's.  Industrial spray devices then in use for cleaning railroad cars and industrial chemical transport tankers were converted to milk plant receiving room use.  This equipment was designed to emphasize physical action as compared to chemical action and high-pressure and impact was used to remove and flush away soil.   The effectiveness of spray cleaning created interest in cleaning in-plant processing and storage tanks. However, the heavy industrial-type spray devices were not easily installed in tanks without top manholes and these mechanical devices, generally containing threaded parts, seals, bearings, and substantial metals other than stainless steel, were quickly discarded in favor of fixed ball-type sprays similar to that shown at the right. 

The fixed ball-type spray has the following advantages as compared to rotating spray devices: 

  • There are no moving parts.
  • It can be made completely of stainless steel.
  • Its performance is not affected greatly by minor variations in supply pressure.
  • A properly established installation will continue to provide satisfactory service for extensive periods of time.
  • It sprays all of the surface all of the time, hence reducing the total time required for cleaning a vessel of a given size.
Cylindrical tanks containing almost any complement of agitating equipment and baffles can be adequately cleaned if sprayed at 0.1 to 0.3 gallons/minute/sq. ft. of internal surface, and patterns are arranged to spray the upper one-third of the tank.  Vertical tanks which are free of agitating equipment, baffles and other internal devices may be cleaned satisfactorily at flow-rates of 2.5 to 3.0 gallons/minute/lineal ft. of tank circumference.   The illustration at the left depicts  the positioning of spray devices in storage and processing vessels of different sizes and configurations. 
  • Note that the presence of a vertical agitator shaft requires the provision of two sources of cleaning solution distribution to avoid "shadowing".
  • Sprays may be used as sparging devices as well as cleaning devices if properly supplied with the required gas and CIP flush, wash and rinse solutions.. Figure II-19 illustrates such an application in which instance the location of the spray assists in cleaning the bottom side of a vertically mounted agitator. 

 
 

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