Dairy processing: Aseptic processing and packaging systems
Constant level tank (CLT)
The constant level tank is a reservoir for a supply, at atmospheric pressure, of raw product to the sterilizer to permit continuous operation of the APPS. It is located at the start of the APPS system. It controls the milk level and provides a uniform head pressure to the product leaving the tank.
General conditions
- Is constructed of stainless steel
- Is in good mechanical and sanitary condition
Design
- Ensure the design and capacity of the tank does not permit air to be drawn into the system with the product when operating at the maximum sealed capacity of the flow control device
- Ensure the raw product will drain to the outlet before the outlet becomes uncovered
- for example, the bottom of the tank is pitched to the outlet at a minimum downward slope of at least 2% (0.2 cm per 10 cm) and the top of the outlet pipe is lower than the lowest point in the tank (see Appendix B: Constant level tank design)
Cover
- Ensure the tank has a removable cover, or an inspection port with a removable cover, of suitable design to maintain atmospheric pressure and to minimize the risk of contamination
- have the cover pitched to an outside edge to provide drainage
- ensure all openings in the cover are flanged upwards and covered
- fit any pipelines entering through the cover (excluding directly clamped lines) with a sanitary umbrella deflector that overlaps the edges of the opening and is located as close to the tank cover as practical
- Ensure the cover is used during processing
Airspace and overflow
- Install any product divert lines, recycle lines and water lines coming into the constant level tank in a way that prevents the siphoning of raw milk or cleaning products into finished product or potable water lines (a cross connection). For example:
- the overflow outlet is at least 2 times the diameter of the largest inlet to the constant level tank
- the divert, recycle, CIP and water lines terminate and break to atmosphere at least 2 times the diameter of the largest inlet above the maximum overflow point of the constant level tank
Level control device
The level control device controls the flow of milk to the constant level tank and therefore provides constant head pressure to the product leaving the tank
- Equip the constant level tank with an automatic device of sanitary design and construction to control the raw product level
- Date modified: