Milk Cooling

Highest Hygiene Standards, Automatic Cleaning System.

We wish to present some of the salient features of Milk Cooling Tanks offered by us : Leistertech Cooling Tanks are equipped with direct expansion type Evaporators, which are fabricated using the Laser Welding technology, thus offering prolonged life compared to the regular spot welded evaporators. As an informed buyer you will realize that this ensures high burst pressure, less thermal distortion around the welding area, thus making these weld joints much stronger compared to the other manufacturers.

This becomes more significant since the evaporator is subject to very high pressure and extreme temperature conditions in cyclic manner, while the system is used for milk cooling application.

The stainless steel used will be of imported PVC coated having original mill finish of 4B, which makes it more hygienic and aesthetically better, compared to the cooling tanks offered by other manufacturers.

The Cooling Tank Control Panel offered by us is in Stainless Steel Construction v/s the Powder Coated CRCA panels usually supplied by the other manufacturers.

Unique Future Of Bulk milk cooler

1 Evaporator:
1.a Laser Welded Evaporator
1.b Imported from Europe
1.c STI Laser Welded
1.d Less Thermal Distortion due to Laser Welding
1.e Semi tubular integrated laser for higher efficiency
2 Inner Surface is original 2B finish with 180 grid as per the European Standards
3 Highly energy efficient Refrigeration system design ensures faster cooling
4 Temperature display is inbuilt with Electrical Control Panel for easy operation
5 CIP system for Closed type tanks: Self Rotating spray ball system at the top portion of the tank ensures very effecting cleaning.
6 Part load operation is possible. Only one refrigeration system out of two can be operated.

Leistertech uses the direct expansion cooling system to effectively cool the milk.



Bulk Milk Cooling Tank:

1.1.1 Material of construction:

Tank inner, outer, intermediate, dimpled jacket and top open able cover shall be fabricated from Stainless Steel AISI 304. All piping, filter, body, top cover, agitator shaft & blade, adjustable ball feet, dip stick, outlet valve and blank flange shall also be manufactured out of AISI 304. Filter screen shall be from nylon wire mesh. All the gaskets shall be from food grade Nitrile rubber material. The skid on which refrigeration unit is mounted shall be of powder coated steel. The evaporation surface in contact with milk shall be passivated by standard treatment to impart corrosion resistance.

1.1.2 Shape & Orientation:

The shape of the tank shall be open type with top openable cover and will be in horizontal-semi-cylindrical shape for capacities up to 2000 Litres & higher capacity units are close type with manhole on top and Horizontal Cylindrical in Shape.

1.1.3 Tank Fittings & Accessories:

The tank shall be provided with inlet opening and blank union with locking arrangement at the outlet, agitator and gas spring assisted top openable cover (open type) & manhole with cover (close tank). All SS fittings shall be of SMS standard.

There shall be arrangement for gentle agitation of milk so as not to have any disturbance capable of producing a uniform distribution of fat in the milk. The agitator provided shall produce Gentle agitation, efficient at any filling level after the minimum filling, due to the unique design of the agitator blades and to the speed of a self lubricating, tight geared and non reversible single phase motor.

The tank shall be provided with 4 Nos. legs with SS 304 adjustable ball feet legs suitable for minor height adjustment.

The tank shall be supplied with SS calibrated dipstick along with value chart to measure the volume of milk inside the tank.

A temperature sensor shall be permanently fixed at the bottom of the outlet cup on the outer surface, to sense the temperature at the outlet and to transmit the signal to the digital temperature indicator. The temperature indicator is provided in the Milk Tank Control Panel.

1.1.4 Insulation:

The insulation of the tank shall be done by injection, in situ, of high density (minimum 40 kg / m3) CFC free (environment friendly) polyurethane foam without having any imperfection and hygroscopicity. The efficiency of insulation should be such that at max 50 °C ambient the rate of rise of the mean temperature of the milk, initially at about 4° C shall not exceed by 1°C in four hours when the rated volume is allowed to stand undisturbed as per the requirement of ISO 5708 2A II (latest version).

1.1.4 Cleaning In place (CIP)

Open tanks (capacity up to 2000 Litres) are meant to be cleaned manually. Tank cleaning brush would be provided.

Incase of close tanks, CIP facility shall be provided, which shall include uniquely designed Self Rotating Spray Ball System positioned at the top of the tank inside & piping from the balance tank through milk transfer pump to the Milk Cooler.

CIP Solution shall be prepared in the Balance Tank using an Electrical Hot Water Geyser or Solar Water Heating System (Heating System to be provided by the buyer) for generating hot water for cleaning.

1.1.5 Welding & Finishing:

Inner, outer, intermediate dimpled jacket and nozzle connections shall be welded with TIG process. Inner surface will be of 2 B Original mill finish (minimum 180 grits) with PVC coated sheets for sheets used for fabrication of Milk Cooling tanks. Finishing of weld joints of inner shell and outer shell all other product contact surface shall be polished upto minimum 180 grit finish.

1.2 Refrigeration System:

The refrigeration system shall be designed to comply with (ISO/ R1662 and to meet the requirements of milk tank (ISO 5708, Class 2A II) with not more than 3.0 hours cooling time from 38 to 3°C for all milking and not more than 1.5 hours from second milking i.e. 10 to 3°C. The refrigeration system shall be of direct expansion type, with Freon – 22 (R-22) or R404 free environmental friendly refrigerant to cool the raw milk form reception temperature to 3°C in the time frame described above. The evaporator (s) of the refrigeration system shall form a part of the milk tank body as dimpled jacket in the bottom plate.

1.2.1 Compressor:

The compressor shall be reciprocating hermetically sealed, suitable for Indian climatic conditions. 2000 litres & higher capacity units will be with double compressor system suitable for operation on Single/Three-phase mains supply. The compressor shall be of Emersion Climate Technologies/Danfoss make. The compressors are selected based on the energy efficiency and optimum capacity to take care of the cooling load.

1.2.2 Condenser:

The condenser shall be air cooled finned tube type having sufficient heat transfer area when the unit is operating at extremely high ambient temperature. For each compressor, separate condenser and air-cooling fan are considered. The air circulation pump shall throw hot air out.

1.2.3 Receiver:

A suitable size sealed receiver shall be provided duly mounted on the skid near compressor.

1.2.4 Thermostatic Expansion Valve:

A suitable size and capacity TX valve of Maximum Operating Pressure type shall be provided. The make of TX valve will be DANFOSS/Equivalent.

1.2.5 Evaporator:

The evaporator in special stainless steel shall be STI type manufactured using laser welding technology, fixed on the bottom plate of the inner tank. The gap between inner shell and jacket plate shall be such that heat transfer taken place in direct expansion of the refrigerant in the jacket. The triangular pitched spots offer high energy efficiency and zigzag path for refrigerant travel shall be designed in such a way so that it reaches up to the extreme corner of the bottom plate. In case of double compressor system, the evaporator area shall be divided and separated to form two independent circuits.

1.2.6 Refrigerant pipe, fittings and controls:

All pipes fittings & controls shall comply with the latest relevant code applicable. Copper tubing shall be routed in such a way that if any leakage occurred during operation can easily be detected and the defective portion can be repaired/ replaced without dismantling the whole system. All the pipes shall be clamped properly with fixed support. In case of double compressor system, the unit shall be designed in such a way that both units can run independently. The tubings shall be insulated, wherever necessary.


2.1 Milk Tank Control Panel:

The milk tank shall be provided with a wall mounted control panel with timer to control the intermittent operation of the agitator & a digital temperature indicator indicating milk temperature up to one decimal place with a least count of 0.1 °C to indicate the milk temperature. The panel shall be provided with contactors, overload relays, ON/OFF buttons & necessary MCBs, control wiring etc. In case of double compressor system, control panel shall be provided with sequence controller and timer to start one compressor at a time. The panel shall also have facility to operate refrigeration unit on auto/manual mode. In the auto mode, as soon as the milk temperature reaches to pre-set value. The compressor will switch-off to avoid freeze of milk and vis-à-vis.

2.2 Cables & Electrical Switch Gears:

All electrical switchgears and controls required for the complete system shall be of reputed make and will be in suitable ratings. The scope shall include the requisite lengths of cables to inter-connect the equipment within the Bulk Milk Cooler.


After cooling the milk at the right temperature, the next important function of milk tank is to keep the milk pure and clean. The smooth inner surfaces ensure the inner tanks are always germ free further; they facilitate easy cleaning of the tank. The unique central cleaning system comes with a dynamic spray‐ball integrated in the agitator of the tank which is a source of high pressure water. And an optional automatic cleaning system helps in keeping the tank clean and hygienic.

The Principle of Operation of the 5 cleaning cycles is as follows

‐ Cold water rinse and flush.
‐ Hot water rise and flush.
‐ Main circulations wash with chemical and flush.
‐ Cold post rinse and flush.
‐ Final cold rinse and flush.


During the whole milk production process, the cooling step is extremely important to maintain the product quality. Based on this principle, Leister technologies cooling tanks present a powerful cooling concept with low energy consumption. The innovative design of the STI evaporator is in charge for excellent cooling performance. Through the planned position of the semi tubular integrated units. The refrigerant goes through the evaporator in a perfect speed. Adequate to reach the optimal point of heal exchange with the milk. Furthermore, a complete use of the evaporator surface gets a best energy effect.


‐ Cool the milk from 35°C to 4°C in less than 3 hours,At an ambient temperature of 32°C.
‐ Operation is ensured at an ambient temperature of 38°C.
‐ Hermetic compressor with high efficiency.
‐ Output valve – butterfly type in stainless steel.
‐ Stainless steel dipstick and calibration chart for precise milk measurement.
‐ Low energy consumption.
‐ Certified calibration system for milk measurement.
‐ Voltage monitoring relays (optional)


Clearly shows all information on a 32 – character LCD display.

‐ A control mechanism for all coding and cleaning functions.
‐ Monitors the milk quality and the tank functions.
‐ Stores the operating data for 2 months.
‐ A safety thermostat ensures emergency cooling.
‐ Can be connected to the Dairy Plan System.
‐ Optional Expertise software enables you to collect and analyses data.
‐ Warning signal when the cleaning agent canister is empty.
‐ Expert XG operation with additional monitoring function (optional).


Rotary diffusers are independent from the agitator So cleaning of the agitator blades is fed through The gear motor and thus no gearbox damage Can occur.


After keeping milk at the right temperature, the next most important function of a milk tank is to keep milk pure. That’s why Leister has invested so much attention to milk tank sanitation. The Leister milk tank offers an unequalled washing system that assures the highest possible milk quality.


Injected through a separate circuit, the water is sprayed On to the inner sides of the tank to remove milk residues And solid particles. It is used in cleaning cycles.