The atmospheric filling method refers to the using of atmospheric pressure. It flows into the packaging container by the weight of the liquid itself. And the whole filling system works in an open state. The atmospheric filling method uses the liquid level to control the filling.
The workflow is:
A. Air inflow and venting: Pour the liquid into the container. And we exhaust the air in the container from the venting pipe.
B. After the liquid in the container meets the quantitative requirements, stop the liquid supply automatically.
C. Exhaust the residual liquid and remove the residual liquid entering the venting pipe, and then prepare for the next charge and discharge.
We mainly use the atmospheric filling method for filling soy sauce, milk, liquor, vinegar, fruit juice and other liquid products with low viscosity, without carbon dioxide and a peculiar smell.
The isobaric filling method is to use the compressed air in the upper air chamber of the liquid storage tank to inflate the container first so that the pressures in the liquid storage tank and the container are close to equal. In this closed system, the liquid flows into the container by its own weight, suitable for inflation liquid.
Its working process:
A: Balance the pressure.
B. Intake the air and return the air inlet.
C. stop the liquid.
D. Release the pressure (release the residual gas pressure in the bottle to avoid the sudden drop of the pressure in the bottle, which will cause bubbles and affect the quantitative accuracy).
The vacuum filling method uses the pressure difference between the filled liquid and the exhaust port. This is to suck out the gas in the container for filling. The pressure difference can make the product flow larger than that of equal pressure filling, especially suitable for the liquid filling of small-mouth containers, viscous products or large-capacity containers. However, the vacuum filling system needs an overflow collecting device and product recycling device. Due to different forms of vacuum, it derives various differential pressure filling methods.
A. Vacuum filling method with low gravity
We need to keep the container at a certain vacuum degree, and need to seal the container. The purpose of low vacuum degrees is to eliminate overflow and backflow during vacuum filling and to prevent gaps from being filled by mistake. If the container does not reach the required vacuum degree, no liquid will flow out of the filling valve port, and the filling will automatically stop when there is a gap or crack in the container.
The liquid in the storage tank flows into the bottle through the thin sleeve valve, and we can use the pipe in the center of the sleeve valve for exhaust. When automatically sent the container under the valve to rise, the spring in the valve opens under pressure, and the pressure in the bottle is equal to the low vacuum at the upper part of the storage tank passing through the exhaust pipe, and gravity filling begins. When the liquid level rises to the air outlet, the filling automatically stops. This method has little turbulence with no need for aeration and is especially suitable for filling wine or alcohol. Wine will not overflow or flow backward if the alcohol concentration is constant.
B. Pure vacuum filling
When the pressure of the filling system is lower than atmospheric pressure, the sealing block of the filling valve faces the container and the valve is opened at the same time. Since the container connected to the vacuum chamber is in vacuum, the liquid is rapidly sucked into the container until a predetermined liquid is filled. Usually, a considerable amount of liquid is pumped into the vacuum chamber, which is recycled after overflow.
The technological process of the vacuum filling method is as follows:
1. Prepare vacuum containers.
2. Intake and exhaust.
3. Stop inflow.
4. The residual liquid flows back (the residual liquid in the exhaust pipe flows back to the storage tank through the vacuum chamber).
Vacuum filling can improve the filling speed, reducing the contact between products and air. And it helps to prolong the shelf life of products. Its fully enclosed state also limits the escape of active ingredients in products.
The vacuum method is suitable for filling liquids with high viscosity (such as oil, syrup, etc.), liquid materials that are not suitable for contacting vitamins in the air (such as vegetable juice and fruit juice), and toxic liquids (such as pesticides and chemical liquid).
The pressure filling method is opposite to the vacuum filling method. The can sealing system is in a state higher than the atmospheric pressure, and positive pressure acts on the product. Liquid or semi-fluid liquid can be filled by pressurizing the reserved space at the top of the storage box or pushing the product into a filling container by using a pump. The pressure method can keep the pressure at both ends of the product and the exhaust pipe higher than atmospheric pressure.
The pressure at the end of the product is higher, which helps to keep the carbon dioxide content of some beverages low. This pressure valve is suitable for filling products that cannot be vacuumed, such as alcoholic drinks (alcohol content decreases with the increase of vacuum degree), hot drinks (90-degree fruit juice, which will evaporate quickly when vacuuming), and liquid materials with slightly higher viscosity (jam, hot sauce, etc.).