Vacuum packaging is another way to extend the shelf life of food products. Here, the product is placed in a sealed package, the suction power of the vacuum pump is used to suck the air out, and the package is sealed. By removing the air around the product, the oxygen level in the packaging is reduced, hindering the growth of oxygen-absorbing microorganisms and the ability to destroy the product. Hypoxia also reduces oxidation-induced spoilage, such as browning of apples and bananas.
However, a certain amount of oxygen will be retained, as it is not possible to create a complete vacuum. At normal atmospheric pressure, the air contains about 21% oxygen - 1000 millibars. When air is extracted during the vacuum packaging process, the pressure in the package decreases.
For example, if the pressure drops to 100 mbar, the equivalent of about 2 will be retained1% oxygen; If you reduce it to 10 mbar, there is still 021% oxygen storage. Is vacuum packaging more effective than modified atmosphere packaging? Engineers at vacuum pump manufacturers believe that in most cases, this is a "circus" – it depends on the production of the packaging.
Vacuum packaging is definitely a more common process than vacuum packaging. Vacuum packaging is essentially a "one-size-fits-all" technique – it relies entirely on removing air. MAP, on the other hand, can be adapted to a specific food. Different gases and different proportions are used in the mixture, so that a particular product has the longest shelf life and maintains the quality and appearance of the product.
For example, for packaged seafood, the ratio of carbon dioxide and oxygen in the modified air may vary depending on the species of fish: oily fish benefit from different air compared to shrimp, for example. For example, the gas mixture of red meat is different from that of bread.
Product presentation is one of the most popular areas compared to vacuum packaging. In vacuum packaging, when the pressure in the package decreases, the packaging material shrinks and forms tightly around the product. For some products, such as fresh meat, this will distort the appearance of the product. Other products, such as grated cheese, are not suitable for vacuum packaging because the pressure of the packaging material on the product can cause the product to deform and lose important properties.
The difference between the two methods is that the engineers of the Water Ring Vacuum Pump Company can easily control the quality of the packaging process. In modified atmosphere packaging, air is removed from the package and replaced with a gas mixture so that the gas content in the package can be continuously monitored during the packaging process. Once the package is sealed, any modified atmospheric leaks can be detected to ensure the integrity of the seal. In the case of vacuum packaging, since there is no gas in the package, the leak test is usually carried out by manual inspection, making quality control less straightforward.
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What are the hazards of centrifugal pump drying.
Centrifugal pump idling is very harmful to the pump and may cause cavitation or mechanical seal damage. Today, I would like to discuss with you the causes and hazards of centrifugal pump drying.
The reason why the centrifugal pump is running dry.
The inlet medium of the pump is insufficient or the inlet pressure is insufficient, or the inlet pipe of the pump is blocked, or the air in the pump chamber is not discharged. Centrifugal pump idling hazards.
The impact on the pump mainly includes the following aspects:
1) The amount of gas in the idling water pump is large, which is easy to cause cavitation and damage the pump body and overflow parts;
2) There is no liquid lubrication for mechanical seals or packing seals, and dry grinding is easy to cause wear;
3) The balance plate of the idling multistage centrifugal pump is not lubricated by anyone (**Pump Manager). Balance plates are quickly burned and damaged.
4) There is no liquid when the water pump is idling. The rotor components and pumps will heat up and not cool. Due to thermal expansion and contraction, some gaps, such as sealing rings, can be easily eliminated.
Early warning and maintenance.
1) Handle the various clearance positions of the centrifugal pump and unfold it under the allowable conditions to prevent biting;
2) Carry out special process treatment, quenching and tempering, heat treatment, etc. on the shaft of the centrifugal pump to improve the hardness, and use low-flexibility materials to prevent the shaft from being bitten to death due to excessive swing when the shaft is idling;
3) Seal and fill the cavity with a machine that does not require lubrication with liquid media;
4) Use closed self-lubricating bearings, no oil;
5) Compared with other centrifugal pumps, the pump chamber volume of horizontal self-priming centrifugal pump is increased and there is a place for water storage. Before the self-priming centrifugal pump works normally, the inner chamber should be filled with liquid. There is a period of self-priming before operation, during which the air is continuously discharged to the outside of the pump. This period of time is partially idling.
6) Set up the idle speed sensing system. The pump is monitored in real time by modern equipment. When the centrifugal pump is idling, it will alarm immediately and stop automatically to protect the safety of the unit.