Warehouse stealth "killer"

 The environmental quality of the storage environment can be characterized by environmental parameters. The more common storage environment parameters are temperature, humidity, dust, dust and so on. Most of the storage of goods sensitive to temperature and humidity; dust is not only harmful to humans, but also the case of fire is extremely easy to explode; smoke produced mainly by burning. However, due to the limitation of warehousing scale, investment, staff lack of experience or lack of professional knowledge and other reasons, the intensity of the light intensity, the intensity of the light intensity, and so on, Air oxygen content and carbon dioxide content and other parameters of monitoring are often overlooked or ignored, resulting in irreparable economic losses and personal injury.

Temperature and humidity

In the storage environment, the common measured parameters are temperature and relative humidity. Ordinary goods in the normal temperature range can be stored. Room temperature, also known as room temperature, is generally about 25 degrees, room temperature, the temperature is generally between 0-30 ℃. Humidity contains four concepts, one is the absolute humidity: the air contains the number of grams of water vapor; Second, the saturated humidity: a certain size of the space to accommodate the maximum water vapor, usually per room to accommodate the number of grams of water vapor; Third, the relative humidity: a certain temperature, the absolute humidity and the percentage of saturated humidity, that is, the actual content of water vapor from the saturation content to the extent; Fourth, the dew point: water vapor saturated air condition to reach the state of the air temperature.

The temperature and humidity of warehousing environment have the most obvious influence on the physical and chemical properties of stored goods. Different types of goods have different degrees of adaptability to the temperature and humidity of their environment. Ordinary goods can be stored at room temperature, the temperature and humidity sensitive goods, such as chemicals, fruits, vegetables and food storage in an inappropriate storage environment will be a large area of ​​mildew or even lead to accidents.

Oxygen and Carbon Dioxide

Oxygen is one of the most important measured parameters in the storage environment. Storage Goods are divided into organic and inorganic, organic goods through the inhalation of oxygen inhalation of oxygen released carbon dioxide decomposition of organic matter in vivo, generate heat and maintain their own life activities. Food is organic, the typical food storage is a large grain depots.

For grain storage, due to insects, rotten, rodent and other reasons, the annual loss of grain amounted to more than 6%. Many large-scale grain depot to implement the hypoxia, low temperature, low-dose methods such as storage of food, and received good results. In order to store food effectively, it is necessary to reduce the oxygen concentration in the grain. This method can be used to control microbial and pest damage to food, but taking into account the food and seed breathing, oxygen concentration is too low will cause food and seed death and mildew, the general grain heap oxygen concentration control in about 5% And not less than 2%, the best food storage.

Respiration of organic matter consumption of oxygen in the environment and the release of large amounts of carbon dioxide, the staff without any protective measures to enter the environment, the light headache discomfort, severe fainting shock. Content of carbon dioxide in the air than the normal value (0.03%) can make people breathe deepened to accelerate the content of 1% when the human respiration increased by 25%, content of 3% of the human breath suddenly increased 2 times, when carbon dioxide In the air content of more than 25% of the time, the human respiratory center paralysis and cause acidosis, so the concentration of carbon dioxide inhalation should not exceed 10%.

Light intensity

Light intensity is the light intensity of the light intensity of the physical quantity, light intensity of the international measurement unit for candela, a common candle luminous intensity of about 1 candela.

In warehousing environments, many cargoes are particularly sensitive to light intensity. Sunlight contains a lot of ultraviolet light, ultraviolet is divided into near ultraviolet, far ultraviolet and ultra-violet, wavelength range between 200nm-400nm. Warehousing of goods by UV damage is very obvious, but often ignored by Cangguan personnel.

Chemical storage generally use the backlight to prevent direct exposure to ultraviolet light, phenol carbonic acid (phenol) is a white crystal, see light that becomes light red or red; wine wine storage, the exposure time, exposure requirements are very strict ; Textiles warehousing, ultraviolet radiation to the textiles, part of the reflected part is absorbed, the higher the UV transmittance, sunlight damage to its greater. For example, the anti-ultraviolet ability of polyester fabric stronger than the cotton fabric, polyester fabric can strongly absorb the following 300nm UV, low UV transmittance; wool, silk and other protein fiber molecular structure of the goods under 300 nm UV absorption ; Nylon, cotton and other fiber molecules less ability to prevent UV. Cotton, linen, wool, silk and other raw materials and their products, in the sunlight, high temperature conditions will produce soft, sticky and so on. Therefore, such sensitive to light intensity of the goods should be avoided qualitative change in direct sunlight or stored in a monitoring environment.

Dust and soot

Dust in a certain space encounter open fire is extremely easy to explode, is one of the important factors causing environmental pollution.

A large number of similar goods in general to establish a dedicated library to store, such as flour, sugar, etc., but this kind of goods can easily lead to dust explosion.

Wheat in the flour mill is processed into very fine flour, the grinder is part of the work done into energy, stored in the crushed particles after the surface, this part of the energy in the physical and chemical is called "surface energy." The greater the degree of crushing the material, the smaller particles, the larger the surface area, the greater the surface energy. Because the dust has a very high surface energy, compared with the bulk of the material, it is prone to physical changes or chemical changes, which will release its energy. Therefore, these fine dust meet the appropriate conditions, fully mixed with the air, it will release a huge moment of rapid energy intense burning.

Not only flour, dust, such as sugar, cement, cocoa, cork, wood, light rubber, leather, plastic and various inorganic materials such as sulfur, iron, magnesium and cobalt dust in the air to reach a certain Of the concentration and encountered a fire will occur violent explosion. Grain in the storage process handling, flat heap, flip grain surface, have a lot of flour, wheat bran, sediment and pesticide impurities and micro-metallic substances such as mixed dust. Grain in the storage and transportation process, the general operating area dust concentration should be less than 10mg / m3 of the national environmental standards, otherwise it will seriously affect the health of staff positions, accelerate the mechanical aging, causing an explosion.

Dust and dust, like the dust filled the air, the object after the release of light and smoke combustion. For the prevention of fire, most of the warehouse is equipped with a fire alarm. However, the sensing area of ​​the fire alarm is limited, the internal intelligent processor is also easy to premature aging, for space, goods and more large and medium storage environment, taking into account the economic benefits and practicality, the alarm distribution in the storage space Not the best choice.

Air flow rate

Storage environment in the various parameters are often interrelated with each other constraints, air velocity, temperature and relative humidity that exists between the three. The air flow rate, ie the velocity of air flow, is measured in m / s. The faster the flow of air, the lower the temperature and humidity in the space, and vice versa. In modern warehousing, storage of temperature, humidity and other environmental parameters are often dependent on natural or artificial ventilation to adjust.

The following is an example of wood storage, which illustrates the role of air velocity monitoring in warehousing environments.

Wood harvested after the body there is a lot of water, wet wood is difficult to store, the general use of hot air as drying medium convective heating of wood to dry wood, is widely used at home and abroad is the kiln method.

The results show that the diffusion of water in the wood is mainly related to the characteristics of the wood itself, moisture content, temperature and other factors. From the perspective of energy saving, in ensuring the quality of dry under the premise of speeding up the wood to the surface of water migration speed, shorten the drying cycle, reduce energy consumption, improve the wet wood storage space in the air flow rate in this process played an important role . Air flow rate on the wood drying rate curve shown in Figure 1.
     
It can be seen from the figure that the drying rate of the wood varies with the change of the flow rate of the hot air. When the air velocity is increased from 5.3m / s to 8.7m / s, the drying rate is obviously increased.

"Air pH" was originally proposed to solve the problem of acid rain, a new concept, refers to the air through the aeration, which dissolved in water soluble substances, resulting in water hydrogen ions, hydroxyl ions relative content changes The displayed pH, expressed in pH.

Goods generally stored in the indoor environment, from a general sense, it is a small threat of acid rain, and air pH value is also small. However, the warehousing environment is a dynamic system, the environment itself directly affects the physical and chemical characteristics of goods, the goods affected by external factors affect the nature of the resulting changes in the phenomenon of evaporation, sublimation, feedback to the environment, resulting in mutual relations and constraints Relationship. For example, in the chemical library, all kinds of chemical powder, liquid, through sublimation and evaporation combined with water vapor in the air, so that the pH value of the air was alkaline or acidic, encountered cold air to form small droplets attached to the surface of the goods, Ranging from damage to the packaging of goods, while the chemical itself in the cargo reaction, resulting in danger.

The security range value for the storage environment parameter

The above storage of goods through the example of seven kinds of storage environment parameters, different storage of the storage of the environment have different requirements. According to the physical and chemical characteristics of warehousing goods and their sensitivity to various storage environment parameters, this paper divides the warehouses into six types: dangerous goods storehouse, cold storehouse, constant temperature storehouse, greenhouses greenhouse, grain depot and medicine storehouse. Table 1 lists the monitoring relationships between the six storage types and seven storage environment parameters.

According to the monitoring relationship between storage type and environmental parameters, it is possible to monitor environmental parameters of certain types of warehouses. Through the field investigation and many aspects of the information to find, collect, sort out the common goods storage environment, the main parameters of safe range values, as shown in Table 2.


Storage of different goods, need to monitor the storage environment parameters are different. In the storage environment, there are many measurable parameters, in addition to temperature, humidity, air velocity, light intensity, air oxygen and other parameters, such as atmospheric pressure, object displacement, soil pH and other physical and chemical quantities are warehousing environment Parameters for the monitoring of environmental parameters of the safety range of values, this paper gives generally applicable reference data, the actual storage environment in the process of monitoring the need to be based on the storage of physical and chemical characteristics and changes.