The vacuum drying oven is especially suitable for drying heat-sensitive, easily decomposable, easily oxidized substances and complex composition items for fast drying. Lab vacuum drying oven furnaces are widely used in biochemistry, pharmacy, medicine and health, scientific research, environmental protection and research applications, powder drying, baking and disinfection and disinfection. So, what should be paid attention to when using and maintaining the how to use vacuum drying oven? Let's take a look at it together!
Vacuum drying steps and precautions:
1. Sample placement: Put the materials to be dried evenly on the sample rack in the drying box, and push them into the drying box.
①Do not place the sample in the heating state of the oven, and place the sample in the state of ensuring that the heating is turned off;
② When placing the sample, a certain space should be reserved around the upper and lower sides to keep the air flow in the box smooth;
③ If the sample will change in phase during the drying process, it must be placed in a tray to avoid contamination of other samples;
④ If the dry items become lighter in weight and smaller in volume after drying, a barrier net should be added to the vacuum port in the box to prevent the vacuum valve (or solenoid valve) is not damaged by inhaling dry matter;
⑤ Any liquid solvent and items whose ignition point and boiling point are reduced to below 150℃ under vacuum are strictly prohibited to be put into the box.
2. Close the box door: gently close the box door.
①Do not use too much force when closing, to avoid causing the box to vibrate greatly;
②There are bolts on the box door. When closing, make sure that the box door is tightly combined with the silicone sealing strip.
3. Turn on the vacuum: connect the vacuum pump to the vacuum valve, turn on the vacuum pump and the vacuum valve in turn, and evacuate.
①According to the performance of the vacuum pump, the limit value of the vacuum pump when the pressure gauge is pumped shall prevail;
②After reaching the vacuum degree, first close the vacuum valve (if the vacuum valve is not closed tightly, it needs to be replaced in time), and then turn off or cut off the power supply to the vacuum pump (to prevent the suction phenomenon);
③ Observe the vacuum pressure gauge to ensure that the value is stable without obvious fluctuation;
④If the vacuum degree is lower than the requirement of dry items, turn on the power supply of the vacuum pump and the vacuum valve again, and continue to vacuumize, which can extend the life of the vacuum pump.
4. Heating: Turn on the heating switch and set the desired temperature.
①The heating step must be carried out in a stable vacuum state, otherwise it will easily lead to the difference between the internal and external pressure and temperature, resulting in sudden situations such as the external atmosphere rushing into the box;
② During the heating process, the heating indicator light will be on for a long time. After reaching the set temperature, the heating will automatically stop and the indicator light will be off. When the temperature is lower than the set temperature, the heating starts again, and the heating indicator lights up;
③The heating indicator and temperature should be displayed normally. If the indicator is not on, the power should be turned off in time and the person in charge of the instrument should be contacted.
5. Temperature setting: Set the desired temperature.
①The setting temperature should not exceed the rated temperature. Under vacuum, the ignition point and boiling point of the material drop sharply. If the setting temperature is unreasonable, the solid material will melt and agglomerate.
②The temperature of the digital display should be indicated normally. If it is not displayed or there is abnormality such as flickering or jumping, the power should be turned off in time and the person in charge of the instrument should be contacted;
③The operator can leave only after the actual temperature is consistent with the set temperature, and the heating indicator light goes out;
④In order to avoid the failure of temperature control, a special person is required to check whether the instrument is running normally, and pay attention to the changes of the baking materials. If any abnormality is found, the heating should be turned off, the power supply should be turned off, the vent valve should be opened, and the report should be reported in time.
6. Sampling: first turn off the heating switch, then slowly open the air release valve, and when the vacuum degree is 0, open the box door to take out the sample.
①Do not open the valve to the maximum at one time when deflating, to avoid the impact of the sample when the external airflow enters the box, causing contamination in the box and between the samples;
②When the vacuum degree is less than 0, it is forbidden to open the box door (the reason is the same as above);
③When the sealing silicone rubber of the box door is deformed due to the vacuum for a long time and the box door cannot be opened, the box door cannot be opened forcibly, just wait for the sealing silicone rubber ring to slowly return to its original state, and then the box door can be opened.
④ After sampling, close the air release valve in time.
Vacuum drying box maintenance precautions:
1. The shell of the vacuum drying box must be effectively grounded to ensure safe use.
2. The vacuum drying box should be used in an environment with relative humidity ≤ 85% RH, no corrosive gas around, no strong vibration source and strong electromagnetic field.
3. There is no explosion-proof and anti-corrosion treatment in the working room of the vacuum drying box, and items that are flammable, explosive, and prone to corrosive gases are not allowed to be dried.
4. When dry items are wet, it is best to add a filter between the vacuum box and the vacuum pump to prevent wet gas from entering the vacuum pump and causing the vacuum pump to malfunction.
5. After the vacuum drying box is used for many times, the phenomenon that the vacuum cannot be vacuumed will occur. To solve the problem, the door seal should currently be changed or the door extension distance of the box adjusted. When the drying temperature of the vacuum box is higher than 200 ℃, slow air leakage will occur. Currently in the case of the back of the back back and use the Allen key to loosen the base heater, change the packing ring or tighten the base of the heater to solve the problem.
6. If the rubber stopper of the air release valve is difficult to rotate, it can be lubricated with an appropriate amount of grease inside.
7. Except for maintenance, the left box cover cannot be disassembled to avoid damage to the electrical control system.
8. The lab vacuum drying oven should be kept clean frequently. Door glass should not be cleaned with reactive chemical solutions but with an esl cotton cloth.
9. If the vacuum drying box is not used for a long time, wipe the exposed electroplating parts and apply neutral grease to prevent corrosion, and put on a plastic cover with dust film and store in a dry room to prevent moisture damage to electrical components.
10. When the vacuum box does not need to be continuously pumped, the vacuum valve should be closed first, and then the power of the vacuum pump should be turned off, otherwise the vacuum pump oil will be poured back into the box.
These are the use methods of the lab vacuum drying oven and the precautions for daily maintenance. The vacuum drying oven is the main drying equipment promoted by Zhengzhou Keda, and you are welcome to purchase it.