A vacuum drying oven is one of the important auxiliary drying equipment. The vacuum drying oven has a wide range of applications and complicated operations. Therefore, it has higher requirements than ordinary drying ovens, and there are more points to be paid attention to in the use process of the vacuum drying oven.
Precautions for Each Operation Step of the Vacuum Drying Oven
1. Sample Placement
Put the material to be dried evenly on the sample rack in the vacuum drying oven box and push it into the drying box.
① Place the sample in the oven without the heating being turned on.
② When placing the sample, a certain space should be reserved on the upper and lower sides to keep the airflow in the box smooth.
③ If the sample changes phase during the drying process, it must be stored in a tray to avoid contamination of other samples.
④ If the dry materials become lighter in weight and smaller in volume after drying, a barrier net should be placed on the vacuum port in the vacuum drying oven box to protect the vacuum pump (or solenoid valve) from damage caused by dry matter inhalation.
⑤ Any liquid solvent or item whose ignition point or boiling point is decreased to less than 150°C under vacuum is strictly banned from being placed in the vacuum drying oven box.
2. Close the Door of the Vacuum Drying Oven
Close the door of the Vacuum drying oven gently.
① Do not use too much force when closing, to avoid causing the box of the vacuum drying oven to vibrate greatly.
② There are bolts on the box door. Make sure the box door and the silicone sealing strip are properly joined before closing.
3. Switch the Vacuum of the Vacuum Drying Oven on.
Connect the vacuum pump to the vacuum valve, turn on each component individually, then expel the vacuum.
① The vacuum pump’s limit value when the pressure gauge is pumped shall take precedence based on how well it performs.
② After attaining the vacuum degree, close the vacuum valve (if the vacuum valve is not tightly closed, it must be replaced soon), and then turn off or unplug the vacuum pump (to prevent the phenomenon of sucking back).
③ Check the vacuum pressure gauge to make sure the reading is steady and devoid of noticeable fluctuations.
④ If the vacuum degree is lower than the requirement of dry items, you should turn on the vacuum pump power and vacuum valve again, and continue to vacuum. It can increase the vacuum pump’s useful life.
Set the desired temperature after turning on the heat.
① The heating process must be performed in a stable vacuum state; otherwise, the difference in internal and external pressure and temperature will readily result, leading to unexpected events such as the outside air bursting into the box.
② The heating indicator light will be on for a long time while the appliance is heating. When the temperature is reached, the heating will automatically stop and the indicator light will turn off. The heating cycle restarts and the heating indicator turns on when the temperature falls below the predetermined level.
③ Normal display of the heating indication and temperature is required. If the indicator is not on, the power should be promptly cut off, and the instrument’s owner should be informed.
Vacuum drying oven
5. Temperature Setting of the Vacuum Drying Oven
Set the desired temperature.
① The setting temperature must not be higher than the recommended value. The material’s ignition point and boiling point will drop dramatically in a vacuum. The solid substance will melt and agglomerate at an inappropriate setting temperature.
② The temperature of the digital display should be displayed normally. If it is not displayed or if there is an anomaly such as flickering or jumping, the power should be turned off immediately and the person in charge of the instrument informed.
③ The operator can leave only after the actual temperature is consistent with the set temperature and the heating indicator light goes out;
④ To avoid temperature control failure, a special person must examine whether the instrument is operating normally and pay attention to changes in the baking materials. If an anomaly is discovered, it is important to immediately stop using the heating system, cut off the power source, open the vent valve, and file a report.
Turn off the heating switch first, then slowly open the air release valve, and when the vacuum degree is 0, open the box door of the vacuum drying oven to remove the sample.
① Do not open the valve all the way when deflating to avoid the impact on the sample when the external airflow enters the box, generating pollution in the box and between the samples.
② When the vacuum degree is less than 0, it is forbidden to open the box door of the vacuum drying oven (the reason is the same as above).
③ When the sealing silicone rubber of the box door is deformed due to a long-term vacuum and the box door cannot be opened, the box door of the vacuum drying oven cannot be opened forcibly. Just wait for the sealing silicone rubber ring to slowly return to its original state, and then the box door of the Vacuum Drying Oven can be opened.
④ After sampling, promptly shut off the air release valve.
Other Precautions of the Vacuum Drying oven
The vacuum box shell of the Vacuum drying oven must be effectively grounded to ensure safe use.
The vacuum drying oven should be used in an environment with relative humidity ≤85% RH, no corrosive gas around, no strong vibration source, and a strong electromagnetic field.
The Vacuum Drying Oven should be kept clean frequently. The door glass of the Vacuum Drying Oven should not be wiped with reactive chemical solutions but should be wiped with a soft cotton cloth.