Talk about the operation precautions of soil freeze dryer:

Soil lyophilizer is also known as soil freeze dryer, the principle is to sublimate the water contained in the soil in a low temperature vacuum environment, so as to obtain dry soil samples, because it is dried at low temperatures, the composition, heavy metals, volatile and heat-sensitive substances in the soil are retained
.

It is used for sample pretreatment before soil testing, and the measured value of freeze-dried soil samples is stable, the reproducibility is good, the element loss is small, and the internal standard recovery rate is high
.

The following small series briefly introduces the operation precautions of the soil freeze dryer to you: 1, the sample in the freezing process, the temperature will gradually decrease, you can take out the sample and then warm up for a period of time, continue to dry, so that you can shorten the drying time
.

2.
Before starting the vacuum pump, check whether the outlet valve is tightened, whether the inflatable valve is closed, and whether the contact surface between the plexiglass cover and the rubber ring is clean and free of dirt, and the seal
is good.

3.
When preparing samples, its surface area should be expanded as much as possible, and it should not contain acid-base substances and volatile organic solvents
.

The sample needs to be completely frozen into ice, which can cause gasification ejection
if there is residual liquid.

Note that the cold trap is about -65 degrees, can be used as a low temperature refrigerator, need to wear thermal gloves to operate to prevent frostbite
.

4.
Turn off the refrigeration machine, press and hold the total opening key for more than three seconds, and turn off the switch
of the total power supply.

After the ice in the cold trap is completely reduced to water, open the water outlet valve on the left side of the chassis and start to release water, and clean the inner wall of the cold trap with a dry cloth, cover with a large sheet of filter paper to prevent dust
.

5.
Start the refrigeration machine and pre-cool for more than
30 minutes.

Place the sample into the sample holder, cover with a Plexiglass cover, and start the vacuum pump
.

After the air pressure is stabilized, the temperature and air pressure values are recorded
.

6.
Record the temperature and air pressure value
before the shutdown at any time.

7.
Close the vacuum pump and press the inflatable valve
of the control panel.

When the barometric pressure is displayed as atmospheric pressure, open the plexiglass cover and remove the sample
.