1, Overview
Specific surface area(SSA) refers to the total area per unit mass
of material. Divided into two categories: external surface area and
internal surface area. The national standard unit is square meters
per gram. The ideal non porous material only has an external
surface area,. This instrument adopts the principle of ventilation
method to measure the time (t) required for air to pass through a
certain amount of sand column, and then substitute the time (t)
into the given formula to calculate the actual specific surface
area of the silicon sand sample for casting.
This instrument measures the porosity and actual specific surface
area of silicon sand (raw sand, recycled sand) for casting
according to the GB/T 9442-1998 standard "Silicon Sand for Casting"
and Appendix B "Method for Determining the Angular Factor of
Silicon Sand for Casting". Using SM high-precision timing
instrument, the timing accuracy is high, and it can be set to 999
seconds and 99 milliseconds. Infrared sensors have high sensitivity
and strong anti-interference ability. Automated control system, one
click completion of the entire measurement process.
2, Structure and principle of the instrument
1. Structure of the instrument: (see Figure 1)
2. Working principle of the instrument: (see Figure 2)
The working principle of the instrument is to remove the mud from
the original sand through strong washing, and after drying, weigh
50 ± 0.01g and put it into a sand bearing glass scale test tube. It
can also be sieved and a single sieve sand can be taken as the
sample. Gently tap the test tube with a small wooden stick until
the volume of sand no longer decreases, record the volume of sand V
(ml), and measure or read the height of the sand column h (cm).
Then fix the sand bearing test tube on the test tube seat and seal
it. Turn on the power switch and observe if the timing instrument
displays 000.00. Otherwise, press the up key (▲) to return to zero
(because this meter has a power-off record keeping function). Press
the "Start" button (the instrument will automatically complete the
entire measurement process), and the three-way solenoid valve DZ
and the exhaust fan will work simultaneously to raise the liquid
level to the infrared control sensor K1. The solenoid valve DZ and
the exhaust fan will stop working at the same time, and the
instrument will automatically switch to timing measurement. When
the float liquid level reaches the infrared timing sensor K2, the
instrument will start timing, and when the liquid level reaches the
infrared timing sensor K3, timing will stop. Record the timing
time, and the test will end. Perform 5 consecutive tests, discard
the larger and smallest values of the recorded time, and calculate
the average time t. Substitute the measured time (t) into the
formula to calculate the actual specific surface area of the
measured sand.
3, Technical parameters
1. Measurement range: 0.001-0.1 ㎡/g
2. Timing range 0-99.9s
3. Power supply: 220V ± 10% 50Hz
4. Pipeline sealing: The liquid level drops by no more than 5mm
within 10 minutes
5. Repeatability: Measure the same sand sample, and the difference
between the larger and smallest values of the ten measurements of
ventilation time should not exceed 0.5 seconds
