1, Instrument appearance inspection
The flash point instrument should have identification such as name, model, manufacturer, and factory number. All parts of the instrument are complete and well connected. The knobs and keys should work normally without any defects that affect the performance of the instrument.
The matching test cup of the flash point tester is in good condition, with clear and smooth inner wall markings. The Binskey Martin closed flash point instrument should have a cup cover that matches the test cup.
2, Pre calibration preparation
1. Placement of flash point meter
The instrument should be installed in a room without airflow and placed on a flat plate. If conditions permit, the instruments should be placed in a fume hood. During the test, the ventilation equipment must be turned off and then turned on after the test is completed.
2. Cleaning of the test cup
Select a suitable cleaning solvent based on the characteristics of the latter measurement object. Low volatile aromatic (benzene free) solvents can be used to remove traces of oil. Mixed solvents such as toluene acetone methanol can effectively remove colloidal deposits.
Rinse the test cup and lid with cleaning solvent to remove any traces of gum or residue left by the previous test. Then dry the test cup with clean air.
3. Loading of reference materials
Select a flash point reference material close to the commonly used measurement temperature of the instrument, and fill the test cup to ensure that the top of the sample meniscus is accurately located on the filling line of the test cup.
When the flash point is turned on and calibrated on time, there should be no bubbles and foam in the test cup. Otherwise, it should be carefully removed and ensure that the liquid level of the sample is at the correct position. If foam exists on the surface of the sample at the later stage of the test, the result will be invalid.
3, Indicator repeatability
When calibrating an automatic flash point instrument, the standard value of the reference material should be set to the expected flash point value. Manual instrument calibration
The standard value should be considered as the expected flash point value, and attention should be paid to controlling the heating rate during the stage.
Record the ambient atmospheric pressure near the instrument during testing
(1) Open flash point meter measurement steps
Place the test cup with reference material on the heating plate and insert the thermometer vertically into the instrument, so that the bottom of the temperature sensitive bubble is approximately 6 mm away from the bottom of the test cup.
Ignite the test flame and adjust the flame diameter to 3.2 millimeters! Millimeters. If the instrument is equipped with a metal comparison ball, the diameter of the metal comparison ball should be the same as that of the metal comparison ball.
At the beginning of heating, the heating rate of the sample is 14/in~17/min. When the sample temperature reaches about 56 ° C before the expected flash point, the heating rate slows down, resulting in a heating rate of 5 ° C min~6 ° C/min at 23 ° C ± 5 ° C. Before flash point C. To avoid interfering with sample vapor, it is necessary to avoid walking or breathing around the test cup.
At 23 ℃± 5 ℃ before the expected flash point, the test flame is swept by the test flame. Sweep and smooth every 2 ℃ increase in temperature. The time required for the test flame to pass through the test cup is approximately 1 second. The test flame should pass through the center of the test cup at right angles to the diameter of the test cup passing through the thermometer. Sweeping should be carried out along a straight line or at least 150 mm radius
(2) Measurement Procedure for Closed Flash Point Meter
Place the test cup with reference materials into the heating chamber, ensure that the test cup is in place or the locking device is connected, and insert a thermometer into the instrument.
Adjust the flame diameter to 3 mm~4 mm by igniting the test flame source. For equipment equipped with an electronic igniter, the electronic igniter should be turned on according to the requirements of the instrument manual and its strength adjusted.
During the entire experiment, the heating speed of the sample was 5/min-6/min, and the stirring speed was 90r/min-120r/min.
When the sample is heated below the expected flash point and ignited at 23+5, stop stirring during the ignition process. The flame descends into the vapor space of the test cup within 0.5 seconds, stays at this position for 1 second, and then rapidly rises back to its original position.
When the expected flash point of the sample is not higher than 110 ℃, ignite once every time the expected flash point of the sample is higher than 110 ℃; When the expected flash point of the sample exceeds 110 ℃, ignite once every time the expected flash point of the sample increases by 2 ℃.
When a significant flashover occurs in the test cup caused by a fire source, immediately record the thermometer reading as the observed flash point T1.
If the difference between the recorded flash point temperature and the initial ignition temperature is less than 18 ℃ or higher than 28 ℃, the result is invalid. The initial ignition temperature should be re measured and adjusted until a valid measurement result is obtained, that is, the observed flash point and initial ignition temperature should be within the range of 18-28 ℃.
To calibrate the manual flash point timer, the test should be conducted strictly in accordance with the above heating rate and flame size requirements. When calibrating the automatic flash point instrument, the heating speed is set by the instrument itself, and the flame size is adjusted according to the above requirements. The flash point meter ignited with a resistance wire should adjust the strength of the ignition head according to the specifications.