The test method for the electrostatic conductivity of finished oil tanks and oil tank coatings can be carried out according to GB/T16906-1997 "Determination of the resistivity of static conductive coatings for oil tanks", as follows.
(1) Principle
When measuring in this method, a parallel electrode is placed on the surface of the sample, a DC voltage is applied between the electrodes, and the value of the current generated during the measurement is represented by the value of the surface resistivity. This method can measure the surface resistivity below 10 10 Ω.
(2) Instruments and materials
(1) The paint resistivity Tester is an instrument that can give the surface resistivity instantaneously after applying a DC voltage.
Note that this method can use the YFT resistance Tester for oil-resistant and anti-corrosion coatings.
(2) Absolute ethanol (chemically pure)
(3) The thickness of the polyester film is 0.03~0.1mm, and the resistivity is greater than 10 9 Ω.
(4) Glass adhesive tape.
(3) Sample preparation
(1) Take a clean polyester film with an area of 150mmx150mm and 140mmx140mm as the substrate, cover one on the other, and stick the edge of the small sheet and the uncovered part of the large sheet with glass adhesive tape.
(2) Clamp the two integrated substrates, vertically insert the substrates into the paint at a uniform speed, leave for 10 seconds, then take them out at the same speed, hang them in a clean place to dry naturally to form a film.
(3) Turn the substrate upside down by 180°, and use the same method to dip-coat for the second time, under constant temperature and humidity conditions (23°C±2°C, 50%±5%) until the coating film is completely cured.
(4) Use a blade to cut off the edge of the substrate with tape paper, then cut it into 6 single-layer samples of 40mmx130mm, and select the sample for testing.
Note that if the paint has primers and topcoats, samples should be prepared separately.
(4) Measurement procedure
1. Laboratory tests
(1) After cleaning the sample with absolute ethanol, heat it in an oven at 50°C±2°C for 2 hours.
(2) Take out the sample and park it for 16 hours at a temperature of 23°C±2°C and a relative humidity of less than 70%.
(3) Turn on the power switch of the instrument and put it in the "0N" position.
(4) Insert the parallel electrode terminals into the jacks marked with "+,_" symbols respectively.
(5) Place parallel electrodes on the surface of the sample.
(6) Select the appropriate range, press the measurement button 1/00, you can read.
(7) Measure the other two samples in the same way.
(8) After the test, turn the power switch to "0FF".
(9) Remove the parallel electrode terminal and place it in a dry place.
(10) Take the average value of the resistivity of the three samples as the measurement result.
2. Field test
(1) Select five flat and clean coating surfaces in the receptacle.
(2) Clean the surface of the selected coating with absolute ethanol, the cleaning area is at least 40mmx130mm, and then let it dry naturally.
(3) Test the surface resistivity of each coating respectively according to the test procedure of the test test.
(4) Take the average value of the surface resistivity of the five coatings as the measurement result.
(5) Standards for electrostatic conductivity of finished oil tanks and oil tank coatings
Measured with a paint resistivity Tester, the test results of the electrical properties of the coating should be less than 1o9a, and each test result should be within the same order of magnitude.
