Industrial formaldehyde solution (3)

4.

4.

Using bromothymol blue as an indicator, titrate the organic acid in the sample with sodium hydroxide standard titration solution

RCOOH+NaOH=RCOONa+H ₂ O

4.

4.

4.

4.

Micro burette: the capacity is 5mL, the graduation value is 0.

4.

Pipette 50.

4.

The acidity expressed in mass percentage ( calculated as formic acid ) X _{2 is} calculated according to formula (2):

In the formula: V ₂ -the volume of sodium hydroxide standard titration solution consumed by titration, mL;

C ₂ —The actual concentration of sodium hydroxide standard titration solution, mol/L;

V—volume of sample, mL;

pt—The density of the sample at a temperature of t°C, g/cm ³ ;

0.

Take the arithmetic average of the two parallel determination results as the determination result, and the difference between the two parallel determination results shall not be included in 0.

4.

According to the provisions of GB/T3143

4.
5 Determination of iron content

4.
5.
1 Analysis steps

Pipette 50.
0mL sample into a 100mL beaker, and perform determination according to GB/T3049
.

4.
5.
2 Expression of analysis results

The iron content X ₃ expressed in mass percentage is calculated according to formula (3):

In the formula; m ₂ -the iron quality obtained from the iron standard curve, mg;

V—volume of sample, mL;

pt—The density of the sample at a temperature of t°C, g/cm ³
.

Take the arithmetic average of the two parallel determination results as the determination result, and the difference between the two parallel determination results shall not exceed 5×10 ^-6 %
.

4.
6 Determination of methanol content

According to the formaldehyde content measured in Clause 4.
2 and the density measured in Clause 4.
1 of this standard, the alcohol content can be found from the "Industrial formaldehyde solution density-formaldehyde content-methanol content relationship table" (see Appendix A (standard appendix)]
.

5 Inspection rules

5.
1 The product is inspected by the quality inspection department of the manufacturer.
The manufacturer shall ensure that all the products manufactured meet the requirements of this standard, and are accompanied by a quality inspection certificate in a certain format, which includes the name of the manufacturer, address, product name, and batch number.
net weight, product grade, standard number and so on
.

5.
2 The user has the right to inspect and accept the delivered products in accordance with the provisions of the standard.
The industrial formaldehyde solution is very easy to polymerize at low temperatures.
Therefore, the user must take samples immediately after the product arrives and follow the inspection rules and test methods of this standard.
Carry out acceptance
.
If the product has already polymerized after arrival, it should be heated and depolymerized before sampling for acceptance
.

5.
3 Sampling shall be carried out in accordance with 6.
6 of GB/T6678-1986 and 2.
3.
1 of GB/T6680-1986, and the total amount of samples shall not be less than 2L
.

5.
4 After shaking the collected samples, divide them into two clean, dry, narrow-necked bottles with ground stoppers, and label them with the name of the manufacturer, product name, batch number and sampling date.
One bottle For analysis and inspection, the other bottle is kept for one month for inspection
.

5.
5 For barreled products, one batch of products filled at the same time, and one tanker for tank packaging
.

5.
6 The judgment of the inspection results shall be based on the GB/T 1250 rounding value comparison method.
When an indicator of the inspection result does not meet the requirements of this standard, samples should be taken from twice the number of packaging containers for inspection: the result of the re-inspection even if there is only one item If the index does not meet the requirements of this standard, the entire batch of products will be judged as unqualified
.

5.
7 When there is an objection to the quality of the product, the user should raise it within half a month after receiving the goods, and the supply and demand parties shall negotiate and resolve it
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6 Marking, packaging, transportation and storage

6.
1 The packaging container shall be painted with firm, durable and clear signs, which include the product name, production name, trademark, net weight and the number of this standard and the signs of "flammable liquid" and "toxic substances" in GB190
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6.
2 Industrial formaldehyde solution should be packed in dry, clean, galvanized steel drum or tank truck with corrosion-resistant lining (the net weight of each drum is 200kg)
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6.
3 When transporting, load and unload with care, avoid collision, and prevent sun and rain
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6.
4 The storage temperature of industrial formaldehyde solution is 8～40℃.
Both the manufacturer and the user should take necessary measures to reduce the polymerization and oxidation of the formaldehyde solution
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7 Security

7.
1 Industrial formaldehyde solution is flammable, and high temperature exposure and contact with open flames should be avoided
.

7.
2 Industrial formaldehyde solution is toxic, so exposure and contact should be minimized, and special care should be taken when using it to prevent contact with eyes, skin or inhalation of excessive formaldehyde gas, and avoid its strong irritation and possible allergic effects
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Related Links: Industrial Formaldehyde Solution (2)