Slugging can be prevented if the containers are located at a height that ensures that the design resistance that occurs in the receiving pipelines is significantly exceeded, or when this method is unacceptable for design reasons, constant pressure is applied into the container with inert gas, gaseous hydrocarbons, etc.

Relative punching resistance is not

Schematically in Fig. 89 shows a polyethylene microcolumn with an automatic device that makes working with it easier. The microcolumn is loaded with an ion exchanger with a grain size of 20-40 microns and a layer height of 50-150 mm. Such a layer has a high hydrodynamic resistance, and solutions are forced through the ion exchanger at an excess pressure in the upper part of the microcolumn of 0.5-1.5 07. The drop counting sensor is two platinum wires connected to 5-10 V. A falling drop of electrolyte solution closes the electrical circuit and the resulting pulse is transmitted to the control unit, a component of which (as a drop counter) is, for example, a radiometric conversion unit. When the number of drops specified by the control device is reached, the latter, using a three-way valve driven by a solenoid, disconnects the column from the source of compressed air (cylinder, compressor) and the forcing of the solution stops. The installation is convenient for both simple ion exchange separations at small volumes (5-

Absolute resistance pushing, n,. and-, not me-

Absolute punching resistance in

Punching resistance according to Mullen,

Relative punching resistance, MN/m

Resistance to pushing the material through the head, sufficient to obtain the necessary compression of the powder by the plunger, arises due to the thermal expansion of fluoroplastic -4 in the heated zone of the head and its friction against the walls of the head. If it is necessary to increase pressure on the material, the cooled product is braked near the exit from the head.

As already mentioned, the speed of the chromatographic process is greatly influenced by the size of the ion exchanger grains. As the grain size decreases, the peaks in the output curves become sharper and the separation efficiency improves. For practical purposes, quite satisfactory results are obtained by using grains of 0.1-0.25 and even 0.25-0.5 mm in size; to separate mixtures of ions with similar properties (for example, rare earth elements), ion exchangers with smaller particles are used. Reducing the grain size has the disadvantage that it leads to a sharp increase in the resistance to liquid flow through the column; therefore, when using finely dispersed ion exchangers, it is necessary to resort to forced pressing of the solution through the column (for example, with compressed air).

There is an opinion that HMCs have a positive effect on such physical and mechanical properties of paper as breaking length, punching resistance, fracture resistance, bulk density, transparency, and negatively the tear resistance of paper, porosity, light resistance, and constancy of paper dimensions.

Resistance to deformation when pushing under a load of 4.8 N at 200°C, % Specific volumetric electrical resistance. Ohm -cm Dielectric constant at 10 Hz Angle tangent Dielectric Losses at 10, Hz

As part of the composition, the concentration of PAA and crosslinker is selected in such a way that the crosslinking reaction occurs after a period of time sufficient to carry out the injection and pressing of the composition. The slow crosslinking speed allows the use of large-volume slugs of PAA solutions. In the case of VUS, more concentrated solutions of PAA and crosslinker are used, which leads to the rapid formation of polymer gels. The polymer hydrogels formed in the formation have very low mobility, a high residual resistance factor and pronounced viscoelastic properties. VUS are especially effective in highly heterogeneous and fractured formations with weak hydrodynamic connection between individual productive layers containing oil of high viscosity. Polymer technologies of the second group are effective at the late stage of development, when the water cut of the produced oil is more than 60%. In recent years, SPS technology in the form of large-volume rims has been developed and applied.

It has been established that, all other things being equal, with an increase in the content of HMC in cellulose, the resistance of paper made from it to punching increases. It is assumed that the adhesive effect of HMC, similar to the adhesive effect of starch introduced into paper pulp, is manifested here. This is confirmed by experiments on the artificial introduction of HMC into paper pulp. It is assumed that HMC, when swelling, creates transverse flexible bonds between adjacent fibers. Swellability in water is associated with the plasticity of fibers when immersed in water. The higher the HMC content, the greater the ductility of the fibers when immersed in water. From above

V, I. ​​Andreev and E. S. Zimina, studying the paper-forming properties of cellulose fibers from larch wood depending on the content of lignin and HMC in them, showed that with an increase in the HMC content from 6.6 to 19.87o, the breaking length and resistance increased fracture and punching, while tear and tensile resistance indicators decreased. According to other data, to obtain cellulose with high tear resistance, a high xylan content should be ensured.

V. K-Malyshkina and A. I. Bobrov, studying the strength characteristics of fibrous semi-finished products obtained from larch wood using sulfite methods, came to the conclusion that their strength characteristics depend on the pH of the cooking solution. In particular, the semi-finished product of bisulfite cooking (pH 4.5) had better strength characteristics than that of acid sulfite cooking (pH 2); the semi-finished product obtained under alkaline sulfite cooking (pH 12) had higher strength compared to the semi-finished product of monosulfite cooking . An increase in the xylan content caused an increase in the coefficient of resistance of castings to tearing and bursting, and an increase in the glucomannan content was accompanied by a decrease in

It has been established that the addition of HMC reduces the grinding time required to achieve maximum paper strength, leads to an increase in tear length, fracture resistance and bursting, while tear resistance is often reduced,

According to E.V. Novozhilov et al. , HMC, sorbed from monosulfite cooking liquors, improves the grindability and paper-forming properties of unbleached sulfite cellulose, increases the breaking length, and the resistance to punching and fracture of paper castings. The greatest increase in strength indicators was achieved by adding 1-3 mg of HMC per 1 g of cellulose.

Interesting experiments were carried out on neutral sizing using black liquors from viscose production. Black liquor containing HMC, obtained after dialysis of squeeze alkali, after concentration was mixed with alum, resulting in the formation of a solution of sodium aluminate with 10-12 g of HMC per 1 g of NaOH. The solution was added to the cellulose during grinding in the Iokro mill. As a result, there was a significant reduction in grinding time, improvement in physical and mechanical properties and sizing of the resulting paper. According to researchers, thanks to this additive, amounting to about 25 kg of HMC per 1 ton of fibrous material, the increase in breaking length was 25-30%, the bursting resistance increased by 30-40%, the number of double bends - by 2-4 times and the degree of sizing - by 10-15%.

The material of the frames and plates is AL9V aluminum. All surfaces in contact with the product are coated with bakelite varnish. Diatomite is used for filtration (TU 6-08-1-62). The melamine resin cellulose backing board must comply with following conditions thickness - 1.8-2 mm

Punching resistance. This indicator of paper quality cannot be considered one of the main ones. It may be important for some types of packaging and wrapping paper, for which, in some cases, a wet burst resistance rating must also be provided.[...]

Punching resistance is one of the main indicators of the strength of many types of papers, although it is a purely empirical criterion, depending on both tear resistance and elongation. There are absolute punching resistance, relative punching resistance - reduced to the weight of 1 m of paper of 100 g and punching index - absolute punching resistance referred to the weight of 1 m of paper. Punching resistance is equal to the maximum pressure that a paper sample in the shape of a circle with a diameter of (30.5+0.025) mm can withstand immediately before destruction.[...]

Punch resistance is a complex function of tear resistance and elongation of paper before breaking. It has been experimentally established that the considered indicator of paper strength increases with an increase in the absolute values ​​of the indicators of its breaking load and elongation at break and when the ratio of the elongation of paper in the machine direction to its elongation in the transverse direction approaches unity. [...]

The type of cardboard is selected based on the values ​​of its punching resistance.[...]

Thus, to obtain the maximum value of punching resistance, the humidity of the paper must be optimal, at which there is no strong weakening of the interfiber bonds and at the same time a sufficiently high degree of elongation of the paper is observed. This paper moisture content is approximately 8-9%.[...]

The strength of corrugated cardboard is characterized by its punching resistance, in-plane compression resistance and fracture resistance.[...]

The presence of molecules with short chains adversely affects the fracture resistance, breaking length, elongation, tear resistance and bursting resistance of films prepared from cellulose derivatives and the strength of cellulose acetate filaments. Fractions with a smaller range of viscosity (molecular weight) produce nitro films with greater fracture resistance than films from unfractionated material with the same average viscosity or from mixtures of substances with high and low viscosity 167]. The tensile strength and other indicators of the mechanical strength of films made from cellulose derivatives (acetate, acetobutyrate, nitrate and ethyl ether) gradually decrease as the degree of polymerization decreases from 1000 to approximately 200. With a further decrease in the DP, the strength decreases sharply. The mechanical properties appear to depend largely on the position of the maximum on the molecular weight distribution curve and on the uniformity of the molecular weight distribution in the (ethyl ether) films. Sukne and Harris believe that the mechanical properties of cellulose acetate films depend on the number-average molecular weight and, in addition, the mechanical properties of mixtures of fractions with different molecular weights are in the nature of the weight-average values ​​of the properties (for example, tensile strength) of the components of the mixture. In the interval they studied there is linear dependence between tensile strength and chain length.[...]

Paper made from long fibers is characterized by a higher degree of crushing resistance. With an increase in the grinding degree of the paper pulp, the bonding forces between the fibers in the paper increase. At the same time, the crushing resistance also increases. However, an excessively high degree of grinding of the paper pulp reduces the crushing resistance, which is associated with a noticeable shortening the fibers and reducing the degree of elongation of the paper before breaking. [...]

Changes in some paper properties (breaking length, volume weight, resistance to punching and fracture) during pressing on presses various designs when working with non-woven cloth and P-181 cloth. The experiments were carried out at pressures of 15, 30, 50 and 70 kgf/cm, speed 200 m/min, cloth dryness before the press 50%, paper dryness 30%. The lower shaft of all presses is 840 mm (cladding hardness 15 units), the upper one is 800 mm. For testing, we used paper samples made from unmilled bleached sulfite cellulose (grinding 18°ShR) weighing 100 g/m2.[...]

When grinding cellulose in the presence of sodium chloride, the paper's breaking length and punching resistance significantly increase. If, when forming a paper sheet, the salt is washed out, the quality of the paper decreases again. When salt is added to a mass ground in distilled water, the degree of grinding increases, which, however, does not affect the strength of the paper. The presence of electrolytes affects the surface tension of the liquid. That's why chemical composition water used in the grinding and preparation department and for diluting the pulp before the paper machine must be completely stable.[...]

The permanganate number of the resulting cellulose is 23 units; For the production of paper and cardboard, cellulose is bleached. Punching resistance is higher than for kettle pulp periodic action; the breaking length is the same.[...]

Strength and physical properties paper also depends on the pH of the environment in which the grinding takes place. At a pH value of 6.3 to 3.1, the bulk density of the paper, breaking length and bursting resistance are reduced. Likewise, the strength properties of paper are adversely affected by alkaline environment. A pH value of 8 produces paper that has satisfactory strength with relatively little energy required for grinding.[...]

From various types starch used for the surface coating of paper, potato starch is absorbed to the greatest extent into the base paper, significantly increasing the resistance to punching and plucking (i.e., separation of individual fibers and even part of the insufficiently tightly bound surface layer of paper from the surface of the paper during printing). This type of starch reduces whiteness less than others and requires least amount enzymes during enzymatic processing. Since any type of starch is food product, when surface processing of paper, it is desirable to replace it or at least reduce consumption. Therefore, when surface processing of paper in a size press, part of the starch is successfully replaced with urea-maldehyde resin, wax and paraffin dispersions of Na-CMC and latexes. Sometimes starch is completely excluded.[...]

IN summer time year, the duration of grinding increases by 5-8% while the strength properties of paper decrease. When grinding the mass at elevated temperatures, the breaking length and bursting resistance increase much more slowly than at lower temperatures. Only the tear resistance increases with increasing temperature during grinding. It was found that when grinding fibrous materials stored in an air-dry state, the most favorable temperature is 30 ° C. At a lower temperature, the fat content of the grind increases faster. The effect of temperature is especially noticeable when grinding parchment cellulose with high content hemicelluloses.[...]

In the first Kamur installations, the mass was unloaded from the digester at the cooking temperature, that is, at 170-175°. However, studies of the blown mass have shown that some mechanical qualities of cellulose (resistance to pushing and tearing, grindability) are lower than those of cellulose cooked under the same conditions, but in periodic digesters. Decline mechanical properties cellulose is caused by exposure to metal devices during high temperature and the presence of alkalinity in the waste liquor. Fiber separation occurs, promoting the dissolution of hemicelluloses and reducing the strength of the fibers. With a decrease in temperature and weakening.[...]

Tests during which the sample slipped between the pressing surfaces or the sample ruptured along the perimeter are not taken into account. It is allowed to test several samples at the same time, folded with the same side up, provided that the bursting resistance of the package is at least 70 kPa. The resulting value in this case is divided by the number of samples.[...]

Samples of parchment measuring 70X70 mm are immersed in water one at a time. The temperature of the water in the bath during testing should be (20±2)°C. After 15 minutes, the samples are removed from the water, placed between two sheets of filter paper, and excess water is removed. Then the punching resistance is determined according to GOST 13525.8-78.[...]

The solid residue after cooking was washed, ground in a disc mill until separated into fibers and in a centrifugal grinding apparatus - up to 35° SR, castings weighing 150 g/m2 were tested using standard methods. The experimental values ​​of the output parameters (averages for two experiments) are given in table. 61; serial numbers in column 1 correspond to the experiment numbers in table. 45. The initial information necessary for synthesis is in table. 62. The best and worst values ​​of the output parameters y/+> and y/-) are taken from table. 61 and rounded. Since the purpose of the experiment was to obtain paper - the basis for corrugation, the largest weights b; = 1 were assigned to the indicators V5 and uv, included in GOST 7377-69, as well as the parameter y, which most influences the economics of the process. The remaining output parameters are assigned lower weights.[...]

Many researchers have studied the effect of pressing on the physical properties and structure of paper. The experiments of the author, G. Mak and G. Bollo showed that with an increase in linear pressure, the breaking length of paper can be increased by 3 times, the volumetric weight, the number of double bends, and bursting resistance significantly increase, but the porosity of the paper worsens.[...]

The variable factors were the proportions of pine (X(), larch (X2) and spruce (X3) fractions in wood raw materials. The experiments were carried out in accordance with the third-order Scheffe plan; all cooking was repeated twice with randomization. The results were assessed by a number of indicators of the strength of the castings. As As an example, we consider the change in one of the indicators - punching resistance.[...]

When the temperature of the blown pulp is reduced to 93°, its performance is not inferior to, and in some cases even exceeds, the performance of pulp obtained in laboratory batch cooking. Cellulose cooked in Kamur installations is homogeneous; fluctuations in quality during the day are insignificant. For unbleached cellulose, the mechanical properties are higher: punching resistance by 15-18%, tear resistance by 7-10%, breaking length by 10-12%.

GOST 13525.8-86

Group K69

INTERSTATE STANDARD

SEMI-FINISHED FIBER PRODUCTS, PAPER AND CARDBOARD

Method for determining bursting resistance

Fiber intermediate products, paper and board. Method for determination of resistance to bursting

MKS 85.040
85.060
OKSTU 5409

Date of introduction 1988-01-01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of Forestry, Pulp and Paper and Woodworking Industry of the USSR

DEVELOPER

N.G. Logvinova

2. APPROVED AND ENTERED INTO EFFECT by the Resolution State Committee USSR according to standards dated May 15, 1986 N 1243

3. Inspection frequency - 5 years

4. The standard fully complies with ST SEV 4239-83, international standards ISO 2758-83*, ISO 2759-83*
________________
* Access to international and foreign documents mentioned here and further in the text can be obtained by following the link to the website http://shop.cntd.ru. - Database manufacturer's note.

5. INSTEAD GOST 13525.8-78 and GOST 13648.7-78

6. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS

7. The validity period was lifted according to Protocol No. 2-92 of the Interstate Council for Standardization, Metrology and Certification (IUS 2-93)

8. EDITION (July 2007) with Amendment No. 1, approved in November 1988 (IUS 2-89)


This standard applies to semi-finished fibres, paper and cardboard, including corrugated cardboard, and establishes a hydraulic method for determining bursting strength.

The method consists of creating a smoothly increasing hydraulic pressure acting through a rubber diaphragm on the surface of one side of a sample clamped in a ring, and determining the pressure value at which the sample is destroyed.

1. SAMPLING

1. SAMPLING

1.1. Sampling of wood pulp - according to GOST 16489.

1.2. Sampling of cellulose - according to GOST 7004.

1.3. Sampling of paper and cardboard - according to GOST 8047.

2. EQUIPMENT

2.1. For testing, a hydraulic device with an electric drive must be used that meets the requirements specified in the drawing and in tables 1 and 2.

Drawing. Hydraulic device with electric drive

Table 1

table 2

Note. It is allowed to use devices with pressure gauges that have other measurement limits, as well as devices with electronic sensors.

2.1.1. The diaphragm transmitting pressure to the test specimen must be made of elastic rubber capable of uniform recovery from deformation under repeated loads. The material and shape of the diaphragm must ensure the dimensions of the bulging boom indicated in Table 2.

2.1.2. The clamping device in accordance with the drawing and Table 1 must ensure reliable and uniform fastening of the test sample without damage and completely prevent its sliding during testing.

The clamping surfaces of the clamping rings must be flat and parallel to each other and have spiral or concentric grooves of an A-shaped section, as indicated in the drawing.

The clamping force must correspond to the values ​​indicated in Table 2. For corrugated cardboard, the clamping force must be such that the sample does not slip and the smooth layers are not deformed.

To measure pressure in the clamping system, pressure gauges in accordance with GOST 2405 must be used.

On a PGB type device for testing semi-finished products and paper, the pressure in the clamping system must be at least 2000 kPa, on a PGK type device for testing cardboard - at least 3200 kPa.

2.1.3. Pressure gauges that record the pressure at which the sample is destroyed must comply with the requirements of GOST 2405, accuracy class 0.6, and must be equipped with control arrows.

The scale division of pressure gauges for thin papers should be no more than 10 kPa.

2.1.4. The hydraulic system of the device must be filled with distilled glycerin in accordance with GOST 6824.

The fluid supply rate under the diaphragm must be uniform and correspond to that given in Table 2.

Air bubbles in hydraulic system not allowed.

The automatic device must stop supplying liquid at the moment the sample ruptures.

3. PREPARATION FOR THE TEST

3.1. To test semi-finished products, five castings are made: for wood pulp - according to GOST 16296, for cellulose - according to GOST 14363.4. Two test locations are marked on each casting.

3.2. From the sample sheets of paper and cardboard, 10 sheets are randomly selected for testing and two samples are cut from each, making a mark on the same side of all samples. The dimensions of the sample must be such that it covers the entire surface of the clamping ring.

Samples must be free of wrinkles and damage, and if possible without watermarks.

3.3. Samples are conditioned according to GOST 13523. Relative humidity, temperature and conditioning time must be specified in the standards for specific products.

4. CONDUCT OF THE TEST

4.1. Tests are carried out under the same atmospheric conditions under which the samples were conditioned.

4.2. The sample is placed on the lower clamping ring of the device so that the entire surface of the ring is covered. Fix the sample in the clamping device with the test side down and gradually increase hydraulic pressure until the sample is destroyed.

The pressure gauge readings are taken with an accuracy of 1 scale division. The measured value must be within the range of 25 to 75% of the maximum scale value, but not beyond the range of 15 to 85% of the full scale.

Conduct five determinations on each side for semi-finished fibrous products and ten determinations on each side for paper and cardboard.

If there are appropriate instructions in the standards for specific products, unilateral tests of ten samples are carried out.

(Changed edition, Amendment No. 1).

4.3. paper with low value the bursting resistance is tested in the form of a stack of several samples, provided that the bursting resistance of the stack must be at least 70 kPa. All samples in the stack should be oriented parallel and placed with the same side up; the obtained value of punching resistance should be divided by the number of samples.

5. PROCESSING RESULTS

5.1. Absolute punching resistance, kPa, is calculated using the formula

where is the sum of the pressure gauge readings for all tests, kPa;

- number of tests performed.

5.2. Relative punching resistance, reduced to the conventional mass of products with an area of ​​1 m 100 g, , kPa, is calculated using the formula

where is the mass of products with an area of ​​1 m2, g.

5.4. The final test result is taken as the arithmetic average of the results of all tests for both sides, or separately for each side, depending on the instructions in the regulatory and technical documentation for a specific product.

5.5. Test results are rounded to the nearest three significant figures.

The relative error in determining the punching resistance does not exceed ±9% with a confidence level of 0.95.



Electronic document text
prepared by Kodeks JSC and verified against:
official publication
Paper and cardboard. Test methods: Sat. GOST. -
M.: Standartinform, 2007

INTERSTATE STANDARDS

PAPER AND CARDBOARD

TEST METHODS

GOST 13525.8-86

MOSCOW - 1999

INTERSTATE STANDARD

Date of introduction 01.01.88

This standard applies to semi-finished fibres, paper and cardboard, including corrugated cardboard, and establishes a hydraulic method for determining bursting strength.

The method consists of creating a smoothly increasing hydraulic pressure acting through a rubber diaphragm on the surface of one side of a sample clamped in a ring, and determining the pressure value at which the sample is destroyed.

1. SAMPLING

1.1. Sampling of wood pulp - by GOST 16489.

1.2. Cellulose sampling - by GOST 7004.

1.3. Sampling of paper and cardboard - by GOST 8047.

2. EQUIPMENT

2.1. For testing, a hydraulic device with an electric drive must be used that meets the requirements specified in the drawing and in the table. And .

Table 1

mm

table 2

Note . It is allowed to use devices with pressure gauges that have other measurement limits, as well as devices with electronic sensors.

(Changed edition, Amendment No. 1).

2.1.1. The diaphragm transmitting pressure to the test specimen must be made of elastic rubber capable of uniform recovery from deformation under repeated loads. The material and shape of the diaphragm must ensure the dimensions of the bulging boom indicated in the table. .

2.1.2. Clamping device in accordance with the drawing and table. should ensure reliable and uniform fastening of the test sample without damage and completely prevent its sliding during testing.

The clamping surfaces of the clamping rings must be flat and parallel to each other and have spiral or concentric grooves V -shaped section, as indicated in the drawing.

The clamping force must correspond to the values ​​indicated in the table. . For corrugated cardboard, the clamping force must be such that the sample does not slip and the smooth layers are not deformed.

To measure pressure in the clamping system, pressure gauges in accordance with GOST 2405 must be used.

On a PGB type device for testing semi-finished products and paper, the pressure in the clamping system must be at least 2000 kPa, on a PGK type device for testing cardboard - at least 3200 kPa.

2.1.3. Pressure gauges that record the pressure at which the sample is destroyed must comply with the requirements GOST 2405 , accuracy class 0.6, and must be equipped with control arrows.

The scale division of pressure gauges for thin papers should be no more than 10 kPa.

2.1.4. The hydraulic system of the device must be filled with distilled glycerin according to GOST 6824.

The rate of fluid supply under the diaphragm must be uniform and correspond to that given in the table. .

Air bubbles are not allowed in the hydraulic system.

The automatic device must stop supplying liquid at the moment the sample ruptures.

3. PREPARATION FOR THE TEST

3.1. To test semi-finished products, five castings are made: for wood pulp - according to GOST 16296 , for cellulose - according to GOST 14363.4 . Two test locations are marked on each casting.

3.2. From the sample sheets of paper and cardboard, 10 sheets are randomly selected for testing and two samples are cut from each, making a mark on the same side of all samples. The dimensions of the sample must be such that it covers the entire surface of the clamping ring.

Samples must be free of wrinkles and damage, and if possible without watermarks.

3.3. Samples are conditioned according to GOST 13523 . Relative humidity, temperature and conditioning time should be specified in product specific standards.

4. CONDUCT OF THE TEST

4.1. Tests are carried out under the same atmospheric conditions under which the samples were conditioned.

4.2. The sample is placed on the lower clamping ring of the device so that the entire surface of the ring is covered. The sample is secured in the clamping device with the test side down and the hydraulic pressure is gradually increased until the sample is destroyed.

The pressure gauge readings are taken with an accuracy of 1 scale division. The measured value must be within the range of 25 to 75% of the maximum scale value, but not beyond the range of 15 to 85% of the full scale.

Conduct five determinations on each side for semi-finished fibrous products and ten determinations on each side for paper and cardboard.

If there are appropriate instructions in the standards for specific products, unilateral tests of ten samples are carried out.

(Modified edition, Rev. No. 1).

4.3. Paper with a low punching resistance value is tested in the form of a stack of several samples, provided that the punching resistance of the stack should be at least 70 kPa. All samples in the stack should be oriented parallel and placed with the same side up; the obtained value of punching resistance should be divided by the number of samples.

5. PROCESSING RESULTS

5.1. Absolute bursting resistanceR O , kPa, calculated by the formula

Where S p - sum of pressure gauge readings for all tests, kPa;

P -number of tests performed.

5.2. Relative punching resistance, reduced to the conventional mass of products with an area of ​​1 m2 100 g, P w, kPa, calculated by the formula

Where m- mass of products with an area of ​​1 m2, g.

5 3. Punching indexX, kPa/g, calculated by the formula

5.4. The final test result is taken as the arithmetic average of the results of all tests for both sides, or separately for each side, depending on the instructions in the regulatory and technical documentation for a specific product.

5.5. Test results are rounded to three significant figures.

The relative error in determining the punching resistance does not exceed ±9% with a confidence probability of 0.95.

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of Forestry, Pulp and Paper and Woodworking Industry of the USSR

DEVELOPER

I.G. Logvinova

2. APPROVED AND ENTERED INTO EFFECT by Resolution of the USSR State Committee on Standards dated May 15, 1986 No. 1243

3. Inspection frequency - 5 years

4. The standard fully complies with ST SEV 4239-83, international standards ISO 2758-83, ISO 2759-83

5. INSTEAD GOST 13525.8-78 and GOST 13648.7-78

6. REFERENCE REGULATIVE AND TECHNICAL DOCUMENTS

7. The validity period was lifted according to Protocol No. 2-92 of the Interstate Council for Standardization, Metrology and Certification (IUS 2-93)

8. REISSUE (October 1998) with Amendment No. 1, approved in November 1988 (IUS 2-89)

INTERSTATE STANDARDSPAPER AND CARDBOARD

TEST METHODS

GOST 13525.8-86

MOSCOW - 1999

INTERSTATE STANDARD

Date of introduction 01.01.88

This standard applies to semi-finished fibres, paper and cardboard, including corrugated cardboard, and establishes a hydraulic method for determining bursting strength. The method consists of creating a smoothly increasing hydraulic pressure acting through a rubber diaphragm on the surface of one side of a sample clamped in a ring, and determining the pressure value at which the sample is destroyed.

1. SAMPLING

2. EQUIPMENT

Table 1

table 2

3. PREPARATION FOR THE TEST

4. CONDUCT OF THE TEST

5. PROCESSING RESULTS

Where S p is the sum of the pressure gauge readings for all tests, kPa; P - number of tests performed. 5.2. Relative punching resistance, reduced to the conventional mass of products with an area of ​​1 m2 100 g, P w, kPa, calculated by the formula

Where m is the mass of products with an area of ​​1 m 2, g. 5 3. Punching index X , kPa/g, calculated by the formula

5.4. The final test result is taken as the arithmetic average of the results of all tests for both sides, or separately for each side, depending on the instructions in the regulatory and technical documentation for a specific product. 5.5. Test results are rounded to three significant figures. The relative error in determining the punching resistance does not exceed ±9% with a confidence probability of 0.95.

INFORMATION DATA