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LY/T 1794-2019: Wood chips used for wood-based panel
Status: Valid LY/T 1794: Evolution and historical versions
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Wood chips used for wood-based panel
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Basic data | Standard ID | LY/T 1794-2019 (LY/T1794-2019) | | Description (Translated English) | Wood chips used for wood-based panel | | Sector / Industry | Forestry Industry Standard (Recommended) | | Classification of Chinese Standard | B70 | | Classification of International Standard | 79.060 | | Word Count Estimation | 10,197 | | Date of Issue | 2019-10-23 | | Date of Implementation | 2020-04-01 | | Older Standard (superseded by this standard) | LY/T 1794-2008 | | Regulation (derived from) | Announcement of the State Forestry and Grassland Administration No. 17 of 2019 | | Issuing agency(ies) | State Forestry and Grassland Administration | LY/T 1794-2019: Wood chips used for wood-based panel---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
(Wood chips for wood-based panels)
ICS 79.060
B 70
LY
People's Republic of China Forestry Industry Standard
Replacing LY/T 1794-2008
Wood chips for wood-based panels
Wood chips used for wood-based panel
2019-10-23 released
2020-04-01 implementation
Published by the National Forestry and Grassland Administration
Foreword
This standard was drafted in accordance with the regulations given in GB/T 1.1-2009.
Please note that some content of this document may involve patents, and the issuing authority of this document is not responsible for identifying these patents.
This standard replaces LY/T 1794-2008 Wood-based Panels.
Compared with LY/T 1794-2008, the main technical changes of this standard are as follows.
──Modified standard name and English translation (see cover).
──Added and modified some terms and definitions (see Chapter 3).
-Added classification (see Chapter 4).
── Modified requirements (see Chapter 5).
──Added inspection instruments and tools (see 6.1).
──The determination of the ratio of retained wood chips and qualified wood chips in each sieve layer has been modified (see 6.2).
──Modified the determination of bark content, the determination of decayed wood chips and the method of distinguishing needles and hardwood chips (see 6.3 and 6.4).
──Added a method for determining non-woody mixtures (see 6.5).
──Modified the determination of the moisture content of wood chips and the method of distinguishing between needle and broad-leaved wood chips (see 6.6 and 6.7).
── Added sampling and judgment (see Chapter 8).
This standard was proposed and managed by the National Timber Standardization Technical Committee (SAC/TC41).
This standard was drafted. Heilongjiang Institute of Wood Science, Heilongjiang Wood-based Panel and Log Saw Product Quality Supervision and Inspection Station, Lu
Li Group Co., Ltd., Shandong Kaiyuan Wood Co., Ltd., Hebei State-owned Forest Management Branch of Heilongjiang Province.
The main drafters of this standard. Wang Hongzhang, Zhou Zhifang, He Jincun, Li Chenqi, Lu Lei, Song Denian, Su Yun, Cui Xiaolei, Zheng Haiwei,
Liu Yinan, Meng Xiangxiao, and Li Yanxia.
The previous versions of the standards replaced by this standard are.
──LY/T 1794-2008.
Wood chips for wood-based panels
1 Scope
This standard specifies the terms and definitions, classification, requirements, inspection methods, quantity calculation, sampling and judgment, marking,
Packaging, transportation and storage.
This standard applies to wood chips for wood-based panel production and wood chip circulation.
2 Normative references
The following documents are essential for the application of this document. For dated references, only the dated version applies to this article
Pieces. For undated references, the latest version (including all amendments) applies to this document.
GB/T 7909-2017 paper chip
3 terms and definitions
3.1
Wood chips used for wood-based panel
Wood chips with certain specifications and dimensions obtained by machining from wood as raw materials are used to make wood-based panels.
3.2
Wood chips used for particleboard
Wood chips used in the manufacture of particleboard.
3.3
Wood chips used for fiberboard
Wood chips used in the manufacture of fiberboard.
3.4
Wood chips used for special man-made board
It is used to make wood chips for directional particle board, waffle chipboard, veneer lumber, etc.
3.5
Sieve plate
A metal plate with a specific shape and a prescribed circular hole.
3.6
Effective sieve area
The actual area along the bottom of the screen.
3.7
Fines pan
A collection tray at the bottom of the shaker screen without any pores and used to catch the wood chips coming out of the screen.
3.8
Weight percent ratio of a certain screen tray
The mass of wood chips remaining on a certain layer of sieve sieve in the screening of wood chips accounts for the percentage of the total mass of wood chips before screening.
3.9
Weight percent ratio of accept chips
Samples are taken and sieved in accordance with the regulations. Except for the wood chips remaining on the first layer of sieve plate and wood chip collecting tray, the sum of the ratio of wood chips remaining in other sieve layers.
3.10
Oversize chips
Wood chips remained on the first sieve plate of the shaker sieve.
3.11
Sawdust fines
Fine woody impurities were measured on the last sieve plate of the sieve by shaking.
4 Classification
By purpose.
a) wood chips for particleboard;
b) wood chips for fiberboard;
c) Wood chips for other wood-based panels.
5 Requirements
5.1 Tree species
All needles and broad leaves are suitable for tree species.
5.2 Technical indicators
Should meet the requirements of Table 1.
Table 1 Technical indicators
Project unit Wood chipboard
Length mm 15 ～ 63 7 ～ 45
Thickness mm 2 ～ 8 3 ～ 5
Qualified wood chip ratio% ≥70
Wood chips content% ≤10 ≤2
Bark content% ≤15 ≤3
Content of decayed wood chips% ≤4
Non-wood mixture content% ≤0.5
Note. Other indicators and other technical indicators of wood chips for wood-based panels can be agreed between the supply and demand sides.
6 Inspection method
6.1 Inspection instruments and tools
──balance, accuracy 0.01g;
──Electronic scale, accuracy 0.01g;
──Stopwatch, accuracy 0.1s;
──Blast drying oven, temperature control range is 10 ～ 300 ℃, temperature resolution is 1 ℃.
──Vibration measurement sieve, sleeve screen composed of multiple sieve plates, usually 5-7 layers.
Determine the number of sieve plate layers and the pore size of the sieve plate according to the size of the largest piece of wood in the sample (target size).
The sheet is left in the middle layer or the middle two layers of the jacket sieve. Table 2 shows the combination of the number of sieve layers and the pore size of several shakers. Effective screening area of sieve plate
1200 ± 100cm2, the height of the edge of the sieve plate is not less than 80mm, the distance between the sieve plate and the sieve plate is 100mm ～ 150mm, and the bottom of the sieve plate is in accordance with every three
The circular holes and the center of the circle form an equilateral triangle. The circular holes with the same diameter are distributed regularly. All the circular holes must be complete and between the centers of any two circular holes.
The distance must be at least 1.2 times the diameter of the circular hole. The distance between the uppermost sieve plate edge and the uppermost edge of the screen sleeve is 100mm ～.200mm.
The plate is fixed and the whole screen sleeve is driven by the mechanical force to perform a nearly circular slewing motion. The frequency of vibration is ≥220 times/min, and the frequency of impact is ≥147.
Times/min, the vibration amplitude is 8mm.
Table 2 Combinations of the number of sieve layers and pore sizes
The sieve size of each sieve layer (from the left is the 1st sieve plate, sorted in order to the nth layer)
Ⅰ 31.8 28.6 22.2 9.5 4.8 Sawdust collection tray
Ⅱ 63 45 31.5 16 8 3.15 Sawdust collection tray
Ⅲ 45 40 30 10 5 Sawdust collection tray
Note. The combination of the number of layers and the hole diameter of other vibration measurement sieves shall be agreed between the supplier and the buyer.
6.2 Determination of the ratio of retained wood chips and qualified wood chips in each sieve layer
Weigh 1000g of wood chips from the sample with a balance or electronic scale. The moisture content of the sample should be less than 20%.
Air dry or constant temperature and humidity treatment until the moisture content of the sample reaches the requirements. Put it in the first layer of sieve plate of vibration measuring sieve, and move the vibration measuring sieve for 7min
± 10s, if you need to extend the screening time, it can be agreed between the supplier and the buyer.
Chip quality, accurate to 0.01g, two sieving determinations are performed in parallel, and the average of the two sieving results is the final wood chip retention ratio
And qualified wood chips ratio.
The ratio of wood chips remaining on each sieve layer is calculated according to formula (1) and is accurate to 0.01%.
Xn =
Gn × 100% ... (1)
In the formula.
Xn- ratio of wood chips remaining on each sieve layer,%;
n-sieve layer (n = 1, 2, 3, 4);
G- total sample mass, unit is gram (g);
Gn-mass of wood chips remaining on sieve layer, unit is gram (g).
The ratio of qualified wood chips is calculated according to formula (2) and is accurate to 0.01%.
Xh = X2 Xn-1 ... (2)
In the formula.
Xh- qualified wood chip ratio,%;
n-sieve layer (n = 1, 2, 3, 4).
6.3 Determination of bark content
According to the provisions of 5.3 of GB/T 7909-2017.
6.4 Determination of the content of decaying wood chips
It shall be implemented in accordance with 5.4 of GB/T 7909-2017.
6.5 Determination of nonwood content
Implemented according to 5.5 in GB/T 7909-2017.
6.6 Determination of moisture content in wood chips
Weigh.200g of wood chips from the sample with a balance or electronic scale, put it in a drying box, the temperature is 103 ℃ ± 2 ℃, and weigh every 2h
Once, until the mass difference between the two adjacent ones does not exceed 0.02g, it reaches a constant weight, which is counted as the mass of dry wood chips. The moisture content of wood chips is calculated according to formula (3).
True to 0.1%.
Wx =
Gan Chu
GG-
× 100% ... (3)
In the formula.
Wx- moisture content of wood chips,%;
G initial-mass of wood chips before baking, unit is gram (g);
G dry-the mass of wood chips after drying, the unit is gram (g).
6.7 How to distinguish between needle and hardwood chips
According to GB/T 7909-2017 5.7.
7 Quantity calculation
7.1 Volume calculation method
The unit of calculation is layered cubic meters, accurate to 0.01 layered cubic meters.
The quantity of bulk wood chips is calculated by multiplying the bottom area of the loading compartment by the average loading height of the middle, front and rear points.
The number of wood chips in the bag is converted into 8 layers of sacks (or woven bags of the same specifications) filled with seams into a layer of cubic meters (the standard size of sacks)
The size is 1050mm × 740mm).
7.2 Mass calculation method
It is calculated in ton (t) or absolute dry ton (BDT). When the total amount is more than 10t, it is accurate to 0.01t. When the total amount is below 10t,
Accurate to 0.001t.
7.2.1 Absolute dry weight calculation
The dry weight of the wood chips was calculated from the wet weight and moisture content of the wood chips. The absolute dry mass of wood chips is calculated according to formula (4).
X = G wet (1-Wx) ... (4)
In the formula.
X-wood chip absolute dry mass, unit is absolute dry ton (BDT);
G Mass of wet-wood chips at moisture content, in tons (t);
Wx-Moisture content of wood chips,%.
8 Sampling and determination
8.1 Sampling
Randomly stacked wood chips are batches every 100t. Choose one point on the top of each batch of wood chips and the middle, front, back, left, and right of each batch.
Samples are 800g ～ 1200g, and the total sampling amount is not less than 4600g. The wood chips taken from different sampling positions are mixed uniformly and used.
There are one batch of wood chips for each vehicle, one sample for each batch. During the unloading process, the samples are taken once in the middle of each door when the door is opened.
When the wood chips are unloaded to about half, they will be sampled again in the middle of the corresponding wood chip pile in front of each door.
The total number of sampling times of the vehicle is at least 10, each sampling is 400g ～ 800g, and the total sampling amount is not less than 4600g.
The tablets are mixed well and set aside.
A batch of 300 to 500 bags is transported in sacks for cars; a batch of 800 to 1200 bags is transported in trains. In each batch
Five bags are randomly selected from the inspected wood chips, and 800g to 1200g are sampled in each bag, and the total sample is not less than 4600g, which will be taken from different sampling positions
Place the wood chips and mix well.
8.2 Judgment
The four quality indicators of qualified wood chip ratio, bark content, decayed wood chip content, and non-wood mixture content all meet the requirements specified in Table 1.
Technically required wood chip products are judged to be qualified. Two or more of them do not meet the technical requirements and are judged as unqualified products; one of them
If the item does not meet the technical requirements, a second sampling re-inspection is allowed. If the re-inspection results meet the technical requirements, it is judged to be qualified.
If it is required, it is judged as unqualified.
9 Marking, packaging, storage and transportation
9.1 Signs
The wood chips in bulk shall be marked with the product name, quantity, factory name, and factory address in the on-board shipping bill.
9.2 Packaging
Each batch of wood chips should use the same specifications of non-leakage sacks or woven bags. Before using the sacks or woven bags, clean the bags and bags.
The debris on the mouth, the residual rope head, etc. should be filled and evenly packed so that the quality of each bag is kept substantially equal. After bagging, press "one pull" with hemp rope
The method sews the mouth, keeping more than 7 stitches per bag mouth, forming two "sheep horns".
The sack with the slit is lifted 0.5m high and falls naturally. The space above the sack is not more than 5cm.
9.3 Storage
Wood chips should be stored in a ventilated and dry warehouse to avoid moisture, mildew and fire.
9.4 Transport
When using special vehicles or general-purpose boxes to ship wood chips, clean the cabin thoroughly before loading the truck to remove all impurities such as sand, coal, and so on.
The car must be covered with tarpaulin or mesh.
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