BS 5711-2-1979 Methods of sampling and test for glycerol - Methods of sampling《甘油取样与试验方法 第2部分 取样方法》.pdf

1、BRITISH STANDARD BS 5711-2: 1979 ISO 2096:1972 Methods of Sampling and test for glycerol Part 2: Methods of sampling ISO title: Glycerols for industrial use Methods of sampling NOTEIt is recommended that this Part of BS5711 be read in conjunction with the general information given in BS5711-0”Genera

2、l introduction”, issued separately. UDC 661.188.1:547.426.1:543.05BS5711-2:1979 This British Standard, having been prepared under the directionof the Chemicals Standards Committee, was published under the authorityofthe Executive Boardand comes into effect on 30 November 1979 BSI 12-1999 The followi

3、ng BSI references relate to the work on this standard: Committee reference CIC/6 Draft for comment 75/53579 DC ISBN 0 580 10983 6 National foreword This Part of BS5711 is identical with ISO2096 “Glycerols for industrial use Methods of sampling”. A British Standard does not purport to include all the

4、 necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii,

5、pages 1 to 8, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date of issue CommentsBS5711-2:1979

6、 BSI 12-1999 i Contents Page National foreword Inside front cover 1 Scope and field of application 1 2 General principles 1 3 Particular precautions 1 4 Methods of sampling glycerols during filling 1 5 Method of sampling glycerols in drums 2 6 Methods of sampling glycerols in tanks 3 7 Sampling repo

7、rt 4 Figure 1 Examples of tapping sampler 5 Figure 2 Example of sampling tube 6 Figure 3 Example of open-ended cylindrical sampler 7 Figure 4 Example of weighted bottle for sampling from tanks 8 Publications referred to Inside back coverii blankBS5711-2:1979 BSI 12-1999 1 1 Scope and field of applic

8、ation This International Standard describes methods for sampling quantities of glycerol, either crude or refined, for industrial use, in the course of filling (seesection4), or already contained in drums (seesection5) or in transportable or fixed tanks (seesection6). 2 General principles 2.1 The pre

9、paration of a representative sample presents particular difficulties owing to the frequent heterogeneity of the lots. This can lead either to sedimentation of the solids in suspension in the case of crude glycerols, or the stratification in layers of different densities in the course of storage, par

10、ticularly if the glycerol has frozen after filling into drums or tanks and has then thawed. 2.2 It is consequently recommended to adopt, as far as possible, a procedure of sampling during filling (section4) or, at least, to carry out the sampling of the lots immediately after this operation, while t

11、he product is still homogeneous. 2.3 If glycerol that has been stored for some time is to be sampled, one of the methods described in this International Standard shall be chosen, according to the container in which the product has been stored and the details supplied as to its condition by several s

12、amples taken from different locations. 2.4 It is customary to divide the composite sample into at least three portions, each being stoppered and sealed by the sampler. One portion is for the purchaser, one for the vendor and one is kept for an independent analysis in case of dispute. 3 Particular pr

13、ecautions 3.1 In view of the very hygroscopic nature of glycerol, it is essential that samples shall at all times be protected from humidity and humid air. The containers used for mixing and storage shall be airtight and kept closed between filling and between the taking of various samples. As far a

14、s possible, sampling shall be carried out under cover, the containers particularly being protected from rain and all other accidental pollution. 3.2 The laboratory samples shall be poured into flasks of chemically resistant glass closed with ground glass stoppers. In certain cases these flasks may b

15、e closed with a screw cap closure having a polyethylene or aluminium liner. The flasks intended for laboratories shall be sealed by the responsible sampler with the aid of sealing wax. 3.3 In the case of samples containing a deposit or suspended material the containers shall be filled to only two-th

16、irds of their capacity in order to aid mixing. Otherwise the containers shall be completely filled. 3.4 All the apparatus and containers shall be clean and dry at the time of use. 4 Methods of sampling glycerols during filling 4.1 Intermittent sampling method 4.1.1 Principle Successive samplings, at

17、 regular intervals, of equal quantities throughout filling. Mixing of these successive samples, homogenization and then taking the laboratory samples. 4.1.2 Apparatus 4.1.2.1 Sampling can, with handle, capacity300to500ml, of brass or, for refined glycerols, of stainless steel. 4.1.2.2 Cylindrical co

18、ntainer, of suitable capacity, of the same material as the can (4.1.2.1) or, preferably, of glass and fitted with a lid making it airtight. This container is used for holding and mixing the successive samples taken. 4.1.3 Procedure Determine the number of samples to be taken and the time interval be

19、tween successive samplings, according to the quantity of product and the rate of flow in filling. Take the product at the discharge end of the filling pipe by means of the can (4.1.2.1), spacing the samplings as uniformly as possible. Before each sampling rinse the can (4.1.2.1), after it has been i

20、nverted and allowed to drain, with the glycerol to be sampled. Place the successive samples together in the container (4.1.2.2), keeping it closed between each addition. Mix the whole sample rapidly with the aid of a stainless steel palette knife or, preferably, by rotating the closed container on i

21、ts side, about its axis. Take the laboratory samples and immediately bottle them in quantities of about500g, taking the precautions described in3.2, 3.3 and3.4. 4.2 Continuous sampling method 4.2.1 Principle and field of application Taking an aliquot part by allowing a constant proportion of the pro

22、duct to flow through a special device fitted to the filling pipe. Mixing and taking the laboratory samples. This procedure is applicable only to glycerols free from materials in suspension.BS5711-2:1979 2 BSI 12-1999 4.2.2 Apparatus 4.2.2.1 Stainless steel continuous tapping sampler comprising the f

23、ollowing parts: a) tubular element bent at 90 , or bevelled at 45 , inserted and fixed in a vertical part of the pipe with upward flow under pressure of the pump, so that the inner end is in the middle of this pipe and pointing downwards (seeFigure 1); b) flow control tap fixed to the tubular elemen

24、t (seeabove); c) flexible discharge tube linking the control tap to the collecting vessel (4.2.2.2), in which it descends to the bottom through an inlet pipe. 4.2.2.2 Cylindrical collecting vessel, of suitable capacity, of stainless steel or glass, which can be closed hermetically and is fitted with

25、 an inlet pipe and a ventilation hole so that the air can escape from the vessel as filling proceeds, without risk to the sample of pollution by moisture. 4.2.3 Procedure Choose the setting of the sampler tap (4.2.2.1) and the capacity of the mixing vessel (4.2.2.2) according to the quantity of prod

26、uct to be sampled. It is recommended that a total sample of about1kg should be taken per tonne of glycerol subject to a maximum of50kg. Allow the glycerol to flow throughout the whole filling period without altering the setting of the tap. Mix the whole sample and take the laboratory samples as desc

27、ribed in the last paragraph of4.1.3. 5 Method of sampling glycerols in drums 5.1 Field of application This method is applicable in its general form only to glycerols containing no compact deposit of solids at the bottom of the drums. 5.1.1 Special case Sampling of crude glycerols having a compact de

28、posit of solids at the bottom of the drums (see5.4.2). 5.2 Principle Taking one sample per drum, submitted to sampling throughout the whole of its height with the aid of a sampling tube inserted through the bung hole. Mixing of the samples, homogenization, and taking the laboratory samples. It is re

29、commended that no more than100drums should be grouped together for each global sample. 5.3 Apparatus 5.3.1 Sampling tube (Figure 2), consisting of two cylinders of brass or, for refined glycerols, of stainless steel or of any other chemically resistant material. The inner cylinder fits exactly into

30、the outer and both have alternating longitudinal slots spread over a quarter of their circumference and their complete length. These slots may either coincide or be sealed by rotation of the inner cylinder by means of a handle fitted with a pointer. The pointer indicates the relative positions of th

31、e slots on a scale fitted on the outer cylinder. In the filling position, the slots form two discontinuous lines of openings, which allow the sample to enter the tube at all levels of the drum simultaneously. The two cylinders are pierced at the base, providing openings which coincide when the point

32、er is in the emptying position, while the longitudinal slots remain closed. The length of the sampling tube should be proportional to the depth of the material to be sampled and its effective volume should be about0.1% of that of the drum. 5.3.2 Wiper plug to fit the bung hole of the drums to be sam

33、pled. 5.3.3 Cylindrical collecting vessel of the same material as the sampling tube or, preferably, of glass, fitted with a cover forming a hermetic seal, having a capacity of about1.5l per tonne of product to be sampled. 5.4 Procedure 5.4.1 General case If the drums are not freshly filled, ensure b

34、y means of a flat-ended probe that no solid deposit has formed at the bottom of the drum. If a deposit is present, and as far as this is still possible, bring this deposit back into suspension by heating the material and mixing it by repeated rotations of the drum while it is lying on its axis. Intr

35、oduce the sampling tube (5.3.1), closed, through the wiper plug (5.3.2) to the bottom of the drum. Open the longitudinal slots by placing the pointer at the filling position. Wait until the tube is full, then close the slots and withdraw the apparatus, the exterior of which is cleansed by rubbing ag

36、ainst the wiper plug (5.3.2). NOTEThe time required for filling varies with the viscosity of the product, influenced by the ambient temperature. It should be determined by a preliminary test.BS5711-2:1979 BSI 12-1999 3 Introduce the filled sampling tube (5.3.1) into the collecting vessel (5.3.3) and

37、 place the pointer at the position “emptying”. Empty the tube and operate in this way for all the samples in turn, keeping the vessel (5.3.3) closed between each emptying operation. Mix and take the laboratory samples as described in4.1.3. 5.4.2 Special case If the solids present remain in the form

38、of a compact deposit after the treatment described in5.4.1, it is not possible to obtain an aggregate representative sample by means of the tubular sampler (5.3.1). In this case, take separate samples of the liquid phase on the one hand, as described in5.4.1, and on the other hand, of the solid depo

39、sit. In order to sample the latter, empty out the liquid phase, weigh the drum with the deposit of solids, dissolve the latter, if possible, in a known quantity of water and take samples from the resultant solution. In addition, estimate the extent of the deposit from the difference between the mass

40、 taken previously and that of the drum only, after completely emptying. NOTERecord in the report, if appropriate, the presence of any insoluble material. 6 Methods of sampling glycerols in tanks 6.1 General remarks It is difficult to define one single standardized method applicable to all cases of s

41、ampling glycerol in tanks. The form of the latter and the arrangement of the premises will determine the choice among the three following methods: taking localized amounts by means of a sampler; localized sampling with a weighted bottle; continuous sampling. Localized sampling takes more time but gi

42、ves more representative samples than those obtained by continuous sampling. If the tank contains a solid deposit, it is not possible to take completely representative samples; the sampling applies only to the liquid phase. However, the thickness of the deposit is estimated, with the aid of a rod sam

43、pler or band sampler fitted with a flat weight at the end, and this shall be mentioned in the report. 6.2 Method of localized sampling, with the aid of a sampler 6.2.1 Principle Successive samplings, at the surface of the liquid, at different levels and at the bottom of the tank, of localized quanti

44、ties representative of the level in question, with the aid for example, of an open-ended cylindrical sampler. Mixing of these successive samples, homogenization and taking the laboratory samples. 6.2.2 Apparatus 6.2.2.1 Open-ended cylindrical sampler (Figure 3), of suitable capacity, made of brass o

45、r, for refined glycerols, of stainless steel, consisting of the following parts: a) a vertical cylindrical shell, open at both ends, the base of which can be closed by operation from another point by means of a set of levers acting on a rubber valve; b) two lines or small chains provided with regula

46、rly spaced guiding marks serving to manoeuvre and control the position of the sampler. This must be capable of removing a sample above about10mm from the bottom of the tank. 6.2.2.2 Collecting vessel, identical to that described in5.3.3. 6.2.3 Procedure Determine the number of samples and the differ

47、ent levels at which they are to be taken, distributed throughout the height of the tank, depending on its shape and the quantity to be sampled. It is recommended that a sample of1kg be taken at a depth corresponding to each successive layer of one tonne of glycerol, subject to a maximum of50kg. The

48、following procedure shall be followed in taking these samples. Using the line or small chain attached to the cylindrical body of the sampler (6.2.2.1), allow it to descend vertically into the contents of the tank at such a speed as to allow the glycerol to flow through the cylinder from the base upw

49、ards during the descent, so that at any moment the contents of the apparatus are exactly representative of the level reached. At the selected depth, close the valve by pulling firmly on the line or small chain controlling the levers, then withdraw the sampler, using this same line or small chain. Carefully wipe the outer walls of the sampler. Empty the successive samples into the collecting vessel (6.2.2.2), keeping it closed between additions. Mix the whole sample and take the laboratory samples as described in the last paragraph of4.1.3. 6.3 Method of locali