DE1972294U - DEVICE FOR DETERMINING THE SPECIFIC DIMENSIONS OF SOLID BODIES. - Google Patents

Description

The innovation relates to a device for determination the specific masses of solid bodies.

It is known to measure the specific mass of a solid body at a given temperature by measuring its Determine mass and the measurement of its volume.

However, the exact determination of the specific masses of solid bodies is currently based on pyK.nometric.en Methods that are tedious and difficult.

Furthermore, when the solid body being examined is a powder, especially a fine powder, it is extremely difficult to to obtain sufficiently accurate measurements, in particular due to the gas retained by the powder grains.

Me! Inflation aims in particular to train such devices so that they better than before meet various practical requirements and allow the specific mass to be determined precisely, even if the amount of the solid is small and the sample is a powder.

The goal direction according to the innovation is through a Chamber marked in which a vacuum is created can, and in which a precision balance with a balance beam is arranged, on one arm of which the examined sample is attached devices are provided to allow the sample to be immersed after degassing without transporting the same and to bring the sample to a given temperature before and after swapping.

The furnace is explained below by way of example with reference to the drawing.

Pig. 1 is a schematic sectional view of part of a device according to the invention.

Mg. 2 is a sectional view of another part the device according to the innovation on a larger scale.

Pig. 3 schematically shows an embodiment according to a modification trained part of the pig. 2 in another Scale"

Pig. Fig. 4 is a sectional view of a detail of Figo 2 on a different scale.

Pig. 5 is a sectional view of an embodiment modification des in Pig. 2 section of the device shown.

Pig. 6 is a section on line VI-VI of Pig. 5.

Assuming that the examined sample has the form of a powder P, the weight in air is first "determined" by weighing with a precision balance

This weighing is expediently undertaken after the powder has been placed in a container G, the mass and volume of which are known, namely the latter as a function of the temperature, ie V _G (t).

The corrections resulting from the buoyancy of the air on the container and the sample are in puncture according to the atmospheric densities Determination of the volume of the sample made.

Thereupon the powder undergoes a degassing, among other things, within
bar / subject to the same container, whereupon, according to the invention, the arrangement is immersed without intermediate transport in a liquid, the specific mass of which is known in puncture of the temperature, ie Ar (t).

By restoring the new balance

becomes the hydrostatic one exerted on the sample by the liquid Buoyancy is determined, and if the parameters of the container are known, the volume of P and thus its specific mass determined after making the above corrections.

According to the innovation, a device with a in Hg. 1 is used a chamber shown schematically at 1, in which a vacuum can be established. In this In the chamber there is arranged a precision balance, represented schematically by its balance beam 2, the shells of which are labeled 2a and 2b are designated. To a bowl of this balance beam,

ζ.Β _β the shell 2a, the examined sample P is attached, and the arrangement formed in this way is provided with devices which, after degassing in a vacuum, undertake the immersion of the sample without transporting it, with further means being provided which the sample in front of and bring it to a given temperature after immersion.

In the illustrated and described advantageous embodiment, a registration scale known per se is used (with a precision balance beam and a mechanism for registering and restoring the balance through electromagnetic compensation, which is not shown and acts on the shell 2b over ¹ a wire 3) , whereby this balance has an accuracy of l / 20 mg and can work in a vacuum as well as in a controlled atmosphere. An electromagnetic device known per se, for example a swivel lever shown schematically at 4, is provided in order to load the shell 2b_ from outside the chamber by remote control with riders or weights M «

The chamber 1 is connected by a line 5 to a pumping system (not shown). The facilities for immersing the sample after degassing without transporting it can be formed by a device of the type shown in Mg ζ.Β. consists of the glass known as "PYREK" and is connected to the chamber 1 via a spherical joint 8, for example. Several nozzles are provided on the pipe 6, namely s

- a connecting piece 6a, through which, e.g., by means of

a conical section 7, a thermometer 9 can be inserted can, which is immersed in the pipe up to the level of the container C,

- a nozzle 6b, on which e.g. a conical one Ground joint 10 a storage container 11 is connected, which is filled with a liquid of known specific mass used for the measurement, which is fed into the tube 6 can be introduced by rotating the storage container 11 about the axis of the connector 6b_?

- A nozzle 6c ,, through which the interior of the tube 6 to a vacuum pump, not shown, or the like connected,

- A nozzle 6 <1, alternatively by means of a conical one Ground section 13, a container 14 is attached, which serves as an overflow for the pipe 6 and allows when immersed of the sample P to maintain a constant level in the pipe 6.

For immersing the sample without transporting it can also do the schematic in Pig. 3 shown device can be used, which is a tube 12 in the form of an inverted Contains TJ, one end of which extends to the bottom of the tube 6, into which the tube 12 is passed through one shown in FIG Wise arranged nozzle 6Jd and the conical ground joint 10 enters, while its other end reaches to the bottom of a container R (in which the tube via a conical Ground joint Rp occurs), which is more familiar with the liquid specific mass is filled. The inside of the container R is through a pipe R ^ with a vacuum (not shown)

pump connected, and the connection between the interior of the tube 6 and the interior of the container E, which takes place via the tube 12, can be interrupted by means of a tap T. To produce a slow transfer of the liquid contained in the container R into the tube 6, a vacuum is produced in the container, which is somewhat less high than that prevailing in the tube 6 at the end of the degassing, whereupon the tap T is opened to allow the To slow down the flow of the liquid in the pipe 6, a constriction S can be provided on the pipe 12 »

The devices that bring the sample to a given temperature before and after immersion can as shown in Pig «2, are formed by a Dewar's vessel which, for example, is filled with water and equipped with a stirrer 16 is provided, the tube 6 in the Dewarse vessel immersed.

The container C _s, the volume of which is about 0.5 cm, and in which the sample P is accommodated, is suspended from a wire 17, suitably made of platinum

Ejection of the substance is prevented at the moment of immersion, clearly evident from Fig. 4, has two appropriately openings, of which only one, namely the opening 18, is visible is.

The length of the wire is such that the container G is located near the bottom of the tube 6.

In FIGS. 5 and 6, a second embodiment of the device shown in FIG. 2 is shown.

In this second embodiment, the tube 6 is provided with a container also made of, for example, Pyrex glass 20 connected via a plate 21 made of metal, for example, which is welded to the lower end of the tube and attached to a Splash 22 of the container 20 with the help of screws 23 below Interposition of a seal 24 is attached.

The container 20 is filled by a system with a pipe 12 and a tap T, as in the case of the one below Reference to Pig. 3 described arrangement. The tightness of the passage is, as shown, by a seal 12a.

In order to prevent the measuring liquid from being introduced too quickly into the container or crucible 0 and to make its filling more effective and practical, a finger 25 is provided which can be moved along its axis and enters the container through the plate 21, e.g. by means of the method shown in FIG parts shown. 5 _s wherein the sealing dureh a seal 26 is carried out. Furthermore, devices 26a for blocking the finger are provided. At its end lying inside the container 20, the finger 25 has a fork 27 which grips under the handle of the crucible T, which allows the crucible to be immersed in the liquid only after it has been brought to a certain level. A division 28 enables this level to be controlled. This division replaces the overflow arrangement of the other "device. The introduction of the liquid through the openings 18 provided on the crucible can be controlled very easily.

To facilitate the use of measuring liquid

with rather high vapor tensions (at which at the exit of the tube 12 a turbulence of the liquid under Bubble formation takes place, which can wrong the measurements by soiling the suspension wire 17) the container 20 is with a vertical partition 29, e.g. made of stainless steel, dividing it into two compartments, one of which is crucible 0 and the other is tube 12 contains. The connection between the two compartments is through a gap provided on the lower edge of the wall 29 30 manufactured. The wall 29 can, as shown, be held in its position with the aid of elastic devices, e.g. with the help of two springs 31.

The apparatus further includes an oven 32 which is attached to the blade 21 by threaded bolts 33 and nuts 34 «Thanks to the presence of this furnace, degassing is more efficient, faster and easier the investigation of powdery substances by quickly determining the air humidity.

When using a degassing with heating, the thermometer, designated here by 35 and inserted into the container through a connector 36, must be withdrawn from the influence of the heat. This may be _{au n} b is provided, the ingredients are shown in Fig. 5 (the thermometer is shown in the retracted position), a moving egg, wherein said sealing is performed by a seal 37.

It should be noted that the connector 36 and thermometer 35 are not actually in the location indicated but are offset by 90 °, i.e. they are available

or behind the drawing plane. The selected bar position should only make the drawing easier to understand »

The above gate direction is used as follows!

The arrangement formed by the sample P and the container G is first weighed by means of a precision balance * for example by means of a balance with a single bowl with an accuracy of 1 / fjO mg. The corrections resulting from the aerostatic buoyancy exerted on the container δ and the sample P are made according to the densities of the air after determining their tolumens _s , it being understood that the weight and volume of the container C can be determined once and for all.

Then the container to the wire 17 "is that is suspended from the shell 2a, whereupon the balance by Ta turing is prepared by certain weights M are placed on the tray 2Td. After establishing the balance weight, the sensitivity of the balance is usually calibrated using one of the calibration weights, e.g. a weight of 10 mg from the set of weights M

Then, in the arrangement formed by the chamber containing the balance and the pipe 6 (hereinafter is in particular considered the modification of the Mg. 2) a vacuum is established for about twelve hours, which enables extensive degassing to be achieved. It is certain that the vapor tension of the liquid contained in the container (which is often due to diethyl orthophthalate is formed) the degassing is limited. In samples that are difficult to degas, it is sometimes desirable to

To reduce tension ', for which it is sufficient to insert the container 11 in to immerse a cold mixture.

Each time the degassing is completed, the liquid in the container 11 is introduced into the tube 6.

It happens that at the moment of contact between the liquid and the sample, small bubbles form, which adhere to the grains of the sample «. In order to excrete these bubbles, a vibration can be used, which causes rapid wetting of the entire sample and by means of an electromagnetic shaking device, not shown of the type currently used in laboratories can be manufactured, the baker's finger of adjustable amplitude with the tube 6 at the location of the container C is brought into contact, the shaking on the sample P over the liquid be transmitted.

After immersion, the normal pressure in the arrangement formed by the chamber 1 and the tube 6 becomes manufactured.

As a result of the on the sample through the pipe 6

This equilibrium is disturbed by the hydrostatic buoyancy exerted by the liquid. It is restored either by taring on the shell 2a or by a new taring on the shell 2b by removing the weights M _n required for this.

It should be noted _s DAJ & due to the knowledge of the changes in specific gravities of the air and the container 11 liquid temperature satisfying the two equilibrium states do not need to be prepared at the same (with the temperature.

Since it is also convenient to reduce the handling of weights as much as possible when establishing the states of equilibrium, it is set up in such a way that one works with samples whose mass is approximately constant on average and
it is expediently chosen so that the hydrostatic buoyancy acting on the sample is of the order of 200 mg. It is then sufficient, when establishing the second equilibrium, to add a weight of 200 mg from the shell 2b and one from the
Liquid to remove buoyancy corresponding to the weight M ^ exerted on the container C. To establish the equilibrium, it is then sufficient to place perforations corresponding to a mass m on the shell 2b_ or to remove them from it.

Which gives the volume of the sample, namely VpCt) Calculation is then very simple.

Assuming that the first state of equilibrium in a gas, ie generally in air, _{corresponds to a taring T 1} on the shell 2b and the second state of equilibrium in the liquid corresponds to a taring Tg, the relationships ϊ are obtained
T "= mass,

_{p + 0} -

with 6 _& (t) = density of the air or the gas used in puncture of the temperature,

T ₂ = mass _{p + 0} ^ ;? _{p + c} : Ct) A _Ij (t)

with Aj ₁ Ct) = density of the liquid used in the puncture of the

Temperature,

or

^T 1 - ^T 2 - W ^ [ ^(A L ^(t) - that is

But now the volume of the container C is known as a function of the temperature, namely V _G (t), so that one obtains

T-T

^ ²

Under the above conditions with regard to the mean amount of the sample (hydrostatic buoyancy in the vicinity of 200 mg) and since the volume of the container and thus the value of the buoyancy Mq exerted on it by the liquid L is known, so that the second state of equilibrium is thereby what is achieved is that weights m are placed on or removed from the shell 2_b after automatically removing from the shell 2t> a weight of 200 mg and M _c corresponding weights, the relationship is obtained:

T ₁ - T ₂ = 200 + H ₀ tm

and the volume of the sample is given by the following expression?

^{200 + M} ö + m

v _p (t) =% (t; - ö _G ctj -v _o (t).

Further, since the of the container is the weight of the container and the sample arrangement formed and the weight alone known, and there runs the density of ^ (or the _gas)} in which carried out the weighing of the assembly formed by the container and the sample, 6 _& (t), it is convenient to calculate the correction due to aerostatic buoyancy and to accurately determine the weight of the sample.

The specific mass is then derived from the knowledge of the weight and volume

In practice, the weighing process apparently only consists of handling the weights - in accordance with the difference the impetus at the moment of the establishment of the two states of equilibrium.

It should be noted that A ^ ft) is determined using a fixed, known Bich field S. One determines the buoyancy exerted on this solid body by the liquid examined and by distilled, deaerated water, for which the change in specific mass with temperature, ie A _E (t), is known with very great accuracy «.

This provision of Aj (t) can be quickly and with great accuracy G _e take place in that the temperature of the liquid contained in the Dewar vessel is changed slowly and the pressure exerted by the liquid on the solid calibration body hydrostatic boosts be registered.

The error calculations which allow the accuracy of the means according to the invention are explained below to estimate.

Weighing is carried out on a scale with a single pan with an accuracy of l / 50 mg or - 0.02 mg.

The temperature of the bath is known down to - 0.02 C, and the forces measured on the register scale are known except for - 0.07 mg.

To this error, add those that occur on all calibration weights used, which are ί 0.02 mg.

Since the bath temperature is known to an accuracy of 0.02 ° 0 is, the errors are in the specific mass of the water

- 14 + 5 «10 mg / mm o

As already explained above, Δ - ^ (ΐ) is obtained by means of of a solid sample S. As a result, the

Calculate the value of —τ— the error in the volume of the

¹
solid calibration body can be calculated.

This calculation gives (for distilled water):

d (distilled water) d Y _g _ d (buoyancy on S) ₊

"Yg buoyancy in S Δ distilled water

But Uun applies d (lift at S) = 0.02 + 0.07 =

0.09 mg.

Assuming that the solid body S is a

Has volume close to 4,000 mm, the one exerted on it is Buoyancy in the region of 4,000 mg, so that one obtains s

^{d Y} S = _ ^ + 5.1O- ⁶ = 3.10-5 Y ^ 4,000

and ~

d Yg = 0.12 m ^; .

Since the density of the measuring liquid, if this Diethyl orthophthalate is, at 20 ° C in the range of 1.1, so that the buoyancy exerted on the solid S is in the range of 4,500 mg, one obtains s

dA _T _ d Tq d (buoyancy on S)

Buoyancy on S

°> ⁰⁹ = 5.5.10-5 "4.500

and f. -2

dA _T -> 6.1Ο "- ³ mg / mm.

It should be noted that this accuracy

_ 15 -

still by using a fixed calibration body S with a larger Volume can be increased.

For the volume of the container C and the immersed part of the platinum wire (this volume is always constant for one and the same temperature due to the electromagnetic compensation device of the balance and due to the fact that the level in the drill 6 is always constantJ always constant ] , taking into account the fact that the

^{1 line}

lumen of the container close to 500 mm and that on it exerted buoyancy is in the region of 550 mg, see the following expression

d V _n dA _T , d (lift on G)

KJ - YY T

Vq Aj ₁ buoyancy at O

= 5.5.1O- ⁵ + ffer- & 2.2.1ο " ⁴

and ~

d V ₀ si 0.11 nmr.

If you now consider the total volume of the container and the sample, namely V ^, and take into account the fact that the volume of the sample is of the order of magnitude of ¹ Z

200 mm is obtained

V _T # 200 + 500 = 700 mm ⁵ and the total buoyancy of about 770 mg »

As a result, we get s d Tm _ d (total lift) d Δ-τ

VgT ^ total lift 2Vj ₁

= °> ° ⁹ + 5.5.10-5

770

Si l, 8.10 " ⁴
and d Vm φ 0.13

The error in the volume of the sample can be derived from the above explanations. There !

- Y _G

you get

d Vp = d Vr ₀ + d Y ₀

= 0.13 mm ³ +0.11 nmr d Yp = 0.24 mn?

and finally

d Vp ₌ 0.24 _{= 1s2e10} -3

? p ~ Ίΰΰ

Therefore, one finally obtains s for the accuracy based on the specific mass of the sample

α Ep ₊ d Vp

and finds

- 0.02 + 1.2.10 " ³ ~ 5iS3

= 10 ~ ⁴ ~ ³ + 1,2.10

Since the accuracy of the specific mass is a function of the same, the following accuracy is obtained, for example, for a specific mass of 3; d (specific mass of the sample) = 10 "" ⁴ + 3.6.1O "" ⁵ = 3.7.1O " ⁵

To further explain the innovation, the results of measurements are given below, which for Determination of the specific mass of sodium chloride were made «.

Sodium chloride was used for this, which

precipitated from its saturated aqueous solution by ethanol, washed with alcohol and then dried at 200 ⁰ O in a Yor vacuum.

Since the parameter of ClNa has the value

ο
a = 5.639 A

and since its crystallographic density is 2.165 ", their Change in function of temperature is given by the relationship j

5O ^l Oo

f = 2.1644 fl - 0.000121 (t-18)] Jo- «- j

four measurements are made, the results of which are given in the table below

I ⁰ t ° 0 measured calculated d 1 21 2.160 g / cm ⁵ 2.163 ₇ -0.004 2 23 2.163 g / cm ^p 2.163 ₂ .0.000 3 19th 2.162 g / cm ³ 2 ₉ 164 ₂ '-0.002
+0.001 4th 25th 2.164 g / cm ³ 2.162 ₇

The device according to the invention has numerous advantages, in particular a remarkable accuracy, very simple handling and in particular the possibility of using very small amounts of the sample, which is expensive or products that are only available in small quantities are extremely valuable.

Claims (7)

5A. <T39U3 "2.8.67 Protection claims 1.) Device for determining the specific masses of solid bodies by determining the volume of the examined sample by determining the buoyancy force which it experiences after immersion in a liquid of known specific mass, characterized by a chamber (1) in which a vacuum is created can, and which contains a precision balance with a balance beam (2), on one arm of which the examined sample (P) contained in a container or crucible (C) is attached, with devices being provided which allow the sample to be immersed after degassing ( P) without! Effecting transport of the same, as well as devices which bring the sample (P) to a given temperature before and after immersion. 2.) Device according to claim 1, characterized in that the devices for immersing the sample (P) be formed after degassing without transport of the same through a vertical pipe (6), near the bottom of the A sample (P) suspended from a bowl of the balance is located, the tube (6) being connected to the chamber (1) by a joint is and has a nozzle (6b_), on which a tight Container (1: 1) is connected, which is filled with the liquid used for immersing the sample (P), whereby the introduction this fluid into the interior of the ear by rotation of the container containing them takes place around the axis of the connecting piece for its connection. 3.) Device according to claim 1, characterized in that that the devices for immersing the sample (P) after degassing without transporting the same through a vertical Rolir (6) are formed, in the vicinity of which the sample is located is located, which is suspended from a bowl of the balance, wherein the inside of the tube is tightly connected to the inside of a reservoir (R) which was used to immerse the sample contains liquid, the transfer of this liquid by creating a pressure difference between the tube and the reservoir takes place. 4.) Device according to claim 1 and 3, characterized in that the vertical tube (6) tightly with a vertical container (20) is connected, which in turn is divided into two compartments by a vertical partition (29) is, where one of these divisions is the sample (P) and the other contains the means for supplying the liquid for immersion of the sample » 5.) Device according to claim 1, 3 and 4, characterized by a movable linger (25), which with the the crucible (C) containing sample (P) can interact in this way » that he only dips the crucible into the vertical container (20) after the liquid used for immersion has been introduced. 6 ") Device according to claim 1, characterized in that that the facilities that the temperature of the sample (P) before and after immersion to a given value bring, are formed by a Dewar's vessel (15), which is filled with a liquid, and in which the tube (6) is immersed. 7.) Device according to claim 1, characterized in that the devices which the temperature of the Bring sample (P) to a given value before and after immersion, to be formed by an oven (32).