natgillin/translations-raw huggingface dataset:
if the copper furnace lid has three openings of different diameters at 90o to each other, various vapour pressure ranges within the overall measuring range can be covered (openings between approximately 0,30 and 4,50 mm diameter).
če ima bakreni pokrov tri odprtine različnih premerov, ki ležijo pod kotom 90o ena na drugo, se lahko zajamejo različna območja parnega tlaka v celotnem merilnem območju (premer odprtin med približno 0,30 in 4,50 mm).
Large openings are used for low vapour pressure and vice versa.
Velike odprtine se uporabijo za nizek parni tlak in obratno.
By rotating the furnace the desired opening or an intermediate position in the vapour stream (furnace opening — shield — balance pan) can be set and the stream of molecules is released or deflected through the furnace opening onto the scale pan.
Z vrtenjem peči se lahko nastavi želena odprtina ali vmesni položaj na tok pare (odprtina peči – zaslon – skodelica tehtnice) in tako sprosti curek molekul ali ga skozi odprtino peči preusmeri na skodelico tehtnice.
In order to measure the temperature of the substance, a thermocouple or resistance thermometer is placed at a suitable point,
Za merjenje temperature snovi se na primerno točko namesti termočlen ali uporovni termometer,
above the shield is a balance pan belonging to a highly sensitive microbalance (see below).
nad zaslonom je posodica zelo občutljive mikrotehtnice (glej spodaj).
The balance pan is approximately 30 mm in diameter.
Premer skodelice tehtnice je približno 30 mm.
Gold-plated aluminium is a suitable material,
Primeren material je pozlačen aluminij,
the balance pan is surrounded by a cylindrical brass or copper refrigeration box.
skodelico tehtnice obdaja valjasta medeninasta ali bakrena hladilna posoda.
Depending on the type of balance, it has openings for the balance beam and a shield opening for the stream of molecules and should guarantee complete condensation of the vapour on the balance pan.
Odvisno od vrste tehtnice, ima odprtine za gredeljnico tehtnice in odprtino v zaslonu za curek molekul ter bi morala zagotavljati popolno kondenzacijo pare na skodelici tehtnice.
Heat dissipation to the outside is ensured e.g. by a copper bar connected to the refrigeration box.
Odvajanje toplote navzven omogoča npr. bakrena palica, povezana s hladilno posodo.
The bar is routed through the base plate and thermally insulated from it, e.g. with a chromium-nickel steel tube.
Palica je napeljana skozi osnovno ploščo in od nje toplotno izolirana, npr. s krom-nikljevo jekleno cevjo.
The bar is immersed in a Dewar flask containing liquid nitrogen under the base plate or liquid nitrogen is circulated through the bar.
Palica je potopljena v tekoči dušik v Dewarjevi posodi pod osnovno ploščo ali pa tekoči dušik kroži skoznjo.
The refrigeration box is thus kept at approximately - 120 oC.
Temperatura hladilne posode se tako vzdržuje pri –120 oC.
The balance pan is cooled exclusively by radiation and is satisfactory for the pressure range under investigation (cooling approximately 1 hour before the start of measurement),
Skodelica tehtnice se hladi izključno s sevanjem in sicer ustrezno glede na preučevano območje tlaka (hlajenje približno 1 uro pred začetkom merjenja),
the balance is positioned above the refrigeration box.
tehtnica se namesti nad hladilno posodo.
Suitable balances are e.g. a highly sensitive 2-arm electronic microbalance (8) or a highly sensitive moving coil instrument (see OECD Test Guideline 104, Edition 12.05.81),
Ustrezne tehtnice so npr. zelo občutljiva dvokraka elektronska mikrotehtnica (8) ali zelo občutljiv inštrument z vrtljivo tuljavo (glej Smernico za preskušanje OECD 104, izdano 12.5.81),
the base plate also incorporates electrical connections for thermocouples (or resistance thermometers) and heating coils,
v osnovno ploščo so vgrajeni tudi električni priključki za termočlene (ali uporovne termometre) in grelne spirale,
a vacuum is produced in the vessel using a partial vacuum pump or high-vacuum pump (required vacuum approximately 1 to 2 × 10-3 Pa, obtained after 2 h pumping).
v posodi se ustvari vakuum z uporabo delne vakuumske črpalke ali visokovakuumske črpalke (potreben je vakuum približno 1 do 2 × 0–3 Pa, ki se doseže po 2 h črpanja).
The pressure is regulated with a suitable ionisation manometer.
Tlak se uravnava s primernim ionizacijskim manometrom.
The vessel is filled with the test substance and the lid is closed.
Posoda se napolni s preskusno snovjo in zapre s pokrovom.
The shield and refrigeration box are slid across the furnace.
Zaslon in hladilna posoda se potisneta čez peč.
The apparatus is closed and the vacuum pumps are switched on.
Aparatura se zapre in vključijo se vakuumske črpalke.
The final pressure before starting to take measurements should be approximately 10-4 Pa.
Končni tlak pred začetkom merjenja mora biti približno 10–4 Pa.
Cooling of the refrigeration box starts at 10-2 Pa.
Hlajenje hladilne posode se začne pri 10–2 Pa.
Once the required vacuum has been obtained, start the calibration series at the lowest temperature required.
Ko se doseže potrebni vakuum, začnemo umeritveni niz pri najnižji potrebni temperaturi.
The corresponding opening in the lid is set, the vapour stream passes through the shield directly above the opening and strikes the cooled balance pan.
Nastavi se ustrezna odprtina v pokrovu, curek pare gre skozi zaslon neposredno nad odprtino in zadene ob ohlajeno skodelico tehtnice.
The balance pan must be big enough to ensure that the entire stream guided through the shield strikes it.
Skodelica tehtnice mora biti dovolj velika, da jo zadene celotni curek, usmerjen skozi zaslon.
The momentum of the vapour stream acts as a force against the balance pan and the molecules condense on its cool surface.
Gibalna količina parnega curka deluje kot sila na skodelico tehtnice in molekule se kondenzirajo na njeni hladni površini.
The momentum and simultaneous condensation produce a signal on the recorder.
Gibalna količina in sočasna kondenzacija povzročita signal na zapisovalniku.
Evaluation of the signals provides two pieces of information:
Ovrednotenje signala da dve informaciji:
in the apparatus described here the vapour pressure is determined directly from the momentum on the balance pan (it is not necessary to know the molecular weight for this (2)).
v opisani aparaturi se parni tlak določi neposredno iz gibalne količine na skodelici tehtnice (za to ni potreben podatek o molski masi (2)).
Geometrical factors such as the furnace opening and the angle of the molecular stream must be taken into account when evaluating the readings;
Pri vrednotenju meritev je treba upoštevati geometrijske dejavnike, kakršna sta odprtina peči in kot molekulskega curka;
the mass of the condensate can be measured at the same time and the rate of evaporation can be calculated from this.
hkrati se lahko izmeri masa kondenzata in iz tega izračuna hitrost izhlapevanja.
The vapour pressure can also be calculated from the rate of evaporation and molecular weight using the Hertz equation (2).
Parni tlak se lahko izračuna tudi iz hitrosti izhlapevanja in molske mase po Hertzovi enačbi (2).
G evaporation rate (kg s-1 m-2)
G hitrost izhlapevanja (kg s-1 m-2)
M molar mass (g mol-1)
M molska masa (g mol-1)
R universal molar gas constant (Jmol-1 K-1)
R splošna plinska konstanta (J mol-1 K-1)
p vapour pressure (Pa)
P parni tlak (Pa)
After the necessary vacuum is reached, the series of measurements is commenced at the lowest desired measuring temperature.
Ko se doseže potrebni vakuum, začnemo niz meritev pri najnižji želeni merilni temperaturi.
For further measurements, the temperature is increased by small intervals until the maximum desired temperature value is reached.
Za nadaljnje meritve se temperatura dviga v majhnih intervalih, dokler se ne doseže najvišja želena temperatura.
The sample is then cooled again and a second curve of the vapour pressure may be recorded.
Vzorec se potem spet ohladi in lahko se zapiše druga krivulja parnega tlaka.
If the second run fails to confirm the results of the first run, then it is possible that the substance may be decomposing in the temperature range being measured.
Če drugi niz meritev ne potrdi rezultatov prvega, je možno, da snov v temperaturnem območju meritev razpada.
Effusion method — by loss of weight
Efuzijska metoda – z izgubo mase
The effusion apparatus consists of the following basic parts:
Efuzijsko aparaturo sestavljajo naslednji osnovni deli:
a tank that can be thermostated and evacuated and in which the effusion cells are located,
posoda, ki jo je mogoče termostatirati in odzračiti in v kateri so efuzijske celice,
a high vacuum pump (e.g. diffusion pump or turbomolecular pump) with vacuum gauge,
visokovakuumska črpalka (npr. difuzijska črpalka ali turbomolekularna črpalka) z vakuummetrom,
a trap, using liquefied nitrogen or dry ice.
past s tekočim dušikom ali suhim ledom.
An electrically heated, aluminium vacuum tank with four stainless steel effusion cells is shown in figure 5 for example.
Na sliki 5 je na primer prikazana električno ogrevana aluminijasta vakuumska posoda s 4 efuzijskimi celicami iz nerjavečega jekla.
The stainless steel foil of about 0,3 mm thickness has an effusion orifice of 0,2 to 1,0 mm diameter and is attached to the effusion cell by a threaded lid.
Folija iz nerjavečega jekla, debela približno 0,3 mm, ima efuzijsko odprtino s premerom 0,2 do 1,0 mm in je pritrjena na efuzijsko celico z navojnim pokrovom.
The reference and test substances are filled into each effusion cell, the metal diaphragm with the orifice is secured by the threaded lid, and each cell is weighed to within an accuracy of 0,1 mg.
V vsako efuzijsko celico se da referenčna in preskusna snov, kovinska membrana z odprtino se pritrdi z navojnim pokrovom in vsaka celica se stehta do 0,1 mg točno.
The cell is placed in the thermostated apparatus, which is then evacuated to below one tenth of the expected pressure.
Celica se postavi v termostatirano aparaturo, ki se nato odzrači do tlaka, nižjega od ene desetine pričakovanega tlaka.
At defined intervals of time ranging from 5 to 30 hours, air is admitted into the apparatus, and the loss in mass of the effusion cell is determined by reweighing.
V opredeljenih časovnih intervalih od 5 do 30 ur se v aparaturo spusti zrak in s ponovnim tehtanjem določi izguba mase efuzijskih celic.
In order to ensure that the results are not influenced by volatile impurities, the cell is reweighed at defined time intervals to check that the evaporation rate is constant over at least two such intervals of time.
Da se zagotovi, da na rezultate ne vplivajo hlapne nečistote, se celice ponovno tehtajo v opredeljenih časovnih intervalih, s čimer se preveri, ali je hitrost izparevanja konstantna v najmanj dveh takih intervalih.
The vapour pressure p in the effusion cell is given by:
Parni tlak p v efuzijski celici je izražen z:
m mass of the substance leaving the cell during time t (kg)
m masa snovi, ki zapusti celico v času t (kg)
t time (s)
T čas (s)
A area of the hole (m2)
A ploščina odprtine (m2)
K correction factor
K korekcijski faktor
R universal gas constant (Jmol-1 K-1)
R splošna plinska konstanta (J mol-1 K-1)
M molecular mass (kg mol-1)
M molska masa (kg mol-1)
The correction factor K depends on the ratio of length to radius of the cylindrical orifice:
Korekcijski faktor K je odvisen od razmerja med dolžino in polmerom valjaste odprtine:
ratio
razmerje
The above equation may be written:
Zgornja enačba se lahko zapiše:
and is the effusion cell constant.
in je konstantna za efuzijsko celico.
This effusion cell constant E may be determined with reference substances (2,9), using the following equation:
Konstanta efuzijske celice E se lahko določi z referenčnimi snovmi (2,9) po naslednji enačbi:
p(r) vapour pressure of the reference substance (Pa)
p(r) parni tlak referenčne snovi (Pa)
M(r) molecular mass of the reference substance (kg × mol-1)
M(r) molska masa referenčne snovi (kg × mol-l)
A typical apparatus used to perform this test comprises a number of components given in figure 6a and described below (1).
Značilna aparatura za ta preskus je sestavljena iz več delov, prikazanih na sliki 6a in opisanih spodaj (1).
Inert gas:
Inertni plin:
The carrier gas must not react chemically with the test substance.
Nosilni plin ne sme kemijsko reagirati s preskusno snovjo.
Nitrogen is usually sufficient for this purpose but occasionally other gases may be required (10).
Dušik običajno zadošča za ta namen, občasno pa je treba uporabiti druge pline (10).
The gas employed must be dry (see figure 6a, key 4: relative humidity sensor).
Uporabljen plin mora biti suh (glej sliko 6a, točko 4: senzor relativne vlažnosti).
Flow control:
Uravnavanje pretoka:
A suitable gas-control system is required to ensure a constant and selected flow through the saturator column.
Potreben je ustrezen plinski kontrolni sistem, da se zagotovi konstanten izbrani pretok skozi saturacijsko kolono.
Traps to collect vapour:
Pasti za zbiranje pare:
These are dependent on the particular sample characteristics and the chosen method of analysis.
Odvisni so od značilnosti posameznega vzorca in izbrane analitske metode.
The vapour should be trapped quantitatively and in a form which permits subsequent analysis.
Paro je treba uloviti kvantitativno in v obliki, ki omogoča poznejšo analizo.
For some test substances, traps containing liquids such as hexane or ethylene glycol will be suitable.
Za nekatere preskusne snovi so primerne pasti, ki vsebujejo tekočine, kot je heksan ali etilen glikol.
For others, solid absorbents may be applicable.
Za druge se lahko uporabljajo trdni absorbenti.
As an alternative to vapour trapping and subsequent analysis, in-train analytical techniques, like chromatography, may be used to determine quantitatively the amount of material transported by a known amount of carrier gas.
Za določitev količine snovi, ki jo prenese znana količina nosilnega plina, se namesto lovljenja pare in poznejše analize lahko uporabijo neposredne analitske tehnike, kot je kromatografija.
Furthermore, the loss of mass of the sample can be measured.
Lahko se izmeri tudi izguba mase vzorca.
Heat exchanger:
Toplotni izmenjevalnik:
For measurements at different temperatures it may be necessary to include a heat-exchanger in the assembly.
Za merjenje pri različnih temperaturah bo morda treba v sestav vključiti toplotni izmenjevalnik.
Saturator column:
Saturacijska kolona:
The test substance is deposited from a solution onto a suitable inert support.
Preskusna snov se iz raztopine nanese na primerno inerten nosilec.
The coated support is packed into the saturator column, the dimensions of which and the flow rate should be such that complete saturation of the carrier gas is ensured.
Z obloženim nosilcem se napolni saturacijska kolona, dimenzije in pretok katere morajo biti takšni, da je zagotovljeno popolno nasičenje nosilnega plina.
The saturator column must be thermostated.
Saturacijsko kolono je treba termostatirati.
For measurements above room temperature, the region between the saturator column and the traps should be heated to prevent condensation of the test substance.
Za meritve pri temperaturah nad sobno je treba del med saturacijsko kolono in pastmi ogrevati, da se prepreči kondenzacija preskusne snovi.
In order to lower the mass transport occurring by diffusion, a capillary may be placed after the saturator column (figure 6b).
Da se zmanjša prenos mase z difuzijo, se za saturacijsko kolono lahko namesti kapilara (slika 6b).
Preparation of the saturator column:
Priprava saturacijske kolone:
A solution of the test substance in a highly volatile solvent is added to a suitable amount of support.
Raztopina preskusne snovi v zelo lahko hlapnem topilu se doda primerni količini nosilca.
Sufficient test substance should be added to maintain saturation for the duration of the test.
Dodati je treba zadostno količino preskusne snovi, da se vzdržuje nasičenost ves čas preskusa.
The solvent is totally evaporated in air or in a rotary evaporator, and the thoroughly mixed material is added to the saturator column.
Topilo naj popolnoma izpari na zraku ali v rotacijskem uparjalniku, nato se temeljito premešan material doda v saturacijsko kolono.
After thermostating the sample, dry nitrogen is passed through the apparatus.
Po termostatiranju vzorca se skozi aparaturo spusti suhi dušik.
Measurement:
Merjenje:
The traps or in-train detector are connected to the column effluent line and the time recorded.
Pasti ali detektor za neposredno analizo se poveže z odtočno cevko kolone in zapiše se čas.
The flow rate is checked at the beginning and at regular intervals during the experiment, using a bubble meter (or continuously with a mass flow-meter).
Pretok se preverja na začetku in v enakomernih intervalih med preskusom z merilnikom mehurčkov (ali ves čas z merilnikom masnega pretoka).
The pressure at the outlet to the saturator must be measured.
Treba je izmeriti tlak pri izhodu iz saturatorja.
This may be done either:
To se lahko stori bodisi tako:
by including a pressure gauge between the saturator and traps (this may not be satisfactory because this increases the dead space and the adsorptive surface); or
da se med saturator in pasti priključi merilnik tlaka (to morda ne bo primerno, ker poveča mrtvi prostor in adsorpcijsko površino) bodisi
by determining the pressure drops across the particular trapping system used as a function of flow rate in a separate experiment (this may be not very satisfactory for liquid traps).
da se določi padec tlaka v posameznem sistemu pasti kot funkcija pretoka v ločenem preskusu (to morda ne bo ustrezno za tekočinske pasti).
The time required for collecting the quantity of test substance that is necessary for the different methods of analysis is determined in preliminary runs or by estimates.
Čas, potreben za to, da se zbere zadostna količina preskusne snovi za različne analitske metode, se določi s predhodnimi preskusi ali ocenami.
As an alternative to collecting the substance for further analysis, in-train quantitative analytical technique may be used (e.g. chromatography).
Namesto zbiranja snovi za nadaljnjo analizo se lahko uporabi neposredna kvantitativna analitska tehnika (npr. kromatografija).
Before calculating the vapour pressure at a given temperature, preliminary runs are to be carried out to determine the maximum flow rate that will completely saturate the carrier gas with substance vapour.
Pred izračunom parnega tlaka pri dani temperaturi je treba izvesti predhodne preskuse, da se določi največji pretok, ki popolnoma nasiti nosilni plin s paro snovi.
This is guaranteed if the carrier gas is passed through the saturator sufficiently slowly so that a lower rate gives no greater calculated vapour pressure.
To je zagotovljeno, če se nosilni plin uvaja skozi saturator dovolj počasi, tako da manjši pretok ne daje nič večjega izračunanega parnega tlaka.
The specific analytical method will be determined by the nature of the substance being tested (e.g. gas chromatography or gravimetry).
Analitska metoda se določi glede na naravo preskusne snovi (npr. plinska kromatografija ali gravimetrija).
The quantity of substance transported by a known volume of carrier gas is determined.
Določi se količina snovi, ki jo prenese znan volumen nosilnega plina.
Calculation of vapour pressure
Izračun parnega tlaka
Vapour pressure is calculated from the vapour density, W/V, through the equation:
Parni tlak se izračuna iz gostote pare, W/V, po enačbi:
W mass of evaporated test substance (g)
W masa uparjene preskusne snovi (g)
V volume of saturated gas (m3)
V volumen nasičenega plina (m3)
M molar mass of test substance (g mol-1)
M molska masa preskusne snovi (g mol-1)
Measured volumes must be corrected for pressure and temperature differences between the flow meter and the thermostated saturator.
Izmerjene volumne je treba popraviti glede na razlike v tlaku in temperaturi med merilnikom pretoka in termostatiranim saturatorjem.
If the flow meter is located downstream from the vapour trap, corrections may be necessary to account for any vaporised trap ingredients (1).
Če je merilnik pretoka glede na smer toka za pastjo pare, bodo morda potrebne korekcije, da se upošteva morebitna uparjena vsebina pasti(1).
Spinning rotor (8, 11, 13)
Rotorska metoda (8, 11, 13)
The spinning rotor technique can be carried out using a spinning rotor viscosity gauge as shown in figure 8.
Metoda z rotorjem se lahko izvede z uporabo merilnika viskoznosti z rotorjem, prikazanega na sliki 8.
A schematic drawing of the experimental set-up is shown in figure 7.
Shematski prikaz postavitve preskusa kaže slika 7.
The measuring apparatus typically consists of a spinning rotor measuring head, placed in a thermostated enclosure (regulated within 0,1 oC).
Značilno merilno aparaturo sestavljajo vrteči rotorski merilnik, postavljena v termostatirano posodo (uravnavanje na 0,1 oC natančno).
The sample container is placed in a thermostated enclosure (regulated within 0,01 oC), and all other parts of the set-up are kept at a higher temperature to prevent condensation.
Posoda z vzorcem se postavi v termostatirano posodo (uravnavanje na 0,01 oC natančno), vsi ostali deli sestava pa se vzdržujejo pri višji temperaturi, da se prepreči kondenzacija.
A high-vacuum pump device is connected to the system by means of high-vacuum valves.
Visokovakuumska črpalka se priključi na sistem preko visokovakuumskih ventilov.
The spinning rotor measuring head consists of a steel ball (4 to 5 mm diameter) in a tube.
Vrteči rotorski merilnik sestavlja jeklena kroglica (premera 4 do 5 mm) v cevi.
The ball is suspended and stabilised in a magnetic field, generally using a combination of permanent magnets and control coils.
Kroglica se postavi v magnetno polje in stabilizira, tako da lebdi, običajno s kombinacijo trajnih magnetov in kontrolnih tuljav.
The ball is made to spin by rotating fields produced by coils.
Vrtenje kroglice povzročajo rotirajoča polja tuljave.
Pick-up coils, measuring the always present low lateral magnetisation of the ball, allow its spinning rate to be measured.
Sprejemne tuljave, ki merijo stalno prisotno šibko lateralno magnetizacijo kroglice, omogočajo merjenje hitrosti njenega vrtenja.
When the ball has reached a given rotational speed v(o) (usually about 400 revolutions per second), further energising is stopped and deceleration takes place, due to gas friction.
Ko kroglica doseže določeno hitrost vrtenja v(o) (običajno približno 400 vrtljajev na sekundo), se ustavi dotok energije in zaradi trenja, ki ga povzroča plin, se vrtenje upočasni.
The drop of rotational speed is measured as a function of time.
Padec vrtilne hitrosti se meri kot funkcija časa.
As the friction caused by the magnetic suspension is negligible as compared with the gas friction, the gas pressure p is given by:
Ker je trenje, ki ga povzroča lebdenje v magnetnem polju zanemarljivo v primerjavi s trenjem plina, tlak plina p opisuje enačba:
average speed of the gas molecules
povprečna hitrost plinskih molekul
r radius of the ball
r polmer kroglice
ρ mass density of the ball
ρ masna gostota kroglice
σ coefficient of tangential momentum transfer (ε = 1 for an ideal spherical surface of the ball)
σ koeficient tangencialnega prenosa momenta (e = 1 za idealno krogelno površino kroglice)
v(t) rotational speed after time t
v(t) hitrost vrtenja po času t
v(o) initial rotational speed
v(o) začetna hitrost vrtenja
This equation may also be written:
Ta enačba se lahko zapiše tudi na naslednji način:
where tn, tn-1 are the times required for a given number N of revolutions. These time intervals tn and tn-1 succeed one another, and tn > t n-1.
kjer sta tn, tn - 1 časa, potrebna za določeno število vrtljajev N. Časovna intervala tn in tn-1 si sledita in tn > tn-1.
T temperature
T temperatura
R universal molar gas constant
R splošna plinska konstanta
M molar mass
M molska masa
The vapour pressure from any of the preceding methods should be determined for at least two temperatures.
Pri kateri koli od navedenih metod je treba parni tlak določiti pri najmanj dveh temperaturah.
Three or more are preferred in the range 0 to 50 oC, in order to check the linearity of the vapour pressure curve.
Za preverjanje linearnosti krivulje parnega tlaka so zaželene najmanj tri temperature v območju od 0 do 50 oC.