natgillin/translations-raw huggingface dataset:
at least two vapour pressure and temperature values, preferably in the range 0 to 50 oC,
najmanj po dve vrednosti parnega tlaka in temperature, po možnosti v območju 0 do 50 oC,
all of the raw data,
vsi neobdelani podatki,
a log p versus 1/T curve,
krivulja log p v odvisnosti od 1/T,
an estimate of the vapour pressure at 20 or 25 oC.
ocenjeni parni tlak pri 20 ali 25 oC.
If a transition (change of state, decomposition) is observed, the following information should be noted:
Če pride do prehoda (spremembe stanja, razpada), je treba navesti naslednje podatke:
nature of the change,
vrsta spremembe,
temperature at which the change occurs at atmospheric pressure,
temperatura, pri kateri pride do spremembe pri atmosferskem tlaku,
vapour pressure at 10 and 20 oC below the transition temperature and 10 and 20 oC above this temperature (unless the transition is from solid to gas).
parni tlak pri 10 in 20 oC pod temperaturo prehoda in pri 10 in 20 oC nad to temperaturo (razen če gre za prehod iz trdnega v plinasto agregatno stanje).
Ambrose, D. in B. Le Neindre, B. Vodar, (Eds.): Experimental Thermodynamics, Butterworths, London, 1975, vol. II.
Ambrose, D. in B. Le Neindre, B. Vodar, (Eds.): Experimental Thermodynamics, Butterworths, London, 1975, Vol II.
NF T 20-048 AFNOR (September 85) Chemical products for industrial use — Determination of vapour pressure of solids and liquids within range from 10-1 to 105 Pa — Static method.
NF T 20-048 AFNOR (September 85). Chemical products for industrial use –Determination of vapour pressure of solids and liquids within range from 10-1 to 105 Pa – Static method.
NF T 20-047 AFNOR (September 85) Chemical products for industrial use — Determination of vapour pressure of solids and liquids within range from 10-3 to 1 Pa — Vapour pressure balance method.
NF T 20-047 AFNOR (September 85). Chemical products for industrial use -Determination of vapour pressure of solids and liquids within range from 10-3 to 1 Pa – Vapour pressure balance method.
Technol.(A), 1987, 'Vol. 5 (4), p. 2440.
Technol.(A), 1987, VoI. 5 (4), 2440.
Thermodynamics 1975, vol. 7, p. 1173.
Thermodynamics 1975, Vol. 7, 1173.
Technol., 1982, vol. 20 (4), p. 1148.
Technol., 1982, voI. 20 (4), 1148.
Estimation method
Ocenjevalna metoda
for providing an estimate or limit value in cases where the experimental method cannot be applied due to technical reasons (including where the vapour pressure is very low),
za pridobitev ocene ali mejne vrednosti v primerih, kadar preskusne metode ni mogoče uporabiti zaradi tehničnih razlogov (in tudi kadar je parni tlak zelo nizek),
to help identify those cases where omitting experimental measurement is justified because the vapour pressure is likely to be < 10-5 Pa at ambient temperature.
v pomoč pri določanju primerov, pri katerih je opustitev merjenja upravičena, ker je verjetno, da je parni tlak pri sobni temperaturi < 10-5 Pa.
ESTIMATION METHOD
OCENJEVALNA METODA
The vapour pressure of liquids and solids can be estimated by use of the modified Watson Correlation (a).
Parni tlak tekočin in trdnih snovi se lahko oceni z uporabo prilagojene Watsonove korelacije (a).
The only experimental data required is the normal boiling point.
Edini potrebni s preskusom pridobljeni podatek je normalno vrelišče.
The method is applicable over the pressure range from 105 Pa to 10-5 Pa.
Metoda je uporabna za območje tlaka od 105 Pa do 10 -5 Pa.
Detailed information on the method is given in ‘Handbook of Chemical Property Estimation Methods’ (b).
Podrobne informacije o metodi so navedene v „Priročniku metod za ocenjevanje kemijskih lastnosti“ (b).
CALCULATION PROCEDURE
RAČUNSKI POSTOPEK
According to (b) the vapour pressure is calculated as follows:
V skladu z (b) se parni tlak izračuna na naslednji način:
T = temperature of interest
T = izbrana temperatura
= normal boiling point
= normalno vrelišče
= vapour pressure at temperature T
= parni tlak pri temperaturi T
= heat of vaporisation
= izparilna toplota
= compressibility factor (estimated at 0,97)
= faktor stisljivosti (ocenjen na 0,97)
m = empirical factor depending on the physical state at the temperature of interest
m = empirični faktor, odvisen od agregatnega stanja pri izbrani temperaturi
further:
Nadalje
where KF is an empirical factor considering the polarity of the substance.
pri čemer je KF empirični faktor, ki upošteva polarnost snovi.
For several compound types, KF factors are listed in reference (b).
V viru (b) so navedeni faktorji KF za več spojin.
Quite often, data are available in which a boiling point at reduced pressure is given.
Precej pogosto so na voljo podatki o vrelišču pri znižanem tlaku.
In such a case, according to (b), the vapour pressure is calculated as follows:
V skladu z (b) se pri takih primerih parni tlak izračuna na naslednji način:
where T1 is the boiling point at the reduced pressure P1.
pri čemer je T1 vrelišče pri znižanem tlaku P1.
REPORT
POROČILO
When using the estimation method, the report shall include a comprehensive documentation of the calculation.
Pri uporabi ocenjevalne metode, poročilo vključuje izčrpno dokumentacijo izračuna.
Lyman, W.F.
Lyman, W.F. Reehl, D.H.
Reehl, D.H.
Rosenblatt (ed).
Apparatus for determining the vapour pressure curve according to the dynamic method
Aparatura za določanje krivulje parnega tlaka po dinamični metodi
1 = Thermocouple
1 = Termočlen
2 = Vacuum buffer volume
2 = Vakuumski pufrski volumen
3 = Pressure gauge
3 = Merilnik tlaka
4 = Vacuum
4 = Vakuum
5 = Measuring point
5 = Merilna točka
6 = Heating element circa 150 W
6 = Grelni element, približno 150 W
Apparatus for determining the vapour pressure curve according to the static method (using a U-tube manometer)
Aparatura za določanje krivulje parnega tlaka po statični metodi (z uporabo manometra z U-cevko)
Test substance
Preskusna snov
Vapour phase
Parna faza
High vacuum valve
Visokovakuumski ventil
U-tube (auxiliary manometer)
U-cevka (pomožni manometer)
Temperature bath
Temperaturna kopel
Temperature measuring device
Naprava za merjenje temperature
To vacuum pump
Vod do vakuumske črpalke
Ventilation
Zračenje
Apparatus for determining the vapour pressure curve according to the static method (using a pressure indicator)
Aparatura za določanje krivulje parnega tlaka po statični metodi (z uporabo indikatorja tlaka)
Pressure indicator
Indikator tlaka
Isoteniscope (see reference 7)
Izoteniskop (glej vir 7)
To pressure control and measurement system
Vod do sistema za kontrolo in merjenje tlaka
8 mm OD tube
Cev z zunanjim premerom 8 mm
Dry nitrogen in pressure system
Suhi dušik v tlačnem sistemu
Sample vapour
Para vzorca
Small tip
Majhna konica
Liquid sample
Tekoči vzorec
Apparatus for determining the vapour pressure curve according to the vapour pressure balance method
Aparatura za določanje krivulje parnega tlaka po metodi s parnotlačno tehtnico
Vapour phase with vapour stream
Parna faza s curkom pare
Evaporation furnace with rotary inlet
Uparjalna peč z vrtljivim dovodom
Furnace lid with opening
Pokrov peči z odprtino
Furnace heating (refrigeration)
Ogrevanje (hlajenje) peči
Measurement of temperature of sample
Merjenje temperature vzorca
Refrigeration box
Hladilna posoda
Shield
Zaslon
Refrigeration bar for refrigeration box
Hladilna palica za hladilno posodo
Balance pan
Skodelica tehtnice
Microbalance
Mikrotehtnica
To recorder
Povezava z zapisovalnikom
To high-vacuum pump
Vod do vakuumske črpalke
Example of apparatus for evaporation at low pressure by effusion methode, with an effusion cell volume of 8 cm3
Primer aparature za uparjanje pri nizkem tlaku z efuzijsko celico z volumnom 8 cm3
1 Connection to vacuum
1 Povezava z vakuumom
2 Wells for platinum resistance thermometer or temperature measurement and control (2)
2 Luknje za platinski uporovni termometer ali sisteme za merjenje in nadzorovanje temperature (2)
3 Lid for vacuum tank
3 Pokrov vatuumske posode
4 O-ring
4 O-tesnilo
5 Aluminium vacuum tank
5 Aluminijasta vakuumska posoda
6 Device for installing and removing the effusion cells
6 Naprava za pritrjevanje in odstranjevanje efuzijskih celic
7 Threaded lid
7 Navojni pokrov
8 Butterfly nuts (6)
8 Krilne matice (6)
9 Bolts (6)
9 Vijaki (6)
10 Stainless steel effusion cells
10 Efuzijske celice iz nerjavečega jekla
11 Heater cartridges (6)
11 Grelni vložki (6)
Figure 6a
Slika 6a
An example of a flow system for the determination of vapour pressure by the gas saturation method
Primer pretočnega sistema za določanje parnega tlaka z metodo nasičenega plina oddušnik razdelilnik
1 = Flow regulator
1 = Regulator pretoka
2 = Heat exchanger
2 = Toplotni izmenjevalnik
3 = Needle valves
3 = Igelni ventili
4 = Relative humidity sensor
4 = Senzor relativne vlažnosti
5 = Saturation columns
5 = Saturacijske kolone
6 = PTFE joints
6 = PTFE spojke
7 = Flow meter
7 = Merilnik pretoka
8 = Trap (absorber)
8 = Past (absorbent)
9 = Oil trap
9 = Oljna past
10 = Fritted bubbler Vent
10 = Kalcinirana cevka za ustvarjanje mehurčkov
Manifold
Slika 6b
Figure 6b An example of system for the determination of vapour pressure by the gas saturation method, with a capillary placed after the saturation chamber
Primer sistema za določanje parnega tlaka z metodo nasičenega plina, pri katerem je za saturacijsko kolono postavjena kapilara
Thermal mass flowmeter
Merilnik toplotnega pretoka
Temperature-controlled chamber
Termostatirana komora
Thermostating coil for carrier gas
Termostatirana tuljava za nosilni plin
Thermometer (Pt 100)
Termometer (Pt 100)
Gas saturation chamber
Posoda za nasičenje plina
Capillary
Kapilara
Absorption vessels
Absorpcijske posode
Gas meter
Plinomer
Cold trap
Ohlajena past
Example of the experimental set-up for spinning rotor method
Primer postavitve preskusa za rotorsko metodo
Vapour pressure apparatus
Aparatura za parni tlak
spinning rotor sensor head;
Vrteči rotorski senzor
sample cell;
Celica za vzorec
vacuum line (turbo pump);
Vakuumska cev (turbo črpalka)
air thermostat.
Zračni termostat
Example of spinning rotor measuring head
Primer vrtečega rotorskega merilnika
Ball;
Kroglica
Evacuated tubular extension of 6;
Odzračen cevni podaljšek 6
Permanent magnets (2);
Trajni magnet (2)
Coils (2) for vertical stabilization;
Tuljava (2) za vertikalno stabilizacijo
Driving coils (4);
Vzbujevalna tuljava (4)
Connection flange.
Vezna prirobnica
The described methods are to be applied to the measurement of the surface tension of aqueous solutions.
Opisane metode se uporabljajo za merjenje površinske napetosti vodnih raztopin.
It is useful to have preliminary information on the water solubility, the structure, the hydrolysis properties and the critical concentration for micelles formation of the substance before performing these tests.
Pred izvajanjem teh preskusov je koristno imeti predhodne informacije o topnosti snovi v vodi, njeni zgradbi, hidrolitskih lastnostih in kritični koncentraciji za tvorbo micel.
The following methods are applicable to most chemical substances, without any restriction in respect to their degree of purity.
Metode, ki sledijo, so uporabne za večino kemijskih snovi, brez kakršnih koli omejitev glede njihove stopnje čistosti.
The measurement of the surface tension by the ring tensiometer method is restricted to aqueous solutions with a dynamic viscosity of less than approximately 200 mPa s.
Merjenje površinske napetosti z metodo tenziometra z obročkom je omejeno na vodne raztopine z dinamično viskoznostjo pod približno 200 mPa s.
The free surface enthalpy per unit of surface area is referred to as surface tension.
Prosto površinsko entalpijo na enoto površine imenujemo površinska napetost.
The surface tension is given as:
Površinska napetost se navede v:
N/m (SI unit) or
N/m (enota SI) ali
mN/m (SI sub-unit)
mN/m (podenota SI)
1 N/m = 103 dynes/cm
1 N/m = 103 din/cm
1 mN/m = 1 dyne/cm in the obsolete cgs system
1 mN/m = 1 din/cm v zastarelem sistemu cgs
Reference substances which cover a wide range of surface tensions are given in references 1 and 3.
Referenčne snovi, ki zajemajo široko območje površinskih napetosti, so navedene v virih 1 in 3.
The methods are based on the measurement of the maximum force which is necessary to exert vertically, on a stirrup or a ring in contact with the surface of the liquid being examined placed in a measuring cup, in order to separate it from this surface, or on a plate, with an edge in contact with the surface, in order to draw up the film that has formed.
Metode temeljijo na merjenju največje navpične sile, ki jo je treba uporabiti na zanki ali obročku v stiku s površino preiskovane tekočine v merilni posodici, da bi ga ločili od te površine, ali na ploščici, katere rob se stika s površino, da bi potegnili nastali film navzgor.
Substances which are soluble in water at least at a concentration of 1 mg/l are tested in aqueous solution at a single concentration.
Snovi, ki so topne v vodi vsaj pri koncentraciji 1 mg/l, se preskušajo v vodni raztopini pri eni sami koncentraciji.
These methods are capable of greater precision than is likely to be required for environmental assessment.
Natančnost teh metod je večja, kot je to običajno potrebno za okoljsko presojo.
A solution of the substance is prepared in distilled water.
Pripravi se raztopina snovi v destilirani vodi.
The concentration of this solution should be 90 % of the saturation solubility of the substance in water; when this concentration exceeds 1 g/l, a concentration of 1 g/l is used for testing.
Koncentracija te raztopine mora biti 90 % koncentracije nasičene raztopine te snovi v vodi; kadar ta koncentracija presega 1 g/l, se za preskušanje uporabi koncentracija 1 g/l.
Substances with water solubility lower than 1 mg/l need not be tested.
Snovi, katerih topnost v vodi je manjša od 1 mg/l, ni treba preskušati.
Plate method
Metoda s ploščico
See ISO 304 and NF T 73-060 (Surface active agents — determination of surface tension by drawing up liquid films).
Glej ISO 304 in NF T 73-060 (Površinsko aktivne snovi – določanje površinske napetosti z dviganjem tekočinskih filmov).
Stirrup method
Metoda z zanko
Ring method
Metoda z obročkom
OECD harmonised ring method
Usklajena metoda OECD z obročkom
Commercially available tensiometers are adequate for this measurement.
Za to merjenje so primerni na trgu dostopni tenziometri.
They consist of the following elements:
Sestavljajo jih naslednji deli:
mobile sample table,
premična mizica za vzorec,
force measuring system,
sistem za merjenje sile,
measuring body (ring),
merilno telo (obroček),
measurement vessel.
merilna posoda.
Mobile sample table
Premična mizica za vzorec
The mobile sample table is used as a support for the temperature-controlled measurement vessel holding the liquid to be tested.
Premična mizica za vzorec se uporablja kot podpora za termostatirano merilno posodo, v kateri je preskusna tekočina.
Together with the force measuring system, it is mounted on a stand.
Skupaj s sistemom za merjenje sile je nameščena na stojalu.
Force measuring system
Sistem za merjenje sile
The force measuring system (see figure) is located above the sample table.
Sistem za merjenje sile (glej sliko) je nad mizico za vzorec.
The error of the force measurement shall not exceed ± 10-6 N, corresponding to an error limit of ±0,1 mg in a mass measurement.
Napaka pri merjenju sile ne sme presegati ± 10-6 N, kar ustreza meji napake ±0,1 mg pri določanju mase.
In most cases, the measuring scale of commercially available tensiometers is calibrated in mN/m so that the surface tension can be read directly in mN/m with an accuracy of 0,1 mN/m.
Merilna skala na trgu dostopnih tenziometrov je v večini primerov umerjena v mN/m, tako da se lahko površinska napetost odčita neposredno v mN/m na 0,1 mN/m točno.
Measuring body (ring)
Merilno telo (obroček)
The ring is usually made of a platinum-iridium wire of about 0,4 mm thickness and a mean circumference of 60 mm. The wire ring is suspended horizontally from a metal pin and a wire mounting bracket to establish the connection to the force measuring system (see figure).
Obroček je običajno narejen iz platina-iridijeve žice, debele približno 0,4 mm, in s povprečnim obsegom 60 mm. Žičnati obroček visi v vodoravnem položaju s kovinske zaponke in žičnatega namestitvenega nosilca, tako da je povezan s sistemom za merjenje sile (glej sliko).
Figure
Skica
Measuring body
Merilno telo
(All dimensions expressed in millimetres)
(Vse dimenzije so v milimetrih)
Mounting bracket
Kovinska zaponka
Pin
Namestitveni nosilec
Ring
Obroček
The measurement vessel holding the test solution to be measured shall be a temperature-controlled glass vessel.
Merilna posoda, v kateri je preskusna raztopina, je termostatirana steklena posoda.
It shall be designed so that during the measurement the temperature of the test solution liquid and the gas phase above its surface remains constant and that the sample cannot evaporate.
Zasnovana je tako, da med merjenjem temperatura preskusne raztopine in plinske faze nad njeno površino ostane konstantna ter vzorec ne more izhlapeti.
Cylindrical glass vessels having an inside diameter of not less than 45 mm are acceptable.
Sprejemljive so valjaste steklene posode z notranjim premerom najmanj 45 mm.
Preparation of the apparatus
Priprava aparature
Glass vessels shall be cleaned carefully.
Steklene posode se temeljito očistijo.
If necessary they shall be washed with hot chromo-sulphuric acid and subsequently with syrupy phosphoric acid (83 to 98 % by weight of H3PO4), thoroughly rinsed in tap water and finally washed with double-distilled water until a neutral reaction is obtained and subsequently dried or rinsed with part of the sample liquid to be measured.
Če je potrebno, se operejo z vročo kromžveplovo kislino in nato z gosto tekočo fosforjevo kislino (83 do 98 masnih % H3PO4), temeljito sperejo pod tekočo vodo in nazadnje še z dvakrat destilirano vodo do nevtralne reakcije, nato se posušijoali splaknejo z delom preskusne tekočine.
The ring shall first be rinsed thoroughly in water to remove any substances which are soluble in water, briefly immersed in chromo-sulphuric acid, washed in double-distilled water until a neutral reaction is obtained and finally heated briefly above a methanol flame.
Obroček se najprej temeljito splakne z vodo, da se odstranijo vse v vodi topne snovi, nato se za kratek čas potopi v kromžveplovo kislino, opere v dvakrat destilirani vodi do nevtralne reakcije ter na koncu na hitro segreje nad metanolnim plamenom.
Contamination by substances which are not dissolved or destroyed by chromo-sulphuric acid or phosphoric acid, such as silicones, shall be removed by means of a suitable organic solvent.
Nečistote, ki niso topne ali razgradljive v kromžveplovi ali fosforjevi kislini, na primer silikoni, se odstranijo z ustreznim organskim topilom.
Calibration of the apparatus
Umerjanje aparature
The validation of the apparatus consists of verifying the zero point and adjusting it so that the indication of the instrument allows reliable determination in mN/m.
Validacija aparature obsega preverjanje ničelne točke in njeno naravnavo, tako da je omogočeno zanesljivo odčitavanje z instrumenta v mN/m.
Mounting:
Postavitev:
The apparatus shall be levelled, for instance by means of a spirit level on the tensiometer base, by adjusting the levelling screws in the base.
Aparatura se izravna, na primer s pomočjo vodne tehtnice na osnovni plošči tenziometra, z nastavitvijo izravnalnih vijakov na osnovni plošči.
Zero point adjustment:
Naravnava ničelne točke:
After mounting the ring on the apparatus and prior to immersion in the liquid, the tensiometer indication shall be adjusted to zero and the ring checked for parallelism to the liquid surface.
Po namestitvi obročka na aparaturo in pred potopitvijo v tekočino se tenziometer naravna na ničlo ter preveri, ali je obroček vzporeden s površino tekočine.
For this purpose, the liquid surface can be used as a mirror.
V ta namen se površina tekočine lahko uporabi kot ogledalo.
Calibrations:
Umeritev:
The actual test calibration can be accomplished by means of either of two procedures:
Dejansko umerjanje se lahko opravi po enem od dveh postopkov:
Using a mass: procedure using riders of known mass between 0,1 and 1,0 g placed on the ring.
Z uporabo mase: postopek z uporabo jahačev z znano maso med 0,1 in 1,0 g, postavljenih na obroček.
The calibration factor, Φa by which all the instrument readings must be multiplied, shall be determined according to equation (1).
Umeritveni faktor Φa, s katerim je treba pomnožiti vse odčitke z instrumenta, se določi po enačbi (1):
m mass of the rider (g)
m masa jahača (g)
g gravity acceleration (981 cm s-2 at sea level)
g gravitacijski pospešek (981 cm s-2 na morski višini)
reading of the tensiometer after placing the rider on the ring (mN/m).
σa odčitek tenziometra po namestitvi jahača na obroček (mN/m).
Using water: procedure using pure water whose surface tension at, for instance, 23 oC is equal to 72,3 mN/m.
Z uporabo vode: postopek z uporabo čiste vode, katere površinska napetost pri, na primer, 23 oC je 72,3 mN/m.
This procedure is accomplished faster than the weight calibration but there is always the danger that the surface tension of the water is falsified by traces of contamination by surfactants.
Ta postopek je hitrejši od masnega umerjanja, vendar vedno obstaja nevarnost, da je površinska napetost vode napačna zaradi sledov onesnaženja s površinsko aktivnimi snovmi.
The calibration factor, Φb by which all the instrument readings shall be multiplied, shall be determined in accordance with the equation (2):
Umeritveni faktor Φb, s katerim je treba pomnožiti vse odčitke z instrumenta, se določi po enačbi (2):
value cited in the literature for the surface tension of water (mN/m)
površinska napetost vode, navedena v literaturi (mN/m)
measured value of the surface tension of the water (mN/m) both at the same temperature.
izmerjena površinska napetost vode (mN/m), obe pri isti temperaturi.
Preparation of samples
Priprava vzorcev
Aqueous solutions shall be prepared of the substances to be tested, using the required concentrations in water, and shall not contain any non-dissolved substances.
Pripravijo se vodne raztopine preskusnih snovi v potrebnih koncentracijah in ne smejo vsebovati nobenih neraztopljenih snovi.
The solution must be maintained at a constant temperature (±0,5 oC).
Vzdrževati je treba konstantno temperaturo (±0,5 oC) raztopine.
Since the surface tension of a solution in the measurement vessel alters over a period of time, several measurements shall be made at various times and a curve plotted showing surface tension as a function of time.
Ker se površinska napetost raztopine v merilni posodi spreminja s časom, se izvede več meritev ob različnih časih in izdela krivulja, ki prikazuje površinsko napetost kot funkcijo časa.
When no further change occurs, a state of equilibrium has been reached.
Ko ni več nadaljnjih sprememb, je doseženo stanje ravnotežja.
Dust and gaseous contamination by other substances interfere with the measurement.
Onesnaženje z drugimi snovmi v obliki prahu in plinov moti merjenje.
The work shall therefore be carried out under a protective cover.
Zato se delo izvaja pod zaščitnim pokrovom.
The measurement shall be made at approximately 20 oC and shall be controlled to within ±0,5 oC.
Merjenje se opravi pri približno 20 oC, ob vzdrževanju konstantne temperature ±0,5 oC.
Performance of test
Izvedba preskusa
The solutions to be measured shall be transferred to the carefully cleaned measurement vessel, taking care to avoid foaming, and subsequently the measurement vessel shall be placed onto the table of the test apparatus.
Merjena raztopina se nalije v dobro očiščeno merilno posodo, pri čemer je treba paziti, da se ne peni, nato se merilna posoda postavi na mizico preskusne aparature.
The table-top with measurement vessel shall be raised until the ring is immersed below the surface of the solution to be measured.
Vrh mizice z merilno posodo se dviga, dokler se obroček ne potopi pod površino merjene raztopine.
Subsequently, the table-top shall be lowered gradually and evenly (at a rate of approximately 0,5 cm/min) to detach the ring from the surface until the maximum force has been reached.
Nato se vrh mizice postopoma in enakomerno spušča (s hitrostjo približno 0,5 cm/min), da bi se obroček odtrgal od površine, dokler se ne doseže največja sila.