Density of Working Liquids for Diffusion Vacuum ... - ACS Publications

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Cite This: J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Density of Working Liquids for Diffusion Vacuum Pumps Damir Sagdeev,† Marina Fomina,† Valeriy Alyaev,† Rashid Musin,† and Ilmutdin Abdulagatov*,§ †

Kazan National Research Technological University, Kazan, Russian Federation 420111 Department of Physical and Organic Chemistry, Dagestan State University, Makhachkala, Russian Federation 367000

§

ABSTRACT: The density of high viscosity working liquids (BM-1C, LEYBONOL LVO 500, and Alkaren-D24) for diffusion vacuum pumps have been measured over the temperature range from 273 to 473 K at atmospheric pressure. The measurements were made using a newly designed densimeter based on hydrostatic weighing method. The combined expanded uncertainty of the density, atmospheric pressure, and temperature measurements at 0.95 confidence level with a coverage factor of k = 2 is estimated to be U(ρ) = 1.0 kg·m−3, Ur(P) = 0.01, and U(T) = 0.02 K, respectively. To confirm the reliability, accuracy, and correct operation of the densimeter, the density of pure nheptane, ethane-1,2-diol (MEG), and propane-1,2-diol (MPG) with well-established PVT properties (REFPROP/NIST/TDE) over the temperature range from 273 to 473 K at atmospheric pressure were measured using the new developed hydrostatic weighing densimeter (HWD). Also, in order to additional validate the reliability of the measured density data all diffusion vacuum pump liquid samples were measured using the pycnometric method. The present study showed that the densities measured using the new HWD agree with the values obtained with pycnometric method within 0.03−0.08 %.

1. INTRODUCTION Density, along with other thermophysical properties such as heat capacity, speed of sound, viscosity, and thermal conductivity, is the most important characteristic of the materials and determines their technological, operational, and consumer properties. Accurate density is an important thermodynamic property of working liquids for diffusion vacuum pumps, because such a property is critical for its design and operation. Therefore, reliable and accurate density data of diffusion vacuum pump working liquids is essential for the different applications, for example, vacuum pump designers and manufacturers must tailor the operating parameters to suit the working liquids. Density defines the size of the equipment. Several methods are available for accurate measurements of the density of liquids. The most widely used techniques to measure the density of working fluids are (1) constant volume piezometer (typical uncertainty in density measurements is within from 0.05% to 0.15%); (2) variable volume piezometer (typical uncertainty in density measurements is within from 0.01% to 0.1%); (3) hydrostatic weighing method (typical uncertainty in density measurements is within from 0.01% to 0.3%); (4) vibrating tube densimeter (typical uncertainty in density measurements is within from 0.002% to 0.08%); and (5) pycnometric method (typical uncertainty in density measurements is within from 0.01 to 0.3%). These methods, their typical uncertainties, and advantages and disadvantages were comprehensively reviewed in our earlier publication.1 Also, a detailed description of different densimeter types, used for accurate measurements of the density of liquids and liquid mixtures, can be found in IUPAC publication.2 There are some disadvantages of these methods. For example, (1) constant volume piezometer has problems with sampling, that is, © XXXX American Chemical Society

depressurization of the measuring system is possible during the sampling. Also, this method suffers from noxious volume, which is significantly effecting on the uncertainty of density measurement. (2) Method variable volume piezometer cannot be applied for viscous liquids (like diffusion vacuum pump working liquids, ionic liquids, some kinds of high-viscosity oils, etc.) with viscosity above >100 mPa·s at low temperatures where the viscosity rapidly increases due to deformation of the bellows. (3) Practical realization of the hydrostatic weighing method required lead (output) from high-pressure zone, many of measuring wires, which complicates the construction of the measuring device. Also, generally, these techniques require many hours to measure a single data point. In addition, in the pycnometric method before weighing with an analytical balance cooling of the pycnometer to room temperature is required. Thus, most existing densimeters are not suitable for measurements of the density of high-viscosity liquids (for example, vacuum oils, superhigh-viscosity oils, ionic liquids at low temperatures, etc.) due to a filling problem. In several of our previous publications,3−8 a new apparatus to simultaneously measure the density and viscosity of liquids has been designed and constructed based on the hydrostatic weighing and falling-body principles. The apparatus can be employed to simultaneously measure the density and viscosity of liquids over the temperature range from 293 to 473 K and at pressures up to 250 MPa with expanded uncertainties of 0.15% and 2%, respectively. The main goal of the present work was the development a new design of the densimeter based on the Received: January 9, 2018 Accepted: April 4, 2018

A

DOI: 10.1021/acs.jced.8b00028 J. Chem. Eng. Data XXXX, XXX, XXX−XXX

Journal of Chemical & Engineering Data

Article

Table 1. Physical Chemical Characteristics of the Working Liquid Samplesa sample name

kinematic viscosity, mm2/s at 323 K

BM-1C (Moscow) BM-1C (Novgorod) LEYBONOL LVO 500 Alkaren-D24

35 35 100 (at 313 K) 45−55

vapor-pressure, Pa at 293 K 5.3 5.3 4.0 1.0

× × × ×

10−6 10−6 10−6 10−5

b.t. K

flash point

413−423 413−423

516 K 516 K >523 K 513 K

453−483

sample description chemical name n-Heptane CAS # 142-82-5 Ethane-1,2-diol (MEG) CAS # 107-21-1 Propane-1,2-diol (MPG) CAS # 57-55-6 a b

source “ChemReactve”Novocherkassk, Russia INEOS Manufacturing Deutschland GmbH (Germany) INEOS Manufacturing Deutschland GmbH (Germany)

initial mole fraction purity

purification method

final mole fraction purity

analysis method

0.9999 0.997

none none

0.9999 0.997

GCb GCb

0.998

none

0.998

GCb

Physical and chemical characteristics of the samples were provided by suppliers; water content in the all samples was zero (provider by supplier). Gas−liquid chromatography.

decomposition of the sample, density ρ20 4 and refractive index n20 D of the samples were checked before and after measurements. The purity information for n-heptane, MEG, and MPG used for test measurements were provided in our previous publications (see also Table 1).3−5,8 2.2. A New Design of the Hydrostatic Weighing Densimeter (HWD). A new HWD for measurements of the density of liquids at temperatures (from 273 to 500 K) at atmospheric pressure has been designed. The densimeter is based on hydrostatic weighing principle. Most available hydrostatic weighing densimeters used ordinary lever scales, which made it difficult to carry out measurements due to the constant movement of the suspension weighing system and extended the experimental time, that is, too long float equilibrium time, due to low speed of float motion. We deduced a new working equation for a new HWD method with an electronic balance, which differs from the working equation for the lever scales. Swaying of the lever scales also affects the difficulty of measuring viscous liquids, like vacuum oils for diffusion pumps (see, for example, ref 11). In difference existing HWD, the main part of the present HWD is an electronic balance HR-250AZG (A&D Co. LTD, Japan). The main advantage of the present densimeter is that it allows one-push calibration, that is, considerable simplifying of the calibration procedure. Also, the method is simpler and faster (takes short measurement time) and at the same time the accuracy of the density measurements is comparable with conventional techniques. The new design of the densimeter allows one to measure the density of working liquids over the temperature range from 273 to 473 K at atmospheric pressure with high accuracy (see below). Schematic diagram of the HWD for the density measurements at atmospheric pressure is shown in Figure 1. On the massive holder (1), the stand (2) with adjustable feet was installed. The centering system (3) was installed on the stand (2) (support, holder, rack). This system was used to move the thermostatting system (4) in the horizontal plane. The table (7) was equipped with three posts and support rings (9) for fixing the shield against heat flows (10), which protects the electronic balance (6). A density measuring system (5) consisting of a ring, a wire, and a float, made of a BT-6 grade titanium alloy is suspended to the lower hook of the balance. The float with the sizes of diameter 10 mm and length of 100 mm was used. At the top, the float has a tab for hanging on a preannealed constantan wire with a diameter of 0.15 mm and a

hydrostatic weighing principle for accurate and fast measurement of the density of working liquids in the wide temperature range from 273 to 473 K at atmospheric pressure. The other purpose of the work is employing the developed new hydrostatic weighing densimeter to measure of the density of working liquids (BM-1C, LEYBONOL LVO 500, and AlkarenD24) for diffusion vacuum pumps.

2. EXPERIMENTAL SECTION 2.1. Materials. The working liquids for diffusion vacuum pumps (BM-1C, LEYBONOL LVO 500, and Alkaren-D24)

Figure 1. Schematic diagram of the hydrostatic weighing densimeter (HWD). 1, support (stand); 2, stand; 3, centering system; 4, thermostatting system; 5, measuring system (ring, wire and float made from titanium alloy BT-6); 6, electronic balance HR-250AZG (A&D Co. LTD, Japan); 7, table; 8, setting of the “zero” position of electronic balance; 9, supporting ring; 10, heat flow screen.

used in this work were supplied by OAO “Moscow Petro-Oil Plant” TY 38.1011187-88 (BM-1C, Moscow), ZAO “VolgaNefteKhim” Nizhnyi Novgorod TU 38.1011187-88 (BM-1C, Nizhnyi Novgorod), Oerlikon Leybord Vacuum (LEYBONOL LVO 500), and Kemerov OAO “KhimProm” (Alkaren − D24). The main physicochemical properties, which characterize the diffusion vacuum pumps working liquids (BM-1C, LEYBONOL LVO 500, Alkaren-D24) used in this study, are given in Table 1. Physical and chemical characteristics of the samples in Table 1 were provided by suppliers. Water content in the all samples was zero. In order to check the possible thermal B



Article

Table 2. Example of the Uncertainty Estimating of the Density Measurements for n-Heptane at Atmospheric Pressure and at Selected Temperature of T = 356.84 K for New Designed HWDa no.

eqs

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 a 0 ρL

2 2 2 2 2 2 2,3

quantity ρL,Τ m m1 ρair Vw Vring VT αT T T0 ΔT VcF m1 ρ0L V

units

u(Xi)

measurements

−3

kg·m kg kg kg·m−3 m3 m3 m3 K−1 K K

627.85 32.5719 27.9534 1.2 1.2134 7.9163 7.3652 8.3394 356.84 293.15 1.0016 7.3651 27.5365 683.69 7.4783

m3 kg kg·m−3 m3

u(%) −1

× 10−3 × 10−3 × × × ×

10−9 10−8 10−6 10−6

× 10−6 × 10−3

1.3549 × 10 4.5545 × 10−7 6.6286 × 10−7

2.16 × 10−2 1.40 × 10−3 2.37 × 10−3

1.2485 × 10−10 4.2232 × 10−10 9.4217 × 10−10

1.03 × 101 5.33 × 10−1 1.27 × 10−2

0.05 0.05

1.40 × 10−2 1.71 × 10−2

9.4214 3.1656 4.4447 6.6489

× 10−6

× × × ×

10−10 10−7 10−2 10−10

1.19 1.15 × 10−3 6.50 × 10−3 8.89 × 10−3

is the density of the liquid under study at 293.15 K from pycnometric measurements; V is the volume of the suspension system in the vacuum.

Table 3. Experimental Temperatures (T/ K) and Densities (ρ/ kg·m−3) of n-Heptane at Atmospheric Pressure Using Pycnometric (PYC) and Hydrostatic Weighing Densimeter (HWD)a T/K

PYC ρ/kg·m−3

HWD ρ/kg·m−3

referenceb ρ/kg·m−3

difference Δρ/kg·m−3

293.15 301.62 310.71 319.85 329.04 338.26 347.53 356.84

683.67 675.75 667.37 659.85 651.92 644.32 635.91 627.85

683.65 675.96 668.05 660.16 652.58 644.01 635.57 627.05

683.82 676.66 668.91 661.04 653.03 644.88 636.55 628.03

−0.02 0.21 0.68 0.31 0.66 −0.31 −0.34 −0.80

Standard uncertainties u are u(T) = 0.01 K; ur(P = 0.101 MPa) = 0.005; u(ρ) = 0.5 kg·m−3; Δρ = ρ(HWD) − ρ(PYC). bReference correlation (REFPROP).13

a

depends on the characteristics of the electronic balance HR250AZG (A & D Co. LTD, Japan), which is equipped with built-in weight, which allows one to calibrate with a single-push of the button. Suspension system of the densimeter consists of a ring, a wire, and a float. It is affected by the reaction force from the suspension of the electronic balance (P), which is numerically equal to the weight difference of the suspension system in the vacuum, and the weight of the suspension system when weighed in the air and directed downward

length of 200 mm. The wire is suspended to the hook of the electronic balance (HR-250AZG) through the adapter, which in turn is connected to the tuning system on “zero” electronic balance (8). This system is a plate in the center of which a hole with a diameter of 10 mm is drilled. A ring with a diameter of 25 mm, located above and connected by a constantan wire with a titanium float, disengages from lifting the plate. This allows the electronic balance to be adjusted to zero. The float is placed in a cylindrical vessel with an internal diameter of 25 mm, which in turn is inserted into the copper block placed in the heat-exchanger through the channels the thermostatting liquid is pumped. The heat-exchanger is covered with asbestos thermal insulation. The thermostatting was carried out with a liquid polymethylsiloxane (PMS-20), which came from the ultrathermostat (U-10) with an accuracy of ±0.02 K. To control the temperature in the copper block, copper-constantan thermocouples, placed in the copper block of the thermostatic system, were used. 2.3. Working Equation for Hydrostatic Weighing Densimeter Method. The final working equation for density measurement for this method (hydrostatic weighing densimeter) was derived using the detailed method described in our previous publications.3,5,8 Weighing on an electronic balance has some peculiarities, because it excludes the movement of a suspension system consisting of a ring, a wire, and a float vertically, as in a lever or spring balance. In our case, the balance of the suspension system during the weighing process

P = (m − m1)g

(1)

where m = mF + mw + mring is the sum of the masses reduced to emptiness, a float, a wire, and a ring, respectively; m1 = m1F + m1w + m1ring is the sum of the masses of the float, the wire, and the ring, respectively, weighed during the experiment to determine the density of the liquid under study. The volume and masses of the suspension system in the vacuum were determined using the method detailed described in the work.9 The final working equation after simple mathematical manipulations for the calculation of the density of liquid under study for the present hydrostatic weighing densimeter at different temperatures is ρL,T =

m − m1 − ρair (0.9Vw + Vring) VT + 0.1Vw

(2)

where VT is the volume of the float made from titanium; Vw is the volume of wire made from constantan; Vring is the volume C



Article

Table 4. Experimental Temperatures (T/K) and Densities (ρ/kg·m−3) of Ethane-1,2-diol (MEG) and Propane-1,2-diol (MPG) at Atmospheric Pressure Using Pycnometric (PYC) and Hydrostatic Weighing Densimeter (HWD)a Ethane-1,2-diol (MEG) T/K 273.15 283.15 293.15 303.15 313.15 323.15 333.15 343.15 353.15 363.15 373.15 383.15 393.15 403.15 413.15 423.15 433.15 443.15 453.15 463.15 473.15

−3

PYC ρ/kg·m 1127.05 1120.50 1113.84 1107.07 1100.19 1093.20 1086.11 1078.91 1071.60 1064.18

273.15 283.15 293.15 303.15 313.15 323.15 333.15 343.15 353.15 363.15 373.15 383.15 393.15 403.15 413.15 423.15 433.15 443.15 453.15 463.15

HWD ρ/kg·m−3 1127.20 1120.58 1113.84 1106.98 1099.99 1092.88 1085.65 1078.29 1070.80 1063.20 1055.47 1047.62 1039.64 1031.53 1023.31 1014.96 1006.48 997.880 989.160 980.310 971.340 Propane-1,2-diol (MPG)

1052.17 1044.74 1037.22 1029.64 1021.98 1014.25 1006.45 998.57 990.62 982.60

1051.77 1044.65 1037.13 1029.87 1022.37 1014.64 1006.75 998.710 990.770 982.380 973.810 965.040 956.090 946.950 937.620 928.100 918.390 908.500 898.410 888.140

referenceb ρ/kg·m−3

difference Δρ/kg·m−3

1127.20 1120.58 1113.54 1107.06 1100.36 1093.45 1086.32 1078.98 1071.43 1063.65 1055.67 1047.47 1039.05 1030.42 1021.58 1012.52 1003.24 993.75 984.05 974.13 964.00

0.15 0.08 0.00 −0.09 −0.20 −0.32 −0.46 −0.62 −0.80 −0.98

1050.57 1043.62 1036.51 1029.25 1021.81 1013.63 1005.84 997.43 989.54 981.30 972.91 964.13 955.47 946.70 937.52 928.51 919.38 909.86 900.53 890.80

−0.40 −0.09 −0.09 0.23 0.39 0.39 0.30 0.14 0.15 −0.22

Standard uncertainties u are u(T) = 0.01 K; ur(P = 0.101 MPa) = 0.005; u(ρ) = 0.5 kg·m−3; Δρ = ρ(HWD) − ρ(PYC). bReference correlation.3 Reference correlation.8

a c

of aluminum ring; ρL,Τ is the density of the liquid under study at given temperature; ρair = 1.2 kg·m−3 is the air density. In the present case, the float is completely immersed in the liquid under study (VF). The float and 0.1 Vw part of a 20 mm long wire were completely immersed in the liquid under study. A ring (Vring) and 0.9Vw of wire was in the air. The length of the wire was calculated so that only a small part of it (about 20 mm) is immersed in the liquid to be examined. In this case, the reducing of the wire’s weight in the liquid was minimized.3 The effect of temperature on titanium (alloy BT-6) float volume can be presented as VT = V FcΔT = V Fc[1 + 3αT]

where VcF is the volume of titanium float at 293 K from pycnometer calibration; αT106 = 8.077 + 0.003135(T − 273) is the linear expansion coefficient of float material; T is the experimental temperature (K), αT=293 = 8.1397 × 10−6 K−1 is the value of αT at calibration temperature of 293.15 K. 2.4. Uncertainty of the Measurements. The experimental density data for working liquids were evaluated using eq 2. All input parameters used for uncertainty analysis are given in Table 2. Therefore, the uncertainty of single density measurement is a function of the input parameters (see Table 2) entering the density evaluation procedure. Table 2 is providing the uncertainty analyses of the density measurements for HWD technique. Assuming that all of the input parameters

(3) D



(

Figure 2. Percentage deviations, δρ = 100

ρexp − ρ rep ρexp

Article

), of the present experimental densities for n-heptane measured using both new designed HWD

and pycnometric techniques from reported data (AAD = 0.05%) and calculated from REFPROP.13 The symbols are reported data from our previous publication5 based on the TRC/NIST archive12 (TDE search result). Dashed line represents the deviation (AAD = 0.01%) between the present density data and the values calculated from REFPROP.13

parameters (see Table 2) in the working eq 2 and the combined standard uncertainty is the square root of the variance.10 Table 2 provides the value of each input parameter Xi and their estimated standard uncertainties. On the basis of the data from Table 2, the total expanded uncertainty of the density measurement at 0.95 confidence level with a coverage factor of k = 2 is estimated to be U(ρ) = 1.0 kg·m−3. 2.5. Test Measurements. In order to check the accuracy of the method, correct operation of the HWD, and confirm the reliability of density data measured by the present method for working fluids (BM-1C, LEYBONOL LVO 500, and ANKAPEH-D24) of diffusion vacuum pumps, the measurements were made on well-studied fluids such as pure n-heptane in the temperature range from 293.15 to 356.84 K at atmospheric pressure and ethane-1,2-diol and propane-1,2diol from 273 to 473 K. The measurements were made using two different techniques, namely, pycnometric11 and the present hydrostatic weighing methods. We used standard pycnometer (PZH2-10-KSH 7/16) with volume of 10 mL. The pycnometer was thermostated using ultrathermostat type of U10 which provides temperature stability within 0.02 K. The results of both techniques were compared with the most reliable reported data (see refs 3, 5, and 8 where comprehensive review all of the data sources from NIST/TRC/TDE Data Base12 were provided) for n-heptane and with the values calculated from reference equation of state (REFPROP13). The results of density measurements for n-heptane, ethane-1,2-diol, and propane-1,2-diol are presented in Tables 3 and 4 and are

Table 5. Deviation Statistics between the HWD and Pycnometric Measurements for Various Liquids at Atmospheric Pressure liquid n-heptane (HWD and REFPROP) n-heptane (PYC and REFPROP) ethane-1,2-diol (HWD and PYC) propane-1,2-diol (HWD and PYC) BM-1C (Moscow, HWD and PYC) BM-1C (Nizhnyi Novgorod) (HWD and PYC) LEYBONOL LVO 500 (HWD and PYC) Alkaren (HWD and PYC)

AADa (%)

bias (%)

RMSD (%)

max. dev (%)

0.11 0.12 0.03 0.02

0.11 0.12 −0.03 0.01

0.02 0.03 0.01 0.01

0.15 0.23 0.09 0.04

0.05

−0.05

0.01

0.11

0.04

−0.04

0.01

0.11

0.03

−0.01

0.01

0.09

0.08

0.06

0.02

0.12

a

Absolute average 100 N AAD = N ∑i = 1 |(ρHWD − ρPYC )/ρPYC |i .

Bias =

100 N

deviation: Bias deviation:

N

∑i = 1 [(ρHWD − ρPYC )/ρPYC ]i . Root mean square devia-

{

tion (RMSD): RMSD = 100

1 N ∑ [(ρHWD N i=1

− ρPYC )/ρPYC ]2

1/2

}

i

.

Max. dev is absolute value of the largest deviation (of deviations of both signs).

X i are independent, the variance of density (Y) is N

u(Y )2 = ∑i = 1

(

∂Y u(Xi) ∂X i

2

) , where N is the number of input

(



), of the present experimental densities for ethane-1,2-diol measured using both new designed

HWD and pycnometric techniques from reported data (deviations are within AAD = 0.03% to 0.23%). The symbols are reported data from our previous publication3 based on the TRC/NIST archive12 (TDE search result). E



(



Article

), of the present experimental densities for propane-1,2-diol measured using both new designed

HWD and pycnometric techniques from reported data (deviations are within AAD = 0.02% to 0.10%). The symbols are reported data from our previous publication8 based on the TRC/NIST archive12 (TDE search result).

depicted in Figures 2−4. These figures also included the reported data taken from our previous publications3,5,8 based on the TRC/NIST archive (TDE search result). The deviation statistics for both methods (HWD and Pycnometer) together with reference data (REFPROP/NIST/TDE13) for n-heptane are given in Table 5. This table also contains the difference, Δρ = ρ(HWD) − ρ(PYC), between both techniques (HWD and pycnometer). As one can see, both techniques show almost the same deviations from reference correlation REFPROP.13 This means that the result obtained using the both methods are in good agreement and good consistence with reference data.13 The deviation statistics between both methods for ethane-1,2diol and propane-1,2-diol are also given in Table 5. As one can see from Table 4, the difference, Δρ = ρ(HWD) − ρ(PYC), between the both methods (HWD and pycnometer) is within their uncertainties. Also, Table 4 provides comparison of the present HWD and PYC results for ethane-1,2-diol and propane-1,2-diol with the reference correlations developed on the bases of reported data from NIST/TRC database12 (these data included in Figures 3 and 4). Figures 2−4 are also containing the values of density measured3,8 using our earlier high-pressure and high-temperature apparatus which combines the method of hydrostatic weighing and falling-body techniques for simultaneous measurements of density and viscosity. Thus, this result helps to confirm the reliability of the method to accurately measure of the density of liquids and correct operating of the new designed HWD instrument. Newly developed hydrostatic weighing densimeter for measurement of the density high-viscosity working fluids has certain advantages over other existing densimeters, for example, constant-volume piezometer, VTD, pycnometer, so forth. In particular, it is much cheaper in comparison with VTD, easier to use, especially for high viscosity liquids (at low-temperature measurements), faster (short measurement times for single data point), the results have the same accuracy, and wide temperature range of the applicability (from 273 to 500 K). Also, all VTD instruments require viscosity correction to measured densities if the sample under study of higher viscosities, that is, for VTD the measured density of the liquid is a function of viscosity. In most cases, there are no accurate viscosity data for the same sample. The most widely used densimeters in comparisdon with the present HWD have a very limited temperature range of applicability, for example, pycnometers, from room temper-

ature to 368 K, and most VTD, usually from room temperature to 353 K.

3. RESULTS AND DISCUSSION The developed new hydrostatic weighing densimeter was employed to measure the density of working liquids for diffusion vacuum pumps (BM-1C, LEYBONOL LVO 500, and Alkaren-D24). The measurements were made over a temperature range from 273 to 473 K at atmospheric pressure. The measured density data for (BM-1C, LEYBONOL LVO 500, Alkaren-D24) are presented in Table 6. In order to confirm the reliability and accuracy of the measurements with a new HWD, the densities of the same working liquid (BM-1C, LEYBONOL LVO 500, Alkaren-D24) samples were measured using pycnometric method (PZH-2-10-KSH7/16 GOST 22524-77) at atmospheric pressure over the temperature range from 293 to 363 K. The high-speed weighing (with 2 s stabilization) and analytical electronic balance HR-250AZG (A&D Co. LTD, Japan) has been used to weight of the pycnometers when the weighing system of the hydrostatic densimeter was turned off. The repeatability of the electronic balance is within 0.1 mg in the mass range from 0 to 200 g. The measured pycnometer densities of working liquids for diffusion vacuum pumps together with the data measured using HWD technique are presented in Table 6. The differences, Δρ = ρ(HWD) − ρ(PYC), between the both techniques are also presented in Table 6. In the same table most reliability density data calculated from reference correlations3,8 based on all reported data from NIST/TRC Database12 (see Figures 3 and 4) are presented for the comparison purposes. As one can see, HWD data are in good agreement with data measured using pycnometric method. The deviation statistics for BM-1C (Moscow), BM-1C (Nizhnyi Novgorod), LEYBONOL LVO 500, and Alkaren are given in Table 5. As one can see, the discrepancy between the both methods are within from 0.03 to 0.08 %. Deviation plot between the measured densities using the both methods are shown in Figure 5. 4. CONCLUSIONS A new apparatus (hydrostatic weighing densimeter) for accurate measure of the density of working liquids has been designed based on the hydrostatic weighing principle. The developed new design of the hydrostatic weighing densimeter for measurement of the density of working fluids has some F



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Table 6. Experimental Temperatures (T/K) and Densities (ρ/kg·m−3) of Working Liquids (BM-1C, LEYBONOL LVO 500, and Alkaren-D24) at Atmospheric Pressure Using Pycnometric (PYC) and Hydrostatic Weighing Densimeter (HWD)a LEYBONOL LVO 500

BM-1C (Moscow) T

PYC ρ

273.15 283.15 293.15 303.15 313.15 323.15 333.15 343.15 353.15 363.15 373.15 383.15 393.15 403.15 413.15 423.15 433.15 443.15 453.15 463.15 473.15

878.39 872.37 866.38 860.40 854.45 848.51 842.60 836.71 830.83 824.98

273.15 283.15 293.15 303.15 313.15 323.15 333.15 343.15 353.15 363.15 373.15 383.15 393.15 403.15 413.15 423.15 433.15 443.15 453.15 463.15 473.15

HWD ρ

878.26 872.20 866.15 860.10 854.05 848.00 841.96 835.92 829.88 824.85 817.82 811.79 805.77 799.75 793.73 787.71 781.70 775.69 769.68 763.68 757.68 BM-1C (Nizhnyi Novgorod) 869.48 863.03 856.67 850.40 844.23 838.15 832.17 826.28 820.49 814.79

868.82 862.66 856.51 850.38 844.26 838.16 832.07 826.00 819.95 813.91 807.89 801.88 795.89 789.91 783.95 778.01 772.08 766.17 760.27 754.39 748.52

difference Δρ

273.15 283.15 293.15 303.15 313.15 323.15 333.15 343.15 353.15 363.15 373.15 383.15 393.15 403.15 413.15 423.15 433.15 443.15 453.15 463.15 473.15

−0.13 −0.17 −0.23 −0.30 −0.40 −0.51 −0.64 −0.79 −0.95 −0.13

880.28 873.83 867.47 861.22 855.07 849.02 843.07 837.22 831.47 825.82

879.52 873.47 867.43 861.39 855.37 849.35 843.34 837.33 831.33 825.34 819.36 813.39 807.42 801.46 795.51 789.56 783.63 777.70 771.77 765.86 759.95

−0.76 −0.36 −0.04 0.17 0.30 0.33 0.27 0.11 −0.14 −0.48

916.20 909.71 903.22 896.75 890.28 883.82 877.37 870.93 864.50 858.08 851.67 845.26 838.87 832.48 826.10 819.73 813.37 807.02 800.68 794.34 788.02

−0.71 −0.14 0.31 0.66 0.90 1.02 1.04 0.95 0.76 0.45

Alkaren-D24 273.15 283.15 293.15 303.15 313.15 323.15 333.15 343.15 353.15 363.15 373.15 383.15 393.15 403.15 413.15 423.15 433.15 443.15 453.15 463.15 473.15

−0.66 −0.37 −0.16 −0.02 0.03 0.01 −0.10 −0.28 −0.54 −0.88

916.91 909.85 902.91 896.09 889.38 882.80 876.33 869.98 863.74 857.63

a Standard uncertainties u are u(T) = 0.01 K; ur(P = 0.101 MPa) = 0.005; u(ρ) = 0.5 kg·m−3; Δρ = ρ(HWD) − ρ(PYC)

diol (MPG) with well-established PVT properties (REFPROP/ NIST/TDE13) over a temperature range from 293 to 473 K and at atmospheric pressure were studied. Additional confirmation shows the reliability of the measured density data of all samples were measured using the pycnometric method. The present study showed that the densities measured using new HWD are in good (discrepancy within from 0.03% to 0.08%) agreement with the values measured with pycnometric method. A newly designed HWD can be successfully used for measurements of the density of highviscosity oils and ionic liquids at low temperatures and other working liquids.

advantages over conventional densimeters, for example, (1) cheaper; (2) easier to use and much faster (short measuring time) than conventional techniques, especially for highviscosity liquids with results of the same accuracy; (3) wide temperature range of applicability (from 273 to 500 K); (4) no filling and sampling problem for high-viscosity liquids; (5) high accuracy (0.02%). The apparatus has been used to measure the density of three working liquids for diffusion vacuum pumps (BM-1C, LEYBONOL LVO 500, and Alkaren-D24) as a function of temperature in the range from 273 to 473 K at atmospheric pressure. To verify the reliability, accuracy, and correct operation of the new HWD instrument, the density of the pure n-heptane, ethane-1,2-diol (MEG), and propane-1,2G



(


ρPYC − ρHDW ρHDW

Article

), of the present experimental densities for working liquids of diffusion vacuum pumps

measured using both new designed HWD and pycnometric techniques. ●, Alkaren-D24; ○, LEYBONOL LVO 500; Novgorod);▲, BM-1C (Moscow); ■, ethane-1,2-diol; □, n-Heptane; ×, propane-1,2-diol.

■

BM-1C (Nizhnyi

(11) Kivilis, S. S. Densimeters; Energy: Moscow, 1980. (12) Frenkel, M.; Chirico, R.; Diky, V.; Muzny, C. D.; Kazakov, A. F.; Magee, J. W.; Abdulagatov, I. M.; Jeong Won Kang. NIST ThermoDataEngine, NIST Standard Reference Database 103b-Pure Compound, Binary Mixtures, and Chemical Reactions, version 5.0; National Institute Standards and Technology: Boulder, Colorado, 2010. (13) Lemmon, E. W.; Huber, M. L.; McLinden, M. O. NIST Standard Reference Database 23, NIST Reference Fluid Thermodynamic and Transport Properties. REFPROP, version 9.0, Standard Reference Data Program; National Institute of Standards and Technology: Gaithersburg, MD, 2010.

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ORCID

Ilmutdin Abdulagatov: 0000-0002-6299-5280 Notes

The authors declare no competing financial interest.

■

△,

REFERENCES

(1) Corti, H.; Abdulagatov, I. M. PVT Properties of Hydrothermal Systems. In: Hydrothermal Properties of Materials. Experimental Data on Aqueous Phase Equilibria and Solution Properties at Elevated Temperatures and Pressures; Valyashko, V. M., Ed.; John Wiley & Sons: London, 2009; Chapter 2, pp 135−193. (2) Wagner, W.; Kleinrahn, R.; Losch, H. W.; Watson, J. T. R.; Majer, V. Hydrostatic balance densimeters with magnetic suspension couplings. In Measurements of the Thermodynamic Properties Single Phases; Goodwin, A.R.H., Marsh, K.N., Wakeham, W.A., Eds.; IUPAC, Physical Chemistry Division, Commission on Thermodynamics; Elsevier: Amsterdam, 2003; Vol. VI, Chapter 5, pp 127−149. (3) Sagdeev, D. I.; Fomina, M. G.; Mukhamedzyanov, G.Kh.; Abdulagatov, I. M. Experimental study of the density and viscosity of polyethylene glycols and their mixtures at temperatures from 293 to 473 K and at atmospheric pressure. J. Chem. Thermodyn. 2011, 43, 1824−1843. (4) Sagdeev, D. I.; Fomina, M. G.; Mukhamedzyanov, G. Kh.; Abdulagatov, I. M. Experimental study of the density and viscosity of polyethylene glycols and their mixtures at temperatures from 293 to 465 K and at high pressures up to 245 MPa. Fluid Phase Equilib. 2012, 315, 64−76. (5) Sagdeev, D. I.; Fomina, M. G.; Mukhamedzyanov, G. Kh.; Abdulagatov, I. M. Experimental Study of the Density and Viscosity of n-Heptane at Temperatures from 298 to 470 K and Pressures up to 245 MPa. Int. J. Thermophys. 2013, 34, 1−33. (6) Sagdeev, D. I.; Fomina, M. G.; Mukhamedzyanov, G. Kh.; Abdulagatov, I. M. Experimental Study and Correlation Models of the Density and Viscosity of 1-Hexene and 1-Heptene at Temperatures from (298 to 473) K and Pressures up to 245 MPa. J. Chem. Eng. Data 2014, 59, 1105−1119. (7) Sagdeev, D. I.; Fomina, M. G.; Mukhamedzyanov, G. Kh.; Abdulagatov, I. M. Measurements of the density and viscosity of 1hexene + 1-octene mixtures at high temperatures and high pressures. Thermochim. Acta 2014, 592, 73−85. (8) Sagdeev, D. I.; Fomina, M. G.; Abdulagatov, I. M. Density and viscosity of propylene glycol at high temperatures and high pressures. Fluid Phase Equilib. 2017, 450, 99−111. (9) Turubiner, I. K.; Ippits, M. D. Methods of the Density Measurements; Mashgiz: Moscow, 1949. (10) Gide to the Expression of Uncertainty in Measurement; ISO: Geneva, Switzerland, 1993. H


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