Microspheres are often used for studies that involve long term suspension of microspheres in an aqueous solution. This is particularly important for closed-system flow visualization studies, where researchers do not have the opportunity to agitate the liquid and re-suspend the microspheres. For long term suspension of particles, neutrally-buoyant microspheres are required.

The density of water changes with temperature and pressure. It also changes when other materials are dissolved in it (for example, salt and sugar). When long-term suspension of microspheres in an aqueous solution is required, it is critical that the density of microspheres is matched as close as possible to the density of water at the correct temperature. If there is a mismatch in density, the microspheres will either sink or float. The rate of separation (or settling) is determined primarily by the difference in densities of the microspheres and the liquid, as well as particle size. The smaller the microspheres, the less sensitive they are to the density mismatch. For larger microspheres (such as close to 1mm in diameter) the density needs to match at least to 0.001g/cc in order for the particles to stay suspended for some time. Particles below 200micron might be able to tolerate density mismatch of 0.005g/cc. Particles below 50micron can potentially handle a difference in density of 0.01g/cc.

Every Cospheric microspheres product has been characterized with a NIST-traceable density measurement with the accuracy of +/-0.002g/cc, using the most accurate density measurement tools available on the market today.

The tables of Density of Water below are supplied to help the researcher select the right density of the microsphere for their application by matching it to the density of water at the correct temperature.

Table of Density of Water (g/cm3 and lbs/ft3) as a Function of Temperature (degrees C and F)
at standard sea-level atmospheric pressure

Temp

°F/°C

Density

(g/cm3)

Density

(lb/ft3)

32°/0°0.9998762.416
39.2°/4.0°1.0000062.424
40°/4.4°0.9999962.423
50°/10°0.9997562.408
60°/15.6°0.9990762.366
70°/21°0.9980262.300
80°/26.7°0.9966962.217
90°/32.2°0.9951062.118
100°/37.8°0.9931861.998
120°/48.9°0.9887061.719
140°/60°0.9833861.386
160°/71.1°0.9772961.006
180°/82.2°0.9705660.586
200°/93.3°0.9633360.135
212°/100°0.9586559.843



Table of Density of Salt Water (g/cm3) by Temperature (degrees C) and permille (‰) Salinity

0 to 100 degrees Celsius

compiled by Niels Ramsing and Jens Gundersen

0‰5‰10‰15‰20‰
0C0.99981.00391.0081.0121.016
5C11.0041.00791.01191.0158
10C0.99971.00361.00751.01141.0153
15C0.99911.0031.00681.01061.0144
20C0.99821.0021.00581.00961.0134
25C0.9971.00081.00461.00831.0121
30C0.99570.99941.00311.00681.0105
35C0.9940.99771.00141.00511.0088
40C0.99220.99590.99961.00321.0069
45C0.99020.99390.99761.00121.0049
50C0.98810.99170.99540.9991.0027
55C0.98580.98940.99310.99671.0004
60C0.98340.98710.99070.99440.998
65C0.98090.98460.98830.9920.9956
70C0.97850.98220.98590.98960.9933
75C0.97610.97990.98360.98730.991
80C0.97390.97770.98150.98530.9891
85C0.9720.97590.97980.98360.9874
90C0.97040.97450.97840.98240.9863
95C0.96940.97360.97770.98180.9858
100C0.96920.97360.97780.9820.9862
25‰30‰35‰40‰45‰
0C1.021.02411.02811.03221.0362
5C1.01981.02371.02771.03161.0356
10C1.01921.02311.0271.03091.0348
15C1.01831.02211.0261.02981.0337
20C1.01721.0211.02481.02861.0324
25C1.01581.01961.02331.02711.0309
30C1.01431.0181.02171.02551.0293
35C1.01251.01621.01991.02371.0274
40C1.01061.01431.0181.02171.0254
45C1.00851.01221.01591.01961.0233
50C1.00631.011.01361.01731.021
55C1.0041.00771.01131.0151.0186
60C1.00161.00531.00891.01261.0163
65C0.99931.00291.00661.01021.0139
70C0.99691.00061.00431.00791.0116
75C0.99470.99841.00211.00581.0095
80C0.99280.99651.00031.0041.0077
85C0.99120.9950.99881.00261.0064
90C0.99020.99410.99791.00181.0057
95C0.98980.99380.99781.00181.0057
100C0.99040.99450.99861.00271.0068
50‰55‰60‰65‰70‰
0C1.04031.04431.04841.05251.0566
5C1.03961.04361.04761.05161.0557
10C1.03871.04271.04661.05061.0546
15C1.03761.04151.04541.04931.0532
20C1.03631.04011.0441.04791.0518
25C1.03471.03861.04241.04621.0501
30C1.0331.03681.04061.04441.0483
35C1.03121.03491.03871.04251.0463
40C1.02911.03291.03661.04041.0442
45C1.0271.03071.03441.03821.0419
50C1.02471.02841.03211.03581.0396
55C1.02231.0261.02971.03341.0372
60C1.01991.02361.02731.0311.0347
65C1.01761.02121.02491.02861.0323
70C1.01531.0191.02271.02641.0301
75C1.01321.01691.02061.02441.0281
80C1.01151.01521.0191.02271.0264
85C1.01021.0141.01781.02151.0253
90C1.00951.01341.01721.02111.0249
95C1.00971.01361.01761.02151.0254
100C1.01091.01491.0191.0231.0271
75‰80‰85‰90‰95‰
0C1.06071.06481.06891.07311.0772
5C1.05971.06381.06781.07191.076
10C1.05851.06261.06661.07061.0747
15C1.05721.06121.06511.06911.0731
20C1.05571.05961.06351.06751.0715
25C1.0541.05791.06181.06571.0696
30C1.05211.0561.05991.06381.0677
35C1.05011.0541.05781.06171.0656
40C1.0481.05181.05561.05951.0633
45C1.04571.04951.05331.05711.061
50C1.04331.04711.05091.05471.0585
55C1.04091.04461.04841.05221.056
60C1.03841.04221.04591.04971.0535
65C1.03611.03981.04351.04731.051
70C1.03381.03751.04131.0451.0488
75C1.03181.03561.03931.04311.0468
80C1.03021.0341.03771.04151.0453
85C1.02911.03291.03671.04051.0444
90C1.02881.03261.03651.04041.0442
95C1.02941.03331.03731.04121.0451
100C1.03121.03521.03931.04331.0473
100‰105‰110‰115‰120‰
0C1.08141.08561.08981.0941.0982
5C1.08011.08431.08841.09261.0967
10C1.07871.08281.08691.0911.0951
15C1.07721.08121.08521.08931.0934
20C1.07551.07951.08351.08751.0916
25C1.07361.07761.08161.08561.0896
30C1.07161.07561.07951.08351.0875
35C1.06951.07341.07731.08131.0852
40C1.06721.07111.0751.07891.0829
45C1.06481.06871.07261.07651.0804
50C1.06231.06621.07001.07391.0778
55C1.05981.06361.06741.07131.0752
60C1.05731.06111.06491.06871.0726
65C1.05481.05861.06241.06621.0701
70C1.05261.05641.06011.0641.0678
75C1.05061.05441.05821.0621.0658
80C1.04911.05291.05671.06051.0644
85C1.04821.0521.05591.05971.0636
90C1.04811.0521.05591.05981.0637
95C1.04911.0531.0571.0611.0649
100C1.05141.05541.05951.06361.0676
130‰140‰150‰160‰170‰
0C1.10671.11531.12391.13251.1413
5C1.10511.11361.12211.13061.1393
10C1.10341.11181.12021.12871.1373
15C1.10161.10991.11831.12671.1352
20C1.09971.10791.11621.12461.133
25C1.09771.10591.11411.12241.1308
30C1.09551.10361.11181.12011.1284
35C1.09321.10131.10941.11761.1259
40C1.09081.09881.10691.1151.1232
45C1.08821.09621.10421.11231.1204
50C1.08561.09351.10151.10951.1176
55C1.08291.09081.09871.10671.1147
60C1.08031.08811.0961.10391.1119
65C1.07781.08551.09341.10121.1092
70C1.07551.08321.0911.09881.1067
75C1.07351.08121.0891.09681.1047
80C1.07211.07981.08761.09541.1033
85C1.07131.07911.08691.09481.1027
90C1.07151.07941.08721.09521.1031
95C1.07291.08081.08881.09691.1049
100C1.07571.08391.09211.10021.1085
175‰180‰185‰190‰200‰
0C1.14571.15011.15451.15891.1679
5C1.14361.1481.15241.15681.1656
10C1.14161.14591.15021.15461.1634
15C1.13951.14381.14811.15241.1611
20C1.13731.14151.14581.15011.1588
25C1.1351.13921.14351.14771.1563
30C1.13261.13681.1411.14531.1538
35C1.131.13421.13841.14261.1511
40C1.12731.13151.13571.13991.1483
45C1.12451.12871.13281.1371.1453
50C1.12171.12581.12991.1341.1423
55C1.11881.12281.12691.1311.1392
60C1.11591.11991.1241.1281.1362
65C1.11321.11721.12121.12521.1334
70C1.11071.11471.11871.12271.1308
75C1.10871.11261.11661.12061.1287
80C1.10721.11121.11521.11921.1272
85C1.10661.11061.11461.11861.1266
90C1.10711.11111.11511.11921.1272
95C1.1091.1131.11711.12121.1293
100C1.11261.11671.12081.1251.1333



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