VISCOSITY Viscosity is the measurement of a fluid's internal resistance to flow. This is typically designated in units of centipoise or poise but can be expressed in other acceptable measurements as well. Some conversion factors are as follows: 100 Centipoise = 1 Poise 1 Centipoise = 1 mPa s (Millipascal Second) 1 Poise = 0.1 Pa s (Pascal Second) Centipoise = Centistoke x Density Newtonian materials are referred to as true liquids since their viscosity or consistency is not affected by shear such as agitation or pumping at a constant temperature. Water and oils are examples of Newtonian liquids. Thixotropic materials reduce their viscosity as agitation or pressure is increased at a constant temperature. Ketchup and mayonnaise are examples of thixotropic materials. They appear thick or viscous but actually pump quite easily. Paste viscosity is a vague term the viscosity of many materials but needs further definition to design a machine. Some paste viscosity materials will seek their own level or flow slowly and the shorter the time it takes, the easier they are to pump. Others do not seek their own level or flow at all and require pressure to move them from the supply container (cartridges. pails or drums) to the metering pump. These materials require special consideration regarding their feeding into metering pumps to assure the metering pump does not cavitate or to prevent air from being introduced into the material. One way to differentiate between easy and difficult to flow pastes is to obtain Brookfield viscosities using the same spindle at two different rotational speeds, usually a tenfold difference (e.g. 1 RPM and 10 RPM). This will provide a"thixotropic index" for the particular material. The higher the difference in viscosity at the two speeds, the more thixotropic the material is and easier to pump. To reduce the viscosity of paste materials to allow easier pumping, heat is often applied. The following graph illustrates how a typical filled epoxy resin reduces in viscosity as it is heated. Solid materials at room temperature that are designed to be melted to allow pumping require heating above their melt point before they become a liquid. Maintaining heat on this material throughout the metering system (feed tank, pump, material supply hose, mixer, etc.) is normally critical to preventing this material from resolidifying somewhere in the system. A heated cabinet that encapsulates all wetted components of the machine is typically employed instead of just heat blanketing the various components. Typically, the closer the "A" and "B" materials are in viscosity, the easier they will be to mix. The most difficult materials will have a high viscosity "taffy-like" consistency for one-component with a water thin viscosity as the other component. Approximate Viscosities of Common Materials (At Room Temperature-70°F) Material Viscosity in Centipoise Water 1 cps Milk 3 cps SAE 10 Motor Oil 85-140 cps SAE 20 Motor Oil 140-420 cps SAE 30 Motor Oil 420-650 cps SAE 40 Motor Oil 650-900 cps Castrol Oil 1,000 cps Karo Syrup 5,000 cps Honey 10,000 cps Chocolate 25,000 cps Ketchup 50,000 cps Mustard 70,000 cps Sour Cream 100,000 cps Peanut Butter 250,000 cps Viscosity Conversion Chart The following viscosities are based on materials with a specific gravity of one. Centipoise (CPS) or Millipascal (mPas) Poise (P) Centistokes (CKS) Stokes (S) Saybolt Universal (SSU) 1 0.01 1 0.01 31 2 0.02 2 0.02 34 4 0.04 4 0.04 38 7 0.07 7 0.07 47 10 0.1 10 0.1 60 15 0.15 15 0.15 80 20 0.2 20 0.2 100 25 0.24 25 0.24 130 30 0.3 30 0.3 160 40 0.4 40 0.4 210 50 0.5 50 0.5 260 60 0.6 60 0.6 320 70 0.7 70 0.7 370 80 0.8 80 0.8 430 90 0.9 90 0.9 480 100 1 100 1 530 120 1.2 120 1.2 580 140 1.4 140 1.4 690 160 1.6 160 1.6 790 180 1.8 180 1.8 900 200 2 200 2 1000 220 2.2 220 2.2 1100 240 2.4 240 2.4 1200 260 2.6 260 2.6 1280 280 2.8 280 2.8 1380 300 3 300 3 1475 320 3.2 320 3.2 1530 340 3.4 340 3.4 1630 360 3.6 360 3.6 1730 380 3.8 380 3.8 1850 400 4 400 4 1950 420 4.2 420 4.2 2050 440 4.4 440 4.4 2160 460 4.6 460 4.6 2270 480 4.8 480 4.8 2380 500 5 500 5 2480 550 5.5 550 5.5 2660 600 6 600 6 2900 700 7 700 7 3380 800 8 800 8 3880 900 9 900 9 4300 1000 10 1000 10 4600 1100 11 1100 11 5200 1200 12 1200 12 5620 1300 13 1300 13 6100 1400 14 1400 14 6480 1500 15 1500 15 7000 1600 16 1600 16 7500 1700 17 1700 17 8000 1800 18 1800 18 8500 1900 19 1900 19 9000 2000 20 2000 20 9400 2100 21 2100 21 9850 2200 22 2200 22 10300 2300 23 2300 23 10750 2400 24 2400 24 11200 2500 25 2500 25 11600 3000 30 3000 30 14500 3500 35 3500 35 16500 4000 40 4000 40 18500 4500 45 4500 45 21000 5000 50 5000 50 23500 5500 55 5500 55 26000 6000 60 6000 60 28000 6500 65 6500 65 30000 7000 70 7000 70 32500 7500 75 7500 75 35000 8000 80 8000 80 37000 8500 85 8500 85 39500 9000 90 9000 90 41080 9500 95 9500 95 43000 15000 150 15000 150 69400 20000 200 20000 200 92500 30000 300 30000 300 138500 40000 400 40000 400 185000 50000 500 50000 500 231000 60000 600 60000 600 277500 70000 700 70000 700 323500 80000 800 80000 800 370000 90000 900 90000 900 415500 100000 1000 100000 1000 462000 125000 1250 125000 1250 578000 150000 1500 150000 1500 694000 175000 1750 175000 1750 810000 200000 2000 200000 2000 925000   Applications |  Products |  About Us |  Contact Us |  Request Information