Our viscosity chart can help you get an idea of how thick your product is. While these are only average estimates, it is useful to have an idea of the viscosity of your product when working with one of our filling system experts. It can also be a great resource when trying to find an appropriate filling pump to be used with your system. If you do not see your product listed, or are unsure of its viscosity, one of our filling system experts would be more than glad to provide assistance.
|Approximate Viscosities of Common Materials|
(At Room Temperature-70°F)
|Material||Viscosity in Centipoise|
|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|
|Sour Cream||100,000 cps|
|Peanut Butter||250,000 cps|
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.
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)|