what is brookfeild viscosity and cranking viscosity?
what is the use of this parameters?
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There are different methods of measuring viscosity and different reasons. Here's a basic overview.
Viscosity
The measure of the internal friction or the resistance to flow a liquid.
Low viscosity fluids flow easily (water);
High viscosity fluids pour slowly (molasses).
Measurement of a fluid’s resistance to flow. The common metric unit of absolute viscosity is the poise, which is defined as the force in dynes required to move a surface one square centimeter in area past a parallel surface at a speed of one centimeter per second, with the surfaces separated by a fluid film one centimeter thick. For convenience, the CentiPoise (cP) — one one-hundredth of a poise — is the unit customarily used. Laboratory measurements of viscosity normally use the force of gravity to produce flow through a capillary tube (viscometer) at a controlled temperature. This measurement is called kinematic viscosity. The unit of kinematic viscosity is the stoke, expressed in square centimeters per second. The more customary unit is the centistoke (cSt) — one one-hundredth of a stoke. Kinematic viscosity can be related to absolute viscosity by the equation:
cSt = cP ÷ fluid density
In addition to kinematic viscosity, there are other methods for determining viscosity, including:
Saybolt Universal viscosity
Saybolt Furol viscosity
Engler viscosity
Redwood viscosity.
Absolute Viscosity
the ratio of shear stress to shear rate.
It is a fluid’s internal resistance to flow.
The common unit of absolute viscosity is the poise and CentiPoise cP (see viscosity).
Absolute viscosity divided by the fluid’s density equals kinematic viscosity.
Absolute viscosity is typically measured by a rotary viscometers to determine the torque on rotating spindle and so measure the fluid's shear resistance. Changing the rotor (spindle) dimensions and the gap between the rotor and stator wall (container) and the speed of rotation can change the rate of shear.
Examples of rotary viscometers that are used for Absolute Viscosity measurements:
Cold Cranking Simulator (C.C.S)
Mini-Rotary Viscometer (MRV)
Brookfield Viscometer
Tapered Bearing Simulator
In relation to oils for Automotive applications such as Motor Oil or Gear Oil, the CCS and MRV test equipment at low temperatures is used to determine if the test lubricant does not get too thick to prevent safe engine or transmission operation at low temperatures.
If Motor Oil is too viscous to flow, even if engine can be started, certain mechanical damage will result due to localized oil starvation. In transmissions both manual and automatic, proper shifting may be impaired, affecting safe vehicle operation once vehicle is put in motion.
Viscosity
The measure of the internal friction or the resistance to flow a liquid.
Low viscosity fluids flow easily (water);
High viscosity fluids pour slowly (molasses).
Measurement of a fluid’s resistance to flow. The common metric unit of absolute viscosity is the poise, which is defined as the force in dynes required to move a surface one square centimeter in area past a parallel surface at a speed of one centimeter per second, with the surfaces separated by a fluid film one centimeter thick. For convenience, the CentiPoise (cP) — one one-hundredth of a poise — is the unit customarily used. Laboratory measurements of viscosity normally use the force of gravity to produce flow through a capillary tube (viscometer) at a controlled temperature. This measurement is called kinematic viscosity. The unit of kinematic viscosity is the stoke, expressed in square centimeters per second. The more customary unit is the centistoke (cSt) — one one-hundredth of a stoke. Kinematic viscosity can be related to absolute viscosity by the equation:
cSt = cP ÷ fluid density
In addition to kinematic viscosity, there are other methods for determining viscosity, including:
Saybolt Universal viscosity
Saybolt Furol viscosity
Engler viscosity
Redwood viscosity.
Absolute Viscosity
the ratio of shear stress to shear rate.
It is a fluid’s internal resistance to flow.
The common unit of absolute viscosity is the poise and CentiPoise cP (see viscosity).
Absolute viscosity divided by the fluid’s density equals kinematic viscosity.
Absolute viscosity is typically measured by a rotary viscometers to determine the torque on rotating spindle and so measure the fluid's shear resistance. Changing the rotor (spindle) dimensions and the gap between the rotor and stator wall (container) and the speed of rotation can change the rate of shear.
Examples of rotary viscometers that are used for Absolute Viscosity measurements:
Cold Cranking Simulator (C.C.S)
Mini-Rotary Viscometer (MRV)
Brookfield Viscometer
Tapered Bearing Simulator
In relation to oils for Automotive applications such as Motor Oil or Gear Oil, the CCS and MRV test equipment at low temperatures is used to determine if the test lubricant does not get too thick to prevent safe engine or transmission operation at low temperatures.
If Motor Oil is too viscous to flow, even if engine can be started, certain mechanical damage will result due to localized oil starvation. In transmissions both manual and automatic, proper shifting may be impaired, affecting safe vehicle operation once vehicle is put in motion.
thanks