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What is Cold Start ?
As winter season is going on, we thought it is imperative that we touch upon the topic of Cold Start.
To understand COLD, START and what it means we need to understand what viscosity is and what effect temperature has on it.
As per Wikipedia “The viscosity of a fluid is a measure of its resistance to deformation at a given rate.”. In simpler terms viscosity tells us how thin or thick a fluid is and how easily it flows. Higher the viscosity thicker the fluid, higher resistance to flow. For example, the viscosity of honey is more than water.
Talking in terms of oil, there are various grades or viscosity of oils which are used in industry from application to application. They are normally called ISO VG 68, 100, 220, 320 etc. Now what is ISO VG 68? ISO VG 68 means that oil viscosity is 68CST at 40deg C. Similarly, ISO VG 220 means that oil viscosity is 220CST at 40deg C. ISO VG 220 hence is more viscous than ISO VG 68.
Now that we have understood what viscosity is, we need to understand what effect temperature has on it. Viscosity is inversely proportional to temperature. Lower the temperature, higher the viscosity and higher the temperature, lower is the viscosity. The below table contains the viscosity value of different oils at different temperatures. What needs to be observed is that the change in viscosity is exponential and not linear. For eg. ISO VG 320 oil’s viscosity changes from 320CST to 550CST when temperature moves from 40deg C to 30deg C. However, when temperature moves from 30deg C to 20deg C the viscosity changes from 550CST to 1050CST and so on.
Viscosity Value of different Oil in different temperatures
So, in a place like New Delhi where average ambient temperature varies from 40deg C in summer to 10deg c in winters the oil viscosity of ISO VG 320 changes from 320CST to 2100CST which is approximately 7 times more.
Increase in viscosity has various implications. It leads to:
This leads to system malfunctioning typically when systems are started in winters. The motor takes excessive load and gets tripped. Pump creates excessive noise. Sometimes, the filter element gets damaged. This condition is known as Cold Start.
How to overcome a Cold Start?
Cold start issues only happen when systems are started afresh in winters. It doesn’t happen in systems which are in running condition. So, whenever you are starting an Oil Circulation System afresh make sure you check the oil temperature and if it is outside the operating parameters, heat up the oil.
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Thanks & Regards
Shweta Jindal | Marketing Manager
