Guidelines for Grease Operating TemperaturesStratson
We would like to share some Guidelines for Grease Operating Temperatures. This is about as well High as Low Temperatures! In 1933 a group of Grease Manufacturers met to address common grease industry issues and to standardize lubricating grease properties. The National Lubricating Grease Institute was born and has served the lubricating grease industry for over 80 years. The Annual Meetings address various issues, regulations, and provide training in the manufacture and application of lubricating grease. There have been several presentations addressing lubricating grease operating temperatures and a condensed version follows:
High Temperature Lubrication
The rule of thumb that the rate of oxidation and degradation doubles for every 18°F over 150°F (or 10°C over 65°C) applies for most greases as well as oils, mainly due to the fact that grease is usually more than 80% oil. The determination of the upper temperature limit is a compilation of factors including the dropping point of the grease, flash point of the base oils, and other components. Most greases can handle operating at 250°F (121°C) with monitoring and relubrication at regular intervals. As the temperature rises the number of greases that can handle those temperatures dramatically drops until a point is reached where common grease will no longer stay in place or will burn up, usually in excess of 600°F (315°C). Beyond that most base oils and many synthetics will burn off in a short period of time leaving the equipment unprotected. Most bearings are shielded or protected from the operating temperature of the equipment, so the actual bearing temperature range may be significantly different than the environment around it. For rolling element bearings, the following are general guidelines for scheduling lubrication intervals:
- 150°F (65°C) 6 Months
- 200°F (93°C) 3 Months
- 275°F (135°C) 1 month
- 350°F (176°C) 1 week
- 450°F (232°C) 1 Day
Assuming an eight-hour day and low contamination levels. Speed, load, and contamination levels will greatly affect the frequency of lubrication and type of grease used. In some cases, such as high load and contamination levels, lubrication frequency may be hours or minutes.
Low Temperature pumpability
There are a numbers of factors that determine the flowability and pumpability of a grease at low temperature. These may include the pour point of the base oil, type of thickener used, penetration grade, and polymer content. Actual pump tests such as the Lincoln Ventmeter, US Steel Mobility Test, and Apparent Viscosity are commonly used to determine the lower operating range. These tests measure the ability of the grease to move under pressure at a given temperature. The greases ability to slump or flow at given temperature is also taken into account. If the grease doesn’t flow from a reservoir into a pump, it cannot be distributed.
Optimum Operating Ranges for SWEPCO Greases:
|Product||Optimum Operating Range|
|SWEPCO 101 Moly Grease||-30°F (-34°C) to 500°F (260°C) Non Melt|
|SWEPCO 103 Moly High Impact Plus Grease||-4°F (-20°C) to 350°F (177°C)|
|SWEPCO 104 High Heat Grease||-30°F (-34°C) to 500°F (260°C) Non Melt|
|SWEPCO 105 High Impact Plus Grease||-4°F (-20°C) to 350°F (177°C)|
|SWEPCO 110 Shock Resistant Grease||-25°F (-32°C) to 250°F (120°C)|
|SWEPCO 115 Food Machinery Grease||0°F (-18°C) to 400°F (204°C)|
|SWEPCO 116 (Food Grade Grease, to be released shortly)||-10°F (-23°C) to 475°F (246°C)|
|SWEPCO 121 Tri-Plex Universal Grease||-30°F (-34°C) to 375°F (191°C) Continuous 450°F (232°C) Intermittent|
|SWEPCO 123 Ultra EP Multi-Service Grease||0°F (-18°C) to 475°F (246°C)|
|SWEPCO 164 Ultra EP Open Gear Lube||10°F (-12°C) to 475°F (246°C)|
|SWEPCO 165 MolyXP Universal Valve Lubricant (to be released shortly)||10°F (-12°C) to 475°F (246°C)|
|SWEPCO 402 Premium EP Chain & Roller Lube||-40°F (-40°C) to 250°F (120°C)|
Operating friction, shielding, cooling vents, etc. will vary the actual bearing operating temperature from the equipment around it. These are typical operating ranges and not dropping points or points where the grease will solidify. SWEPCO greases typical last two to five times longer than conventional greases.
As the title is Guidelines for Grease Operating Temperatures, it is a guideline!
Southwestern Petroleum Corporation®