Hi All!
I am looking for information on Viscometers. My doubts/queries are:
1. For Reduction Gearbox lube oil which viscosity measurement is more relevant Kinematic or Dynamic?
2. Since oil grades are specified(ISO VG) in cSt , if I measure in cP , how can I convert it to cSt since the sp. gravity might have changed.
3.Does SKF TMEH1 measure viscosity ?
4.viscometer Range- Economical- ? Rough

Thank You

There are no viscometers available that measure in cSt ?

Check these sites for conversion factors:
http://www.cannoninstrument.com/Viscosity%20Definitions.pdf

http://www.106.us/gb/conversions/viscosity_kinematic.htm

http://www.106.us/gb/conversions/viscosity_absolute1.htm

http://www.hydraulicsupermarket.com/upload/db_documents_doc_15.pdf

Thanks Darth,
Kittiwake supplies viscometers that measures in cSt.Also if I measure absolute vicosity, I should be able to measure sp. gravity too to get correct kinematic viscosity.

Seemant

I know the Kittiwake box.

You can check internet for TMEH1.

Hi Josh!
Howz your experience with Kittiwake? Does it measures directly into cSt and what is it about "heated viscometer" it offers ?

Thanks

TMEH 1 does not measure viscosity.

http://www.reliabilitydirectstore.com/TMEH-1-OilCheck-O...r-p/skf-tmeh%201.htm

http://www.reliabilitydirectstore.com/VisGage-Pocket-Viscometer-p/lou-vis.htm

http://www.reliabilitydirectstore.com/TMVM-1-Handheld-V...ter-p/skf-tmvm-1.htm

Seemant,

Your question is insightful. Absolute viscosity is probably the better mode to measure viscosity of in-service lubricants, because it more closely reflects the viscosity property changes that impact bearing lubrication. However, it is almost universal at this point that folks present and compare viscosity readings in kinematic units. I have heard some instructors suggest that we measure viscosity with absolute methods (rotating cylinder, etc) but report values in kinematic units for ease of comparison. It does make it a more involved test to add the extra step of measuring specific gravity to convert cP to cSt. For reduction gearbox, however, I don't know that we are that concerned with very subtle viscosity changes. The most likely conditions that we are trying to measure with viscosity changes are dilution with the wrong oil or a foreign fluid (such as water or a nearby process fluid). These are generally gross changes that can be regularly monitored with "quick and dirty" test methods. One nice unit is the Visgage. It is a falling ball viscometer test that uses a reference fluid tube. You introduce the oil to be tested with its integrated plunger into a measuring tube. You place the device in its wood case to thermally equillibrate, and then race tiny metal balls down the tubes when held at a 45 deg angle. It takes a little practice, but can be very repeatable. It is important to note that when performed at room temperature, the results are only accurate for oils with a VI of about 95, which is the VI of the oil in the reference tube. With oil of any other VI, the test must be performed at 40 deg C to be accurate.
For reduction gearboxes, I would suggest utilizing a simpler test measuring in cSt for ease of testing and comparision, for routine analysis. But I would also suggest periodically sending a sample for analysis to a lab that can perform both kinematic and absolute viscosity, and has the ability to convert units as needed. This will allow you to have data points with greater accuracy to confirm the field tests, and to be able to occasionally look for subtle viscosity changes from time to time. But realize that most of the conditions that would lead to subtle viscosity changes (oil oxidation, particulate accumulation) should be measured more quickly and accurately by other tests such as particle counting, additive loss and oxidation (RULER, FTIR), and fluid contamination (FITR).

Hope this is helpful.

Rich Wurzbach
Certified Lubrication Specialist (CLS)
Laboratory Lubricant Analyst (LLA)
MRG Power Labs

Thanks Rich!
Certainly you gave me a very practical suggestion.
So I believe for Go-No Go Kind of thing like SKF TMH can serve the field purpose and sending the sample at labs for more detailed analysis.

Seemant