We buy 5 gallons pails of NLGI0 and 1 greases for motor operated valves.
When we open the NLGI 1 we frequently find a pool of oil, perhaps a couple of ounces, on the top.
Is this a concern?
Original Post
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Some greases bleed oil more than others. Ideally it shouldn't bleed out that much before it's even used. Personally I would look for a grease with a better ASTM D-1742 Oil Separation rating.
What is the grease being used for?
What is the grease being used for?
The grease is MOV LL (Motor Operated Valve Long Life)
Because of environmental qualifications, we can't just go find a better grease.
I need to go look up D-1742 and the vendor specs. My answer may lie in that.
Thanks for the pointers.
Because of environmental qualifications, we can't just go find a better grease.
I need to go look up D-1742 and the vendor specs. My answer may lie in that.
Thanks for the pointers.
Here's a couple of documents I found on it. Looks like the NGLI #0 has a Oil Separation rating of 1.1%. That would explain why your finding oil.
http://www.forsythe.on.ca/lubricants/product_012_3.html
http://mydocs.epri.com/docs/public/000000000001014669.pdf
http://www.forsythe.on.ca/lubricants/product_012_3.html
http://mydocs.epri.com/docs/public/000000000001014669.pdf
Oil separation is an essential part of a grease.
No oil separation = poor lubrication.
Oil separation likely to increase as the NLGI Number decreases for the same type of grease.
Data sheet should give a typical figure for oil separation, but not so critical for soft greases
as regreasing intervals are shorter(auto greasing) or when used as a gear grease.
No oil separation = poor lubrication.
Oil separation likely to increase as the NLGI Number decreases for the same type of grease.
Data sheet should give a typical figure for oil separation, but not so critical for soft greases
as regreasing intervals are shorter(auto greasing) or when used as a gear grease.
Well, I found out that under thermal aging and irradiation this grease loses 5% of its oil and still passes testing.
So I am leaning to an ounce or 2 being ok.
So I am leaning to an ounce or 2 being ok.
The Grade 0 of MOV Long Life is about 80% so a bit of oil separation is not a problem. You would need to lose an awful lot to change the grade. For MOV's most use a Grade 3 as the maximum in-service limit. The free oil can normally be mixed back in or decanted. If an issue consider using the Grade 1 which has less oil separation. The alternative is the age hardening problems of the previous calcium complex grease and lack of lubrication. The previous grease was considered 'marginal' in some of the EPRI testing. Plus in oxidation testing MOV Long Life is outstanding. Some stations are approaching 4 times the service life in high ambients.
Robert,
If or not oil separation is a concern depends on the application and if or not it can be regarded as excessive.
IP 121 is a good measure for storage stability as a result of oil separation.
Some oil separation is required to provide sufficient lubrication. It should not be <0.5% according to FTM 791 at the operating temperature and preferably not >6%.
An IP 121 ranging from 1-5% is normally regarded excellent and FTM 791 should be between 0.5-6% at the operating temperature.
Thickener content, thickener type and base oil type affect the oil separation rate as well as method of manufacture. Method of manufacture you can't do much about except picking a quality supplier.
NLGI 0 grades typically have oil separation >5% because of very low thickener content so going for a higher consistency can reduce bleed.
Switching to a synthetic e.g. PAO could also improve bleed as thickener content is typically 25-50% higher due to poor solubility of the thickener in PAO.
However, if you are using a mineral oil based product it also depends on type of mineral oil. Products based primarily on naphthenic base stocks have poorer oil separation but lower cost due to a lower thickener content than those based on paraffinic base stock. The VI can give you a hint to the origin of the base oils.
Switching to lithium complex could also improve bleed as this thickener type hold the oil better and typically reduce separation by half.
If the oil separation corresponds to a couple of paper cups in a 400lb drum just pour it off. It should not have any significant impact. If you are referring to a couple of inches on the surface then I would say you have a problem.
Don't ever try to mix in that separated oil!!
Question is what is the actual grease requirement of those valves and does it have to be an NLGI 0 and does it have to have the type of thickener you currently use?
Cheers,
GG
If or not oil separation is a concern depends on the application and if or not it can be regarded as excessive.
IP 121 is a good measure for storage stability as a result of oil separation.
Some oil separation is required to provide sufficient lubrication. It should not be <0.5% according to FTM 791 at the operating temperature and preferably not >6%.
An IP 121 ranging from 1-5% is normally regarded excellent and FTM 791 should be between 0.5-6% at the operating temperature.
Thickener content, thickener type and base oil type affect the oil separation rate as well as method of manufacture. Method of manufacture you can't do much about except picking a quality supplier.
NLGI 0 grades typically have oil separation >5% because of very low thickener content so going for a higher consistency can reduce bleed.
Switching to a synthetic e.g. PAO could also improve bleed as thickener content is typically 25-50% higher due to poor solubility of the thickener in PAO.
However, if you are using a mineral oil based product it also depends on type of mineral oil. Products based primarily on naphthenic base stocks have poorer oil separation but lower cost due to a lower thickener content than those based on paraffinic base stock. The VI can give you a hint to the origin of the base oils.
Switching to lithium complex could also improve bleed as this thickener type hold the oil better and typically reduce separation by half.
If the oil separation corresponds to a couple of paper cups in a 400lb drum just pour it off. It should not have any significant impact. If you are referring to a couple of inches on the surface then I would say you have a problem.
Don't ever try to mix in that separated oil!!
Question is what is the actual grease requirement of those valves and does it have to be an NLGI 0 and does it have to have the type of thickener you currently use?
Cheers,
GG
