We manufacture Hydraulic oil,as we known, particle in hydrualic oil is limited, so we have filters to control particle. our requirment is NAS6. But it takes so long cylce time to get NAS 6, the filter size is 6 micron and 10 micron. so i want to know what's the reason, oil temperature? Filter efficiency? air bubble in oil? or others? Your kindly inputting would be highly appreciated.

Thanks in advance.

Kelly zhang

Especially at around NAS 7,it is so difficult to get down to NAS 6, and for Hot oil, it is easier to get down NAS 6 than Cool oil. Our particle counter on-line is a kind of Optical Scanning analysis system. so, if the air bubble in oil can impact on the test result?

Remember that the difference from NAS1638 class 7 to class 6 is 100%.... so its not strange it takes time.

You should evaluate even finer filters (1-3 micron). This would give you cleaner oil faster.

How large are your storage tanks (or where you filter your oil)?

The tank are about 10000L, and the filter is located about 20m far away the tank, and located about 2m far away the filling nozzle. the pipe's dia. is about 10 cm.

But for the new filter, it is very fast to get to match the requirement NAS 6.( Yes, NAS6 is higher than NAS 7). but it takes long time with day after day using.

Is this single pass filtration. If so perhaps an offline system that is continually filtering tank contents would probably result in improved cleanliness of the oil

You may considerplacing a more coarsefilterinitially beforethe 10 micron filtertobring down the load on the final setoffilters.. We triedthis andhave been succesful in reducing the over all time for filtration to achieve even lowere NAS level (say 4-5). The filter mayhave element around 20 micron level.

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Originally posted by Kelly:
We manufacture Hydraulic oil,as we known, particle in hydrualic oil is limited, so we have filters to control particle. our requirment is NAS6. But it takes so long cylce time to get NAS 6, the filter size is 6 micron and 10 micron. so i want to know what's the reason, oil temperature? Filter efficiency? air bubble in oil? or others? Your kindly inputting would be highly appreciated.

Thanks in advance.

Kelly zhang

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Thank you all very much! Your kind advice are very useful for me.

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Originally posted by Tapas:
You may considerplacing a more coarsefilterinitially beforethe 10 micron filtertobring down the load on the final setoffilters.. We triedthis andhave been succesful in reducing the over all time for filtration to achieve even lowere NAS level (say 4-5). The filter mayhave element around 20 micron level.

quote:

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Originally posted by Kelly:
We manufacture Hydraulic oil,as we known, particle in hydrualic oil is limited, so we have filters to control particle. our requirment is NAS6. But it takes so long cylce time to get NAS 6, the filter size is 6 micron and 10 micron. so i want to know what's the reason, oil temperature? Filter efficiency? air bubble in oil? or others? Your kindly inputting would be highly appreciated.

Thanks in advance.

Kelly zhang

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In Germany there have been made tests with the different oils, hydraulics, motoroil, transformation oils and other lubricants.
They find out that even in brandnew oil there was a contamination for more than NAS 9 - 10. In realising this all new oils have to be filtered by a microfiltration. We changed the NAS from 8 down to 4 - 5 with an online microfiltration.
This filtration takes time, but it is a low price product and guarantees the NAS class after a period of time.
For example: We had in Spain a turbine hydraulic with more than 20.000 l. This oil was ready to change. After filtering 3 months we receiverd NAS 6 and the oil stands at this contamination.

Kelly, you might want to look at the beta rating of the filters you are using, Donalsdon makes a really good beta4<1000 that should do the trick. also you might want to increase the surface area that the oil has to pass through, you can do that by installing several filters in line, and as always a kidney loop system works great to polish the oil, but I would look at the efficiency of the filters, that would do more to decrease the time it takes to clean up the oil.

The filter efficiency are to bad.
I would recommend to put an EUROPAFILTER on your oil. This filter will clean the oil down to NAS 1638 1 or 0! It does excist in one size, but you can put 2 pieces of it. In less than 48 hours all the oil would have passed through the filter. If you filter the oil from one tank to another.

If the Oil tank is not cleaned from inside before applying off line filtration, it may take indefinate time to get even NAS cleanliness level as sediments and silt deposited at the bottom of the tank will go on releasing loose micron size particles in billions and you can wait indefinately to get the desired result.
Ther best method is to clean the tank from inside before undertaking such superfine filtration.
V.S.Dave

we are blending Turnine oil in our plant and our target is to acheive NAS 6 level by using 3 micron bag filters. however, the results shows that we are on NAS 9 &10 only. we are looking to have 1 micron filters, any body can help me to find the manufactureres of 1 micron filters.

regards

Hi Haykelly,

NAS 6 = ISO 15/12

Depending on the viscosity of your oil and the time you need to clean the oil it is possible to get a bypass micro filter which cleans up your oil to even higher levels that NAS 6.

let me know what your exact specifications are..

so:

viscosity
temperature of the oil in the tank
and your expactation towards the time.

Best regards

Martin

If you really want high levels of purification of hydraulic oil, you should be looking at electrostatic purification. We would be interested in working with you to solve your problems. Please, give me a call and we can explain our process.

Our electrostatic oil conditioners are well known to improve particle counts. Please contact me for details.elevitt@uasinc.com