Air or nitrogen purging of industrial gearbox to keep dirt out

Dear Frank,

I have background in the Hydrocarbon Processing Industry. In than Industry we have been installing oil mist for centrifugal pumps and we use oil mist as purging in gearboxes of cooling towers. Results are excellent!

Regards,

Hi Christian, thanks for the reply, why oil mist? corrosion? what pressure?
I'm interested in anything you can freely share on the application.

Regards
Frank

Thanks for the info Rob, low pressure filtered air is the way to go, how low is the pressure?
What is a membrane dryer?

Regards
Frank

Hi Frank, it's the movement of air in one direction that removes the moisture and keeps dirt out, the flow rate is soft and would be decided by the size of the tank and whether the out flow is restricted and the amount of water requiring removal, once the system was applied the amount of water remaining would decide flow rate and you could increase the flow rate at the start and decrease once the target level has been reached. The gas sites we service use nitrogen over the reservoirs and nitrogen will also remove water but this requires special application equipment so unless an explosive atmosphere I think air would be best and easiest, Norgren Australia supply membrane dryers, these are used on any air supply and are solid state and have a molecular sieve that allow water to drop out into the atmosphere and dry the air, ask for the membrane dryer similar to what’s used on the train braking systems, most likely $3-4K to setup so other dryers may be a lesser cost or if the factory air is already dried that would also suit, Regards Rob S

Hi Frank, In addition Dry air purging is most applied for water removal, if only dirt unidirectional breathers are well proven and far less expensive to apply, http://www.rttech.com.au/wp-co...tional-breathers.pdf
Regards Rob S

Frank,

Check with Fluitec, they sell a dry air blanket device that will help.

R

We use oil mist to purge gearboxes but we have trouble with the viscosity of the gearbox oil being decreased over time. I thought about switching to nitrogen. Has anyone experienced this problem and what are anyone’s thoughts on nitrogen purging? Thanks!

Hi EA, Usually the nitrogen would be used on intrinsically safe gas sites, the nitrogen will remove water but dry better for just water as no corrosion biproducts, how quick does the vis decrease on the oil mist purge drives??
Thanks Rob S

It drops about 10-15 cSt per month. I work at Kraton Polymers in Belpre,Ohio which is a chemical plant. We use oil mist as a purge to keep moisture out of the gearboxes. So you would not recommend nitrogen as a purge to keep water out? Thanks for your response.

Hi EA,

if you are using Oil Mist, that mean you are already having Dry Air source. (i.e: Instrument Air).
Instead of Nitrogen, why you're not trying to use Filtered Dry Air?

Regards,

OK. Thanks for your help. Nitrogen is more accessible than the instrument air.

Dear EA

I would like to comment that we have to much experience with Oil Mist in Cooling Towers and a drop of 10-15 cSt per month is very much. Maybe, your oil mist system needs a calibration or revision. Oil Mist is the best technology for purging gears in cooling towers. I think you could analyze this point.

If this isn't a problem, could you share with me the following data:

1- Viscosity of the fluid (is it 220 or 320?).
2- Viscosity of oil mist (is it 46, 68 or 100?).
3- Volume of the oil reservoir in the gearbox.
4- Quantity and type of reclasifiers installed (of course, if you could share brand of your application that will be great).

Thanks for the information.

Regards,
Cristián Schmid.

Frank, sorry, I didn't read this post from you!

Regarding oil mist, it is a very good application for gearboxes in cooling towers, since this creates an small pressure that avoid the water (vapour) ingressment, and lubricate the differents oil rings in the gear (when the shaft isn't working).

I have a lot of information about that that I could share with you. We will present in May a paper in the STLE Meeting in Detroit.

Regards,
Cristián Schmid

quote:

Originally posted by Frank C:
Hi Christian, thanks for the reply, why oil mist? corrosion? what pressure?
I'm interested in anything you can freely share on the application.

Regards
Frank

quote:

Originally posted by EA:
OK. Thanks for your help. Nitrogen is more accessible than the instrument air.

Hi EA,
apologies for the late reply, I've been away from computers for 2 weeks,
The applications we monitor using nitrogen purge on the gas sites have large 100-150 mm diameter breather vent pipes and over 10 years or so we have not seen any significant dirt ingress that we would recommend an oil change off.
The pros have been brought to attention in this discussion,
The cons are Nitrogen and water can under the correct circumstances form nitric acid with the onsite engineers asking us to monitor for corrosion bi-products with nothing significant found in the reservoir bottom samples although the steel pipe venting the nitrogen does show a brown corrosion type layer that is not defoliating any oxide particles, I don't have data on the flow rate of nitrogen used but that data would be related to running an intrinsically safe machine on a gas site.
Regards
Rob S