Oil & Fuel Bypass oil filter for those that care

[ponytug]

I'd just point out that this setup expects a 30psi (+/-) pressure differential and a rather limited flow (1/8gpm), as it is designed to be a parasitic oil drain from the oil pressure sender port.

Both could be rather hard to achieve on PT hydraulics. Surplus Hydraulics does sell some filters suitable for use at high pressure on the supply side and some high volume filters suitable for the return paths.

Nonetheless, it isn't clear to me how one would achieve 30psi on a return line without plumbing in a high flow relief valve set at 30. Ideas?

All the best,

Peter

 

[BobRip]

I'd just point out that this setup expects a 30psi (+/-) pressure differential and a rather limited flow (1/8gpm), as it is designed to be a parasitic oil drain from the oil pressure sender port.

Both could be rather hard to achieve on PT hydraulics. Surplus Hydraulics does sell some filters suitable for use at high pressure on the supply side and some high volume filters suitable for the return paths.

Nonetheless, it isn't clear to me how one would achieve 30psi on a return line without plumbing in a high flow relief valve set at 30. Ideas?

All the best,

Peter

Peter, I am not a hydraulics expert or even close. It seems to me you could use an orifice in parallel with a relief valve, also in parallel with the filter. Again, I understand fluid flow theory, but I don't know the practical components involved. J_J, any ideas?

 

[J_J]

There are some people that say that suction filters are bad, and I guess they have their reasons. Power-Trac has been using the 10 micron filter as a suction filter on the hydro transmissions, for about 30 years. I also think the filtering on the Power-Trac is not adequate, because it only filters one of the circuits. My PTO and steer pump draws directly out of the tank, although some of the fluid is filtered some of the time for the entire reservoir. I would venture to say, that just about all hydrostatic transmission have a suction line filter. Some equipment use tank suction filters of 150 to 200 microns. They say a suction filter will clog up and destroy the pump, and yes , it will, if not checked or changed often. There are indicators to indicate when to change filters, or a switch to prevent starting.

You could install a high pressure filter in the PTO circuit, and filter ever time you run the machine, They are not cheap, cost around $60 to $100.

Another idea, is to make yourself a hyd caddy, that has a small oil pump, pushing hyd fluid through a 10 micron filter in parallel with a 1 micron filter. and hook it into your system and let it run for 24 hrs. Once a week should thoroughly clean you hyd oil.

 

[ponytug]

Dear JJ,

Agreed. The upside to suction filters is that they keep gunk out of the pump. The downside is that they can have significant flow restrictions when the oil is cold or the filter clogged. When they are restricted, they are prone to degassing the fluid, which causes bad things (cavitation) downstream.

The fact that there is a debate is the answer that there isn't one answer. I think your idea of occasionally hooking up a finer filter is great- it would help get the oil really clean, and that is always good.

As Bob wrote, an inline orifice and relief would do it, but if the orifice plugged, you would have a high pressure situation and I worry about the safety issues.

All the best,

Peter

There are some people that say that suction filters are bad, and I guess they have their reasons. Power-Trac has been using the 10 micron filter as a suction filter on the hydro transmissions, for about 30 years. I also think the filtering on the Power-Trac is not adequate, because it only filters one of the circuits. My PTO and steer pump draws directly out of the tank, although some of the fluid is filtered some of the time for the entire reservoir. I would venture to say, that just about all hydrostatic transmission have a suction line filter. Some equipment use tank suction filters of 150 to 200 microns. They say a suction filter will clog up and destroy the pump, and yes , it will, if not checked or changed often. There are indicators to indicate when to change filters, or a switch to prevent starting.

You could install a high pressure filter in the PTO circuit, and filter ever time you run the machine, They are not cheap, cost around $60 to $100.

Another idea, is to make yourself a hyd caddy, that has a small oil pump, pushing hyd fluid through a 10 micron filter in parallel with a 1 micron filter. and hook it into your system and let it run for 24 hrs. Once a week should thoroughly clean you hyd oil.

 

[BobRip]

Dear JJ,



As Bob wrote, an inline orifice and relief would do it, but if the orifice plugged, you would have a high pressure situation and I worry about the safety issues.

All the best,

Peter

Peter, wouldn't the relief valve then kick in and give you the safety?

 

[SpringHollow]

We had a pretty good discussion on external filter carts a couple of years ago. I thought people had some very good comments:

http://www.tractorbynet.com/forums/power-trac/102333-filter-cart-tank-magnets-etc.html

Ken

 

[ponytug]

Yes, but... The filter is designed for 30 psi, while the hydraulics are upto 3000psi, or a factor of 100 more. So a relatively small error on the relief valve might still generate a catastrophic failure. (Just trying to keep everyone here alive and in one piece...I think it is a great group!)

As Ken pointed out above, the issues have been walked through before...It was a productive thread.

All the best,

Peter

Peter, wouldn't the relief valve then kick in and give you the safety?

 

[J_J]

Lets just back up here a sec. The suction filters are not made for high pressure. There are special filters to filter high pressure fluid. Some of the filter bypass settings on suction filters are 15, 20 30 psi, and no one would want to use these filters in a high pressure line. Without a doubt, they will come apart.

High pressure hydraulic filters - 414 MPa (60 000 psi), ASME, 316 SS - IVS-TESTER-CORPORATION - Hydraulic filter, Oil treatment

These filters will filter up to 500 psi, and up to 50 GPM.

http://www.directindustry.com/prod/baldwin-filter/hydraulic-filter-22198-373139.html

So if you want filters, they are out there. For the most part, I would think the filters are doing the job they were designed for. However, something like the filter caddy would probably not cost more than $150. If used weekly, it would allow the filter on the tractor or whatever to last much longer.

 

[SPYDERLK]

On Earth a suction filter bypass must be set at less than 15psi in order for it ever to bypass in a suction line.
larry

 

[Bob999]

I priced the filter carts a couple of years ago and found prices ranging from $1000 and up. Just a pump from Northern Hydraulics was $300+ as I recall.

If you can find one for $150 I would sure like to have the opportunity to buy one!