For the forging press:
1. Do I need a 10 micron return line filter if I have a 25 micron suction filter between the tank and the pump?
2. How hot is the returning oil if it was pumped at 4GPM and 3000psi(ones) I understand that it will gain the heat when circulating.
3. If I have a 16\4GPM 3000psi pump and 20 gallon tank, do I need additional oil cooler?
4. Do I need to put additional oil in the system to fill up the hoses, pump, filters or this is negligible?
5. How often I suppose to change the filters? Should I drain the oil from the tank to do that?
I would appreciate some explanations in the your answers.
I didn't stay in a Holiday Inn Express last night, but I did just build a press and it's working pretty well, so I'll take a stab at some of these.
1) Let me answer the question that you should be asking: Yes, you do need both a suction and a return line filter. The suction filter can save your pump - it's well worth the investment.
Return filters are (typically) measured in microns and suction filters (also called strainers) are (typically) measured in mesh size. Using a return-type filter on the suction line will starve your pump and destroy it in short order. And the press will peform like garbage.
Be aware that many (all?) suction strainers have a pressure relief built in, so if the mesh gets clogged it will open and not completely starve the pump. So you do need to inspect the thing from time to time - flow is not by itself an indication of non-cloggedness. (Technical term)
I used a 100 mesh strainer in the tank on the suction side, and a 20 GPM 10 micron return line filter. I would highly recommend you do the same.
2) No clue. How hot was it to begin with? Seriously, I've no idea how to calculate that, sorry. Be aware that your pump is likely to spend very little time at high pressure vs. low pressure. But really what you want to know is:
3) I would say no. It depends on how much you run the press, shop temperature, length of lines, where the tank sits, etc. A 20 gallon tank is big (maybe too big) though - my gut feeling is that you are safe by a very wide margin.
I am running a 16/4 GPM pump at 1750 RPM, so halve those GPM's. I only have a 5 gallon reservoir, and my relief is set at about 2900 PSI. I don't have heating problems. I don't run the press for hours on end, though - I use it for hours on end but if it's going to run for more than a minute or two without squishing something, I shut it down. Even at 1750 RPM the noise bugs the hell out of me.
If I were doing production work, if I were faster, etc. etc. etc. I would likely need a bigger reservoir. 5 gallons is at the low end, I'd say. I have never gotten my oil to even "quench oil temps," (i.e. 130 or so) though. More like "slightly warm." I'd still go with a 10 gallon tank on a re-build.
4) With a 20 gallon tank, it's negligible.
I put 5 gallons into my system, minus some spills from filling and swapping a couple of lines. Yeah, I have air space in my reservoir and I keep meaning to top it off, but I am having no problems and don't need the additional half gallon or gallon or so for cooling - see above. If I ever feel the oil get on the warm side I will try adding oil first, then maybe a fan on the reservoir.
5) It's recommended (though I forget where - maybe the pump docs?) that you change the return filter element after the first 50 hours, then something like annually after that. Depending on your geometry, you may or may not find you need to drain the tank.
I am not sure how often to check/clean the suction strainer, to be honest. On my setup, that's going to take draining the tank. The only leak on my system lives there, too - it has seeped exactly one drop in about three months - right there where the strainer screws into the tank.
Hope this helps.
Dave
, my precious buck....