Do I need a return AND suction filter?

[woodsroad]

Hello,

I'm rebuilding a log splitter. It has a 16 GPM pump and 5" cylinder. The return filter was undersized, and I have replaced it with a filter that exceeds the flowrate of the pump. The reservoir tank does not have a suction strainer. I have added a good breather/filler cap, however. Do I need to add an inline (outside the tank) suction filter? If so, does anyone have any suggestions for a good one? I looked at the Northern #4014, but it is only rated to 15 GPM.

Thanks,

 

[glastron23]

this is a very contentious issue.. i'm of the side that thinks that suction filters are useless!!! at a filter rating of 100 mesh all suction filters will stop is big chunks from going into the pump, with a good return filter of 5 or 10 micron and a good beta rating then it will keep the oil clean, if the tank is sealed with a good vent filter, the tank is clean from the start and the new oil ( yes i know that NEW oil is rather dirty and should be filtered before using it) then everything will be ok. We throw a magnet in the tank at first start up just to help in case there is a stray bit of metal floating about.
In a unit like yours you don't have the same problems with pump starvation when the oil is cold that we have in a large piece of equipment.
Thats my take on this...Jim

 

[woodsroad]

Thanks, Jim

The suction filter that I'm looking at:

https://www.surpluscenter.com/item.asp?UID=3508012608361577&item=9-4544&catname=hydraulic

OK, it's 25 micron, not 150 like a tank strainer, but I get your point. If the tank is clean, and the oil is being cleaned by a 10 micron return filter, then why would you need a suction filter?

So, I'm not going to add one, it's good enough.

Thanks.

 

[AKKAMAAN]

Hello,

I'm rebuilding a log splitter. It has a 16 GPM pump and 5" cylinder. The return filter was undersized, and I have replaced it with a filter that exceeds the flowrate of the pump. The reservoir tank does not have a suction strainer. I have added a good breather/filler cap, however. Do I need to add an inline (outside the tank) suction filter? If so, does anyone have any suggestions for a good one? I looked at the Northern #4014, but it is only rated to 15 GPM.

Thanks,

I think it is more important to refill oil into tank thru a "FILL-ter".....and have a breather and fill cap designed so it don't let water in.....pressure and fluid level, in tanks, varies when when piston rod goes in and out in cylinder....and that requires a GOOD vent system....

 

[oldnslo]

Like Jim stated, be very careful with inlet filters/ strainers in cold weather use. They need to be sized for worst case scenario. I.e. The coldest temperatures you expect to be operating this splitter.

Are you willing to let the unit idle for a few minutes on a cold start to get the fluid warmed up? If yes this will help reduce the pump cavitation also.

Personally, I think an inlet screen is cheap insurance to help keep any big particles from destroying your pump or possibly jamming a valve.

Be sure to size your return filter to handle the higher volume return flow. Typically around 1.2 - 1.4 times pump flow. Figure in cold oil for this also so you blow the canister apart.

Good luck

Roy

 

[woodsroad]

Hello,

Thanks for the good advice, folks, you stopped me from over-engineering this.

The tank is clean and it has a good breather on it. But since there isn't a "fill" filter, I'll fill through a funnel with an 37 micron sieve on top. It should be interesting to see if the sieve catches anything.

The return filter is rated for 20GPM, and the pump is rated at 16GPM, so that should be sufficient...I'd love to put pressure gauges, thermometers and flow meters all over this rig and really see what it going on! As it is, the return filter housing has a 15 PSI bypass, and there is a 30 psi pressure gauge on it.

And, yes, I always allow the splitter to warm up before using, running at a lower rpm until the tank is warm to the touch.

Thanks again, I'll post back with pix and a report when it is up and running.

 

[oldnslo]

Sounds like you should beready to split wood. Keep your fingers and toes where they belong.. it hurts less

 

[woodsroad]

Thanks,

I got the cylinder reassembled today, what a PITA that was. Turns out that the front piston has to go on the ram from the back. So I had to disassemble the whole thing and start over again! Then one of the wipers kept getting caught in the cylinder threads. Anyway, I have all the connections dry-fit now, and I'll get is assembled with teflon pipe dope tomorrow, then get the two hoses made.

After all that I've learned on this project, I really want to go and build a second splitter. I think it might be easier the second time around....

 

[woodsroad]

OK, so the HF 30 ton POC splitter is up and running, running like a champ.
I replaced the woefully undersized return filter with a new one rated for 20 GPM (16 GPM pump), replumbed with new 3/4" fittings and lines, rebuilt the cylinder yadda yadda yadda....

I also put a pressure gauge on the inlet to the valve and on the inlet to the cylinder.

At first, both stayed well below 500 PSI until the end of the stroke, when the valve gauge went to 2250 (relief valve setting). The cylinder gauge barely budged, and harley moves when splitting. Today, when I started the splitter, the valve gauge went to 750 and went as high as 1200 or so (until the end of the stroke or the return, when it shot up to 2250). When I shut the splitter off, it stayed at 750.

These are both new gauges from Northern. Defective?

If so, can anyone suggest a source for reliable gauges?

Thanks!

 

[glastron23]

Nice looking unit... glad everything worked as planed... as far as the pressure gauges, you really only need the gauge on the cylinder as this is the only pressure that is looked at, the cylinder return pressure is unimportant, the pressure will only spike high to relief pressure when the valve is in auto return. This is a high spike and is a real gauge killer. the max pressure when splitting is when the cylinder bottoms out or stalls in a big piece of wood..
one thing we do when we use our wood splitter is to count your fingers when you start... then count them when your done... if both numbers are the same then its MILLER TIME....... LOl Jim

 

[woodsroad]

the cylinder return pressure is unimportant, the pressure will only spike high to relief pressure when the valve is in auto return. This is a high spike and is a real gauge killer.

The return filter head has a 15 psi bypass. I have a 30 PSI gauge to install on it, so that I can see when the filter needs replacement... you think the spike pressure will destroy this gauge?

the max pressure when splitting is when the cylinder bottoms out or stalls in a big piece of wood..
one thing we do when we use our wood splitter is to count your fingers when you start... then count them when your done... if both numbers are the same then its MILLER TIME....... LOl Jim

I guess that's where the Amish polydactylist's have one up on us. Start with six fingers, you have a little more room for error.

Any ideas about these gauges that don't seem to be working properly?

 

[glastron23]

It was more than likely the pressure spikes that damaged the gauge, the gauge at the control valve takes a real beating. as far as the return gauge it should be ok, any equipment that we work on that has a gauge plumbed in with out a shut off is never trusted as being correct, we normally install PD series quick connectors so we can install/remove gauges when required, i think that you will find after a while you will never be looking at the gauges until you have a problem.. Jim.. 6 fingers.... HUMMMMM .. would be come in handy for pouring a good glass of RUM.....

 

[AKKAMAAN]

The return filter hea
d has a 15 psi bypass. I have a 30 PSI gauge to install on it, so that I can see when the filter needs replacement... you think the spike pressure will destroy this gauge?

It is not the pressure it self, in the spike, that kills the gauge....it it is the "high" volume that enter the bourdon tube...
http://en.wikipedia.org/wiki/Pressure_measurement

If you cant monitor that 15psi pressure with a lower resolution gauge like a 100psi??....there can be ways around the spike problem....

I have seen a volume restricting little orifice,somewhere between 1/32 and 1/64", in the line to the gauge....


even a piece of long hose line from the Tee, can help to save the gauge form high ENERGY spikes, that would basically work like an accumulator....

A larger diameter gauge, like a 4" instead of a 2" can be enough too....

It all depends on the volume part of the energy in the spike......

 

[woodsroad]

The gauges that went bad are 5000 psi. My splitter should top out at 2250 (the relief valve setting), so I thought that gave me some headroom. I guess not.

The 30 psi gauge that I have will go on the return filter head, but it isn't installed yet.

I will have to think about a way to put a small orifice and buffer between the high pressure line and the gauge.....maybe welding shut the middle of the 1/4" adapter fitting that the gauge screws in to, and then drilling the orifice through the weld?

Thanks for all the pointers and opinions.....

 

[J_J]

woodsroad ,

The purpose of the oil in the gage is to dampen the indicator, and I notice on yours, that it is not in the fluid , but in the air bubble. Do you think that had something to do with gage failure? Like someone else mentioned, I install QD's at desired test positions, and simply plug the gage in when I need a reading. Only plug them in with pressure relived.

 

[woodsroad]

Yeah, it appears that gauge has a fluid leak. Lots of glycerin dripping. The needle was submerged when the gauge was installed, but no more. Maybe that WAS the problem.

Now, the gauge on the cylinder hasn't moved much at all from the start. I'm sending both of them back, putting QD's in and new gauges.

Any learned opinions on this gauge?:
0-5000 psi 2.5" Liquid-Fill Hydraulic Air Water Gauge - eBay (item 170413063788 end time Feb-26-10 06:25:09 PST)

 

[AKKAMAAN]

I will have to think about a way to put a small orifice and buffer between the high pressure line and the gauge.....maybe welding shut the middle of the 1/4" adapter fitting that the gauge screws in to, and then drilling the orifice through the weld?

No no....just tap the hole in the fitting to a common thread....take a regular 8.8 or 12.8 machine pin screw with no head and allen fitting...either drill the screw or jack the threads out on a 45 deg part of it.....
also if you drill a center hole, whick can be a pain in the a** with a tiny drill bit....drill an slightly oversized hole, or use your dremel grinder on the side of the screw...and put a piece of steel wire in it to reduse the hole area....that also works as a cleaning tool in the orifice...
See pic....