Splitter Problem-Filter Blew(Pic)

[cabinman]

New build

Cabinman I believe it Boyles law that covers the expansion of gasses Vs. volume and to me it looks like just a few ounces at 2500psi could expand enough to do the job.

It could be that the small wood strokes never went to the end of the stroke. Or it could be that as the small pieces were split the filter was damaged at that point only to fail a stroke or two later. When the piston gets to the end of either stroke it should push out any remaining air but often when wood splits the operator stops the ram and backs it up. It does sound like it would be a good practice to always run rams to full extension and back whenever changing hyd fluid.

Treeco, If it was never fully stroked,/purged, I agree on traped air,.and port location wouldnt matter, If thats a cross cylinder, I have the same one, and wood guess maybe 1 to 1.5 oz area between piston and cylinder end, Thanks Eric

 

[triptester]

Often on a new build there could be a combination of little things that could add up to cause a problem. We can only guess at the cause and the correct solution to the problem.

Glad to see the splitter is working. It looks like a well designed machine.

 

[kevin j]

Couple previous posters got it:

As the cylinder strokes out (or in), most of the air is pushed out but not all if the ports are sideways. Let’s say it has cycled, but the closed end has that cubic inch of air above the ports when totally retracted. The next time it extends and hits a load and builds pressure, that bit of air, even only a cubic inch, then compresses basically full of oil (to maybe .01 cubic inch compressed 100 to 1 or so) to say 2500 psi. Then when the valve is shifted to retract, the oil pressure immediately drops and starts back through the filter from the pump, Before anything even moves, this little bubble at 2500 psi expands back to one inch at 20 or 50 or whatever psi. Acts like a spud gun in a way-sends one cubic inch into return and filter. Doesn't sound like much, but 1 cubic inch in a few milliseconds is mega gpm. Since flow creates pressure drop, the line pressure sees a spike faster than a gauge can see, but blows the can.

That was my original theory, thinking he put the valve into retract and it blew. OP said pulled to neutral but not yet to retract. Thus, this trapped bubble is in the cylinder (valve is blocked center, at least I assume so?) and the pressure doesn’t blip to the filter yet. Hence my later theory that the compressed oil/air that is relieved of pressure and can expand to send the surge would have to be in the line before the valve. The oil moves through a second after pump starts and air in the hose would have been gone long before. The only way I can envision a continuous supply of compressible air/oil is if there is a suction hose leak, a pump shaft seal leak, low oil level, or extremely aerated oil in the tank. This is a likely culprit, if there was a lot of trapped air stirring things up and still entrained in the oil in the tank.

I have seen a 4 foot x 5 foot tank lid, with 200 lbs of air filters and fans for other stuff, blow off over 75 feet into the weeds at a startup. Hydraulic fluid trapped in one corner couldn’t get away fast enough, it pressured the lid, bolts tore, the resulting snapping steel bolts ignited the seriously aerated fluid and boom. No one hurt, increased WalMart sales for new underwear.

Usually air at startup is harmless. If this was one of those normal weird startup issues, especially with aerated oil as the culprit, no more worries. You needed the bigger return lines anyway, good change. I would still check the tank oil for aeration, and all suction connections just to be sure it was a one time thing.

Air in a cylinder with resistance load, always pushing or pulling, is safe and will purge out. A cylinder that goes past center, from pushing to pulling, can be very dangerous at first startup if not properly purged. The push side fills with oil, slowly, as the valve is metering the oil INTO the cylinder. The other side is still full of air. When the load goes past center, if the cylinder far side is full of oil, it is controlled by the valve restricting flow OUT of the far side. If that side is full of air, when it starts to overrun, the spool can be totally closed and the cylinder won’t stop. It just compresses the air in the cylinder and hoses and keeps going with the load.

Eric-farm machinery: fold up wings on a disc or chisel. The wings are folded up, past center, and tend to fall to the inside when stowed for travel. Usually a toggle linkage and cylinder pushes them out (a resistive load) until it goes past center at straight up, and turns into an overrunning load. Control on the way down is from metering OUT of the cylinder not in. If full of air, no control, throws that puppy down so fast the earth shakes. Or so I’ve heard…. Even cycling back and forth a few inches before it goes past center won’t properly purge air in that situation. They may have to be loosened hose and bled out. Or better, change cylinder with wings on the ground…

Eric, it’s coming slow. I’m going to PM you a file on Pumps for review.

Here is a good site for farm machinery discussion. Also many other BB back at the home page, this one is machinery.
http://talk.newagtalk.com/forums/forum-view.asp?fid=2


kcj

 

[cabinman]

Got it

Couple previous posters got it:

As the cylinder strokes out (or in), most of the air is pushed out but not all if the ports are sideways. Let’s say it has cycled, but the closed end has that cubic inch of air above the ports when totally retracted. The next time it extends and hits a load and builds pressure, that bit of air, even only a cubic inch, then compresses basically full of oil (to maybe .01 cubic inch compressed 100 to 1 or so) to say 2500 psi. Then when the valve is shifted to retract, the oil pressure immediately drops and starts back through the filter from the pump, Before anything even moves, this little bubble at 2500 psi expands back to one inch at 20 or 50 or whatever psi. Acts like a spud gun in a way-sends one cubic inch into return and filter. Doesn't sound like much, but 1 cubic inch in a few milliseconds is mega gpm. Since flow creates pressure drop, the line pressure sees a spike faster than a gauge can see, but blows the can.

That was my original theory, thinking he put the valve into retract and it blew. OP said pulled to neutral but not yet to retract. Thus, this trapped bubble is in the cylinder (valve is blocked center, at least I assume so?) and the pressure doesn’t blip to the filter yet. Hence my later theory that the compressed oil/air that is relieved of pressure and can expand to send the surge would have to be in the line before the valve. The oil moves through a second after pump starts and air in the hose would have been gone long before. The only way I can envision a continuous supply of compressible air/oil is if there is a suction hose leak, a pump shaft seal leak, low oil level, or extremely aerated oil in the tank. This is a likely culprit, if there was a lot of trapped air stirring things up and still entrained in the oil in the tank.

I have seen a 4 foot x 5 foot tank lid, with 200 lbs of air filters and fans for other stuff, blow off over 75 feet into the weeds at a startup. Hydraulic fluid trapped in one corner couldn’t get away fast enough, it pressured the lid, bolts tore, the resulting snapping steel bolts ignited the seriously aerated fluid and boom. No one hurt, increased WalMart sales for new underwear.

Usually air at startup is harmless. If this was one of those normal weird startup issues, especially with aerated oil as the culprit, no more worries. You needed the bigger return lines anyway, good change. I would still check the tank oil for aeration, and all suction connections just to be sure it was a one time thing.

Air in a cylinder with resistance load, always pushing or pulling, is safe and will purge out. A cylinder that goes past center, from pushing to pulling, can be very dangerous at first startup if not properly purged. The push side fills with oil, slowly, as the valve is metering the oil INTO the cylinder. The other side is still full of air. When the load goes past center, if the cylinder far side is full of oil, it is controlled by the valve restricting flow OUT of the far side. If that side is full of air, when it starts to overrun, the spool can be totally closed and the cylinder won’t stop. It just compresses the air in the cylinder and hoses and keeps going with the load.

Eric-farm machinery: fold up wings on a disc or chisel. The wings are folded up, past center, and tend to fall to the inside when stowed for travel. Usually a toggle linkage and cylinder pushes them out (a resistive load) until it goes past center at straight up, and turns into an overrunning load. Control on the way down is from metering OUT of the cylinder not in. If full of air, no control, throws that puppy down so fast the earth shakes. Or so I’ve heard…. Even cycling back and forth a few inches before it goes past center won’t properly purge air in that situation. They may have to be loosened hose and bled out. Or better, change cylinder with wings on the ground…

Eric, it’s coming slow. I’m going to PM you a file on Pumps for review.

Here is a good site for farm machinery discussion. Also many other BB back at the home page, this one is machinery.
http://talk.newagtalk.com/forums/forum-view.asp?fid=2


kcj

Kevin I understand the theriory, and, compressed air, my question is, are you saying after 15 minites of opperating a two way hydraulic system there is still air in the system,? Its easy to understand not getting (all) the air out when your bleeding the brakes on your truck, I looked around the yard at cylinders on our tillage tools, and most have the ports on the side of the cylinder, I guess Ill have to except that there is air in the system, But have never got that accumulator or spongy feeling after a few full strokes, Thanks Eric

 

[cmetalbend]

Damn this thread got long winded. Air in my hydralic system is really about the last thing I worry about. Not that it isn't a problem. But I agree with kevinj and gordie. Do not put a filter on the suction side. A pump that runs dry in the severe cold due to oil thickness will burn your wallot and the pump.

 

[timbrjackrussel]

It's not rocket science

Damn this thread got long winded. Air in my hydralic system is really about the last thing I worry about. Not that it isn't a problem. But I agree with kevinj and gordie. Do not put a filter on the suction side. A pump that runs dry in the severe cold due to oil thickness will burn your wallot and the pump.

Suction strainers have a by-pass on them so cavitation doesn't happen. If the strainer is vertically mounted the crap will plug only part of the screen and will be cleaned off of the screen at MAINTENANCE time.

 

[user 19670]

Suction strainers have a by-pass on them so cavitation doesn't happen. If the strainer is vertically mounted the crap will plug only part of the screen and will be cleaned off of the screen at MAINTENANCE time.

Some do and some don't so you have to be careful of what you are buying.

In line filter heads, however have a built-in bypass that opens typically at 25 psi which is about 10 psi MORE than you can generate from suction (in a perfect system and we don't have a perfect world). When mounted in the suction line they can plug and starve the pump ($bucks.xx a plenty).

 

[turnkey4099]

Suction strainers have a by-pass on them so cavitation doesn't happen. If the strainer is vertically mounted the crap will plug only part of the screen and will be cleaned off of the screen at MAINTENANCE time.

So you fire it up, suction opens the bypass....why have a strainer on there at all?

I want no restriction of any kind between my oil supply and the pump...well a screen strainer to keep gravel out

Harry K

 

[timbrjackrussel]

So you fire it up, suction opens the bypass....why have a strainer on there at all?

I want no restriction of any kind between my oil supply and the pump...well a screen strainer to keep gravel out

Harry K

Originally Posted by timbrjackrussel
My suction strainer has a by-pass on it so cavitation doesn't happen. If the strainer is vertically mounted the crap will plug only part of the screen and will be cleaned off of the screen at MAINTENANCE time.
My suction screen strainer,125 square inches of #100 mesh stainless steel wire cloth rated at 25GPM is mounted at a 45 degree angle upwards at the shoulder of an inverted propane tank used as a reservoir. I use ATF fluid that is still thin even in very cold temps. The tank crap is drained out at maintenance time and a new return line filter put on. The suction screen sits up high enough not to be in any crap. A magnetic plug is also on the tank. The pump is a 2 stage 16GPM. If the oil was very very thick and cold say # 30 weight and the pump was started at full flow 16GPM and the screen was partially plugged the suction by-pass sitting on the top end of the suction screen up off of the tank bottom would open letting a good flow until the oil warmed and a flow through the partially plugged suction screen could start. Keep the tank clean, use the proper weight oil for the right temp. The reason the return filter ruptured was because of hose restriction from the filter base output to the tank and perhaps a heavier cold oil. Take a look at my pictures of a clean unobstructed 1 inch line from the intake screen to the pump intake,tank oil level always above the pump.The output from the return filter base is also short and direct to the tank. This system has worked great for 15 years.

 

[user 19670]

So you fire it up, suction opens the bypass....why have a strainer on there at all?

I want no restriction of any kind between my oil supply and the pump...well a screen strainer to keep gravel out

Harry K

Ideally, the bypass opens after the strainer is clogged. I know it sounds redundant but redundancy is what keeps industrial hydraulic systems working long after a redneck system fails. They just might be doing something right.
As an aside, we had a filter blow out on an excavator here this winter and we had to work on it in the - temps. Just couldn't believe how solid the hydraulic oil was. Couldn't get it through my funnel at all. No wonder it takes so long to warm up the hydraulics before you can work.

 

[skid row]

Hi all, great site. This is my first post. I have had a splitter filter rupture also. It was a 10 micron cross brand filter and cross filter head. Just recently I brought the home made splitter into the garage for a log lift upgrade and after removing the low pressure side black iron pipe fittings I found that the bypass valve had failed and became lodged in the 90 elbow.

I would of never found this failure had I not removed this section of the hydraulics. The splitter has 245 hours on it since built 8 years ago. I use the splitter in the 90*+ days of summer, as well as in the single digits temps of winter.

My .02 worth of how mine failed. To heavy hydro oil, cold temps, possibly to high of engine RPM at cold start up.( everyone including my brother BORROWS it)

My remedy: 1 Replace the destroyed filter head with a parker brand higher flow head and just bush the 1" ports to 3/4" and a 10 micron filter.

2 Purchase a magnetic block heater from TSC and place it on the hydraulic tank a couple hours before splitting in very cold temps.

3 Relocate the filter farther downstream but still above the tank fluid level.

 

[michigander]

Skidrow, Nice first post. Welcome to the site. Just by coincidence my filter that blew was a Cross 25 micron and I would guess a cross filter head. Can you see the bypass in the outlet side of the filter head? I will check it. The TSC website says the bypass opens at 15psi and the filter is rated to 200psi. Mine blew, dont know how much it endured for a split second. Where did you get your Parker filter head at? I will look into the magnetic heater too. I didn't know they made them. I used 10w-20 hydraulic. I will be doing a lot of splitting in summer too. Thanks for posting!

 

[ray benson]

Some 10 micron hydraulic filters have a bypass in the filter at least one I am aware of does not. Do the filter blocks also have a bypass?

 

[skid row]

Its a straight thru shot now in the filter head, the pin and plastic valve that were wedges in the ell are in the background. I dont know if the 10m filter has a bypass.

 

[skid row]

Yea, all the splitter filter blocks I have seen have a bypass valve. The new one I ordered is 100psi, 30 gal/min, 25lb bypass valve setting.

 

[user 19670]

The filter head on the excavator that was working at our place didn't have a bypass valve in place. Can't say why, as this is not the original owner. Anyway, might as well have a piece of pipe in there as there is now no incentive for the oil to pass through the filter. The owner is unmoved by my explanation (sigh) so he changed the filters and left the filter head as is. That oil is never filtered!

Oh well, the customer is always right and he is a good friend and I want it to stay that way so I'm not arguing with him. :deadhorse:

 

[timbrjackrussel]

Pump intake hose 1"

So you fire it up, suction opens the bypass....why have a strainer on there at all?

I want no restriction of any kind between my oil supply and the pump...well a screen strainer to keep gravel out

Harry K

Straight into pump few restrictions

 

[mga]

hey man, is that the gas tank sitting on top of the engine?

 

[user 19670]

opcorn:

 

[timbrjackrussel]

G400 Honda Engine

hey man, is that the gas tank sitting on top of the engine?

G400 Honda 406cc 10 HP Starts first pull every time!!!

http://www.honda-engines.com/Engines_owners_manuals/ownersmanuals/g400.htm