Paul Heney: My name is Paul Heney, and I’m the vice president, editorial director for Fluid Power World. A little background on me, I have a mechanical engineering degree from Georgia Tech, and I’ve been covering the engineering and manufacturing world for more than 20 years. I’m pleased to be your moderator today.
I’d like to take this opportunity to thank our presenter for being here today, and to introduce him. Josh Harrison is a technical customer service representative for FluiDyne Fluid Power. With more than 15 years in the industry, John has the knowledge to assist customers through complex situations. He’s an expert in start-up and commissioning, and he’s very involved with the company’s returned goods authorization process; and is the primary contact for warranty reviews.
Now without further ado, I’m going to hand the mic over to Josh.
John Harrison: Hi everybody, this is John. We’re going to go through some of the specs of contamination on your pumps and valves, and your hydraulic products. First off, we’re going to go over some of the types of contamination, especially the ones that we see most of when they come in here. We go through and evaluate them.
There’s a number of different types. You got built-in, mainly at start-up or at the beginning of commissioning of hydraulic systems and pumps, values. Then you have ingressed, which is a lot of the environmental stuff that will try and get in to your parts and products. We don’t see a whole lot of that, and the same thing with water. They are types of contamination that will definitely degrade and destroy your product, but mainly what we see is the internally generated from worn parts and a lot of the stuff that’s been in the system kind of floating around and continues to because of not keeping your system up-to-date with cleanliness, and filter changes, and oil changes, and complete cleaning.
The first one we’re going to go on is built-in contamination. Again, these are all contaminants that are … in the hydraulic system during it’s build stage. Those are left behind after everything has already been kind of assembled and put together, which would include the burrs, chips, remaining dirt, cloth fibers from whatever wiping out the reservoirs and tanks, just trying to clean stuff off that are just kind of left behind.
Some of the stuff is oxidation. It will accumulate inside your tanks and reservoir after sitting for a while when you’re getting all your components and everything together, try and get your system pieced together, and up and running. A lot of those would probably be washed out and cleaned, and you won’t see a whole lot of that; but those will run through the pumps and your filters once you start getting your system going and moving through your valves. You might see some basic little scoring and some wear, but usually when you’re starting to get your system up and running, apart from any real catastrophic failures, this built-in contamination I wouldn’t really think should play a large role in any kind of internal damage to any of your pumps or valves, cylinders, motors, or anything like that.
Next is the ingressed contamination. That’s a lot of the environmental stuff. Now, that … after your system’s been in place and running, the picture there obviously shows a fairly kind of dirty system. That’s common. When you’re servicing parts on that, a lot of times the area’s not the cleanest; especially out in mobile hydraulics, when you’re out servicing it in the field. It’s not always the cleanest environment, but if you’re not careful, when you pull out the hose or disconnect something and then just let it hang there. It touches the ground, it starts scraping in dirt. Then, you just put it all back together and start running your system; all that stuff picked up starts running through your system. Depending on where it’s at, if it’s kind of on the other side of your pump, then it may already have passed through and back into your reservoir through some filters, and kind of cleaned some of that out.
Another way some of that environmental contamination will get in your system obviously is from worn seals, on cylinders, and on pumps. A lot of the dirt and stuff gathers up on the front of them and will start chewing them up, and start wearing them out. After a certain amount of time, the stuff sets on your cylinders and retracts back in, and starts pulling in that dirt into the system, and starts passing through. There won’t be a large pieces of it, but it will be enough to start to accumulate if it’s working its way through a system; and score up some cylinder rods and motors, and internal parts on the pump.
Another small thing is your breather quality. If that’s not … If it’s plugged or if it’s not of good quality, that will start to pull in a lot of dirt, and soot, and ash; just from the system running and the oil level inside the tank, when the cylinders expand and retract. Going low and raising up, and pulling in air from outside. The breather quality, it’s a small thing but it’s really something to make sure that it’s changed and cleaned out; just so you don’t get a whole bunch of the surrounding environmental dirt, soot, and everything else getting inside the tank and then sitting down there in the bottom and start washing around the system.
That, I don’t see a whole lot of that when we’re going through the pumps, and valves, and motors, and checking out what kind of damage is in there. It is something you always want to look out for if you are inspecting your pumps in your product, and you’re absolutely sure that there’s no other fault. You might want to check around the area and make sure that you’re not getting anything inside the tank.
Now the internally and externally generated. This one, the cavitation, aeration, abrasion, and parts failure; that’s more of commonly what we see. Especially the abrasion part of it, which we’ll get to. The cavitation one first is a restriction on your inlet, which obviously is creating more a vacuum. The pump’s trying to pull in more oil than what your line is able supply, and it creates an inlet vacuum. What it does is create the vapor bubbles in there, and they explode and start to pit your parts up; especially on the plates. You’ll start to see just some pitting in there, even if it’s real light. It’s still a sign you’re either getting cavitation or aeration in there, even if you think you have everything tightened up.
Let’s say you have an old pump and you replace it with a new one. After a short period, you noticed it’s not sounding right so you take it apart. You’re starting to see some of this pitting in there. That can be a sign that there’s something restricting your inlet and you’re going to want to check that, either a suction strainer, or even your suction line; maybe there’s some build-up in there. You got to clean it out or rinse it out. That’s a common one.
Piston pumps, if there’s any kind of restriction on your inlet, you’re going to notice the cavitation on your plates and on the bottom of your cylinder block. Your piston heads, too, those are going to start to get sloppy. We see quite a bit of that. We get piston pumps in here, they may have, like I said, an old pump on their system and replace it with a new one. Well, the new one is running at a much better efficiency than the old one. The old one may have been sloppy and now the new one is really trying to overwork the system. It’s trying to pull oil in, and it’s just not able to keep up, so the new one starts to lose efficiency and fail rather quickly if everything’s not cleaned out.
The next one there is aeration. It’s fairly the same as the cavitation. It’s just air in the system, obviously. Pictures here kind of shows pitting, and then on the camera, you’ll see wash boarding, a lot of ripples and stuff in your cam ring. The piston heads, those will start to get rounded and some of them will start to smear because there’s air in between your lubricating film, between your piston head and your swashplate. That will start to wear those parts out fairly quick, especially if you’re … You got a hard bite system, and you have to remove a lot of the piping to exchange the pump. You put it in there and it seems like everything’s running fine, but then you notice something sounds a little off.
Really, a good way to check if you do hear something kind of aerating or … cavitating and rattling, grease to put around all your connections, and your inlet connections. That’s a really good way to verify that everything is tight and it’s not pulling air in through any of those connections if you do service your pumps, and have to remove some of your plumbing off there. Aeration, that’s a really big one that we see coming in here and evaluating the pumps, and the valves; especially the vein and piston pumps. Those will … They can tear it up fairly quick. That one’s really something to look out for, like I said, when you’re switching over stuff and removing pipe, and plumbing, putting them back together. Sealing it up is key.
The abrasion, really major one. These are all the solid particles obviously that can pass through the system that aren’t caught in your filtration systems. These really start scoring up, even the smallest silt-type particles will go in and act like … almost like a lapping compound, and continue to wear away your parts down to the point where your efficiency starts dropping off. … It might start heating up. We’ve seem them … build up fairly, fairly … The amount of wear on a lot of the stuff we get in, where they’re still operating; maybe not at the best efficiency. The customer just keeps running it because they have to get some jobs done.
The abrasion particles, really the biggest type of damage to all our hydraulic parts. You’ll see a lot of scoring, grooves. Now, a lot of the parts are … have a certain hardness … hardness on them in coating, to kind of withstand some of those particles; but once they start passing through the system, obviously there’s nothing you’re going to be able to do to stop them from damaging your hydraulic components.
The vane pumps are usually … They’re pretty good about passing larger particles, same thing with the gear pumps. The piston pumps, not so much. They do have a larger cavities inside the cylinder bores for the pistons, but the tolerances between that system and that bore are fairly tight. Once they start getting in between there, they’re really going to start to score it up and eat away at the parts to the point where your efficiency is just going to start to drop.
The abrasion, that’s really where we see the largest type of failures on the pumps. That can come from … Even if you have a filtration system on the outlet of your pump, a high pressure filter setup, your tank is still going to hold a lot of the contaminants that are going to be passing through your pump. If you do change your oil with a pump change, and you don’t open a tank out and clean a tank, or have any kind of … suction strainers, or anything like that before you pump, you’re really asking for a premature failure on any kind of replacement pumps you’re going to be putting into service. The abrasion, like I said, is really one of the biggest things that we see as far as failures in the hydraulic products; pumps, and motors, and the gear pumps.
The part failures, another big one. Obviously because you’re just going to get large pieces running through your system. Once the pump just catastrophically fails, it’s a lot of downtime and a lot of cleaning, and a lot of filter changes, and oil changes, and everything else. Usually by the time you realize that your pump is completely failed, or just broken apart, a lot of those pieces have already passed through your system and you may not have realized it, and plugged up some of your filters to where they bypassed; and those larger particles are now moving downstream through your valving and your cylinders.
The part failure is fairly obvious. A lot of times, it can be avoided. Some of the vane series, like the quiet, the SV vane type, those are very prone to being very delicate as far as set-up and getting them into service. You don’t align them correctly because they have the … more of a journal type of bearing, and a heavy duty roller bearing, or paper roller bearings, or ball bearing. If they’re not aligned properly, those will wipe out fairly quick. You could run the shaft into the plates, and it will run for a short time but you’re starting to grind away metal on the plate and on the rotor, and that starts passing through your system. Then, it starts heating up and breaking down your oil, and moving all those contaminants through your system.
The part failure is really … it’s a big major one. If you’re going to try and keep your system clean, and make sure that when you replace your pump and your other products, that you remove everything from your system and get all those large pieces out of there; if they haven’t already moved through your valving and everything else, and causing your valve to stick in place and not shift properly. That’s a really big one there … is part failure. …
Water and moisture contamination, obviously it’s going to get in your system, especially depending if you’re … the environment you’re in. If you’re in more of a humid environment, then you’re going to get a lot of moisture buildup. We don’t see a lot of that, but it’s obviously a concern. The moisture will definitely reduce the viscosity of the oil, or mixing two different types of oil by accident. That’s going to definitely mix up the viscosity of the oil, and could detrimentally damage the hydraulic pump’s components, seals; if you mix them by accident.
An easy way to tell if the oil is contaminated with any kind of moisture is it starts to get cloudy. That’s … fairly obvious once you see it start turning milky and white, then you have a moisture problem. Any kind of washing down or anything like that. If you do have old seals, especially on mobile equipment. When people try and wash it down and you have old seals on your cylinders and motors, and you’re power washing it. You always run the risk of trying to get … of getting moisture inside your system, whether you think it is or not, and moving through. Some of it may dissipate as your system is running, but if you have a lot of frequent cleaning and stuff, you really want to be careful on … to make sure that your seals aren’t damaged or old.
You’ll notice the sludge build up; just like with your motor oil and you see it mix with any kind of water. It’s like the same thing. It just kind of gets cloudy and turns into a milky white substance. While obviously moisture is a big concern and that you have additives, and stuff you can do, to put in your oil to try and deter any kind of water or moisture buildup. It’s always a concern. You want to be careful to make sure that you’re able to clean that up and keep it out of your system. Breathers are a good thing.
Like I mentioned earlier, if you have an older breather and you’re not paying attention. It’s going to pull in the surrounding atmosphere. If there’s moisture in there, it will constantly pull that in and let it build up in your system. Will it build up quickly? Probably not, but it still runs a risk of contaminating your system with moisture. That’s a big one. Your pumps and stuff will run a little bit of moisture in there, but probably not for long. You’ll notice some internal rusting.
We had a couple of them come in and the housings were just rusted inside. It didn’t look like there was a lot of moisture in there, but after speaking with a customer and the location, and what they were using it for, we were able to tell that they did have a moisture problem. It was getting in the oil, and thinning it out, and reducing the viscosity of the oil … and also starting to rust up the inside of the piston pump housings a little bit, and getting some oxidation in there.
While it’s not a major thing, like I said, depending on your environment and where you’re at, it’s always something to kind of think about and just keep in your mind that it will contaminate your system; whether you really think it will or not.
Really, we’re just kind of looking right here at what everybody thinks their … I know they’ve had … you guys have had pumps fail, and you’ve had them evaluated or had to check them to find out what the cause of failure is. We’re just kind of looking here at what everybody thinks their most common types of failure are so that we can get some feedback and everybody else can kind of see what they think it is. From what we see, it’s mostly of the particle, and air, and cavitation. Mostly internal, but we’re just curious to see what everybody else kind of thinks of what their types of failure are.
It’s key to figure out what type of failure, obviously, so you can pinpoint the problem and resolve it. You really want to get down to the bottom of what causes failure, even if it starts as aeration and maybe it turns into … just complete product failure. Well, is it the oil? Is it your connections? It turns into a very lengthy process, sometimes; and really just getting an idea on maybe what some other people have found what their failures are will help you pinpoint and give you a better idea on how to stop it. …
I guess we’ll move on to the next one. … All right, so yeah, we got some good feedback on it. I’m guessing the ingressed and the built-in, a lot of people have seen that … from … Must be a lot of people seeing that from mobile applications or systems that have obviously been in service for decades, and not the most favorable type of environments. We can’t all be in a completely clean doctor office type of environment, so it’s understandable. Again, this helps out with what other people are seeing as far as their … what causes their types of failures on their pumps. The internally generated, that’s one of the biggest ones. Like I said, that’s what we see. Nothing in water, huh? That’s good. I’m glad nobody’s got to deal with any water in their system. That’s really good. …
Usually what you want to do, and everybody kind of knows this, but you always want to take your system down and clean it. Either have a kidney loop hooked up so you can at least clean your oil. They say the favorable place to put a filter on your system is on the outlet side; a pressure filter so it can catch 80% of your contaminants, or 90% of your contaminants that come out of your pump in case something goes catastrophically fail on your pumps. Really, that’s like flooding your system; to keep it going.
Even those that don’t have a high pressure filtration system on their outlet, a kidney loop or a filter cart, depending on how big your reservoir and your tanks are, it’s a really good idea that’s not real expensive. It’s good to have because at least you can run it in, in the tank and reservoir, kind of filter that oil, and then run your system a little bit, filter the oil again. The kidney loop system, usually you can run that while your system is running. You always want to try and have your system go down. At least plan it so you can clean your tank, because a lot of times, everybody will take their hoses off, clean their hoses.
They’ll change their filters, clean the bowls in the filter, clean everything else, but they leave their tank closed up. They just drain the oil and then put new oil in. When you’re always getting sediment and metal, and all kinds of material, and fabrics, and everything else accumulating in your oil through your breather and through filling it, and other oil. It always accumulates in there, and it starts to settle in the tank. If you don’t clean your tank out but you clean everything else, you’re just eventually asking for some issues down the road. Maybe not right away, but eventually it’s going to catch up and it’s going to pull it in and start running through your pumps, … and actuators, and everything else.
Cleaning your tank and I’m sure a lot of the tanks are just way too large to kind of take apart and clean. If you can’t get in there, you can’t get in there. If you are able to get into your tank and clean that out, even on mobile applications, draining the oil, and putting some kind of kidney loop or filter cart in there, rinsing it out and cleaning it always, always a great idea to help prolong the life of your system, and all your components. That just kind of goes without saying, you always want to try and keep your reservoir and your tank clean from sediment and stuff setting down in there.
Taking a break from production isn’t always easy, but sometimes it’s necessary; unless you want to deal with long downtown to have to clean everything out once it does catastrophically fail and just kind of shut down your whole line. …
Early signs, those are for who are familiar with the hydraulic pumps and actuators, and motors, and everything else. When things are running hot, obviously that’s a sure sale sign that something’s running … going to run wrong and fail. Noise, unusual noise, big key. If you’re … Always get familiar with your system, and what it sounds like, temperature, looks. You’re always going to notice something or walk by it a few times. Just get familiar with how it sounds.
One time you might walk by it and hear something odd, and it could be the pump, it could be a cylinder, it could be a clamp. It could be a line shaking, or a cylinder, or a valve shuttering from turbulence or something. Always listen to your system, whether it’s new or old, and get familiar with what it sounds like so you can always tell if something’s starting to go wrong, or you think it’s going to go wrong. Now obviously, slow operation, once your pumps and everything, and products, start to lose efficiency, they’re going to start to slow down. That kind of goes back to internal contamination.
When your system starts to slow down, obviously your pump’s losing efficiency. When you put a new pump in, your new pump may start to cavitate because your old pump isn’t trying to pull in as much oil. You put a new pump in and it sounds loud and starts cavitating, and you’re wondering why. That’s from all the internal contamination either building up maybe in the line, maybe in a suction strainer that you have, or a suction filter; or in the actual suction inlet line, depending on how long it is and where it’s located. Slow operation, obviously that’s another indicator that you’re going to have some damage going on inside your pumps.