[The following is a lightly edited transcript from the webinar, “Hydraulic hose 101,” with presenter Josh Cosford.]
Paul Heney: Thank you, everyone, for attending today’s webinar, Hydraulic Hose 101, brought to you by Intertraco, Stauff, The Fluid Power Technology Conference, and Fluid Power World Magazine.
My name is Paul Heney, and I’m the VP 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 here today. I would like to take the opportunity to thank our presenter for being here today and to introduce him. I’m sure a lot of you have heard him before. Josh Cosford, he’s a long-time contributing editor to Fluid Power World and he is definitely a reader favorite. Josh studied fluid power at Mohawk College in Hamilton, Ontario where he currently resides. He has more than a decade of experience with fluid power systems and he has held the Certified Fluid Power Hydraulic Specialist designation from the Fluid Power site since 2009. And lastly, I’ll mention the Fluid Power Conference we mentioned a minute ago, he will be one of our speakers. So if you’ll be in Milwaukee next May, you’ll get to meet Josh in person and I’m sure he will autograph a copy of the magazine for you. So without further ado, let me hand the mic over to Josh.
Josh Cosford: Thank you so much, Paul. It’s great to be back behind the mic with you. Like Paul mentioned, I’ll be at the Fluid Power Technology Conference and funny enough, I’m actually doing a presentation on troubleshooting hydraulic hose. So I cover that a little bit in this webinar, but mostly this is gonna be more of a 101 type thing. So it’s gonna be the basic of hydraulic hose and thanks for the introduction and I guess we’ll get right to it.
So Hydraulic Hose 101. So obviously hydraulic hoses exist on nearly every hydraulic machine. Hose is often overlooked, but it’s critical to the function and longevity of every machine. This webinar provides you with the essentials of hose construction, application considerations and hose assembly tips. So we can understand hydraulic hose by understanding how it’s applied and how it’s assembled. So new hydraulic hose assembly should be chosen with consideration to their specific application. For example, a STAMPED method is the go-to standard. And I’ll go over that. It’s an acronym. S-T-A-M-P-E-D. Each one of those stands for something. S for Size, T for Temperature, Application, Material, Pressure, Ends, and then Delivery.
Starting with size, so this is probably the most critical of the factors when it comes to choosing your hydraulic hose. If you don’t get this right, so much can go wrong in your hydraulic system. So for example, long length lead to increased energy required to move fluid. So if you have an undersized hose, you’re spending more energy trying to push fluid through the hose than you are energy moving your load. So hydraulic systems move loads through force that has to be transmitted through that hose. So if you need to conserve energy moving fluid, so you have the least amount of pressure drop possible, that allows most of that energy to be used to move your load.
So for example, if you have 20 gpm flowing through a half inch hose, and let’s say that half inch hose was about 20 feet long, if that’s on your work lines, that’s 20 feet going out to your actuator and 20 feet coming back to your actuator. Each one of those directions is about 170 psi of pressure drop just from moving the fluid. So you’re losing about 350 psi and that energy is wasted as pure heat. It provides no function to your hydraulic system whatsoever. And so you gotta imagine, 350 psi. If you’re running a 2,000 psi system, you all of a sudden, with a four inch bore cylinder for example, you’re losing a good 300 pounds plus. Actually, 3,000 pounds plus of force, just lost to pressure drop. So make sure size is always sized appropriately.
We talk about the size of a hose, we’re talking about the ID, and that’s what I mean by sizing it appropriately. A half inch hose means half inch internal diameter. But size also includes the external diameter, so the OD, and also the length. So all three of those factors play into what kind of hose you choose. So thicker hoses with higher pressure capacity, like a six wire spiral hose is gonna have larger OD to stack up all those layers. But when it comes to sizing, start with the ID and size all your hose based on flow, and make sure you do it based on the length of that hose, because a one foot hose where you might have borderline on your ID size could not be effective by pressure droppage you’ve got 20 plus feet.
Size, just as I mentioned, so hose must be sized appropriately to handle to flow with little pressure drop. So size also matters for length, not just for pressure drop considerations, but for accurately sizing it to fit in the spaces that are allowed on the machine. So this picture shows overall hose length assembly, and when we measure overall length, the length we’re talking about is from fitting the fitting of the males that would be going into this hose. So for example, on either end, we have some JSC swivels. One’s on a 45, one’s on a straight. It’s not from tip to tip of the hose. That’s less important because that nut that swivels on the end can be give or take length. It’s where the face and the seat of the GIC coupler will meet each other and that’s smack dab in the middle. So overall hose length includes the hose, and it includes the cutoff factor, as well as the length of the hose as well. I’ll get to the cutoff factor in a minute.
The cutoff length is subtracted to obtain hose cut length. So for example, you can see this one where on the left hand side, you have GIC fitting, but on the right hand side it’s NPT. So measuring from the NPT, it’s right to the tip of the fitting. But like I was saying of the GIC, that’s gonna be measured right to the face of the GIC male. And so the cutoff length is the difference between where the hose is cut and the extra length that is required for those fittings. So if you go for the Intertraco catalog, it’ll show you what those cutoff lengths are.
Cutoff factor, like I said, is subtracted from the total length of the hose. So if you’re measuring tip to tip, just say you’re gonna be replacing a hose or you’re at your machine and you’re trying to size up for hose length, make sure that you factor that in when you’re asking for a hose assembly and often when you have a new hose assembly, either the manufacturer or your local hose shop will ask you what the overall length is and make sure that you have an understanding of the difference in that. You may have had an old piece of hose laying around saying “Oh, it looks like it’s about three feet. That’s how long the hose is.” And then you find out that your hose ends up being either too long or too short. Either it’s not gonna fit, or you have to have too many bends and kinks in it and those kind of bends can have an effect on the longevity of your hose.
The next step is temperature. So consider how temperature in your hose selections. So two things for temperature. One, what is the temperature of the fluid, because that’s important. The type of hose construction has an inner and outer carcass and the fluid temperature itself has mostly a factor on what the ID rubber material is. And then also with the ambient temperature. So ambient temperature is if you’re in an environment that has sometimes either hot or cold ambient temperature, that’s gonna have an affect on the hose itself and you need to consider those as well.
So a typical hydraulic hose is good for about -40 to about 212 and that’s pretty much industry standard and that’s actually a pretty good range. If you’re getting colder than -40, that’s not a place I wanna be and then as well as 212, once again, that’s not a place I wanna be. But regardless, these are two extremes. But believe it or not, you can get more extreme than these. And I should actually mention that this temperature is the ambient temperature. So if your hydraulic fluid is 212°, it’s getting cooked and oxidized and baked and it’s gonna evaporate shortly, but there are some fluids that can handle that temperature, but there’s no reason to do that because your pump and other components would be failing because viscosity would be so low that it wouldn’t be lubricated properly. So I should mention that’s ambient temperature. So that the ability for the outer carcass to resist that ambient, either in a furnace or in a steel mill, or whatnot.
You can get a high temperature hydraulic hose and it can be good for up to 300° F. Like I said, this is ambient temperature. So the fluid inside should then be cooled or conditioned appropriately to handle the increased temperature that will be radiated inside of it. So if your hose is being run near a coil, like in this example, that is going to be absorbed through the hose, through the carcass and into the fluid itself. And in most of these applications, they have chilling towers and cooling systems in place to cool that fluid as it goes back into the hydraulic system. Those things are typically in place, but in the meantime, you don’t wanna be melting your hose. So the hose has to be constructed appropriately to handle that.
Conversely, there are places where you need to run a very low temperature. So you have forestry and snow grooming equipment. These are all places where temperature extremes are even less. So the hose has to be pliable and flexible. The reason people choose hose over tubing is because it has that flexibility. And it has to stay flexible, especially if it’s in a bending application. So it has to swing through motion of a boom or an arm that requires that kind of flexibility. If the temperature is too cold, especially when the machine just starts up and it hasn’t had time to warm the hydraulic fluid yet, you have to make sure that that hose doesn’t become brittle or hard or can crack or can put fatigue on the connection right at the hose fitting.
Then we must talk about the application itself. So application is where it’s being used and what’s happening. So where it’s being used is gonna have an affect on what type of hose you have and, for example, is it gonna be in a cable track, or is this gonna be run as part of a coolant line and it was just easier for the technician to make a hose rather than a tube? And on top of that, part of the application is understanding what the bend radius is. So the bend radius is defined as the radius, if you bend it, from the center point of a circle of the hose. So in this example, the radius is from the center, and it would stretch half of the diameter from fitting to fitting. Bend radius is important because there are some examples, like I said, in a cable track where hose goes back and forth and that requires a tight bend in it. Other times, hydraulic hose is just used because it’s there to absorb vibration.
And so, for example, I’ve done applications where there was a kidney loop on a gear pump and in this particular application, there was something about the housing on the cooler and the tubing that we used. It was just making this really annoying harmonica vibration, being transmitted from the gear pump. So we tried moving the components, we tried mounting the pump in the tank. And what ended up working to kind of dampen that noise was we switched a bunch of the tubing to hose. So the hose has an inherent flexibility and because of the rubber design, allows it to absorb some sounds. So in this example, this was a machine that was going into a place where the operators were near the machine and the sound was just so chilling and grinding on anybody’s ears, it would have been unacceptable for this application. So switching to hose actually allowed it to absorb some vibration and take away some of the noise that was being transmitted through the solid tube.
So another factor is what are the external conditions. So when you’re talking about application, it’s not just about either sound or bend radius. Is there a chance of abrasion? Is this going in an application where you know it might be rubbing on something? So do you have to use a thicker carcass on the outer cover? Or do you have to use some hose with protective wrap with the application? Is it gonna be in an abrasive environment, like dusty environments? Is it going to be in a corrosive environment? So you might have some machinery that are used for material handling in a plating or coating or chemical factory and the braiding that’s inside of it … So even though the hoses are generally pressure resistant from the inside out, the outer carcass doesn’t always lock out all moisture. So sometimes you can have the wire braiding that’s between the outer cover can start to rust or corrode and that leads it to failures itself. So considerations from external factors like that are important when it comes to application.
Another one is electrical conductivity. Obviously a hydraulic hose with steel braids in it is going to be able to conduct electricity. Oil itself is not the most amazing conductor, but when you have steel fitting attached to steel braided hose that are running the length of an entire machine, you can see that this man lift application in the image here where the guys are working on electrical power supplies and lines and transformers and whatnot, that there’s a lot of potential for that to be grounded and to send shocks through the machinery and down to the person on or near the truck. So you can get hydraulic hoses that are made with synthetic braiding materials that prevent electricity from being conducted through the hose. Obviously, in applications like this, in some jurisdictions it’s actually a law that requires that.
Next up is the material. So the material construction of the hose itself and that can be defined by the type of fluid being used and this is critical to the application of the hose. So if you are in a situation where standard mineral-based hydraulic fluid, most hydraulic hose with nitrile is gonna be compatible with that. However, when you get some exotic fluids like phosphate esters, although toxicity and nastiness in these kind of fluids is being replaced by synthetic flame resistant fluids, but still, it’s still out there and it requires synthetic materials like EDPM that are able to handle that fluid without just kind of turning to gel and softening and becoming useless over time. So it’s kind of like the equivalent of … I’ve never seen viton used on a hydraulic hose, like it’s used in overhangs and fittings and stuff like that, but there are things you can get. There are Teflon-based and that does have an affect on things like bend radius and other application details. So make sure that you check the catalog, check with your supplier, and work with them and make sure they understand what it is you’re using, what your fluid is and that you have the material data sheets and information on that, so you know what all your fluid compatibilities are.
And pressure. Next to size, pressure is really … It’s the defining criteria for hydraulic hose. So if you know your hydraulic pressure, you have to make sure that your hydraulic hose is suited to match that well. And the pressure that you need a hydraulic system to operate at, it also dictates its construction. So there are a couple things that you should know about hydraulic hose. One is that a smaller hose inherently can handle higher pressure. And that just has to do with the ratio of surface area to diameter. As it gets bigger, there’s more surface area in the ID for fluid to push upon, almost like having a larger cylinder. Larger cylinders require a larger wall of tubing. So you might be able to get away with 3/8 tubing on a four inch bore cylinder, but then eight inch bore and higher, like 12 inch bore cylinder might require half inch wall tubing. That’s just the nature of the force being applied against a larger area.
So because construction dictates the pressure capacity of hydraulic hoses, there are various types of hose construction you can get. And the factors with how far you can achieve a high pressure rating has to do with construction type and economics as well. So this pic here, for example, is a basic construction of a hydraulic hose. You have your tube in the center. And like I was saying earlier, most often, that’s being a nitrile type rubber. Then your reinforcement, most often, that’s a steel reinforcement. In this case, it’s braided. You can see that it’s woven together and this is done with some big, fancy weaving machines that do it as the tube is extruded from the extruder. And then the cover that’s applied to it afterwards. So the cover will often dictate the abrasion resistance, the chemical resistance, and often time will have an embossing and details on it that you know what the pressure rating is, what diameters are, if it’s an R1 or 2.
So that last one, we often call it a factitious layering, one wire, two wire. Maybe just say “What kind of hose do you have?” It’s a two wire hose. That used to have a meaning to it because you could say “A two wire hose” would have to take their pressure capacity. But because of the different and exotic hose constructions that are out there, there are some examples where you have a single wire hose that could be good for 5,000 psi and you can get inexpensive two wire hose that can’t handle 1,200. So this is, once again, make sure you collaborate with your hose and fitting supplier to make sure that what you choose is good for your application. So this example, it’s another two wire hose. This is two layers of braiding. You can see you have the tube, a braiding layer, a separating layer, another braid layer, and then the cover. Those are the typical, when you see a two wire … Or one wire, it’s gonna be this type of hose.
Here we have now, spiral wire. So this particular hose has alternating helical spirals that go through the tube, spiral, and then the insulating layers, and then the cover. So this type of wire is very strong, but it’s also very rigid. So because of the nature of this hose, it’s very inflexible. It tends not to have a very good bend radius. So for some of the things we were talking about earlier, unfortunately, you would not be able to choose some hoses like this. Going even more extreme, you see we have spiral wound six wire hose. So this has got a couple of different covers on it. It has no separations between the wires. So obviously this is good for high pressure, but has reduced flexibility. Imagine this is gone on a hose where you’re running hose sections like on an excavator arm or a boom or whatnot that don’t tend to move too much, but require some amount of flexibility or vibration resistance. And you can imagine that the expense of a hose like this compared to that one layer of braided wire we saw earlier can be quite extreme.
When coming to choose your hose application, if you go to Intertraco and download their documentation, you can see these types of documents that have each of the hoses and all their defining characteristics. This particular hose is a heavy duty hose and it’s gonna have some different bits of information on it. So starting with the hose size and you’ve heard people use the dash size, an O8SE fitting or 12GIC. If you’re not already aware, someone decided to be clever and come up with a way of describing a hose without actually using fractions. Any time you see a dash size, it’s just that number over 16. So a -16 is 16 over 16, which means it’s a one inch hose. So a -6 is a 3/8 hose. Any time you see that, you can do that math in your head and figure out exactly what diameter hose it is. And going through the chart here, you can see that, for example, the -10 number is 5 inch nominal ID. Nominal means like an average size because the manufacturing process isn’t gonna give you too much tolerance on the ID of that. And also it’s gonna describe the OD of your hose, and that plays a factor on what kind of fittings you use, or where your hose can fit through in a bulkhead or whatnot.
You can see in this picture example that the -10 hose, even though it’s 5/8 of an inch, the outside of it is over an inch. So there’s a good bit there that’s just being used up for the tube, the braids and the outer cover. And in this hose, you can see something interesting here, is that it shows maximum working pressure. So maximum working pressure is generally defined in the hose industry as being one-quarter of the safety factor. If you look at the next column to the right, it actually shows your minimum burst pressure. So you can see that’s about four times what the maximum working pressure is. What they’re saying is that this hose can run all day long at 6,100 psi. If you have pressure spikes to 12,000 psi to 15,000 psi, these kind of things happen and some occasions you can blow a hose, especially if you choose the wrong one for your application. But this hose was tested and it meets a minimum pressure of 24,400 psi before it will burst. And they say “Okay, we tested this in a lab. This is the pressure it can handle. We’re gonna rate this now or 6,100 psi.”
So in that case, this particular hose is interesting because every single one of its sizes is rated for the same pressure and I would imagine still that the 3/8 hose, the -6, if you were to run that, nine times out of 10 to 3,000 psi, would still handle that pressure, than maybe running the two inch hose to 3,000 psi, it probably would burst sooner. That’s just the nature of science and physics. However, the fact that they rate all these the same size, it’s good quality hose and that they make it easy for you to select any given size based on the flow that you have and not be limited by diameters and having to choose a different kind of hose because you have to run it 4,000 or 5,000, or 6,000 psi.
Also to the right of this one, it shows the minimum bend radius. We talked about that earlier. So if you were to take say that -10 hose once again, it has a bend radius of 4.3 inches. That means if you were to take a length of this hose, about 15 inches, the tightest that you could bend it in a circle is 8.5 inches in a circle, which is actually still pretty good for a hose that is such highly rated for pressure and is also a spiral type hose. Then it’s gonna show you the average weight, and that’s gonna show you, in this case, either kilograms from either or pounds per feet of hose. That’s gonna be a factor of mostly the braiding construction, how many layers of braiding. If it’s braided or spiral bound and how thick that is. And then here, it’s actually, in this picture catalog, it’s gonna be the same thing for Intertraco that is gonna show you what your coupling series that will match up to this particular hose is gonna be. If you’re unsure, download the catalog, pore through it and just get an idea of what’s available for you.
So conversely, that was a heavy duty hose, and if we go to a standard, everyday, off the shelf hose that you might get at a tractor supply store, you might have this kind of single wire braided hose so this particular hose is available in kind of smaller sizes, down to 3/16 of an inch, but what you need to notice is beyond the hose size and nominal hose ID, is that A, how much smaller the OD is based on every given size. So the last -10 hose was over an inch, but this one is only 0.93 inches. And what I need to bring your attention to on this is that there were some pressure ratings. So even this tiny 3/16 hose, which I hardly ever see in any application other than potted lines or test points, is still only good for 3,600 psi working pressure. So this smallest one, which has a size advantage based on physics and construction, is only good for 3,600, but that spiral bound hose was good for 6,100 right across the board.
But going down the chart, you can see the affect a larger ID has on the pressure capacity of a hose. You go down to a two inch hydraulic hose, it’s only good for 580 psi working pressure. To be honest, I don’t know any hydraulic systems that have only been to 580 psi and most times I would actually choose something different than a hose if I needed to flow that much. You can see where the minimum burst pressure. Once again, it’s about four times your working pressure. You gotta imagine on that two inch hose, it’s only rated for 580, it’s not gonna take a lot to get over 2,300 psi and actually burst that hose. So in that case, this would not be a good choice. But looking down to lower sizes, everything down to the -8 and smaller that are rated for 2,300 psi or better, have a look at the bend radius on these. So bend radius is a lot smaller. So it’s more flexible and as well, you can see that it’s a lot lighter. And rather than you guys remember what was there before, I kind of wanted to compare both sizes. So these are the two different kind of hoses, one was spiral bound and one would have been a single wire braided.
The -16 size I decided to pick for both of these. You can have a look at the difference in the hose OD. Not a heck of a huge difference in this case actually. So this one is only 80 difference on the heavier duty hose, but look at the pressure difference. So we’re talking five times the pressure difference of these two hoses, not only what they’re rated for working pressure, but maximum burst pressure. Then once again, on the bend radius. So that’s one inch of bend radius is quite a bit. And so with the heavy duty hose being 6.5 inches and the single braided wire, one wire hose, being good for 5.5, if you’re talking about diameter, that’s two inches smaller of a circle that this thing can bend into.
And then weight. So look at the weights on these. So you can see that the heavy duty spiral hose is twice the weight. And when you get in large diameters, and I’ve done lots of hose assemblies in my day, some of these things can get really bulky and hard to work with. So these weights can be quite a bit when you’re doing some long lengths of hose, not only in handling, because they don’t wanna bend or move very easily, they don’t wanna twist or torque, so the handling of some of these larger hoses can be quite extreme.
Okay. So after you’re done discussing pressure and seeing what kind of hose you need to select on there, you need to find out what kind of ends that you’re gonna have. So the ends available on any hose … And a good thing about a hose assembly, it’s not an off-the-shelf component where you have to pick this hose and it only comes with these fittings. The combinations are infinite. So you need to look at what type of threads you have, and that can be if you’re designing a new machine, you get to choose what types of thread you want. And then if you’re replacing it, you have a lot more questions here. So is it gonna be a male or female thread on the end? Is it gonna have swivels or is it gonna be solid? Is it gonna have straighter elbows? Or do you want permanent or reusable hose ends? So these are kind of selections that are available for a hose. You have banjo bolts, you have metric, you have GIC, O-ring face, SEE flange couplers, 90° GIC, as well as MTP swivel. So the options are infinite. And as you can imagine, in each of these hose types is available with every type of hydraulic hose construction and size.
So reusable fittings, which are also called fuel detachable fittings, are the one type that you can get. The other type are the crimped on fittings, which are permanent. Once they’re crimped on, other than cutting them off, there’s no way of getting them apart. So these reusable hose ends, I’ve spent a lot of time working with these back in my car wash days. So we would have the hose and the brush out in the south wash base, it would break and get a customer wet and I’d have to apologize and pull this whole hose assembly down, rip it apart, cut it off, and you could reuse the exact same fitting that was on it the first time. So in that case, these kind of things are really good, because hose can be expensive and if you don’t have to replace the whole hose, you can get away with this. However, we were only operating a 1,200 psi and it was only water. If one of these hoses breaks, you get sprayed with water rather than oil. And in the case of a car wash bay, there’s nobody up on a load. There’s no human being or safety factor that is considered when it comes to these things.
You don’t want a man lift or a piece of construction equipment that is being used with a reusable hose end. You can emergency backup thing, you need to get it going. But it’s just like the foam spray you use to fill up your tires to get you to the service station. It’s like that. It’ll allow you to get by, but you shouldn’t consider it permanent. But they do have their place. So then crimped ends. So just like we saw in the previous picture, there’s all kinds of crimped end choices you can have. And then, once I said, these are permanent.
So once you have your ends, there are various ways to crimp them on. So this particular crimping machine, it’s got a hand pump on it. So you’re die set that’s attached to a hydraulic pump and you just pump away. You can see that little dial setting, that’s a little micrometer at the bottom where you set your crimp settings into it and you crimp and it will stop at a particular point. Sometimes a light will just come on. It depends on the scope of your machine. One like this that has easily replaceable die sets in it, this one’s electric. And once again, that would set manually. You can see that there’s a dial on there at the base of the black part. But it’s electric and it works a lot faster and a little more powerful too. You’re not gonna be pumping away with your arm all day. The hand pump ones are good because they’re portable and you can bring them onsite to do some work. Obviously, something like this is required to be stationary, use a tabletop.
If you’re super heavy duty, you can get CNC hose crimp machines that are absolutely ginormous. You can see in this example, there’s the cartridges with the die sets that are down below and then some of the larger ones that are in the shelves beside it. Those are the hose that this thing crimp five inch hose. Pretty heavy duty, but also very expensive. Unless you’re crimping hoses for a living, especially purposes in everyday machine, only the high end hose shops have this kind of equipment in it. So pretty typical one is like this. You get your machine. Once you know what kind of ends you’re gonna put onto it, you have to crimp them on, but there’s a particular way to do it.
After you choose your hose fitting and, like I said, you download that in your catalog, you choose the appropriate one, it’ll let you know which ones are available for which hose. Like I said, a six wire spiral hose will not be able to use the same fittings as your one wire braided hose. The carcass and the layers are just too thick and it won’t even fit. And conversely, if you try to use the fittings for a larger hose on a smaller one, it crimps down too much and bunches up and you don’t get a good crimp either. So there are types you use based on the hose. So download the catalog, or talk to your supplier to make sure you choose the right series. And after you read series, like we talked earlier, you have to make sure that you have your cutoff links considered, so that when you cut your hose, it’s the correct length. And after you have that, you have to dial in your crimp settings and your machine.
So depending what hose you’re using, as long as the fittings work for that particular hose, you have to dial in your crimp settings. If you look at the yellow column, the orange column in this picture, you can see what the crimp diameter is. So for any particular hose, it’s gonna give you the fitting size, the range that fits on that, then the crimp diameter. So you see in this example, we’re on the orange where it says crimp diameter, then it says plus or minus tolerance of 8,000 of a inch. So that means, for example, the third one down, you wanna crimp it to 0.728 inches, and you will measure that with a set of digital calipers to make sure that it’s accurate. And 8,000 isn’t a whole lot. So this is what I mean where if you were trying to crimp some oversized braided hose in a fitting that it shouldn’t work on, A, you’re not gonna be able to crimp down as deep as you need to, and it’s gonna cause an unreliable hose crimp to pop off and be very unsafe. So make sure you do it and you have to make sure that’s within an 8,000 range.
Under crimped, it could come off. Over crimp, you can damage the braiding and it also could come off. So having it at that accurate diameter is very important. It also gives you the mark length. So the mark length actually shows on the fitting what that cutoff length is on the hose, so it should actually match up. So when you push that hose in, that dimension that it gives is gonna match up how much that you measure for that cutoff length that we discussed earlier.
So after you measure it and check it, you know you’re good to go. That’s generally how you make a hose assembly. The other need to discuss with your hose supplier and manufacturer is delivery. So that not only means how are they gonna get it to your door, but you need to discuss how many hose assemblies do you need, and when do you need them. Are you a lean company? Do you wanna have 20 hose assemblies a day, every day, or do you like to stock a lot of inventory? You’re just gonna have just 100 sets of assemblies come in and you stock them on the shelf and use them as you need them. How soon do you need them? And then is there any special tag or lay line information?
A lot of hose manufacturers will actually do hose kits for you. So what they will do, just say you have a stone slinger machine and you know that they have 36 different hose at various lengths and sizes, they can actually tag those hoses and tell you where the hoses go on the machine, what the hose is for. They can do special tags attached to the hose, and if you’re ordering enough bulk hose, hose manufacturers can actually give you custom lay line information. So if you’re somebody who likes to have a lot of residual sales and you know you’re doing millions of dollars in hoses, the manufacturer can actually tag your brand and your name onto it, the hose itself. So these kind of things, when you work with your supplier, they’ll often help you out with these things.
What if you are replacing an old hose? A hose failure, it’s not always gonna be in a car wash. It can be on a machine. You need to get back up and running. What is the best thing to do here? So do not try to repair the old hose unless it’s absolutely necessary. Like I said, if you have an old hose that has been on a machine that’s been fatigued, it’s been through pressure cycles and heat cycles, the rubber is hard or brittle or too soft, or there’s abrasion on the outer cover. If it’s a stop gap and it’s a Sunday evening and you just need to get something fixed so you can continue working for the day, I understand that. You can hit your hose shop on Monday. So unless absolutely necessary don’t try to fix old hoses, unless there’s an example, you just had the hose made on a Friday and the people making your hose, they didn’t crimp it properly and the hose popped off and you can bring it back and you can kind of cut the tip off and redo it, you can sacrifice those few inches.
Other than that, if you have an old hose, like I said, try not to have to replace it. Replace the entire assembly. Nine times out of 10, they’re not that expensive and for your safety, for your machine reliability, for protection of the environment of hose having to break and spill oil all over your field or your plant, it’s just not worth it. And if you do replace your hose, make sure you follow the STAMPED protocol. Often, your hose technician or person making your hose will ask you these right questions to make sure that they’re making the right hose for you as well. But if you’re doing it yourself, make sure you go through the STAMPED protocol. But if you bring it into a hose repair shop, they’ll kind of ask you those questions and do that for you.
When you cut your hose, this is whether it’s brand new or whether to use a piece of hose that you need to reassemble, ensure that you’re only cutting it with specialized hose cutting saws. So these saws have a metal blade on them that prevent your hose from being frayed and just generally having the … If you ever try to put a fitting, like a hose crimp fitting on a hose that has frayed wires, it’s also impossible. The hose is kind of frayed like I’m showing in this rope, and it prevents you from … It’s like trying to thread frayed yarn in through a needle. It’s just almost impossible. So using a metal bladed specialized cutoff saw gives you a clean, smooth cut and the material is really easy to fit inside your hose fitting.
Also, make sure that you’re only cutting exactly at 90° across the hose. If you cut on an angle, it won’t go all the way into your fitting and it’s not gonna get the engagement on the teeth of the crimp. So you can have that hose pop off as well, or leak. So make sure you always cut it right at 90°. Most of the hose crimp machines have dies and equipment that force you to cut it at exactly a 90° angle, but some guys might use a cutoff saw or an angle grinder with a cutting wheel on it. If that is absolutely necessary and you’re not prone to fraying your hose, just make sure that’s on a 90° angle. So like I said earlier, once you’re ready, you put your fitting on, you crimp it to the specifications that are spelled out by the hose and fitting manufacturers, measure it, make sure it’s accurate. Like I said, you’re gonna measure it to the dimensions that are given in the manufacturer’s catalog. And then you have your finished hose assemblies.
Last step, when it comes to any kind of hose is that just like brand new hydraulic oil, brand new hoses are not clean. You have to clean that hose assembly. So the cutting procedure, the manufacturing of the hose, the ambient air and the conditions in which it’s made or installed leave a lot of particles, dirt and metal chips, whatever, that are in, on, or around the hose. You need to clean it out before you assemble your machine, especially if you have a high end with proportional valves, you have to make sure that you’re not introducing any particles into that system. Any one of those things can be damaging.
So clean hose assembly and only use approved hose cleaning apparatus. And immediately cap the hose ends to protect it from environmental contamination. So you’ve seen these hose cleaning assemblies. It has a little lid, you put in a pellet, connect up to the airline and you shoot it through the hose. As it goes through the hose, it collects all the debris and the dirt. So for example, if you have a three-quarter inch hose, so a 0.75 inch ID, that’s gonna be a one inch diameter pellet probably that goes through it. The friction of that foam as it goes through cleans all the material out of the hose. Do it both ways through the hose because there could be some direction particles that are trapped in the coarseness of the hose material, and as well as at the ends of the fittings. And then shoot it through the hose. If you’re like me in my days of hose assembly, you shoot the pellets at your friends at work. That’s always fun. They were generally harmless. Hopefully there wasn’t any medical filings or particles stuck to the pellet.
And then after you’re done cleaning it, you cap the hose assembly. So to make sure that between leaving your shop or your place of manufacturer, it doesn’t get contaminated. Sometimes hoses can sit on a shelf for a while and any manufacturing facility or OEM that builds say off highway equipment or whatnot, some of those places can have welding gases and debris and airborne particles that just kind of collect of stuff. So just make sure you cap it so that when the machine is finally assembled that you’re not introducing that into that. And that’s it for Hydraulic Hose 101.
Filed Under: Hose Assembly Tips