This is an unedited version of the webinar: Proper Hose Assembly Guidelines. To watch the presentation in full, click here.
Michelle: Hello, and thank you everyone for coming to today’s webinar Power Hose Assembly Guidelines, brought to you by FluidPower World magazine. Thank you to our sponsors, Lillbacka and Tribute, and a special thanks to our presenter Josh Cosford for being here today. I’m Michelle Difrangia assistant editor for FluidPower World Magazine and … host [inaudible 00:00:29] and I’ll be your moderator today.
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A little bit about our presenter to start. Josh Cosford, contributing editor of FluidPower World, studied fluid power at Mohawk College in Hamilton, Ontario where he currently resides. He has over a decade of experience with fluid power systems and is [inaudible 00:01:33] a certified fluid power hydraulic specialist of the [nation 00:01:36] from the Fluid Power Society since 2009. Josh will be available to answer questions after the presentation. Without further ado I will hand the mic over to Josh.
Josh: Thanks Michelle, and welcome everybody. Thanks for joining into the webinar. We’ll make it another good one. This is my second one so far and I’ve got some more coming up. This one is Proper Hose Assembly Guidelines. This is based around the selection and assembly of hydraulic hoses of various sorts.
Hydraulic hoses exist on nearly every hydraulic machine, that’s obvious. It is critical to ensure hose assemblies are fabricated with care to ensure reliability of the hose as well as the hydraulic system they’re a part of. This presentation covers the essentials of hydraulic hose assembly to ensure the machine is safe and dependable.
We’re going to cover how to ensure the hose assembly is free from contamination. If you have that much dirt inside your hydraulic hose you’ve got some serious issues. We’re also going to discuss how to measure a fitting to ensure the most secure crimp, also discuss which fittings are required for different types of hydraulic hose, and how to ensure your finished hose length is accurate.
There is an important first step when it comes to selecting a hydraulic hose. Identify what you need. This could be, are you doing a new hose assembly. This could be a new application, something being engineered. You have somebody coming in to measure on your machine. You’re not a [inaudible 00:03:29] company or a machine builder. Is that the direction you’re taking or is it a replacement assembly?
You have a [inaudible 00:03:39] hose, a busted hose and stuff like that, [the 00:03:41] port considerations either way. If you have a new hose assembly there could some flexible in how they’re selected. You have a lot more options. If you’re replacing a hose and your components on a machine that are already in specific locations that can’t deviate from their position then your hose has to be very exact to what replacement was.
When you select a new hydraulic hose the assembly should take in some consideration specific to the application. If some of you are involved with the industry or are familiar with creating hose assemblies there is a familiar word, STAMPED. This is an acronym that’s going to describe all the different characteristics of a hose that you need to consider before you make your selection. Once again, this is mostly for when you’re designing from new but also from making sure that the hose that you select to replace an old one adheres to all these criteria as well.
The stamp acronym stands for size, temperature, application, material, pressure, hose ends and considerations for delivery. We’re going to start with size. The size, [considerations 00:05:07] you need are the ID, the OD, and the length. Those are the three different criteria that will make up. Hose must be sized appropriately to handle flow with little pressure drop. Considering the ID of a hose, if you have a particular flow rating that you need to accommodate you need to have the internal bore of that hose large enough to handle the fluid flow with little or no pressure drop.
You have to keep in mind that the longer the hose the more friction or the more pressure drop that will be created, the more back pressure. That goes up exponentially as you decrease the size of your hose. For example, if you had a 2-inch hose and you reduced it to a 1-inch hose you’d have 4 times the back pressure, not twice the back pressure. Also, if you have a long length of hose you also have special considerations for ensuring there’s less back drop, back pressure especially running, 5, 10, 20 feet, things like that. You may need to up size the size of your hose to accommodate the flow that you have in your system.
They’re are lots of resources you can find online. There’s normal graphs or flow calculators and things like that. If you’re not sure how large your hose should be sized for any giving flow or length of tubing find one of those online calculators or normal graphs because the selection depends on if you have a suction line, if you have a pressure line, if you have a return line. They all vary from each other and require different sizes of hoses.
Also, considering measured length from tip to tip. This picture image shows the overall hose assembly length. We generally don’t measure from tip to tip of the hose. This one has 2 JIC fittings on either end. One is a straight on the left side and the other is a 45. We’re not measuring tip to tip on the fittings for a couple of reasons. If you have a JIC male on either side of the assembly and you measure from tip to tip of those fittings the hose may be too short to actually be threaded on to the fittings.
If you look on the left side with the straight fitting the length is measured at the seat of the JIC. The part with the hose fitting on the left actually fits against the JIC male part on the machine. On the other side we’re going to measure on a 45, so at the center point of the fitting. You can see that it goes right through the center. It doesn’t measure to the tip on the corner. It doesn’t measure to the leading edge. It measures right in the center. This what we call your overall hose assembly length. This is the critical part to remember. It doesn’t matter what kind of hose you have. You want to measure where the fitting are, not where the tips of the hose are.
Thirdly, when it comes to hose length, we also want to cut the hose to a particular length. Depending on what manufacture of crimp fittings you have you can vary on what you’re actual hose cut length is base on what those fittings are. Every manufacturer is different and what you’re going to have is something called ‘the cut off length’ added to your fittings.
You can see on the right side we have an MPT fitting and we are going to consider the entire length used there from the tip of the MPT right to where the hose stops inside the fitting. You can see that through the cutaway where the Ts grab into the hose and then that CA dimension on coupling 2. Also, when you go to the [either 00:08:42] side of the JIC fitting there that CA fitting stops at the seat of the JIC and then over to where the hose stops inside the ferrule.
Those are critical dimension to know, those CA dimensions, because once you have your finished hose length that you want to achieve you have to find your hose fitting that your using in a catalog and reference material for that particular hose fitting manufacturer, in this case RYCO. It could be Gates, Parker or Eaton or whatever. Whatever they are they will have information available to you. You subtract that cut off length and that will allow you to have your finish length of your hose.
This case, here’s another fitting, this is a flat face fitting uncrimped. That cut off factor in this case would be the D in this picture. That’s the number that you will subtract that will be in the catalog, so that the entire hose length subtracted by 2D in this case, 2 times this on the other end, is what you’re going to cut your hose to.
The second part of stamped is temperature. After you have selected your size your ID, your OD … I didn’t mention in the last slides, but OD is critical if you’re passing your hose through bulk heads or if they’re being clamped on hose clamps and stuff like that. If you have 1-wire, 2-wire, 4-wire, 6-wire hose the more layers of braiding in there the thicker the hose is going to be and that could affect how something is clamped down. OD is important for application and I’ll discuss more of that later.
Back on the temperature, temperature is an important consideration. Every application is different but you need to consider what is the temperature of the fluid. There’s kind of a limited range on hydraulic fluid [likely to 00:10:30] operate in just like motor on our car. Ideally, it’d stay between 90 to 120 degree Fahrenheit depending on the viscosity in the application, but in general you want the internals so that the fluid passing through it likes to be at a particular point but also consider what ambient temperature is.
This is more critical for hydraulic hose applications because you’re not dealing with steam, you’re not dealing with [refridgerenders 00:10:56]. This is really just limited in what you’re moving through a hydraulic hose and that’s hydraulic fluid. Hydraulic fluid has a range of usability, too cold and it’s too viscous, it’s too [inaudible 00:11:05] not so good, too hot, looses lubricity. It has more friction wear inside your components and oxidation. You want to keep it in a limited range and most hoses are good for that but it’s the outside temperature that’s also critical.
Typical hydraulic hose is good for -40 up to 212, and that will cover the gambit of 99% of the applications you’ll see. Your general machinery or industrial machinery or in things like that but if you want to get a little more extreme, if you’re on a steel mill and at a place where there’s high ambient heat conditions once again, if you have hydraulic fluid that’s up to 300 degrees Fahrenheit that is cooked, it’s pretty much going to vaporize. It’s no good for hydraulic fluid. It’s no good for your machinery, but the carcass, which is typically [neoprene 00:11:55], might have to be a different material to handle that 300 degrees of ambient temperature. Like I said, in mills …
If you have low temperature extremes, once again, low temperature application might be -58 up to 212 Fahrenheit, if you have hydraulic fluid that’s -58 degrees it’s probably not moving very well, probably not pumping very well. It’s really just the ambient cold condition. If you have any arctic machinery, you might have snow grooming machinery, stuff like that that have hydraulics on it you want to make sure that the outer carcass, the outer layer of the hose is constructed with material that can stay pliable and flexible in cool temperatures so that it doesn’t crack as easily, doesn’t go through heating and cold cycles that cause it to fail prematurely. When it comes to the temperature application of the hose mostly it’s the ambient considerations.
Now we’re on to application. This discusses the nuts and bolts, the details of how it’s going to be used. Where is the hose used? What kind of machinery is it used? What’s the ambient temperature? It kind of goes within temperature as well, but what is the required bend radius and some other factors?
If you have a tight bend radius in some applications or specific hose, that’s called HighFlex hose, that will typically have half the radius of bending or more. This is advantage in a couple of ways. Not only it allows you to fit a hose bend into a tighter space, in this picture image that we have here that would take a HighFlex hose to achieve that, but how often it bends. Does the general flexibility and the fatigue, how many times the hose can bend through it, through an arc without failing early. As you know, any kind of steel braided kind of wire, even rubber, the more times you flex it back and forth the quicker it’ll fatigue. HighFlex hose is more resistant to that.
There are also external conditions you need to consider for an application. Is there risk of abrasion? Most hose has a neoprene outside but if you have hoses that inevitably will rub against materials, against machinery, against the jib or boom, any application where it can rub back and forth, a high abrasion carcass is a good way to go. Hoses tend to fail by rubbing on the outside until they wear through the outer wall into the braiding and start wearing that away, and eventually, enough so that the hose can no longer contain pressure. You get a hose burst. Probably the number 1 cause of hose failure would be external abrasion.
Most of the hose assemblies that I’ve done repairs on a customer would come in with a blasted a part hose that’s been sitting there rubbing against something for months or years and finally just gave way. There are some cases where even on an abrasion resistant outer carcass you may still require a hose wrap. That will be either a braided or a nylon wound wrap that goes on the OD of your hose that protects it from direct abrasion from machinery, from engines, or wherever you can name that would be vibrating and rubbing against the hose.
Also of consideration is corrosion. Is there something in the environment that’s caustic that would cause fluid to permeate through the outer carcass of the hose and perhaps rust, corrode or breakdown the layers of spiral or winding that are around reinforcement? You need a hose that maybe perhaps says synthetic material that won’t rust, that is non-reactive against whatever the ambient conditions that cause corrosion.
On top of that, another application consideration is electrical conductivity. In the image here you have an electrical boom truck. You can imagine that any opportunity to conduct electricity back through the machine or to an individual want to be reduced. If there is some sort of electrical break or that electricity is not transmitted through the hose itself. A hose would be constructed of a synthetic material that is non-conductive and so you can get non-conductive hydraulic hose, sometimes with reduced pressure, but nowadays they’re all really well-made and can be just as high performing as a regular hydraulic hose albeit with often extra cost.
Now on to the material. By material, not necessarily meaning the construction of the hose itself, but that can play a part in it, but what type of fluid or material is being used. Considering this is critical to hose selection. If you have something exotic and requires a specific rubber compound you need to consider at this stage. Most mineral based hydraulic fluid is compatible with most types of hose. Majority of hydraulic hose has a nitrile interior with a neoprene outside, but if you were running exotic fluids sometimes you need to change that up.
For example, if you have a phosphate ester, which is a kind of fluid that is used in Skydrol, it’s non-flammable but it’s kind of nasty stuff, so you might have to have synthetic core like EPDM. Most hydraulic hose is synthetic, nitrile and neoprene, both synthetic rubbers, but you can get the more exotic and obviously, these kind of things are extra cost as well. The material could also be outside. Like I discussed earlier, if you’re exposed to any kind of caustic or nasty environmental conditions that could cause breakdown or corrosion on the outside you may have to choose that as well.
Probably the most important when it comes to consideration of hydraulic hose is pressure. Without the capacity to resist pressure hydraulic hose [inaudible 00:18:24] just use some cheap old garden hose and [connect it 00:18:28] to your hydraulic system, but pressure capacity in hydraulics is the defining criteria for hydraulic hose and pressure dictates construction. The fact that hose exist for hydraulic applications in a lot of ways it’s ideal to use tubing so you would bend tube or piping and it’d be permanent. They tend to last longer, whatnot, but any kind of application in fluid power that requires any kind of motion between two parking services like a boom or a crane or in some applications where you want to reduce vibration hydraulic hose can be chose. How the hose is constructed fully dictates what pressure capacity [it’ll 00:19:10] have.
This a general example of a slice of hydraulic hose. What we have here is the outer cover. Like I said, most times it’s made out of neoprene. It’s fairly abrasion resistant, fairly chemical resistant. It’s [inaudible 00:19:28] for a reason. This one has one layer of reinforcement. This is braided hose. You may have heard the term 1-wire hose, 2-wire, 4-wire, when you hear those terms to describe a type of hose you generally have an idea of its pressure capacity. I just want 1 wire hose, depending on the size and diameter, that could play a part in how much pressure the hose can take, but this would be an example of a 1 wire hose.
You have your outer cover, you have your reinforcement, which is a 1-wire in this case, braiding. You can see that it’s crisscross braided pattern, very flexible. Then you have your tube or your inner carcass and most often it’s nitrile, which is very resistant to oil, won’t breakdown. It’s a synthetic rubber. It’s good for a lot of different types of fluid and temperature ranges as well.
What we have here is an example of a 2-wire braided hose. This particular example, it has the inner tube, the carcass on the inside, one single piece of that. By an outer braid another piece of tube or carcass and then another outer braid. Sometimes the wires can be wrapped directly on top of each other, each layer of wire and then you would have your outside of your outer carcass. This is what you call 2-wire hose. This example, previously … All right, 1-wire hose, 2-wire hose, pretty straightforward.
I don’t know if anybody has ever seen the inside of a hydraulic hose or worked on them but you may have heard people use that kind of terminology. It’s pretty common. Stepping up a notch … 2-wire hose, I should mention, this is generally in most applications, I’d say 90% maybe even more of the applications that I’ve worked on have been 2-wire hose. This particular 2-wire braided hose, generally pretty flexible. The way the crisscross pattern of wires work it allows you to bend it either way without a lot of rigidity. I believe most Highflex hoses will be made from braided wire such as this.
It’s a good general purpose hose. If I were one person stocking a hydraulic hose in my own shop I would stock mostly 2-wire hose. It has good high pressure capacity. The diameter is pretty fair. The OD won’t be as small in a 1-wire hose but over most applications it’s good all-round choice.
Stepping up a notch, here we have a 4-wire hose. This example is spiral wound hose. You have your tube here that is got one set of wires being wound, looks like clockwise or kind of clockwise depending on which way you’re looking at it, and you have another caracass and the wires of the next layer of spiral wire in the opposite direction. Then you have the inner carcass and then the opposite direction of wire again, another carcass and then opposite direction of wire again.
This is a very strong way of creating a hydraulic hose. When you get up to a 4-wire hose pressure capacity starts to rise but you have the downside of a lot more rigidity. Larger diameter hoses require this type of construction, so if you’re talking 1 and a half, 2 inch hose, if you want to have 3000 psi pressure rating or more you have to get away the braided hose and go to these spiral wound hoses. There’s no other way around it.
You want to go really extreme you can have construction made from 6-wire. This one is similar as the other styles except you have 6 layers of crisscross spiral wound wire, in this case, laid right on top of each other. There’s no separating carcasses between them. What I’m [going to do 00:23:44] is present you with an example. This came from RYCO.
This is an example of a chart for choosing a hydraulic hose. It would have their part number then dash sizes. In case anybody’s ever wondered what a dash size is, it’s really that number over 16. It describes in inches for example a dash 8 is 8 over 16, which is half an inch, or a dash 16, which is 16 over 16, which is 1 inch. This is a 1-wire hose I believe. No, 2-wire hose, but if you look at some of the performing criteria of it each one of these hoses is … Sorry, my apologies. This is a spiral wound hose, this would be a 4-wire application.
Sorry about that, and if you look at the maximum working pressure, that would be right around the middle there, every single one of these hoses, whether it’s 3-8ths, dash 6 all the way up to inch and a half, 2 inches is ready for rated for 61,000 psi. This is one of the advantages of a spiral wound hose, high burst pressure of course. If you look over at the bend radius, some of the larger hose have a bend radius. This is if you were to make a circle with the hose what would the smallest size circle you can make with this hose?
In this case some of these larger sizes, like 2 inch, would be 16 inch circles. To be honest, I wouldn’t want to bend a hose that big into a 16 inch circle to be pretty rigid. Also, we’re going to discuss the average weight of them. Bigger hoses, especially larger diameter, with more layers of wire will have more weight and that’s a given. Those are things to be considered for your application.
Next page, this one here is … I believe this one is a 2-wire hose. This would be standard braided wire. One thing I want you to notice about this page is how the performance changes with the size of the hose. If you look at a dash 3 size, that’s pretty rare, 3/16. Typically, you see a quarter of an inch as being a small hose. This one has a pressure rating of 32,050 psi, three thousand two hundred and fifty. It’s important to consider that smaller diameter hoses, just by their nature are able to resist higher pressures.
The construction allows them to have less force across any given perpendicular surface. I won’t get into why that is, but there’s less surface area for any given direction of force to push on. It has less ability to burst easily. As you go down the sizes here, if you go to say, half inch, pressure all of a sudden drops to 23,000 psi. Not a whole lot bigger of a hose, it’s only a quarter of an inch bigger but you lose 900 psi worth of working pressure.
Going down the line a little more you go down to the 2 inch hose, the dash 32. Now all of sudden this one is only good for 580 psi. This particular construction of hose you need to be careful. I’m sure it’s probably inexpensive and be readily available but you’re severely limited in what you can do with your hydraulic applications. Going over to the right a little more, go to the average weight. This is the weights per foot. If you guys remember what they were for the spiral wound hose, a 2 inch one per foot you’re talking 4.7 pounds per foot of hose but a 2 inch one of 1-wire hose is 1.4 pounds per foot, quite interesting.
I did an amalgamated chart here. These are 2 hoses, one being a 1-wire and another being a spiral wire, this is 1-wire braided versus a 4-wire spiral wound I believe. I created this chart to show them side-by-side. Both 1-inch hoses, but the bottom one being a spiral wound 1-wire. It’s only good for 13,000 psi. Whereas, as you remember from a few slides ago, all of the spiral wound hoses were good for 61,000 psi and that was regardless of size.
They’re good for pressure but if you go down the line here, you look a little bit, you can see the bend radius. You need 1-inch farther of bend radius on these spiral wound hose. You just can’t get in a tight radius. I should also mention that the spiral wound hose I selected, that T116A, I don’t think that was a HighFlex hose. If you had a HighFlex hose you might go get half of that bend radius as well, so even further improved.
From a weight perspective you can see that the spiral hose is almost twice the mass per foot. Hydraulic hose can be heavy as it is especially as you get larger diameter but if you’re thinking about something like an excavator or pieces machinery that are already sensitive to load capacities then you want to have the most amount of work out of the vehicle as possible and have less weight allocated to things like hydraulic hoses. These are important considerations.
After pressure we want to talk about ends. Ends are literally the fittings that you’re going to be attaching to the hose itself. Lots of things to consider here. It’s really application specific. It could be geography specific. The type of threads, if you’re in North America you’ll have different threads than if you’re in Japan or Europe. You’re hose is going to have male or threads and that’s going to depend largely one what exists on the machine already or what you can put there.
Is there a reason you might use a swivel? Could it be a [swivelon 00:29:57] like a JIC that swivels until it locks? Do you need a live swivel? Does the machine bend as well as pivot? If you have something like a [grample 00:30:09] that might bend if you need one hose that has a live swivel.
Also, should you have straights or elbows this is going to depend a lot on how the hose lies. If a hose coming perpendicular from a machine so that the gravity wants to pull down on the hose that puts a lot of stress on the joint, especially right were the hose meets the fitting. You want to have a 90 degree fitting to let that hose take advantage of gravity so that it goes vertical with the machine, not stick out perpendicular to it. You want permanent or reasonable fittings. These are two things we’ll discuss certainly.
Here’s the general selection of hoses you might see. Starting from left you have pretty much any fitting that exists in hydraulics or any machine. This is available with a hose end for that type of hose. On the left you have a banjo bolt, and looks like you have a [metric 00:30:59] or could be BSVP but probably metric. You have a male JIC, the third one from the left, then you have a flat face coupler. Next to that you have what could be a code 61 or 62 flange, a C flange. It’s also a [face 00:31:19] style coupler. You have a 90 degre. That one could also be a JIC but could also be MPT. The far one on the right, that’s actually a swivel MPT fitting. That one would go on to a male end swivel [on 00:31:36] so that you didn’t have to twist the whole hose around.
They’re also reusable fittings. These are some fittings that you can use in the field. They also call them field attachable but the crimped on fittings are permanent. These are 2 criteria. Sometimes the field attachment ones are needed in the pinch. You can’t really get around it. Most often, if you can, the crimped on fittings are the most reliable. They’re crimped on and fairly permanent. Vibration or heat cycles aren’t going to let them come loose like you can with a reusable fitting.
This is a reusable hose end. The piece on the right gets threaded onto the hose. You can picture that the hose comes in from the close end, you thread that on. It goes on to the hose. The teeth in threads dig into the hose carcass and locks it in place. Then you insert the left hand piece would get inserted inside the hose. The threads would engage and as you tighten it down it would compress the hose outward into the teeth of the right-side piece. This allows you to install a hose in the field.
They get pretty tricky to do. You usually need a vice to do these. When I use to use a reusable fitting I use an impact gun to assemble. There’s a lot of work involved. It’s pretty high [twirk 00:33:12] application and I wouldn’t want to do these with hand tools. You can put a lot of stress on your wrists.
Crimped ends, you can get these in 1 or 2 piece. These are pre-assembled [inaudible 00:33:27] one piece style fittings. You just slip on the hose, insert into your machine and crimp away. You have a selection there, pretty self-explanatory. Also, consider what kind of crimping machine you want to use. We’re getting past the hose selection phase and working on what it takes to actually crimps a hose.
Right here you have a fairly economical hand-pump style crimper. Let’s look at the die sets, those are required. On the bottom left-hand side you have micrometer that sets your adjustment depending on what dies that you have. Upgrading a bit, we have a hydraulic-powered semi-automatic crimper. You still got to adjust some setting on this but it’s all powered, no hand-pumping required. If you’re a heavy duty shop and all you do all day is hydraulic hose you’re going to need one of these bad boys, something like this, a CMC crimper. Everything is computer programmed. If you look below you can see all the different types of die sets that are required for installing different types of hose, different size fitting. The finished diameter of a hose very particular so having a full complement of these dies is required if you want do every diameter of hose.
Looking at this picture, this disc crimper right here, I prefer these 8 die applications. If you see inside that black head there are those 8 little die holders. The little holes, they hold the dies. When you have 8 of them it’s great for doing 90 degree assemblies. You can imagine that each one of those dies is 45 degree spaces around. If you had an application where you were doing dozens or hundreds, who knows how many hoses then you have one that is perpendicular or 90 degrees to another this one is really easy for lining up. Some of them have six dies.
The visual gets a little harder to imagine. Doing 90 degrees you have to put markings on the machine or what not to do that but I prefer this style here with the 8 dies. When it comes to choosing your fittings they’re very vastly. It’s going to depend on which hose selection you have, how many wires it is, what the finished OD is going to be, which fittings you’re using. If you have ever looked in the catalog for a hydraulic fittings, especially for hose ends, there’s thousands of choices. Nearly any combination of fitting and hose and available and making the right choice is … If you’re not comfortable with it make sure you consult your local hose shop and they’ll help you.
If you just look inside any given catalog these are examples of some MPT fittings. There’s your straight one, straight swivel, 90 degree swivel, a female swivel. Your options are endless. Also, every catalog will specify to you which types of fittings you will use and how they will be crimped based on what kind of hose you’re using as well. These picture fittings might be usable for these 1 or 2-wire braided hose but they might not be suitable for a 4-wire spiral hose.
This [particular 00:36:56] page is going to be all the information you need when it comes to actually crimping your hose. Once you have you hose and it’s crimped if you look at these dimensions right here it’s going to give you a crimp diameter. The tolerance is 8000th of an inch. In this case you will crimp it with your settings on your machine. You’ll adjust it so that it’s final crimp diameter, in this case, I will take the first one. It’s .598. If you take out your calipers and measure it that’s what you want your measurement to say. Depending on what fitting you use, depending on what hose you’re using all your crimp specs will be different. Just make sure that you measure it accurately, you don’t guess.
The crimp spec is important because not only does it make sure that you have a safe crimp, that you don’t have a hose fitting that pops off within the first minutes or pressure cycles or whatever, the most reliable crimp is the most accurate one. Also, because if you over crimp it may stay on but it also might just eat through the carcass and the middle braiding and pop off anyway. You also crush the ID of the hose and you restrict flow. Ensuring that you have an accurate crimp, in this case they specify within 8000th of an inch, that really tells you how specific a crimp should be.
For your catalog, when you’re doing a hose crimp make sure you get as close to that number as possible. Anywhere outside that should be redone. It’s just not worth messing around for an $8 fitting. The time it takes to redo it there’s no point in doing anything but the right way. You measure with calipers. You’d do your hose crimp and measure right across the center points and that’s your most accurate way.
Next is delivery. This is if you are an OEM or a large company and you need to consider the specifics of when you’re going to get your hose, how many do you need, how soon do you need them, just any special tagging or lay line information. The lay line is the embossed part numbers in the description that you see on a hydraulic hose. If you’re a large OEM and you want some resell business come your way you might have hose assemblies made up with all of your own identification numbers on it so that all [inaudible 00:39:17] sales go to you. You could have some information about application or temperature or whatnot. If you buy into hydraulic hose manufacturers are good enough to do whatever you want.
After the stamped acronym is taken care of, and it needs to be considered for every new application, what happens if you’re replacing an old hose? Don’t try to repair an old hose unless absolutely necessary, unless you need to do it in the field and you have the proper attachments and tools. Even still, it’s pretty sketchy. I wouldn’t trust it. It’s just not worth it. You could fix a hose, it might last you an hour. You’d fail again, next thing you know you’re dumping fluid all over the place. If you’re in [inaudible 00:40:07] equipment you could be dumping on your field. It’s always best to get things done right.
Also, follow the STAMPED protocol to ensure that correct replacement is made. All the criteria that you need to do is to make sure that you make a new hose should be done for a replacement hoses as well. When you are making a hose, whether it’s old or new, whatever your doing replacing or creating anew. Make sure that it’s cut correctly as well. Make sure you only use a specialized hose cutting saw. Most of these have a metal blade. The advantage of a metal blade is that it cuts clean and smoothly and it doesn’t leave fraying.
Sometimes when you cut with like a cut off wheel the edges could be frayed. I’ve seen hydraulic hose nearly look like this because it wasn’t cut properly. You see guys cut it with a hacksaw, that just can be a disaster. You’re not going to get the fitting on all the way. You have a good chance of it popping off again. Sometimes the fibers, the middle spirals or the braiding will bend backwards on itself. It would be very difficult to get the fitting on.
Also, ensure that you cut 90 degree across the hose. Most of the machinery is made so that it does a good 90 degree cut. Specialized cut off saws for hydraulic hose are good at that. They have some dies you put in place that as you push them across the middle of the cutter it automatically cuts them at 90 degrees. This is important because if you have any kind of angular cut it will bottom out sooner and needs to be so that the entire fitting isn’t inserted as deep as it needs to be inside the fitting. The less area to grab on to and just an inferior crimp.
Like I mentioned earlier, make sure you crimp it to the specifications that were spelled out earlier. Make sure you measure it correctly. Once again, those will all be spelled out in the catalog of the manufacturer. If you’re one particular company using one 3 or 4 different types of hose and fitting just make sure you have those posted somewhere near your crimper and everybody’s [trained 00:42:26] properly on how to use that machinery. You want to make sure you have a nice good clean hose in the end. These little stubby guys are just for an example but those are good looking hoses right there.
Also consider how to clean the hose assembly. There’s really only one way to do this as far as I know of. I’ve seen people just try to pass air through them but that doesn’t always get everything out. Only use approved hose cleaning apparatus. We’ll get to those in a second. Also, immediately cap the hose ends to protect them from environmental contamination. Any hose shop or any hydraulic shop they can be pretty dirty places all to themselves. You want to make sure you cap them right away so that any ambient dirt, dust, whatever doesn’t get inside the hose and eventually get inside your hydraulic system and damage your components.
Everybody’s probably seen these hose cleaning machinery. They send a foam pellet through the hose to clean any debris, anything from the cutting, could be metal debris from the wire that’s introduced into the hose. It just could be the particles of dust and whatever existed when they manufactured the hose itself. These are all things that you want to get out. They send a foam pellet right through the hose. As it goes through it … The pellet itself is a smaller [diameter 00:43:56] of the hose but the air pressure is always more than enough to shoot it all the way through and picks the particle and clean them as they go.
What I recommend, because these pellets are really soft, make sure shoot the pellet at someone. It’s good clean fun. You can get one of your friends, knock them in the head with a pellet, fun for the whole family. You’ve done that, make sure that after you clean it, you shoot the pellets, that you cap them as discussed earlier. This prevents contamination, especially if you do hundreds of thousands of hoses, [assembly 00:44:34] that will be sitting around for a while. It’s just good practice especially with the strict cleanliness code that you can get with some hydraulics machinery. That’s it on proper hose assembly guidelines.
Michelle: All right, well thanks Josh.
Josh: Thank you.
Michelle: I’m sorry, go ahead. Of course. Well, we are now open for questions. If you have any questions during our Q&A be sure to type them into our Q&A box. All right, the first question I’m going to start off with is, when should you choose tube over hydraulic hose?
Josh: Tube I think it’s for good permanent applications. Sometimes it has a higher pressure capacity. It also has a cleaner look. They last longer and they don’t fail as rapidly. It all depends on application. I would always go for tube first and if application requires either some sort of vibration resistance like for example I’ve had hydraulic power units that were plumbed up with coolers and a whole bunch of components that were on top of this power unit and there’s this vibration noise that we couldn’t seem to track down. It was all plumbed up with tube.
We tried to isolate where the resonant frequency was coming from, where the vibration was coming from. We ended up adding some hoses there. The hoses have some flexibility and some give so they will absorb some of those vibrations and can kill some of those annoying noises The other thing too is if you need that flexibility. You have any kind of machinery where there’s 2 different actuators or components reports that are moving on different planes you absolutely need to have a hose. I would generally always pick tube first because it’s more permanent first because it’s more permanent and reliable. If tubes don’t work then go for the hose.
Michelle: Okay, thank you. All right, next question I have is, if the fitting comes a part from an old hose should I crimp a new fitting or replace the hose?
Josh: I addressed that a little bit earlier, but I have seen fittings pop off. With the exception of an improperly crimped hose, just say you went in and got a hose made, whatever the technician did, he made a mistake and did it to an improper crimp spec and it popped off immediately. You brought it back and you have enough room so that you can cut off four inches of that hose and then reuse it.
I think that’s the exception of when I would actually reuse a hose, when you knew it’s brand new, it’s barely been used and you can fit a fitting onto it and recrimp it. Otherwise, almost every other circumstance I would just get a new hose assembly. Hose is cheap, even like a half inch hose you’d be hard pressed to spend $20 more on it depending on how long it is. Just get a new one made. That’s always the best practice.
Michelle: What can be done to seal a minor leak where a hard line enters the hose fitting. Would a copper washer work?
Josh: A copper washer … Could you read that again Michelle?
Michelle: Sure. What can be done to seal a minor leak where a hard line enters the hose fitting. Would a copper washer work?
Josh: A hard line enters the hose fitting. I’m going to say mean actually where it’s actually at the fitting itself, so if a copper washer could be used. This is what I’m gathering the question is asking is that, if you have a hard line or a fitting and all of a sudden it’s attached to a hose and another fitting and leaking at the fitting if you could add a copper washer.
I’ve never seen copper washers used in hydraulics. Even though it’s a little bit malleable, it’s not soft enough to allow positive seal between too hard surfaces. There are some companies that make some seals that can go on a JIC so that it has a soft seal between two surfaces. If it’s a temporary thing the chances of getting a copper washer to the exact shape and dimensions of the fittings that you’re trying to seal up again it’s going to be probably hard to come by. You’d be better off instead of going out to look for washers is going out look for somebody that can redo your hose or get some new fittings for you.
I wouldn’t recommend that either. It sounds like a disaster for leakage. The pressure is just too high. If there’s any imperfections in the surfaces between the copper washer and the metal of the fitting or the tubing or whatnot, 3000 psi, it’ll find it’s way through there. The copper washer is not going to stop it.
Michelle: Okay, and Josh, I’ve got one final question for you. Is blowing air through the assembly enough to clean it?
Josh: I would say no. If you need a hose that is clean enough … If you have a particular [ISO 00:49:39] code that you’re trying to achieve, if you have several valves, if you have proportional valves, if you have any high-end equipment that you have a program for cleaning a hose and that’s require blowing air won’t be good enough. If you’re code requires that your particle contamination is so refined I would just do a proper pellet and do it that way. If you have [mow 00:50:02] machinery, your 1950s tractor and you haven’t even replaced your filter in 20 years by all means blow air through air through it. It’s not really going to make a difference one way or the other. I suppose it’s better than nothing but as far as standards go it’s ideal to do it with a pellet.
Michelle: Thank you Josh. That concludes our webinar for today. Thank you for attending our webinar from FluidPower world. This presentation will be emailed to [inaudible 00:50:30] later today and will also be available at www.fluidpowerworld.com.
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