Fitting types for hydraulic lines

[dan_m]

So I'm about to start building my press, and am slightly confused by the recommendation to not use NPT/NPTF fittings on the hydraulic system. Pretty much everything new you read on hydraulics now recommends against using these fittings as they are prone to leaks, so I was planning on getting hoses made with JIC 37 degree flares. However, ALL of the components I ordered (and pretty much all of the ones I looked at in various places around the internet) have NPT or NPTF ports. If I have to use hose fittings that are JIC 37 on one side and NPT or NPTF on the other, doesn't this defeat the purpose? Am I missing something here? I ask mainly because I would prefer to use schedule 160 seamless pipe instead of hose for the majority of the lines, but that would mean all NPT/NPTF fittings. Anyone here have some experience with this issue? Thanks!

EDIT: Sorry, forgot the basic info I'm sure you'll ask for. Running two, parallel 6" bore/20" stroke cylinders with a 28 GPM two-stage pump. Relief valve set at 2500 PSI. Cylinders mounted up top. Also, when I start the build later this week I'll make a thread for it with progress pics.

[ptree]

I believe if you look a bit you can find components with SAE O-ring ports. You can run the seamless tube, just have to weld them. You can Butt wed them, use socket weld fittings or use weld on flanges. There is a series of SAE hydraulic flanges that use O-rings as the gasket.
Now the low cost components one finds at the farm store will usually be NPT.
At 2500 PSI you could also use Swaglok brand double ferrule fittings on tube. They have a reccomendation on tubing, ie on hardness. If the tubing is rated for the pressure, and is at the hardness stated, these are the worlds best hydraulic fittings.The are priced as the worlds best as well.
I have used Swaglok on pressure testing machines that cycled to 10,500PSI in production use for manay years with no leaks.
On hydraulics at 2500 psi, I would also consider Parker Brand Ferrululok ferrule fittings. At 2500 PSI should work a treat. Depending on tube size you may need a preswager for the Parkers.

[dan_m]

Ah, well I most certainly appreciate the detailed response, but I just ordered everything about an hour before you posted that (trying to start the build this Thursday, waited way too long to ask the question). Given that I'll have NPT fittings, what's the best way to deal with it? I'd rather not return the components, especially since I can't order new ones until I get a refund. Is pipe dope the best way to go for that? I understand the potential/inevitable leakage issues, but at least with overrated rigid lines I won't have the safety issues of pinholes or bursting and can always convert things as needed down the road.

[Daniel.85]

As long as you can make them work safely Id say just use them and upgrade later if you need. I just read through Don Foggs hydraulic book and plan on ordering the first set of parts here soon, I'll be doing just a 24ton, 5x8cyl, 5hp, Hframe. If it ever pays for itself I may do something bigger like yours!

Surpluscenter.com and northern tool seem to be where Ive been able to find most of what I need.

Do you plan on making it foot operated or hand lever?

[jimmy seale]

just some ideas....forged fittings is the way to go..heavier the better,also you may want to build target tees as it will help with pulsation issues and give the lines a "cushion". i would also put in unions so the piping could be removed with out being broke down a piece at a time for repairs,etcc. ok some more obnoxious advice...if you are building a oil resaviour,make sure you have enough room for expantion,a vented cap,a suction screen, and if possable put in a partition in it so your suction is seperated from your discharge,as to let any "junk" settle out. also blow out all fittings/piping before installation. use non detergent oil, and maybe install a liquid filled pressure guage in the line. AND at the risk of sounding stupid....make sure the pump/motor rotation is the same way.and....if equiped check the motor/pump coupling, and besure of the alignment.a oil drain port would be good to have,as would be having the discharge hoses down low so it dosen't "slough" up the fluid and make the pump cavitate,AND.....good luck, be safe and make some guards to cover stuff up, jimmy

[dan_m]

Mine will be foot operated, electric though rather than mechanical linkages to a manual control valve. Solenoid and manifold with a double, momentary foot switch. Try baileynet.com too, their customer service is top notch. Last week I spent over an hour on the phone with a guy there, and he had me explain what I was doing and then helped me assemble a list of components that worked with each other, and even went through each part of the system and recommended hose sizes etc although he knew I wasn't buying those from them. I asked if I should order with him over the phone so he could get a commission but he said no, he's just technical support. They'll always get my business from now on, that phone call saved me at least a few days of research since this is my first hydraulics project. And I figured I'd build a larger press from the start...I'll end up saving in the long run by not building a smaller press and then needing the bigger one shortly after. I had originally planned on building a 35 ton (one 6" cylinder), but after Randy was nice enough to have me over and show me his press, I decided I didn't want to go any smaller than that so I just got another matching 6" cylinder. I'll take some pictures of the materials I've got in the next couple days and start a thread for it.

[Daniel.85]

I was also looking over the solenoid control valves for what I would need, didn't want to use the hand lever. I know I need a 20 gpm open center non-dentent control valve just haven't looked into that part specifically yet, still debating on Ibeam or tubing for H-frame. I'll give bailey a call when I get to ordering the control valve and the other components.

[dan_m]

Get a spring centered valve, it has springs on either end that are depressed when you are in either of the engaged positions, so it automatically returns to the open center when you take your foot off the pedals.

[dan_m]

Thanks for the tips Jimmy. I'd already planned on what you recommended for the tank, the fittings, baffle, drain etc. Got a filled gauge too. Didn't think about unions in the lines, but that's a good idea. Grainger has an adapter to make a 184T frame a 184TC, so I can use of of those pump/motor adapters that covers the coupling and keeps everything in alignment. The motor is three phase, so I can set its rotation to match the pump.

[ptree]

As a guy who worked in the valve and fitting trade for 21 years, I would not now, or ever use pipe unions in a hydraulic system at 2500 psi. AND we made the best in the world and rated to 6000psi working pressure.
They will leak. Pipe unions are not the right thing for schedule 160 pipe in the service you will have. Use weld on 2 bolt flanges made for hydraulics that are O-ring sealed.

For thread sealant do not use pipe tape. Use an anerobic thread sealant like Loctite PST and use the primer. Best on the market for this service.

Consider running thin wall tube over the pipe where ever leakage could spray on hot steel. Run the open end to a safe spot where you will notice and then you can fix safely.

For a bigger solenoid valve as you are looking for be sitting down when you get the price. In this size you actually get 3 valves, 2 pilot valves that are solnoid operated that shift the big spool that delivers the oil. A manual valve may well be MUCH cheaper and that is why many presses of this size have manual valves.

Good luck.

[dan_m]

Thanks ptree! I'll definitely take your advice on the o-ring flange connections, thread sealant, and tubing guards. This is the solenoid I ordered: https://baileynet.com/index.php?page=Search&id=14&srchsrc=SearchBox&sbmfrmas=Submit&baileynum=220-308. The guy at Bailey told me that would work, hopefully you won't tell me he wrong.

[ptree]

Dan That valve will make a press go up and down, and in the center(No solnoid energized) will connect both the cylinder and pressure and tank ports. This will allow the press to drift down over time. Depending on the friction in the system, the drift down may be an over the weekend off to down or may be a watch it ever so slowly move.
Normally for a vetrical press I would go for a center position that would block the A & B ports and connect P & T. that way the pump, which I assume is a fixed displacement pump is running with no pressure when not pressing or retracting. The blocked a & B ports would tend to hold the press in position in the short term. It will still drift down over time but would be a much slower drift.

[dan_m]

Gotcha, I was trying to figure out whether I should get the open center or tandem center (what you're referring to). I went with open center because I figured not blocking the flow to the A & B ports would maybe ease the pressure slightly when I took my foot off the switch, saving a little heat in the workpiece. Probably nothing significant, but that was the only real difference I could think of. Never considered the press at rest with the dies open! I just looked at ordering the tandem center version of the open center solenoid I posted the link to, but the GPM rating on that is just under what my pump puts out, and the next size up is double the price, and I'd need a bigger manifold too. I guess it'll just fall down when I'm not using it, but it's good info to have. Thanks!

[ptree]

A wood block to place under the ram will keep it up.

[Steve H]

Sorry I missed this one Dan, sounds like a neat project. I've ran both Tandems and Open centers. Open centers deliver less shock as the spool is cycling back and forth because all ports are open to the tank. You may think you only shift the spool once in awhile but after I studied what I was doing while forging, the thing must've changed direction twenty times while I was working a heat.

Tandems will hold the pressure after you let off the solenoid, UNTIL you change direction. I liked the positive feel a tandem had but it will rob the heat even faster than you've already heard about, mainly because of the increased contact time with your material. I also blew off a filter with a Tandem setup, presumably because of those shocks as mentioned. I run a spendy baffle type water hammer arrestor now on the open center and it seems to really help smooth out whatever shocks are left.

Are you running the 28gpm pump at 14 or 28 gpm?

How the heck do you get an attachment here?
I was going to put up a file of D03 to D10 (100gpm) valve and subplate info that makes me question Bailey's 32gpm claim on their D05 valve.
Most D05's are maybe up to 20gpm. I have a Northern that is rated for 24. If you can find a D05H , they use an extra tank return and are rated for 25 but I've never heard of 32gpm out of ports that are 7/16"dia.

Let me say this, I'm getting alot of heat in my system from running the 22gpm pump with my D05. I have recently picked up some D08 bodies that need piloting, either D03 or 05. They are a true 3/4" port and are rated up to 60 gpm. The heat is definately coming from squeezing all that fluid through little ports as everything else is 3/4, 1" or 1 1/4"
It's always something~!

[dan_m]

Are you running the 28gpm pump at 14 or 28 gpm?

How the heck do you get an attachment here?
I was going to put up a file of D03 to D10 (100gpm) valve and subplate info that makes me question Bailey's 32gpm claim on their D05 valve.
Most D05's are maybe up to 20gpm. I have a Northern that is rated for 24. If you can find a D05H , they use an extra tank return and are rated for 25 but I've never heard of 32gpm out of ports that are 7/16"dia.

Let me say this, I'm getting alot of heat in my system from running the 22gpm pump with my D05. I have recently picked up some D08 bodies that need piloting, either D03 or 05. They are a true 3/4" port and are rated up to 60 gpm. The heat is definately coming from squeezing all that fluid through little ports as everything else is 3/4, 1" or 1 1/4"
It's always something~!

Thanks for the detailed info Steve. I'll be running my pump at the full 28 GPM, should move it just under 2 in/sec before the pump shifts gears. Are you sure my solenoid valve has 7/16" ports, or is that what D05 means? I can't find the port size on the Bailey site now, which seems odd, but I'll go down to the shop after dinner and try to check. The D05 manifold I ordered with it has 3/4" P&T ports and 1/2" A&B ports, here's the link: https://baileynet.com/index.php?page=Search&id=14&srchsrc=SearchBox&sbmfrmas=Submit&baileynum=220-498.

Now that we're talking about the manifold, do you know what I'm supposed to do with the second valve station? Can I just make a steel or aluminum cap plate to bolt on and stick a rubber gasket in between?

[dan_m]

Also, my cylinders have 9/16" ports! Makes me wish I'd done more research before purchasing them, but that was my way of committing myself to the project. At this point I'm stuck with the 9/16" ports though, the cylinders were surplus so I can't return them and I don't have another use for ones that large. I didn't build the reservoir yet, so I'll make that larger than the 30 gallons I had figured on to help compensate. Worst case I could always put a coil around the return line and stick a little pump on the side of my slack tub to draw some heat off.

[Steve H]

Hi Dan, Heat is the definately the enemy in hydraulics. You'll know after you've been running for a few minutes if it's a problem. A large resevoir is something I haven't had the luxury of, yet- I have a 60 gallon one waiting for a pump and motor transplant. Your 30+ gal. tank should help.

Those Bailey subplates seem a little spendy. I found this site: http://www.hyvair.com/pdf/subplates.pdf
Take a close look at the 'normal' D05 and the 'High Flow' pattern. Also check out the rated flow. The High flow pattern has that extra tank return I talked about.
I like Surplus Center for hydraulics but just noticed they didn't have a 3/4" manifold for A+B. Price is right at 50 bucks though...

As P-tree mentioned, the next valve size up; D08 suddenly starts getting spendy. I'm still running a D05 but have a few D08 bodies lying around waiting for a retro-fit. With the D08, your D05 becomes a piggy-back pilot for the bigger valve body. Seems convoluted but I believe what happens is when the amount of fluid gets to a certain point, say approaching 30 gpm, the little solenoids can't push against that much fluid. They have to instead control another spool which resides in the D08 body. From there it's lights out, They are rated to flow like a fire hose. xxxx things weigh close to 30 lbs by themselves!~

Good luck and be prepared to have fun. I gave up a 3B to get into the hydraulics and don't regret it for a moment. It's become my main mangler in the shop

[ptree]

Heat control in hydraulics are not a hard thing to control. the PRIME principal is this,

If liquid under pressure moves to a lower pressure state, without doing work, the pressure energy degrades to heat.
So... If you have a seal leak on a piston, as the high pressure oil leaks across the seal, no work is done moving a load and heat is generated. If you make back pressure by too small lines, when the oil gets to a bigger line or the tank, the pressure drops and heat results. If you have the worst case, a fixed displacement pump, deadheaded, and dumping the full flow across a relief valve, much noise and heat results, nearly the total Hp(Kw) rating of the prime mover. So, if you have a 1 Hp motor dumping full flow across the relief, you are sending about 750Kw of heat back to the tank the entire time the fluid is flowing across the relief.
That is why a valve that dumps the full pump flow back to tank when the valve is at nuetral makes less heat.
That is the reason the return valves are usually at least the next size bigger than the pressure lines.

Return filters failing from flow? Probably had a filter without a bypass valve. A bypass lets a spring loaded poppet open when the flow would generate too much pressure if it all went thru the element.
I NEVER use less than a 50 GPM spin-on as a return filter. At 20 gpm these bypass little. The Parker 50-AT spin-on or equiv is cheap and gives large filter capacity.
There are charts to calculate the heat transfer of tanks but simply, a 28 GPM pump, on a 30 gallon tank, is too small. Usually the rule of thumb is to go at least twice pump flow and 4 times is better. This lets the oil returned travel around a long path as it goes around the center baffle, giving debris a chance to drop out is the slow flow, ai to rise out and the heat to radiate out the walls and floor. Too small and that hot dirty foamy oil short circuits right to the suction and then you often hear a gravel crusher sound as the pump cavitates. A caviating pump can self destroy in minutes.

[dan_m]

Thanks guys, I guess I'll go with a 60 gallon tank, that eight cubic feet and I have more than enough 1/8" plate in the shop already. Steve, thanks for the link to the subplate specs. Let us know how it works out if you switch to D08. You should post some pictures of your press if you have time, I'd love to see it. Ptree, my return filter is rated at 55 GPM, and has a bypass. Would it be advisable to put two offset baffles in the tank instead of one in the center? Seems like it would help, but let me know if I'm missing anything. I'm building the tank myself, so it'd be no trouble to do. Here's a picture of what I mean:



EDIT: Just remembered the flow is supposed to go over the baffle, not around it (I think). Let me know, I can't remember offhand where I was reading about tank design. Thanks again for all the help.

[ptree]

The flow goes around the baffles, not over.Think along the lines of give the oil they longest chance to contact the walls and transfer heat, and allow air to rise out and bigger debris to settle. You want the baffles to allow a nice SLOW movement. Too many make the fluid move faster and that is counter productive. I would go with one. You have the right idea about the return at one extreme and the suction at the other. If wleding your tank from plate, DO NOT PIAINT the inside. Bad chaice as the paint almost always fails and becomes filter clogging stuff. Remember that oil will protect everything under the level and the vapor above helps there as well. Industry standard is called "Pickeled and oiled"

Now lets talk about breathers. As your cylinders travel the volume in the tank will change by the volume of the rod that travels. SO you will have a tank that breathes every cycle. Since forge shops are often somewaht less than pristene, have you thought about how you will keep the pump/valve killing abrasive crud from entering with every breath? My suggestion is to NOT use a standard filler breather. They are good to filter out dead rats and oil dry and cigerrette butts but will allow system killing crud to enter. Weld in a suitable threaded nipple and use a pipe cap to seal it as the filler. Now you can buy special spin-on filters and mounting nipples from you hydraulics supplier. My suggestion is to run to the nearest auto parts store with spin-on oil filters on sale and buy a number of a common spin on that fit onto the pipe nipple you take with to try. Then weld in the nipples to your tank roof and spin those $3.50 filters down to allow breathing but only clean air.

You do plan to put a drain in as well? Use a ball valve, with a plug in the outlet, and place it at the lowest point in the tank. You are planning a gentle Vee bottom to funnel the water and debris to your ball valve to allow you to "Burp" the water and debris out every so often right? When you breath, especially in a un heated shop, cold air in the winter hits hot oil and then cools and then you have water in your oil. Solution is to change the oil often, or burp often or use a tank heater to maintain warm oil or to buy a very expensive water trap breather. I vote for a $6 ball valve:)

Going to install a sight glass to check level?
Starting to see why many companies buy ready made tanks?

[dan_m]

Ptree, that makes sense about not speeding the oil up with multiple baffles. And I won't paint the inside. I am going to put a drain in, though I hadn't thought making the bottom of the tank a sloping vee, but will do that now. I'm assuming it should slope down towards the side where the return flow enters, to help keep debris away from the pump inlet. Would you use a separate magnetic plug uphill from the drain to stop debris from clogging the ball valve, or is that not a concern?

Also, what type of filter are you referring to from the auto parts store? I don't really know anything about auto stuff, but the oil filters I've always used don't seem to breathe, they have a solid shell and a rubber gasket, like this one:

I'll return my filler/breather and go with your suggestion, I'm just not exactly sure what I'm looking for at the store. I have a picture in my head of what you are probably talking about, but don't know how to ask for it.

And I'm going to put a sight glass and thermometer in also. I do see why it's much easier to just buy a tank, but I have a sheet and a half of 1/8" plate that's not rusty, so I figured it's worth the savings to just put it together myself. Looked like something prefabbed in the size I need would run upwards of $500.

[ptree]

Dan, you have the photo above of exactly yhe type filter you need. Look at the threaded hole in the center. You need one that will screw down on a threaded pipe nipple. Most of the US car type filters will do do. Does not have to be a perfect fit, just use a bit of pipe dope. The 8 holes around the center hole are where the air goes in/out. The air has to go thru the filter to enter the tank. And since you weld the nipple vertically into the tank the solid side of the filter goes up making a nice little dust dirt and water shedding roof, and all for less than $5 for the filter:) You will need at least two for the flow/speed of your cylinders.
If I were to add a magnet to the tank, I would thank about a stack of the cheap ceramic disc magnets spaced down an all thread rod, so that they run vertically from top to almost bottom of the tank. Find a coupling that will allow the magnets to pass thruogh, and weld into the top of the tank. Weld the all thread to the plug and you have made a magnetic system sold on the market for several hundred. Place it close to the return.
The ball valve should not clog, if it is you either have a real dirt ingression problem or you waited far too long to drain.
I would pull the magnet after say 3-4 hours of run, and maybe change the main return filter then as well as cheap insurance junk from the build and from manufacture of the fittings tube components etc.

[Ten Hammers]

For me the simple answer is, there will be plumbing fittings ( read water ), US, Chinese or other. These have a burst rating perhaps 200 psi (and I indeed can be off). STANDARD HYDRAULIC fittings are designed for the pressures involved in fluid power. BOTH will have pipe threads (NPT ). The hydraulic fittings will of course have other ways of mating connections (example " O " ring, JIC, etc. ). No shame in using 2 wire standard hoses made to your order (crimped ends). Agriculture is full of it. So is industry.

Higher pressures will require 4 wire hose and fittings (these ratings are simply used on the system pressures and this is a very simple explanation ). Solid line is fine too. Aviation is full of it and that whole thing is rated a bit differently if you check on it.

Farmers and others will use a plumbing fitting on hydraulics in a pinch. I SAY this is asking for a disaster. Hydraulic injection is nasty stuff.

STANDARD rated fittings to match the lines of your choice are the answer. Perhaps the places you read the cautions were referring to plumbing fittings (rather than pipe thread per-se). The world is full of pipe thread hydraulic fittings. Just use the best thread dope you can find.

As a post script, some issues will come up looking like pipe thread when in fact they are straight thread ( O ring ). There should be a shoulder where the o ring will seat in this case. Parker fittings are a standard. The local farm store has miles of them (2 and 4 wire).