i want to add a pressure gauge to my hydraulic press. it has a two way ram in it, what i mean, two hoses to control travel, one at bottom and one at top. which port to i tee into to add the gauge. let say the cly travel down when operation, so to read pressure on what being press and not what the pump putting out, would it be the top hose since the top hose is feeding the ram to push down
hydraulic question
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racecougar
Well-known member
Yes, it's likely the top port that you would want to read pressure at. A photo or two would confirm.
andyvh1959
Well-known member
If you want to know the pressure is when the ram is operating down, you can put the gauge anywhere in that line. For something like a press which is slow steady operation with low flow, pressure will be the same anywhere in the circuit after the control valve or at the cylinder connection.
jack stand
Well-known member
....and with a little measuring and an online chart lookup you can put in an easier to use/understand "measurement" of pounds of force vs the psi.
nadogail
Well-known member
Your hydraulic press is pushing at a force calculated by multiplying the PSI of the fluid times the area of the piston.
Piston area is PI times the Square of the Radius. To get more force you can increase the pressure or the diameter of the cylinder.
The Hydraulic Pressure can be measured with a gauge, the piston size will be a physical measurement.
Piston area is PI times the Square of the Radius. To get more force you can increase the pressure or the diameter of the cylinder.
The Hydraulic Pressure can be measured with a gauge, the piston size will be a physical measurement.
Steve W.
Well-known member
You will know the PSI, but you won’t know the pounds until you measure the piston diameter.
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Monza Harry
Well-known member
As stated above on the extend port line anywhere convenient after the valve. If you want retract force same calculation as noted by @nadogail minus the same calculation fot the cylinder rod. IE; cylinder area minus rod area. Retract and extend would require 2 gauges or placing in the supply line and would only be accurate at full lever pull in the supply line [pressure feed]. Harry
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What part of post #5 do you not understand?
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There's no post 15
BillK
Well-known member
If you want the gauge to tell you the pressure on the item you will have to find a press that has a gauge and also has the same size ram as yours does. Then buy a replacement gauge for that press.
Otherwise you will have to do the math and calculate the ram force from the hydraulic pressure.
Rockable
Well-known member
Force = Pressure X Area
Area = π X Diameter of piston / 4
You will have to figure out the diameter of the piston. Can't help you with that.
andyvh1959
Well-known member
Even if you find a press with a gauge on it, and use that guage on your press it will still only tell you the pressure in the circuit. If the press guage has been altered to show a force scale with the math conversion built in it could show the actual force.
Or, just buy this: https://www.woodysrocks.com/store/p86/Pressure_to_Force_Gauges.html#/
Its a calibrated gauge/piston to show the actual force applied BETWEEN the ram and the workpiece. Its designed to show the real force in pounds sensed by the pressure inside the gauge piston block.
Just curious, why do you even want to know the actual force to do the work? If the press is able to do the work, its done. If your press has no gauge, a common pressure gauge from McMaster Carr or Grainger, plumbed in the circuit will tell you the pressure. Then using the piston diameter you calculate the force. Done.
Or, just buy this: https://www.woodysrocks.com/store/p86/Pressure_to_Force_Gauges.html#/
Its a calibrated gauge/piston to show the actual force applied BETWEEN the ram and the workpiece. Its designed to show the real force in pounds sensed by the pressure inside the gauge piston block.
Just curious, why do you even want to know the actual force to do the work? If the press is able to do the work, its done. If your press has no gauge, a common pressure gauge from McMaster Carr or Grainger, plumbed in the circuit will tell you the pressure. Then using the piston diameter you calculate the force. Done.
nadogail
Well-known member
Apparently you slept through Eighth Grade Math. Time for a refresher.
Firebrick43
Well-known member
you cant know what the force your press is exerting unless you know the size of the ram/piston. The size of the ram is literally everything!
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Monza Harry
Well-known member
Here read a few of these links to familiarize yourself to the workings of hydraulic systems. These principles do apply to second hand as well. Just more math away! [Area of the plunger (which may or may not be the cylinder rod) verses the area of the secondary process. That would likely require way more info! But that isn't what you asked about as I read it. Harry
You are correct in that the size of the ram doesn't matter, however what does matter is the size of the piston that the hydraulic pressure is acting on. Read and understand post #12 or #5. You asked for force, are you sure that you don't want the pressure per square inch, PSI, on the item you are pressing against? Force is what it is, PSI is force /area.
lg
no neat sig line
You do not use a simple pressure gauge in the hydraulic circuit to measure force. All that will give you is the pressure of the fluid. Force has to be derived from the pressure of the fluid to determine the force that the cylinder is delivering.
lg
jsaw
Well-known member
On some presses, There is a gage that is calibrated to the size of the cylinder so that it is graduated to display the force exerted. The pressure and area of the cylinder would be used to calculate the force and the gage would be graduated to display the force
whateg01
Well-known member
Wrong. If you want to know the pressure on the item, you need the area of the end of the ram or tool. The total force applied divided by that area is your pressure on the part. If you want to know the force applied, you need the hydraulic pressure times the area of the cylinder. The gauge in the hose only tells you the hydraulic pressure applied to the cylinder.
Force is not the same as pressure.
we break concrete samples at work, when we break 6x12 we divide "load" by 28.27 when we break 4x8 we divide load by 12.45 to get psi. I want to read "load" on my hydraulic press, not psi, so ram size doesnt matter, because with load you can see failure, a 1/2 second before it happens. I just dont want to take my company break machine apart to see how the gauge is attach, too lazy and boss likes to yell
TurnipTruck
Well-known member
In my spare time, I hope to eventually add a gauge to the spare output port on my 2 post so I can weigh my cars.
After some tests to confirm my calculations and to weigh the carriages, I will reface the gauge.
-maybe, if I have a 3000?psi gauge and a 10000psi face, I could possibly make a direct readout-
*hugely zoomed in screenshot stolen years ago from a forgotten GJ member*
After some tests to confirm my calculations and to weigh the carriages, I will reface the gauge.
-maybe, if I have a 3000?psi gauge and a 10000psi face, I could possibly make a direct readout-
*hugely zoomed in screenshot stolen years ago from a forgotten GJ member*
johnre
Well-known member
Man, I sure hope this thread doesn’t segue off into the energy added by the press and the power needed to deliver it ….
1. Terminology
What you say is "ram" is the plate that smashes (and completely covers) your concrete samples. If the ram is bigger than 6x12, then the size of the ram doesn't matter.
6x12=72
4x8=32
72/32=2.25
28.27/12.45=2.27
Your "load" conversion factors listed are tied to surface area so your "load" has to be weight.
Your "ram" is "loaded" by a hydraulic "piston". Two completely different parts of the machine
If you want to see how much weight of load your piston is producing by reading a pressure gauge, you have to know the size of the piston in surface area.
Rockable
Well-known member
You can lead a horse to water.......
Firebrick43
Well-known member
You would have had a much higher quality of results if you had said that you were testing concrete samples to start.
It sounds as the gauge on your press is already modified to be direct reading of force/load the press is outputting. It still is a PSI gauge, the face has just been replaced with the correction factor applied.
The concrete sample, depending on size, has to have a correction factor applied to get the PSI strength of the concrete. This correction factor is because a bigger sample will take more force to break but concrete PSI rating is pounds "per square inch" since the sample have the area of 28.27 square area for a 6" circle of the cylinder and 12.45 square inches for a 4" circle area of a cylinder that is the correction factor.
The PSI of the concrete is in no way related to the PSI inside the hydraulic cylinder, as hydraulics multiply force by using surface area of the piston. In many presses the piston/ram are one in the same as very few are two way cylinders. The only way the psi would matter directly is if the samples were exactly the same size as the piston in the cylinder of the press
In your press what you are calling the ram is the actually on the end of the cylinder rod.
*note* Multiple gauges could be installed and have the faces replaced the correction factor applied to be direct reading. One gauge would be for a 4" sample and another for a 6" sample.
There are some digital pressure gauges that can be programmed to displace force such as described a little bit down on this page.
https://www.apgsensors.com/about-us/blog/convert-psi-to-lbs-using-a-digital-pressure-gauge/
The few that I have seen with a quick google fu search that can do this cost in the $1000-1200 range. Again you would need one for each sample area size. The math wouldn't be quite the same as you would have to have the aforementioned correction factor for sample size as well.
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andyvh1959
Well-known member
Wrong, you're missing the point. By what you're saying if you're pressing a five square inch area it determines the force, or if you're pressing a 10 square inch area it determines the force you're pressing. Nope. only the size of the ram (ram diameter determines square area of the ram), with the applied pressure, determines the force applied. The force applied doesn't change with the size of the surface area of the piece being pressed.
Size of the ram DOES matter because it determines the force applied for a given pressure.
A 2" diameter piston (the end of the piston may be the ram), at 1500 psi will produce a force of 4,712.4 lbs.
A 3" diameter piston at 1500 psi will produce a force of 10,602.9 lbs.
So for any pressure, the surface area of the piston (the ram) determines the force. If you can vary the pressure, one ram size will produce a variety of force. Or, if your pump can only produce 1,500 psi max, then the surface area of the piston (the ram) determines the force.
alteredimage
Member
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- Jun 30, 2023
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top hose
gauge as in psi?
Then listen to responses. UNLESS we are speaking of very low pressure.
Or gauge vs. load cell calibration
Force or pressure?
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