PSI Torque Gauge?

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Permalink Reply by Cory Davenport on November 25, 2011 at 4:48pm

Try this link. http://www.plasticsgroup.com/professor_polymer/conversion_factors/

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Permalink Reply by Dustin Frazier on November 25, 2011 at 5:22pm

Thanks but didn't find what I was looking for

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Permalink Reply by Tex on November 25, 2011 at 5:29pm

I will reply to this one. I would have to believe that either the DW or the cat-heads did not just arrive from NOV. I would have to assume that these are not new Cat-heads anyway. There is no direct conversion between between psi or any hydraulic pressure unless the bore and piston size is known. You must also understand if the piston and force from the fluid pressure is acting against the cylinder side of the piston or the rod side of the piston(being that there are less sq/inches) to react against on the rod side. Just as an EZ torq is creating line pull from hydraulic pressure being exerted against the back side (cylinder side) of the piston pushing the rod out of the cylinder which in return is pulling your line. There are two ways to resolve this. You can contact NOV and they should be able to supply you with the proper gauges which will show two scales (one in psi and the other in actual line pull) as is normally found on an EZ torq unit.

If you are in a hurry to resolve this then connect a good correctly calibrated normal line pull tong sensor as is found on any conventional set up to your hydraulic cat head line. Secure the other end of the sensor to a snub post. Pull on the cat head at different pressures. This will tell you the psi required for a specific line pull. Actually it is telling you how many square inches of piston the hydraulic pressure is reacting against. This is assuming that it is a single line pull and there is no sheaves, pulleys or double lining taking place. If it is a straight line (one line pull) coming from a stroking cylinder then the calculation is very simple. Hydraulic pressure x sq/inches of piston area = line pull x tong lenght = ft/lbs of torque at the tool joint. Example: 1000 psi on your new cat-head = 8333 lbs line pull on your standard tong line sensor. The piston inside your cat head has a surface area of 8.33 inches. This being the case for each psi of hydraulic pressure your cat-head pulls 8.33 lbs. 100 psi pressure = 833 lbs line pull. 1000 psi pressure = 8333 lbs line pull. 3000 psi pressure = 25,000 lbs.

 

Hope this helps.

Tex

 

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Permalink Reply by George Henry Pennings on November 25, 2011 at 5:29pm

  If these are hydralic rams being used for catheads the followiing formula would apply

piston size x 2 x .785 x the hydralic psi = linepull in pounds, that would be straight line pull if the ram was pushing (pressure on the end of the piston)

piston size x 2 x .785 - (rod size x 2 x .785) x hydralic psi = line pull in pounds, if the ram is pulling (pressure on the side where chrome rod is a attached to piston)

  If the pulls lines are doubled to the tong  that would be a multipling fact, if in doubt take some calibration pulls against an accurate tong pull guage(I am sure there still some out there) cheers all, keep a strain on 'er. 

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Permalink Reply by Cory Davenport on November 25, 2011 at 5:30pm

Let me know if you find it

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Permalink Reply by Joel Ferrell on November 25, 2011 at 5:36pm

Here are a few options that I hope will help.

 

http://www.asknumbers.com/PressureConversion.aspx

 

http://convert-to.com/195/pressure-units.html

 

http://dershin.com/conversion.html

 

http://www.plasticservice.com/conversions.htm

 

http://www.matweb.com/tools/unitconverter.aspx

 

One of these should have the proper conversion formula for you.

 

Hope it helps- Joel

 

 

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Permalink Reply by isaac vasquez on November 25, 2011 at 6:18pm

I just built a new rig and my owi 1500 have the same hy catheads its better not to trust the gauges on the drawworks it better to just get you a tong torque cylinder and a ft/lbs gauge you can't go wrong 

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Permalink Reply by kyle loney on November 25, 2011 at 10:06pm

You right on with that the best thing to do is use a old school cylinder and gauge, Hydraulic catheads are awesome but you can never go wrong with an old school gauge and cylinder.

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Permalink Reply by Dustin Frazier on November 26, 2011 at 2:59pm

I'm not sure of the piston size, I'm currently waiting on a complete scematic book on the whole d.w.. The d.w. isn't new but its in very good shape, its been well maintained, which you don't see much of. I'm going to use the old school line pull gauge and cylinder, its all I've ever used, to check it against the new gauges, I've just never seen a torque gauge with PSI and thought I would inquire and see about picking a brain or two. I've always work old conveintional rigs, these hydrualic cats and st-80 are all new to me.

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Permalink Reply by Horizon3 on November 26, 2011 at 4:04pm

You might check with the folks that made your tongs, most of them supply Martin Decker inline gauges for their tongs that are calibrated to the arm length.

(Ft/Lbs) = Length of lever from center of pivot (inside of the fixed tong jaw) to the attachment point of the load (where you hook the clevis on the tong arm) in Feet, times Force applied in Lbs.

 

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Permalink Reply by Natik Hajiyev on November 27, 2011 at 2:12pm

psi is a unit of pressure and cannot be converted  Nm( torque), but it could be converted N/m2, which is a pressure

1 pound/square inch = 6 894.757 28 newton/square meter

http://www.onlineconversion.com/pressure.htm

 

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Permalink Reply by Natik Hajiyev on November 27, 2011 at 2:31pm

Example:
100PSI, 1" diameter nozzle acting on a 1" cup with a 1ft radius arm attached to a shaft.

circle area = pi * r^2 = 3.1416 * (.5)^2 = .785 sq-in

point force = Pressure * area = 100 * .785 = 78.5 pounds

torque = force * dist = 78.5# * 1 ft = 78.5 ft-lbs

or Multiply psi x 144 to get lb/ft².

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