Conversion of Pressure (Bar) to kg x 1000 or Ton

[jcvilla789]

I have a pressure gauge on a unit, and it reads in two scales: kg x 1000, and Ton.

When pressure was applied to the gauge, the readings were recorded (see below).

Guage (Tons) Standard (bar) Guage (kgx1000) Standard (bar)
1 12.25 1 13.76
2 29.05 2 31
3 46.5 3 45.8
4 64.2 4 64.2
5 82 5 82

I do not know, and have not been able to find out, how to make the correlation between Ton and Bar, or Kg x 1000 and Bar.

Any help would be much appreciated.

 

[DRWeig]

I'd like to know the brand and model of the pressure gauge.

Tons is a measure of weight, not pressure.

kg x 1000 is a measure of mass, not pressure.

bar is a measure of pressure.

Pressure is force per area. Tons per square inch, perhaps, Newtons per square meter, or Pascals.


Good on ya,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[IRstuff]

Can't make heads or tails from the numbers. They are not even linearly increasing with supposed increased in pressure. I think it's seriously broken. 13.76bar = 140.3 kg*g/m^2

TTFN
faq731-376

 

[zdas04]

kgf/cm^2 is starting to be a very common pressure measure. I find it quite funny that now we're starting to see tonne-f. Welcome to the world of g[sub]c[/sub].

The funniest thing about kgf/cm^2 is that it is such a worthless measure. According to Katmar's excellent Uconeer program 1 bar = 0.981 kgf/cm^2 (something quite memorable about the digit-order in that number) so there is zero benefit to bastardizing SI further for this silly unit.

I would guess that the messed-up table in the OP is just sloppy handling of parallax issues.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[IRstuff]

Well, the data is otherwise absurdly smooth, just the slope and intercepts are inconsistent. Neither goes through zero, which suggests that the meter is seriously out of calibration or is broken.

TTFN
faq731-376

 

[danw2]

Pressure gauges are used on hydraulic presses to indicate the applied force.

Pressure = force/area. The area the force is applied over is the area of the cylinder ram.

So force/area*area = force

 

[jcvilla789]

Apologies for the original sloppy post. Didn't come out as I had hoped.

I have attached a picture of the gauge and the unit it is part of.

 

[jcvilla789]

Complete unit is attached. I have cleaned up the results and taken a snapshot.

 

[jcvilla789]

Take 3!

This is the complete unit that the gauge is part of.

There is a lever on the side of the unit that is "pumped" manually (like an old water pump), bringing the cylindrical bar down onto a metal part.

The gauge measures the applied force (or mass) to the part. The gauge is acting on pressure, so it made sense to me to apply pressure from a reference standard an find the correlation between the applied pressure and the mass readout.

This is all I'm looking to do. I just need to know how to get from my ref. std. pressure reading (in Bar) to the Ton / kg x 1000 reading on the gauge.

 

[zdas04]

The gauge is going to sense a pressure (bar, kgf/cm^2, psi, etc.) The scale has that pressure multiplied times the area of the plunger to get a total force applied. The "ton" scale could be tonne (or metric ton or 1000 kg or 2204.6 lbm), long ton (1016 kg or 2240 lbm) or short ton (907 kg or 2000 lbm). With as close as the two scales are I'm thinking that the "ton" scale is "long ton". When the kg X 1000 scale reads 25, a long ton scale would read 24.6 which is about what I see on your pictures.

David Simpson, PE
MuleShoe Engineering

"Belief" is the acceptance of an hypotheses in the absence of data.
"Prejudice" is having an opinion not supported by the preponderance of the data.
"Knowledge" is only found through the accumulation and analysis of data.

 

[ScottyUK]

The tons / kg x 1000 looks plausible, one tonne being equal to 1000 kg and also being equal to 0.9842 long tons. You need to know the diameter of the piston or ram which the pressure is acting upon to find the relationship between the applied pressure and the applied force. I didn't find it on the manufacturer's website but here's the datasheet for the press:

http://www.specac.com/userfiles/file/50AtlasManualHydraulicPress.pdf.

Maybe a call to the manufacturer...?

 

[jcvilla789]

Thanks for all your help people...

I will have to try and take it from here I think, doubt there is much else anyone can do for me.

 

[jont21]

Ask an ISO17025 accredited lab with certified force calibration in compression mode to bring a calibrated loadcell up to 25 tonf or above to get it calibrated against the gauge in situ on your site. You will be give a certified report to give you confidence of the force read from the pressure gauge marked in force. Not necessary to be calibrated by pressure. If calibrated by pressure, the effective area of the hydraulic piston-cylinder need to be known.