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 Post subject: Try to understand ArcProPosted: Fri Jul 11, 2014 2:28 pm

Joined: Thu Jun 05, 2014 5:52 pm
Posts: 19
Hi there,

I reviewed an Arcpro report in which the Reporter provide a CLOTH SELECTED with 2 range of value of "TO THE RIGHT" and "ABOVE" of the Arc. Can any one explains the science behind of "TO THE RIGHT" and "ABOVE" the Arc and how to determine the ABOVE while the program only provide the marker on the right base on working distance?

Thanks

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 Post subject: Re: Try to understand ArcProPosted: Mon Jul 21, 2014 4:39 pm

Joined: Thu Apr 17, 2014 12:43 pm
Posts: 1
Arcpro provides a graphical representation and numerical values for the incident energy in cal/cm2 at various distances away from the arc, and also at various angles from the arc.

Not only does Arcpro tell you the incident energy radially perpendicular from the center of the arc (often, but not always the worst case), but it also shows you the incident energy at other points in a hemi-sphere around the arc. A 2-dimensional slice through this hemisphere is illustrated in the Arcpro output. The 2-dimensional plane is defined by 2 axes. The R axis indicates moving radially away perpendicular to the arc, defined as "to the right of the arc". "Above" the arc is indicated by the Z axis.

You can move your cursor around on this plane space and find the arc energy at any point "to the right" (it is symmetrical on the left) or above the arc. (The default position for the marker is at the distance to the right of the arc that you specified in the inputs)

Why give energies in this 2 dimensional space? It illustrates that arc energy can vary depending on where the worker might be in relation to the arc. If the arc were a point source and all the energy were purely Radiated, the energy at a given distance, no matter in what direction from the arc would be the same as the energy at that same distance in any other direction. Arcpro, however, considers the realistic case that some of the energy is delivered by Convection. The convected hot air rises. Therefore for arcs of long duration, there can be more energy delivered to surface at a particular distance "above" the arc, than at that same distance "to the right of the arc".

An engineer doing an arc hazard assessment where the worker might in fact be above the arc, would be prudent to consider the convected energy above the arc. Note that all other calculation methods are empirical curve fits derived from test results which measured only the energy radially outward from the arc, and therefore do not include the convected energy above the arc. Arcpro is a physics-based model of the arc and its heat transfer.

You mention that the `program only provide the marker on the right base on working distance?` Please note that the marker is moveable. You can move the marker with your cursor at find the energy at any point in the hemisphere around the arc. The color bands also give you an indication of the `hottest spots`around the arc.

Kinectrics provides training on the science and engineering Arc Hazard Analysis using Arcpro and other computation methods. Please see www.kinectrics.com .

Let me know if you wish more details.

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 Post subject: Re: Try to understand ArcProPosted: Mon Jul 21, 2014 9:15 pm

Joined: Thu Jun 05, 2014 5:52 pm
Posts: 19
Steve,

Thanks for you help. It is really interesting to look that way. I am news to ArcPro and wish to know more....thanks in advance.

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