I haven't used the Perspective device Symbols before, but just looked at using the "vessel" now, and noticed a simple issue with the level bar chart that precludes me from looking at using it any further. I.e. the bar chart rectangle is offset by a pixel
The rectangle simply needs to be pushed down by a pixel. However there's another discrepancy with the tank borders being rounded and the level bar being straight..
Looking at the Motor symbol, it seems to be unusable in percent mode coordinate containers, as the circular symbol resizes out of sync with the page, despite the view's aspect ratio being fixed:
1K resolution
2K resolution (circle is offset)
This is only an issue when you have the label and/or speed shown, as the heights of these are based on the size of the font, not the scale of the component, so when the resolution changes, these remain the same, while the circle changes size disproportionately...
And as always, stacking strokes in SVGs is never a good idea, as you end up with stacked anti-aliasing which makes the lines appear slightly thicker:
(this is the "fixed" bar from the vessel symbol, with the bar shifted down a pixel, however in doing that, you can see that the bar is just a rectangle with a stroke which stacks on top of the tank stroke and causes it to look slightly thicker than the rest of the vessel's stroke 
the weird bit in the corner is due to the vessel corner being rounded)
If I was remaking this SVG, the vessel would have, in z-order:
- a stroke component for the vessel on top of everything
- a line stroke for the right side of the level bar, with end nodes halfway into the top and bottom vessel strokes (so as not to stack anti-aliasing)
- a level bar fill rectangle
- a fill below everything
This issue is present in the piping tool pipes as well, e.g. when you have T junctions as well as corners:
