I ran across this when trying to adjust the distance from the valve symbol that flanges are placed when the 'flanged end connection' type is selected.
When I edit the block for 'Flanged' end connection, the flange is 0.5" tall. Huge. But when the connections are added to a valve or other piece of equipment the come in the correct size.
Checking further, I noticed that all the valves are being inserted at 1/4 scale, but no other equipment is.
My question is this: Why would the valves be drawn four times larger and scaled down on insertion?
I think that you'll find that most blocks have been drawn unitless so that they can then be scaled to suit Imperial or Metric projects by changing the scale factor. Unfortunatley, the same scale factor is also applied to the end connections when they are added to Inline Assets.
I find this rather strange. I was under the impression that a block can be inserted as 'unitless', but the any actual block or geometry will have a unit.
It seems that certain items in the project are automatically scaled down by 25% for imperial and scaled up by 10 for metric. Was 1" length just an arbitrary starting point for the valve size?
If you insert a control valve: the valve will be inserted scaled down, but the actuator is inserted at 100%.
Items like rotometers can not use the default text styles because any text in the block has to be scaled up.
P&ID does not use the standard AutoCAD block scaling rules when it inserts symbols.
Basically, all blocks are drawn and saved unitless in projSymbolStyle. When placed, the blocks assume the same units as the Project and are scaled up or down according to the symbol scale factor within the Project.
Why are different symbols scaled differently? I have no idea, however, I would hazard a guess to it possibly being a case of re-using existing symbols from different sources when the package was initially put together. I may be wrong, of course.
Hence the scaling anomalies that you have mentioned.
If you look at the settings of the OOTB valves, you'll notice that their scale factor is set to ".25".
If you scale all of your hand valves up by a factor of 4 within the block editor and then click on "Edit Symbol" for each of your valves, you should change your scale factor setting to ".25" and they should come in correctly. Not sure why they did it this way, seems strange, but if you follow suit it will work with no problems.
As far as the end connections go, you might have to scale them down to a factor of 1/4 within the block editor, and all should be well from there.
Hope this helps!