Pressure release before filling?

Currently, we use IJM carts only for Piezoflush, cleaning or storing our printers. Our IJM carts have the following printed in red on the label: " Slowly release pressure before re-filling." The instructions posted for the carts don’t mention this—or, at least the ones I downloaded and printed at least 18 months ago don’t. I would think pressure would be released when one removes the filler plug. I have not had problems relating to filling yet, but am I missing something?

There’s also an arrow on the label, that points to a plug that I have not seen discussed anywhere. It is round, translucent, and the cap fits flush with the side of the cart when in place. It seems to access the exit port of the cart. It is near the air inlet port that is plugged with an orange cap when the cart is not in use. Unlike the arrow pointing to the orange cap, this arrow is un-captioned. Does the plug have any purpose for users?

Pressure is released when one removes the filling plug. It is recommended that you slowly pull that out so that you do not get sprayed by quickly pulling it.

We do not recommend using the access port to prime the cartridge. We recommend instead that you use the ink outlet port (the part that the ink comes out of into the printer’s ink line). Check our latest cartridge filling videos here:

Thanks for clarifying the confusing cartridge label.