Three things I've noticed:

1. I'd suggest renaming the expander to "decompressor", or both to "pressurize"/"depressurizer".
2. The flow rate on compressors/expanders is far lower than pumps. This makes them difficult, sometimes impossible to use where high flow rates are required. A high capacity version could be useful here.
3. They cannot be connected to the circuit network. I presently get around this by combining them with pumps.

1. The original name was decompressor, but that's not a real word, and pressurizer/depressurizer is derived from the verb. I opted for the official names after some suggestions.

2. Have you considered grouping some buildings to a single compressor/expander or even a single one for each building? You can get a compressor to work full time in vanilla just by beaconing your oil factories, the original design was not made just for the pipe, but more in combination with a building. However, there are settings you can tweak to change the speed and/or compressing rate. You can go really crazy with it. Just try it ;)

3. They are furnaces (similar to put iron ore in, get iron plate out), these cannot be connected to the circuit network sadly. There are other mods that allow you to enable/disable buildings through the circuit network. Maybe try to combine mods?