Track equipment capacity in MS Project

Hello,

I have decent experience using MS Project desktop but currently struggling with how or if MS project is able to track equipment capacity in terms of quantity/units. Ideally, I would like project to 

1. alert/show capacity for an equipment based on task start/end date
2. show capacity for future planning.

For example, I have 70 samples to run on the equipment but capacity is 40 samples. I know that the 70 samples can't go through, but how can I set the equipment capacity in project to call this out? I have been tinkering with resource sheets, names, %, but don't understand how to manipulate it so that if I set an equipment capacity at 40 units (not %), it will show me capacity alerts. I also want to enter in tasks that are happening months out and would like capacity alerts to be called out in this situation too.

This is how I'm tracking it in project. I don't want to put each sample as it's own line item as there are many projects with X samples so I keep it as a high level task with the project and associated sample count. Maybe it's how I am tracking that doesn't allow for tracking capacity in units?

Any suggestions are appreciated.

Thank you.