I can't say I've had experience with a liquid particle counter so all I can offer up is some general thoughts.
OQ is generally testing the equipment functionality (does it do something with a given stimulus). OQ is also used in many cases to establish process capability. In OQ, you can establish operational ranges for the equipment (so, for example, if one product needs to run at a low-end and another product needs to run at a high end, you can execute OQ across the full range and not have to repeat the exercise for each product).
PQ is essentially showing that it will perform as expected over time. In the past, the de facto approach was to run the equipment for 3 full shifts to give such assurance. (There's a bigger push now to provide a statistical basis for the number of runs / duration of runs so take that with a grain of salt).
So given just the description of the test classes you list, my first inclination would be to say that all are OQ tests at least and possibly need to be considered also for PQ. They all sound like they are either confirming a specific function or establishing operational capability in a range.
Bear in mind that validation is expected to be risk based. If there's no risk that the equipment will operate any differently at startup or after 8 hours of continual use then PQ may either be unnecessary or can be scaled down.
I don't know if that's helpful or confusing. Validation (especially for complex equipment) is not an easy subject so if you're struggling, you may want to consider getting some outside help (expertise). There are literally hundreds of things to consider that are only revealed through experience.
