Prevent Logic Hook/Workflow Trigger Firing from a Custom Scheduler

Hi,

I have a custom scheduler job to calculate and update an SLA timer field on Cases, currently running every 5 minutes.

Is there anyway to prevent a bean save ($myCase->save()) from firing logic hooks or initiating workflows?

For example, we are using Sierra workflow to update a datetime field the first time a case is modified (first response time). However our custom scheduler causes the workflow to trigger and the field to be set. We only want it set on a user-initiated modification.

Thanks

Gary.