CDI uses a criteria of < 1% for fabric and steel cord at the minimum operation tension along the carry flight. Up to 3% momentary dynamic sag is allowed. This also depends on the structural arrangement.

The low sag ~ 2% allowed by CEMA and other standards, drives up the demand power and belt rating, However, you must have the analytic tool to see and evaluated these conditions, such as BELTSTAT.

If you are trying to drop the counterweight tension to justify installing low sag, heaven forbids it.

Clients hire those that don't know, but, hoping you will get the message since you asked and have arisen above the eternal dark forces we meet too often. ■