PPAP stands for Production Part Approval Process. It typically would be used on parts that are being produced to be installed on the automotive assembly line, or service parts to be installed by automotive dealerships.
However, I've seen the PPAP process expanded to well beyond the automotive industry. However, it is not typically used for equipment, since equipment is often purchased as one-offs. I had a client who made progressive dies and an OEM customer wanted them to do a 300 part PPAP (these dies run about $100K ea). You don't PPAP 300 parts to sell a dozen or less. But your customer might have a slightly different process they want you to go through.
If you have a customer asking for PPAP, you should get clarification of why the "Production Part Approval Process" applies to your product and what process they want you to follow.