Compositepro - yes and no. Just 'Dew Point' normally does refer to dew point at atmospheric pressure (also 'atmospheric dew point' is used sometimes) but there's also a 'pressure dew point', which is the dew point at some specific higher pressure. A lot of guys (like me) just get lazy when they're talking about plant instrument air systems and just shorten it to dew point, but it's implied that it's dew point at rated pressure for the I/A system. Gets taken in context with the application, I suppose. I'm used to Northern Alberta where the I/A systems are typically rated somewhere below -40C pressure dew point @ I/A package rated pressure to prevent water forming & freezing in the uninsulated outdoor headers around the plant.
Agreed about dryers being sensitive to surge, so in my experience the instrument air system, which needs to be dry, has a larger dry air receiver downstream of the dryers to stabilize the flow through the dryers (normally the dessicant type). If there is to be a utility air system for tools or things like that which don't require low dew point air they'll either use a separate compressor with the air supply coming directly off a wet air receiver, or they'll provide a separate takeoff upstream of the dryers on the main compressor package, or depending on the client they'll just heavily oversize the dry air receiver and run the whole plant off that, including utility air.
Regards,
Mike Henderson