FOR VSD/VCD/VRD DIFFUSERS
A relief ring is a product supplied in instances where the particular application of our VAV ceiling diffusers is in a system where the supply air pressure cannot be readily controlled.
The purpose of the relief ring is to provide the necessary pressure relief to ensure that the pressure in the diffuser stays “relatively” constant. If no pressure relief is provided, the pressure in the ducting and diffuser will increase immensely as the control disk closes. This has the undesired effect of making the diffuser noisy, as well as not being able to control the air volume flow rate sufficiently.