A controlled discharge ostomy appliance assembly, comprising: (a) a controlled discharge ostomy appliance having a body-facing side for facing towards a stoma in use, the appliance comprising: a seal support wall ; a flexible seal membrane sealed to the support wall to define a seal chamber ; a resilient device disposed in the seal chamber and configured for generating, in response to compression of the resilient device from the body facing side, a resilient return force for urging the seal membrane in a direction towards the body-facing side to a deployed seal state; and at least one port communicating with the seal chamber for permitting the transfer of inflation fluid with respect to the seal chamber , said at least one port defining a fluid flow property to effect a dynamic damping characteristic for changes in volume of the seal chamber ; and (b) a seal displacer fastened releasably to the appliance forming a combined assembly therewith, the seal displacer being manipulable by hand to displace the seal membrane against the return force of the resilient device , to place the seal membrane in a non-deployed seal state ready for the appliance to be fitted at a stoma, wherein in the non-deployed seal state the resilient device is substantially compressed, and the seal membrane is displaced to a substantially non-operative position, and whereafter, upon separation of the seal displacer from the appliance , the seal membrane advances progressively towards the deployed seal state by the resilient return force damped by the dynamic damping characteristic. (a) a controlled discharge ostomy appliance having a body-facing side for facing towards a stoma in use, the appliance comprising: a seal support wall ; a flexible seal membrane sealed to the support wall to define a seal chamber ; a resilient device disposed in the seal chamber and configured for generating, in response to compression of the resilient device from the body facing side, a resilient return force for urging the seal membrane in a direction towards the body-facing side to a deployed seal state; and at least one port communicating with the seal chamber for permitting the transfer of inflation fluid with respect to the seal chamber , said at least one port defining a fluid flow property to effect a dynamic damping characteristic for changes in volume of the seal chamber ; and a seal support wall ; a flexible seal membrane sealed to the support wall to define a seal chamber ; a resilient device disposed in the seal chamber and configured for generating, in response to compression of the resilient device from the body facing side, a resilient return force for urging the seal membrane in a direction towards the body-facing side to a deployed seal state; and at least one port communicating with the seal chamber for permitting the transfer of inflation fluid with respect to the seal chamber , said at least one port defining a fluid flow property to effect a dynamic damping characteristic for changes in volume of the seal chamber ; and (b) a seal displacer fastened releasably to the appliance forming a combined assembly therewith, the seal displacer being manipulable by hand to displace the seal membrane against the return force of the resilient device , to place the seal membrane in a non-deployed seal state ready for the appliance to be fitted at a stoma, wherein in the non-deployed seal state the resilient device is substantially compressed, and the seal membrane is displaced to a substantially non-operative position, and whereafter, upon separation of the seal displacer from the appliance , the seal membrane advances progressively towards the deployed seal state by the resilient return force damped by the dynamic damping characteristic. <EOS>