a downhole flow device has a sliding and ported sleeves . a seal has a first component on the sliding sleeve and a second component on the ported sleeve . these components engage one another to seal flow through the ports in the ported sleeve . the components move apart to allow fluid flow through the ports . the components are protected from abrasion and flow by virtue of the seal &# 39 ; s structure and how it is opened . the sliding sleeve moves hydraulically along an axis of the ported sleeve to reveal successive ports defined along the sleeve &# 39 ; s axis . operation of the device and the seal address both erosion and damage from differential pressure problems . thus , the seal prevent damage when unloading a differential pressure across it , and abrasive flow does not have the opportunity to impinge on the sealing surfaces to cause erosion .