pressure relief valve

combined pressure and vacuum relief valve

relief valve

check valve / non-return valve

non-return valve / check valve

pressure reducing valve

pressure regulating valve

civil relief

civilian relief units

disaster aid / relief

disaster relief

disaster relief assistance

disaster relief operations

disaster-relief operation

emergency relief

emergency relief operation

humanitarian operation; humanitarian relief operation (HUMRO)

humanitarian relief

humanitarian relief worker

international disaster relief

International Disaster Relief Operation (IDRO)

plastic relief map

plastic relief photomap

relief

relief features

relief in place (RiP)

relief map

relief operation

relief order

relief road

relief shading

relief-in-place

safeguarding humanitarian relief supplies