Abstract: Bag sealing apparatus comprises a compressed air source which pumps air through a supply pipe towards an opening in a bag. Bag material is advanced by rollers from a roll. The material is in the form of two layers open at one side. The supply pipe extends between the layers through the open side and the open side is sealed by heat sealing by two side members. Each of the rollers defines a circumferential recess and the two recesses together receive the supply pipe. The apparatus further comprises heat sealing elements for sealing the opening in the bag and spring mounted clamp parts for clamping the bag downstream of the sealing elements to reduce fluid back pressure from the downstream bag.