without mixing of air corresponds to 0 air whilst the same volume filled only with air corresponds to a 100 air content adjustment of the air content can occur for example by means of the addition of tenside the agitation speed in the pulper foam generator 111 and or in that compressed air is released into the pump 133 the foam with included fibres is pumped into the inlet box 117 on a paper machine with the aid of a suitable pump 133 said machine in the shown example being of fourdrinier type the type of paper machine is however of secondary importance for the invention which can also be used on for instance suction breast roller machines and double wire machines the pump should be able to cope with large amounts of air and at the same time be able to handle long synthetic fibres where these are present without spinning effects occurring several different pump types fulfil these requirements one example is a conventional piston pump another is a vacuum pump of the water ring type e g of the helivac make manufactured by berendsen teknik as an additional example is a pump type manufactured by discflo corp which has a rotating disc pack with radial gaps in the depicted embodiment the inlet box 117 and the suction box 119 can be considered as an integrated unit the forming of the fibre web is completely closed i e there is no free fluid surface a dewatered and ready formed sheet comes out of the inlet box 117 the foam fibre dispersion is divided over the width of the machine to the inlet box 117 and fills.