Abstract: A fluid flow regulating valve adapted to prevent the operation of the valve from violent pressure change, namely the hydraulic ram effect, in the fluid, particularly during closing and opening of the valve, the valve comprising a casing that houses a regulating plate slidably mounted within the casing. The plate has a regulating orifice having a variable fluid pass section which decreases from an end to another end of the orifice. The orifice is adapted to be aligned, through its different sections, with inlet and outlet ports provided in the casing, whereby the inlet and outlet ports communicate to each other through the orifice and the fluid flow can be regulated by those different sections of the orifice.