Abstract: A fluid valve comprises a valve housing having at least one fluid inlet and at least one fluid outlet and having a valve axis. At least one of the inlet and outlet is arranged in a wall extending circumferentially about the valve axis. The valve further comprises a rotary valve body arranged within the valve housing for rotation about the valve axis. The rotary valve body comprises a frusto-conical valve body wall and at least one inlet or outlet valve body opening through the valve body wall, the valve body being rotatable about the valve axis so as selectively to place the valve housing inlet and valve housing outlet into fluid communication via the at least one valve body opening. The at least one inlet or outlet valve body opening is a slot which extends in the direction of the valve axis.