Abstract: An in-line pressure regulator for regulating fluid flow comprising a housing having an inlet and an outlet, said housing providing a first chamber open to the inlet and having a first port open to a second chamber, a second port opening to the second chamber, the second chamber having a third port opening to the outlet, a support element movably received within the first and second chambers and accommodating a set of three valve members wherein a valve member is associated with each port; the support element being movable within the first chamber to vary the extent of engagement of the valve members with the first and second ports, said support element being biased to an end position at which the first and second ports are open, and the third port is closed, said support element supporting a pressure surface in the secondary chamber whereby the force exerted by fluid pressure in the secondary chamber on the support element counteracts the biasing force applied thereto to move the support element from its end