INJECTOR APPARATUS

An injector apparatus () for injecting fluid under pressure into an associated chamber (), the apparatus including a body (), a first piston () moveable in the body, the first piston () defining a first working area facing an associated chamber (), a high pressure piston () defining a high pressure working area () facing a high pressure chamber (), the first working area being greater than the high pressure working area (), the first piston () being operable to compress fluid in the high pressure chamber (), the first piston () further defining an injector orifice () through which the fluid can be injected into an associated chamber () from the high pressure chamber () and defining a valve seat (), a valve member () selectively operable to engage the valve seat () to operably isolate the high pressure chamber () from the injector orifice () and selectively operable to disengage the valve seat () to fluidly connect the high pressure chamber () with the injector orifice ().