A filtration and monitoring system for online monitoring of a parameter in a fluid system, the filtration and monitoring system comprising: an online monitoring device configured to monitor a parameter of a portion of a fluid in the fluid system; a filter block forming a filter block chamber therein and comprising a filter element; an inlet pipe configured to provide fluid to the filter block chamber, said inlet pipe defining an inlet axis and further having an inlet valve located therein configured to shut off the flow of the fluid through said inlet pipe; an outlet pipe configured to remove fluid from the filter block chamber, said outlet pipe defining an outlet axis; and a filtered fluid conduit fluidically connecting the filter block with the online monitoring device, said filtered fluid conduit having a pressure accumulator located therein; said filter block chamber configured to provide cross flow filtration such that only a portion of the fluid flow entering the filter block chamber through the inlet pipe proceeds through the filter element and is directed on towards the online monitoring device through the filtered fluid conduit; wherein the outlet axis of the outlet pipe is offset from the inlet axis of the inlet pipe such that the fluid undergoes a change of direction while passing through the filter block chamber thereby causing a turbulent cleaning vortex flow within the filter block chamber to sweep particles off from a filter block chamber-side of said filter element and the inlet valve is configured such that closing the inlet valve in the inlet pipe to stop the flow of fluid through the filter block results in an accompanying pressure drop in the filter block chamber and a pressure differential in which the pressure in the pressure accumulator is greater than the pressure in the filter block chamber, the pressure differential thereby back-flushing a flow of fluid from the pressure accumulator to the filter block chamber through the filter element, thereby dislodging filter cake accumulated on the chamber-side of the filter element for removal of the dislodged filter cake through the outlet pipe on opening of the inlet valve to restore the flow of fluid through the filter block. an online monitoring device configured to monitor a parameter of a portion of a fluid in the fluid system; a filter block forming a filter block chamber therein and comprising a filter element; an inlet pipe configured to provide fluid to the filter block chamber, said inlet pipe defining an inlet axis and further having an inlet valve located therein configured to shut off the flow of the fluid through said inlet pipe; an outlet pipe configured to remove fluid from the filter block chamber, said outlet pipe defining an outlet axis; and a filtered fluid conduit fluidically connecting the filter block with the online monitoring device, said filtered fluid conduit having a pressure accumulator located therein; said filter block chamber configured to provide cross flow filtration such that only a portion of the fluid flow entering the filter block chamber through the inlet pipe proceeds through the filter element and is directed on towards the online monitoring device through the filtered fluid conduit; wherein the outlet axis of the outlet pipe is offset from the inlet axis of the inlet pipe such that the fluid undergoes a change of direction while passing through the filter block chamber thereby causing a turbulent cleaning vortex flow within the filter block chamber to sweep particles off from a filter block chamber-side of said filter element and the inlet valve is configured such that closing the inlet valve in the inlet pipe to stop the flow of fluid through the filter block results in an accompanying pressure drop in the filter block chamber and a pressure differential in which the pressure in the pressure accumulator is greater than the pressure in the filter block chamber, the pressure differential thereby back-flushing a flow of fluid from the pressure accumulator to the filter block chamber through the filter element, thereby dislodging filter cake accumulated on the chamber-side of the filter element for removal of the dislodged filter cake through the outlet pipe on opening of the inlet valve to restore the flow of fluid through the filter block.