The FGG FLOWGRIDS are most popular. They are used to measure the velocity pressure accross the complete duct area to provide an average velocity pressure measurement. They are manufactured as a standard galvanised duct frame with multiple Aluminium Flowprobes positioned internally. The total velocity pressure is captured by the FGG Flowgrids averaging tank to ptovide a smooth velocity pressure..

FGG data sheet

The all stainless steel VSS VELOGRIDS are used to measure the velocity pressure accross the complete duct to provide an average velocity pressure measurement. They are manufactured as a standard stainless steel duct frame with multiple stainless steel Veloprobes positioned internally. The total velocity pressure is captured by the VGS Velogrids averaging tank to ptovide a smooth velocity pressure..

VSS data sheet