Rolamite valve swap
This video shows how to change the position of a large Rolamite valve on an Alicat gas mass flow controller (part numbers beginning with MCR), from upstream to downstream. Moving the valve is done to place the sensor in a different location of the flow stream relative to the valve, because of differences in pressures and ranges. The procedure is reversible if you need to move the valve from downstream to upstream. It is essentially the same on a high-flow Alicat pressure controller (part number beginning with PCR). The procedure takes about 10 minutes. It is not highly technical, but is best performed by an experienced technician.Printable Directions
If you have a flow or pressure controller with a smaller valve, see our video for changing a small valve.