Rotameters are adjustable, direct-reading flowmeters. Flow is indicated by the amount a ball rises in a stream of gas. Each Rotameter is calibrated for a particular gas, with +/- 5% accuracy; Repeatability is +/- 0.25%. Flow tubes are 65 mm long and have a maximum pressure rating of 200psi. They can be panel mounted as is, or used on a bench top with the optional stand. The Triple Rotameter is especially useful for FIDs and is calibrated for either He or N2 as the carrier. Gas flow of 1/10th the maximum flow is necessary to raise the indicating ball. Fittings are 1/8" female NPT.