This study determines acceptable flow rates for both SKC and 10-mm nylon cyclone samplers to match the sampling efficiency curve specified by the new American Conference of Governmental Industrial Hygienists (ACGIH) criteria for respirable dust sampling. Monodisperse test particles were used to evaluate the relationship of particle collection efficiency versus particle aerodynamic diameter by fluorometric technique. Original flow rate at 1.7 L/min for the 10-mm nylon cyclone sampler has been confirmed to match the ACGIH (1984) criteria for solid particles. The original flow rate at 1.9 L/min for the SKC cyclone sampler has been found to result in a solid particle collection efficiency curve slightly lower than the British Medical Research Council criteria. When sampling solid particles, the new ACGIH criteria was matched at the flow rates of 1.3 and 2.2 L/min for 10-mm nylon and SKC cyclone samplers, respectively. While the 2.2 L/min flow rate for the SKC sampler is consistent with most previous studies, the 1.3 L/min flow rate for the 10-mm nylon cyclone is quite different. Furthermore, experimental results indicate that the collection efficiency of the 10-mm nylon cyclone sampler is lower for liquid particles than solid particles when particles are larger than the cut point. The difference in collection efficiency due to particle material has been found to be insignificant for the SKC sampler. Pump pulsation and the orientation of a sampler also influenced particle collection efficiency.