1. Constant Flow Pumps

2. Pump is an “air-mover” used to draw air Pump is an “air-mover” used to draw air  Through filter medium(ex. impinger)  Into collection container(ex. sample bag) Constant flow necessary Constant flow necessary  Accurate flow rates  Uniform media absorption/deposition

3. Constant Flow Pumps Types Types  Low-Flow <1L/min  High-Flow 1-4 L/min  Multi-flow <1L/min-4L/min  Ultrahigh-flow >4L/min  AC power only

4. Constant Flow Pumps Operating parameter Operating parameter  Provide constant flow of air  Despite battery voltage  Despite tubing diameter or length  Despite filter medium

5. Constant Flow Pumps Method of Operation Method of Operation  Calibrated orifice plate  Provides ability to measure pressure differentials pre/post orifice  Pump speed is then adjusted to compensate, thereby maintaining the constant flow

6. Constant Flow Pumps Method of Operation Method of Operation  Alternately critical orifice utilized  Based on maximum flow through orifice, constant flow maintained

7. Constant Flow Pumps Calibration Calibration  Rotameter  Flow is calibrated against ball “floating” in air in the chamber  Bubble tube(Manual or Electronic)  Flow is calibrated by timing bubble travel speed in vertical column

8. Constant Flow Pumps Calibration Train with Electronic Bubble Tube Calibration Train with Electronic Bubble Tube

9. References Cited SKC Inc. Corporate Web Page http://www.skcinc.com/http://www.skcinc.com/ accessed 03/06/01 http://www.skcinc.com/

10. Bibliography DiNardi Salvatore R. (1998) The Occupational Environment-Its Evaluation and Control, AIHA, Fairfax, Virginia DiNardi Salvatore R. (1998) The Occupational Environment-Its Evaluation and Control, AIHA, Fairfax, Virginia Goetsch David L. (1999) Occupational Safety and Health for Technologists, Engineers, and Managers, Prentice Hall, Upper Saddle River, New Jersey Goetsch David L. (1999) Occupational Safety and Health for Technologists, Engineers, and Managers, Prentice Hall, Upper Saddle River, New Jersey