| 摘要 |
A peak flow meter has an element (4) displaceable along a hollow body (2) by the exhalation of a subject, and means for indicating the maximum displacement of that element as a measure of peak flow. Pre-set markers (20) are located at selected positions to indicate selected displacement values. The markers are in the form of elements that are snap-fitted onto the meter body at chosen positions and they have a toothed interengagement (12,28) with the body as they snap-fit into place. Accidental or careless movement of the markers is thereby precluded while permitting ready placement when required
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