Item Brochure

Advantage #1: Our innovative design prevents cross-contamination.

The air inside the flow transducer's measurement pipe works as a buffer, preventing the expired air from entering the pressure

tubing even during high flow rates (15 L/s) and repeated spirometry efforts.

The maximal differential pressure signal of the flow transducer is ±77 mm H2O, corresponding to a flow of ±15 L/s. Average

atmospheric pressure is 10 000 mm H2O. The air is therefore compressed in the pressure tubing up to

77 / 10 000 parts = 0.77 %

In 2-meter long pressure tubing, this amounts to

0.77 % x 2000 mm = 15.4 mm

Since the internal diameter of the pressure tubing is 1.5 mm, the cross-sectional area is 1.77 mm2. The amount of air entering

the flow transducer's measurement pipe during the expiration amounts to

15.4 mm x 1.77 mm2 = 27.2 mm3

This is the maximal volume of expired air entering the measurement pipe of the flow transducer via the pressure-sampling hole

at the top of the measurement pipe. In the measurement pipe, the "contaminated" air will start moving toward the pressure

tubing adapter. The air entering the measurement pipe through the hole at the top of the measurement pipe will potentially

reach the pressure tubing first.

Because the maximal volume of expired air entering the measurement pipe of the flow transducer is 27.2 mm3, and the air

volume in the measurement pipe between the adapter and pressure-sampling hole is 136.3 mm3, the air buffer between the

contaminated air and the pressure tubing adapter is

136.3 mm3 - 27.2 mm3 = 109.1 mm3

This air buffer prevents the aerosols of the contaminated air

from entering the pressure tubing even during repeated forced

expiratory efforts. In slow efforts, the air entering the measure-

ment pipe is even smaller.

Advantages of Disposable Flow Transducers

No Expired Air

Pressure Sampling Hole

Measurement Pipe

PAGE 1
Advantages of Disposable Flow Transducers Advantage #1: Our innovative design prevents cross-contamination. The air inside the flow transducer's measurement pipe works as a buffer, preventing the expired air from entering the pressure tubing even during high flow rates (15 L/s) and repeated spirometry efforts. The maximal differential pressure signal of the flow transducer is ±77 mm H2O, corresponding to a flow of ±15 L/s. Average atmospheric pressure is 10 000 mm H2O.
PAGE 2
Advantages of Disposable Flow Transducers Advantage #2: Bacteria filters are unnecessary. Because no contaminated air enters the pressure tubing, and because the flow transducers are discarded after each patient use, no bacteria filters are needed. In fact, because Welch Allyn spirometers use a measuring principle based on pressure (pneumotachometer), filters would interfere with accuracy by adding resistance. Advantage #3: Disposable flow transducers are more costeffective, accurate, and convenient.