9
For example: To change the units of measurement from feet per
minute (fpm) to meters per second (m/s):
• Push the UNIT key.
• The display annunciator
S
moves to m/s, selecting meters per
seconds.
• Release the key.
Measurement Modes
You can set the AXD530 for pressure or velocity measurement by
pressing the UNIT key.
Pressure Selection:
The AXD530 is a pressure-measuring instrument. Its factory
default setting is to measure pressure in inches of water (in.H
2
O)
or Pascals (Pa).
Velocity Selection:
Air velocity measurement can be accomplished using a Pitot-
static probe.
The following equations are used for pressure to velocity
conversions:
Pressure
4005
(fpm)
Velocity
=
where Pressure is in inches H
2
O
or
Pressure
1.29
(m/s)
Velocity
=
where Pressure is in Pa
The velocity calculations assume standard conditions. Use
Appendix
D to determine the correct multiplier if conditions other
than standard exist. Refer to Appendix B for pressure to velocity
conversion.
