TSI Instruments ALNOR AXD 530 User manual

AXD 530
MicroManometer
OWNER’S MANUAL

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Seller warrants that this product, under normal use and service as described in the
operator's manual, shall be free from defects in workmanship and material for a period of
two (2) years, or the length of time specified in operator's manual, from the date of shipment
to the customer. This limited warranty is subject to the following exclusions:
a. Batteries and certain other components when indicated in specifications are warranted for
a period of 90 days from the date of shipment to the customer.
b. With respect to any repair services rendered, Seller warrants that the parts repaired or
replaced will be free from defects in workmanship and material, under normal use, for a
period of 90 days from the date of shipment to the customer.
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with respect to, and shall have no liability in connection with, any goods which are
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Service Policy
Knowing that inoperative or defective instruments are as detrimental to TSI as they are to
our customers, our service policy is designed to give prompt attention to any problems. If
any malfunction is discovered, please contact your nearest sales office or representative, or
call Customer Service department at [phone] (USA) and (1) 651-490-2811
(International).

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Table of Contents
Features ..............................................................................................3
Using the AXD530 Safely ..................................................................3
Getting Started ...................................................................................4
Installing Batteries ......................................................................... 4
Preparing the Instrument...............................................................5
Attaching the Optional Pitot-Static Probe...................................... 5
Start-Up Sequence........................................................................ 6
Zeroing the Instrument .................................................................. 6
The Display.........................................................................................7
Modes............................................................................................ 7
AXD530 Keypad .................................................................................7
The AXD530 Keypad..................................................................... 7
Key Functions: ........................................................................ 8
Using the AXD530 .............................................................................. 8
Basic Functions ............................................................................. 8
To Change Units: .................................................................... 8
Measurement Modes.....................................................................9
Pressure Selection:.................................................................9
Velocity Selection:...................................................................9
Appendix A: Traversing a Duct to Determine Average Air
Velocity or Volume...........................................................................10
Where to Take the Measurement................................................ 10
Traversing a Round Duct ............................................................10
Traversing a Square Duct ...........................................................12
Notice of Disclaimer .................................................................... 13
Appendix B: Pressure to Velocity Conversion Charts................ 13
Appendix C: Maintenance and Troubleshooting........................15
Maintenance ................................................................................15
Troubleshooting........................................................................... 16

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Appendix D: Correction Factors for Non-Standard Conditions.16
Method 1......................................................................................17
Method 2......................................................................................17
Method 3......................................................................................18
Density Correction Factors ..........................................................19
For Different Altitudes and Temperatures.............................19
Appendix E: Effects of Resolution on Accuracy Statement.......19
Service Information..........................................................................21
Instructions for Return ....................................................................22
Service and Repair ......................................................................22
Instructions for Return .................................................................22
Damaged in Transit .....................................................................23
Ownership/Calibration Log .............................................................24
Equipment Log.............................................................................24

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Features
The AXD530 MicroManometer is a meter that measures differential
pressure. It is also capable of measuring and displaying air velocity.
Functions are selected through a three-key pad.
The AXD530 displays measurement results on a liquid-crystal display
(LCD), with additional display segments for units of measure and low
battery indication.
It features two built-in pressure ports for attachment to the pressure
source you will measure. Optional hoses and Pitot-static probes are
available.
The AXD530 uses three (3) AA size alkaline batteries for low
replacement cost.
Using the AXD530 Safely
• When using the instrument to
check airflow in an elevated
workplace, make certain that you
can safely raise and hold the
instrument while making
measurements. This is especially
important when you are working
on a ladder.
• Avoid catching hoses or
attachments in moving
machinery.
• Use the instrument only for
measurements using air.
• Avoid any corrosive or other
dangerous or explosive gas
mixtures.
Please dispose of used batteries in a
responsible manner.

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Getting Started
Installing Batteries
The AXD530 uses three (3) AA size non-rechargeable batteries. The
unit was shipped with batteries not installed. You will find the
batteries in the instrument package.
Back view of the instrument
To install the batteries:
• Loosen the battery cover screw on the back of the instrument.
• Slide the cover up and lift it out.
• Install the batteries over the pull strap, taking care to observe each
battery’s polarity.
• Replace the cover and tighten the screws.
Note: When the batteries become low, the LCD will show [LO BATT]
above the reading. From that point, you will have about one
hour of normal use left. If [ ] comes on continuously and
replaces the reading, the battery voltage is too low for
accurate measurements and the meter will turn itself off.

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LO BATT
Low battery displays
Always keep a replacement set of new batteries available.
Preparing the Instrument
Attach hoses to the pressure ports at the top of the instrument. Do not
exceed maximum pressure.
Attaching the Optional Pitot-Static Probe
To attach the probe for measuring air velocity:
• Remove the Pitot-static probe and rubber tubing from their
carrying case.
• Remove the protective caps from the probe and save them for
restoring the probe later.
• Attach one section of flexible tubing to the probe’s static pressure
port and another to the probe’s total pressure port.
Pitot-static probe

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• Identify the (+) and (-) pressure ports at the top of the AXD530.
• Attach the tubing from the total pressure port of the Pitot-static
probe to the (+) port of the MicroManometer.
• Attach the tubing from the static pressure port of the Pitot-static
probe to the (-) port of the MicroManometer.
• Check to ensure that all tubing connections are tight.
Start-Up Sequence
Each time you turn the instrument on, some basic functions are tested.
The following will occur:
• All the LCD segments will turn on.
• The current software revision level will be displayed.
• The message [ ] will appear.
• The last unit of measurement will be displayed along with a
measurement value.
• [ ] followed by [ ] will appear.
• The meter will begin to measure.
Zeroing the Instrument
Before you begin taking measurements, the AXD530 must be zeroed
by following these steps:
• Most hand-held meters using differential pressure sensors require
a warm-up time. Turn on your Alnor AXD530 a minimum of five
(5) minutes before zeroing and taking your first measurements.
• Make sure there is no airflow past a Pitot-static probe (also verify
that none of the tubing is pressurized by accidental squeezing).
• Press the ZERO key until [ ] appears on the display.
The instrument will automatically zero its readings. Repeat this
procedure, if necessary, because at high resolutions the AXD530 will
read small pressure changes.

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The Display
The AXD530 uses a 4-digit, 7-segment LCD. As a result,
measurements exceeding 9,999 of a given unit of measure will be
displayed in a scientific notation format of XXEY. The actual reading
will be rounded to the nearest thousand, XX. The Y indicates the
number of zeros after XX. For example, 12,664 is displayed as
[].
Modes
The AXD530 operates and takes measurements in the RUN mode.
You may be in the RUN, ZERO, or UNIT select modes.
AXD530 Keypad
The AXD530 Keypad
The internal clock rate of the AXD530 software may cause the meter
to react slowly to a key push. The reaction time of a key push will
vary with different functions (1–3 seconds). Maintain pressure on the
desired key until you see the required response on the display.

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Key Functions:
ON/OFF This key is used to turn the
instrument on or off.
ZERO The AXD530 will zero the
instrument any time this key
is pushed. To get a proper
zero, make sure no pressure
difference is applied across
the ports and no kinks are in
the hoses.
(See also “Zeroing the
Instrument.”)
UNIT This key is used to select the
desired unit of measurement.
Using the AXD530
Basic Functions
To Change Units:
• Push and hold the UNIT key.
• The display annunciator Swill move to the left of the LCD
beginning from the right.
• Release the UNIT key at the desired location.
Display with annunciator and units of measure

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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 Smoves 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.H2O)
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:
Pressure4005(fpm)Velocity =
where Pressure is in inches H2O
or
Pressure1.29(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.

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Appendix A: Traversing a Duct to Determine
Average Air Velocity or Volume
The following techniques can be used to measure airflow inside ducts
using a velocity probe or Pitot-static tube. When using a Pitot-static
tube, the individual velocities must be calculated for each pressure
reading then averaged together.* Averaging pressure with a Pitot tube
and then converting that average into velocity will give an incorrect
result, especially if many readings are more than ±25% from the
average pressure. Remember that for a Pitot tube, velocity is
proportional to the square root of the pressure.
Where to Take the Measurement
In order to make air velocity measurements in a duct, it is best to
measure at least 7.5 duct diameters downstream and at least 3 duct
diameters from any turns or flow obstructions. It is possible to do a
traverse as little as 2 duct diameters downstream or 1 duct diameter
upstream from obstructions, but measurement accuracy will be
impaired. When measuring rectangular ducts, use the following
formula to find the equivalent diameter of the duct when calculating
how far 7.5 diameters downstream or 3 diameters upstream is.
4HV/PiDiameterEquivalent =
Where: H = horizontal duct dimension
V = vertical duct dimension
Pi = 3.14
It is also possible to take a single reading to measure air velocity or
air volume flow in a duct, measuring in the center of the duct and
multiplying the reading by 0.9 to correct for the higher velocity at the
duct’s center. If conditions are very good, accuracy of ±5 or ±10
percent can be obtained this way. This method is not reliable,
however, and should only be used where small duct size or other
conditions do not permit a full traverse.
Traversing a Round Duct
Using the log-Tchebycheff method, the duct is divided into concentric
circles, each containing equal area. An equal number of readings is
taken from each circular area, thus obtaining the best average.
Commonly, three concentric circles (six measuring points per

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diameter) are used for ducts with diameters of 10 inches or smaller.
Four or five concentric circles (eight or ten measuring points per
diameter) are used for ducts with diameters of 10 inches or more.
The preferred method is to drill three holes in the duct at 60½ angles
from one another as shown in Figure 1. Three traverses are taken
across the duct, and the velocities obtained are averaged at each
measuring point. The average velocity is multiplied by the duct area
to get the flow rate. (A different method uses two holes at 90½ angles
from one another, decreasing the number of traverses with the probe
by one.)
Figure 1: Location of measuring points when traversing a round duct
using the log-Tchebycheff method
Number of measuring
points per diameter Position relative to inner wall
60.32, 0.135, 0.321, 0.679, 0.865, 0.968
8 0.021, 0.117, 0.184, 0.345, 0.655, 0.816, 0.883, 0.981
10 0.019, 0.077, 0.153, 0.217, 0.361, 0.639, 0.783,
0.847, 0.923, 0.981

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Before taking the measurement, multiply the numbers in the table by
the duct diameter to get the insertion depth for the probe. (Do not
forget to use the inside dimension of the duct if it is lined with
insulation.)
Traversing a Square Duct
Using the log-Tchebycheff method, the duct is divided into
rectangular areas, which are further adjusted in size to account for the
effect of the duct wall on airflow. A minimum of 25 points must be
measured in order to get a good average. The number of data points to
be taken along each side of the duct depends on how wide the duct is.
For duct sides shorter than 30 inches, five traversal points must be
taken. For duct sides of 30 through 36 inches, six points must be
taken. For duct sides longer than 36 inches, seven points must be
taken. Multiply the numbers in the table by the duct dimension to get
the insertion depth for the probe.
Figure 2: Location of measuring points for traversing a rectangular
duct using the log-Tchebycheff method

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Number of points or
traverse lines per side Position relative to inner wall
50.074, 0.288, 0.500, 0.712, 0.926
8 0.061, 0.235, 0.437, 0.563, 0.765, 0.939
10 0.053, 0.203, 0.366, 0.500, 0.634, 0.797, 0.947
The duct in Figure 2 has a horizontal dimension between 30 and 36
inches, requiring six points (or six traverse lines). The duct’s vertical
dimension is less than 30 inches, requiring five points (or five
traverse lines).
Notice of Disclaimer
TSI Incorporated has made a good faith effort to provide reliable
information regarding the use of the AXD530 to conduct a duct
traverse. However, we cannot guarantee conformance to any
particular method of specification, or that this material is free from
error. Traverse methods outside of the USA will be slightly different.
TSI recommends purchasing a copy of the duct traverse specification
you require from an approved regulatory or professional organization.
For further information, refer to the 1993 ASHRAE Fundamentals
Handbook Section 13, or to ASHRAE Standard 111 (1988).
Appendix B: Pressure to Velocity Conversion
Charts
The AXD530 MicroManometer converts pressure readings to velocity
using the formula for standard conditions:
P∆4005=V(fpm) Pressure in inches H20
P∆.291=V(m/s) Pressure in Pa
Please note that for small pressure readings, an increment in pressure
can cause large steps in velocity, but at larger readings, the steps in
velocity are much less pronounced as a percentage of reading. A
MicroManometer should not be used with a pitot tube at very low
differential pressures to measure velocity, because resolution errors
will be large.

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The following graphs show approximate velocities for certain
differential pressures in the range 0.01 to 0.10 inches H2O
(2.5–25 Pa).

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Appendix C: Maintenance and
Troubleshooting
Maintenance
Periodic maintenance should be performed on the meter.
• Batteries should be replaced when the low battery indication is on
or when the unit turns itself off after power-up.
• Batteries should be removed from the meter if it will not be used
for two (2) months or longer.
• Calibration checks are recommended every 12 months.
• Keep the meter clean by using a mild detergent on its case. Do
not use abrasives or solvents. Also, do not allow liquids to enter
the meter’s case. Dry thoroughly after cleaning.
• Use an eyeglass cleaner and lens paper to clean the LCD window.

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Troubleshooting
Symptom Check
DISPLAY SHOWS [ ] The measured value is beyond the
instrument’s range. Be sure there is
no applied pressure, then press
ZERO.
DISPLAY SHOWS The internal connection between the
meter and [ ] the sensor is
faulty. Turn the meter off, then turn
it back on again.
DISPLAY DOES NOT CHANGE Press the ON/OFF key until the unit
turns off. Then turn it on and try
again.
Your input might simply be very
stable. Test your meter by pinching
the hoses.
METER TURNS OFF The batteries are too low for your
completing start-up meter start.
Watch for the [ ] cycle
indication just before the meter turns
off, then replace the batteries.
MEASURENENT IS ERRATIC The input is not steady.
Check to see that your Pitot-static
probe is held steady.
ERRONEOUS READINGS Make sure that your Pitot-static
probe is perpendicular to the air flow
you are measuring.
Clean your Pitot-static probe—it
may be dirty.
Take measurements at a different
location.
If any of these problems persist, call TSI for assistance.
Appendix D: Correction Factors for Non-
Standard Conditions
The AXD530 is a differential pressure instrument. When it is
connected to a Pitot-static probe, it can be used to measure velocity.
When a Bernoulli’s equation is applied to the Pitot-static probe, the
resultant equation has the form V(ft/min) = 4005 [P(in H2O)]1/2 when

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the density of the air is 0.075 lb/ft. The velocity values displayed by
the AXD530 are the actual velocities only if the density where the
Pitot probe measurements are being taken is 0.075 lb/ft3. Otherwise, a
correction step must be performed to obtain a correct value. Listed
below in decreasing order of accuracy are methods for determining a
correction factor.
Note: In the United States, the barometric pressure reported by the
National Weather Service is corrected to sea level and,
therefore, cannot be used unless your measurements are taken
at sea level. The preferred method is to use the atmospheric
pressure at the location of the measurement. If you do not
have access to that value, then Method 3 in this appendix can
be used. This method is most accurate when the pressure
reported by the national weather service is 29.92 in Hg due to
the assumption of standard density.
Method 1
If you have the absolute pressure, temperature and relative humidity,
record the differential pressure from the AXD530, the absolute
pressure, the temperature, and the relative humidity at the
measurement location. Compute the density using the techniques used
in the 1993 ASHRAE fundamentals handbook. With the density and
the differential pressure, use the formula for Pitot probes also found
in that handbook to compute the actual velocity.
Method 2
If you have the absolute pressure and the temperature, you have two
options.
a) Record the displayed velocity measurement along with the
absolute pressure and temperature. Convert to units of °F and in
Hg if the temperature and pressure were not taken in those units.
To obtain actual velocity, use Equation 1 in this appendix to
calculate the correction factor and multiply the velocity reading
by that factor.
b) If using the equation is not convenient, the Air Pressure vs. Air
Temperature chart in this appendix can be used to determine the
correction factor. However, inaccuracies can result from using the
graphical technique instead of a direct calculation to obtain actual
velocity.

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Method 3
You can use this method if you know the altitude above sea level and
the air temperature but are unable to determine the absolute pressure.
Using the AXD530 Density Correction Factors chart, find the
appropriate correction factor value. Multiply the displayed value by
the value in this chart to get the “corrected” value.
Equation 1: