Alnor 275 User manual

Thermo-Anemometer
Probe Model 275
OWNER’S MANUAL

LIMITATION OF WARRANTY AND LIABILITY
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 twenty-four (24) months, 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.
c. Seller does not provide any warranty on finished goods manufactured by others.
Only the original manufacturer's warranty applies.
d. Unless specifically authorized in a separate writing by Seller, Seller makes no
warranty with respect to, and shall have no liability in connection with, any goods
which are incorporated into other products or equipment by the Buyer. All goods
returned under warranty shall be at the Buyer’s risk of loss, Seller’s factory prepaid,
and will be returned at Seller’s risk of loss, Buyer’s factory prepaid.
The foregoing is IN LIEU OF all other warranties and is subject to the conditions and
LIMITATIONS stated herein. NO OTHER EXPRESS OR IMPLIED WARRANTY OF
FITNESS FOR PARTICULAR PURPOSE OR MERCHANTABILITY IS MADE.
THE EXCLUSIVE REMEDY OF THE USER OR PURCHASER, AND THE LIMIT OF
THE LIABILITY OF SELLER FOR ANY AND ALL LOSSES, INJURIES, OR DAMAGES
IN CONNECTION WITH THIS PRODUCT (INCLUDING CLAIMS BASED ON
CONTRACT, NEGLIGENCE, STRICT LIABILITY, OTHER TORT, OR OTHERWISE)
SHALL BE THE RETURN OF THE PRODUCT TO THE FACTORY OR DESIGNATED
LOCATION AND THE REFUND OF THE PURCHASE PRICE, OR, AT THE OPTION
OF SELLER, THE REPAIR OR REPLACEMENT OF THE PRODUCT. IN NO EVENT
SHALL SELLER BE LIABLE FOR ANY SPECIAL, INCIDENTAL OR
CONSEQUENTIAL DAMAGES. SELLER SHALL NOT BE RESPONSIBLE FOR
INSTALLATION, DISMANTLING, REASSEMBLY OR REINSTALLATION COSTS OR
CHARGES. NO ACTION, REGARDLESS OF FORM, MAY BE BROUGHT AGAINST
THE SELLER MORE THAN ONE YEAR AFTER THE CAUSE OF ACTION HAS
ACCRUED.
The purchaser and all users are deemed to have accepted the terms of this
LIMITATION OF WARRANTY AND LIABILITY, which contains the complete and
exclusive limited warranty of Seller. This LIMITATION OF WARRANTY AND LIABILITY
may not be amended or modified nor may any of its terms be waived except by a
writing signed by an authorized representative of Seller
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
1. GENERAL DESCRIPTION..............................................................2
2. SAFETY...........................................................................................4
3. OPERATION....................................................................................4
4. THEORY/CORRECTION FACTORS ..............................................5
5. TROUBLESHOOTING GUIDE........................................................7
6. MAINTENANCE .............................................................................. 8
7. CLEANING ......................................................................................8
Handle, Telescopic Tube and Electronics Housing ......................8
Probe Tip ....................................................................................... 8
8. PERFORMANCE CHECK............................................................... 9
9. SERVICE AND REPAIR................................................................ 10
Service and Repair......................................................................10
Instructions for Return .................................................................11
Damaged in Transit .....................................................................11
275 PROBE SPECIFICATIONS

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1. GENERAL DESCRIPTION
The Model 275 is a thermo-anemometer probe that can be used with
Alnor 8575 CompuFlow®, APM 150, or APM 360 meters to measure
air speed and temperature. The probe can measure air speed from 20
to 6000 feet per minute (0.1 to 30 meters per second). Air temperature
can be measured from 32° to 122°F (0° to 50°C). Calibration
information is stored digitally within the probe. When used with
either meter, measurements can be made in the following units:
• fpm Feet per minute
• m/s Meters per second
• ft/s Feet per second
• mph Miles per hour
• km/h Kilometers per hour
• °C Degrees Centigrade
• °F Degrees Fahrenheit
• *cfm Cubic feet per minute
• *l/s Liters per second
• *m3/h Cubic meters per hour
*When a Volume mode has been chosen and an area has been input.
There are two sensors located at the tip of the probe. The small round
sensor at the very tip is a heated thermistor used to measure flow
speed. The sensor below it is a nickel resistance temperature detector
(RTD) used to measure air temperature and to make corrections to the
air flow speed when air temperature changes. The thermal
anemometer probe is operated in a constant temperature mode. The
probe’s calibration constants are stored digitally in memory. The
probe’s memory and other functional components reside on a printed
circuit board located within the electronic housing.

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Temperature Sensor
Velocity Sensor
Note: Arrow points in
direction of air flow
Pivot
Knurled Retaining Nut
Telescopic Tube
Circular Connector
with a Knurled Screw
Electronics Housing
7’ Cord

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2. SAFETY
All ordinary precautions must be observed when operating the
Model 275 thermo-anemometer probe near moving equipment such as
motors and blowers. Exercise care to ensure that the probe or
instrument does not interfere with any moving equipment.
The operational range of the probe is 32° to 122°F (0° to 50°C) and
must not be exceeded.
The Model 275 probe is not designed for gas mixtures other than air.
Use with corrosive or other dangerous gas mixtures is not
recommended.
Although the sensing element is protected, it can be damaged if
subjected to abuse. If broken, it must be repaired and recalibrated at
the factory. See Instructions for Return.
Opening or otherwise attempting to service your instrument may void
the warranty or factory calibration. Please read the warranty statement
carefully.
3. OPERATION
1. The probe can be shipped separately from the meter. Make sure
that you have read the meter manual before proceeding.
2. Connect the probe to the matching connector located on the
meter.
3. Remove the plastic tip protector from the probe and store in a
safe place.
4. Place the probe in the air stream with the arrow on the tip of the
probe pointing in the same direction as the air flow. Hold the
probe perpendicular to the flow.
Note: Probe identification, calibration constants, last set of units
used, and other information are stored in the probe’s memory.

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4. THEORY/CORRECTION FACTORS
Thermo-anemometers operate on the principle of heat transfer. A
sensor is heated above room temperature by passing current through a
resistance. Electrical energy is converted to heat. Through convective
heat transfer, the heat is passed on to the fluid passing over the heated
element. The fluid in this case is air. There are a variety of air
properties that affect the heat transfer. The most important is the
velocity of the air passing over the heated element. Others include the
temperature difference between the heated element and the air, and
density. As the density increases, the number of molecules that come
in contact with the heated element increases. Thermo-anemometers
are corrected to account for the change in heat transfer due to
different ambient air temperatures. These are considered “temperature
corrected.” However, temperature also has an effect on the density.
This means that for the same velocity, you will have a different
displayed velocity if the density changes. Temperature corrected
thermo-anemometers are mass flow rate sensors that can be corrected
to give actual velocities.
Velocity is generally expressed in one of two ways: actual (true)
velocity or standard velocity. Actual velocity is the average speed at
which the molecules are traveling. Standard velocity is referenced to
standard conditions and is equal to the actual velocity of the air only
when the air is at standard density. The calibration facilities at TSI
Incorporated adjust the actual velocity so that the same number of
molecules per unit time are passing over the heated element as if the
density were standard density. This makes the instrument display
standard velocity.
To correct the standard velocity to actual velocity use the equations
below.
Va= Actual velocity
Vstd = Standard velocity (this is displayed by the instrument)
ρstd = Standard density 0.075 lb/ft3(at 70°F and 29.92 in Hg)
ρa= Actual density in lb/ft3
CF = ρstd/ρa(Correction Factor)
Va= Vstd xCF

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For your convenience we have made a chart for determining the
correction factor given temperature and pressure.
Note: The atmospheric pressure as reported by the National Weather
Service is corrected to sea level and cannot be used if
measurements are not at sea level.
For more information on calculating local air density, call the
Customer Service Department at TSI.

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5. TROUBLESHOOTING GUIDE
Symptom Possible Causes and Corrective Actions
Measurement is
erratic
Probe is not being held steady—secure probe on test
stand.
Flow field is unstable.
Measurement is being made at edge of jet or behind
fan—try slower time constant as described in meter
manual.
Erroneous readings Probe sensing element is dirty—clean probe tip.
Arrow on probe tip is not pointing in same direction
as flow—make sure arrow is parallel to flow and in
same direction.
Probe stem is not held perpendicular to flow—orient
probe stem to be perpendicular to flow.
Density is significantly different from standard
conditions—calculate correction factor.
Probe is out of calibration—return to factory for
calibration. See Service Information.
Meter shows 0 or
over
Air flow is beyond range of the instrument. It is
either above or below the measurable range. The
measurement cannot be made.
Probe tip sensing element is broken—probe must be
repaired.
Meter shows No
Probe
Probe connection is bad—make sure connector is
tight.

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6. MAINTENANCE
The 275 probe is manufactured with solid state components.
However, periodic maintenance consisting of a performance check
should be made every six months as described in the Performance
Check section of this manual. The probe should also be cleaned and
checked for signs of physical damage.
There are no adjustable potentiometers in the probe’s circuits.
Calibration adjustments are done digitally at the factory.
Note: There are no user serviceable parts or batteries inside the
electronics housing. Do not open the housing.
7. CLEANING
Handle, Telescopic Tube and Electronics Housing
Use mild soap (dishwashing detergent) and water solution on a damp
cloth to remove finger marks, oils or residue. Do not use abrasives or
solvents. Do not immerse or allow liquids to enter the electronics
housing. Dry the electronics housing thoroughly after cleaning.
Probe Tip
Periodically check to be sure that the sensing area of the probe is
clean, and the sensors are free of foreign particles. If cleaning is
required, use denatured or isopropyl alcohol. If denatured alcohol is
used, make sure that the denaturizing agent leaves no solid residue
material after evaporation. Extreme care must be used to avoid
damaging the sensor. The preferred method is to immerse the probe
tip briefly in denature or isopropyl alcohol and then dry it in a gently
stream of air. If moisture appears on the probe, allow it to dry
thoroughly before use. Do not apply direct heat.

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8. PERFORMANCE CHECK
Performance of the 275 probe should be checked every six (6)
months. If the probe is used in dirty environmental conditions,
calibration should be checked more often. When checking the
performance of the probe, verify that all instructions in both the probe
manual and the meter manual are being followed. If a calibration
check is made by the user, the following points should be considered:
1. The probe is calibrated with the arrow pointing in the same
direction as the air flow. The arrow must be parallel to the flow.
Small angular differences (as small as 10%) between the arrow
and the flow may affect the calibration by as much as 2% of
reading. This effect is less severe at flow rates below 2000 fpm
(10 m/s).
2. The probe stem must be perpendicular to the direction of flow.
Small angular differences (about 10%) from the true
perpendicular may affect the calibration by as much as 5% of
reading. This effect is less severe at flow rates below 2000 fpm
(10 m/s).
3. Ideally, velocity should be checked against a standard that is at
least 4 times more accurate than the 275 probe. This is likely to
be very difficult to accomplish. Therefore, a standard at least as
good as the 275 probe must be used. This means that a pitot-
static probe will generally not be a good standard at flows under
1000 fpm (5 m/s). Thermal anemometers, orifice plates, or
venturis are preferred standards below 1000 fpm (5 m/s).
4. Air velocity is rarely distributed evenly in a duct or in an air
stream. Usually, the velocity will be higher in the center of the
air stream and lower at the periphery. This may cause
discrepancies when comparing different probes in the “same” air
stream. You should also realize that the insertion of a probe in a
channel of relatively small cross-sectional area changes the air
velocity from the undisturbed case. Flow blockages generally
should not exceed 5%. This means that a 8 in. (200 mm)
diameter duct is about the smallest size that can be measured
without considering blockage effects.

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5. If the probe has been inserted through insulation in a duct, be
sure that the tip is clean. Dirt can adversely affect the calibration
of the probe.
6. The 275 probe reads standard fpm. Read the Theory section
describing standard conditions and how the probe should be
corrected. Be sure that the proper corrections for temperature and
atmospheric pressure are applied to both the probe being tested
and the measurement standard being used. Measurement
standards may require a different correction technique. Know
your equipment and the theory behind each before proceeding.
7. Turbulence levels in the air stream can affect the calibration
accuracy.
8. The temperature distribution in an air stream may not be evenly
distributed. Temperature differences of 1°F (0.5°C) can easily
exist. When temperature comparisons are made against a
standard, it must be verified that the temperature is the same
between the location of the standard and the probe. Furthermore,
temperature usually changes over time. If there is a difference
between the time response of the standard and the time response
of the probe, this may result in a perceived error.
Note: Any adjustments void all calibration certification that may
have accompanied this probe.
9. SERVICE AND REPAIR
Service and Repair
Please return your Product Registration Card immediately. This
allows us send you service reminders, special offers, and important
information about your product.
Before sending your instrument for calibration or repair, you should
call Customer Service. The Service Department will provide you with
the cost of service or calibration, Return Material Authorization
(RMA) number, and shipping instructions.

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Please have the following information available when you call:
 Owner’s name, address, and phone number
 Billing address, if different and applicable
 Instrument name or model
 Serial number
 Date of purchase
 Where purchased
TSI recommends that you keep a “calibration log” and keep all
records of service on your instrument.
Instructions for Return
Send the instrument prepaid. Securely package your instrument in a
strong container surrounded by at least two inches (5 cm) of suitable
shock-absorbing material. Include the Purchase Order showing
instrument model number, cost of service and/or calibration, and the
RMA number. Mark the outside of the shipping container with the
RMA number. This will expedite processing of your instrument when
we receive it.
Damaged in Transit
All orders are carefully packed for shipment. On receipt, if the
shipping container appears to have been damaged during shipment,
the instrument should be thoroughly inspected. The delivering
carrier’s papers should be signed noting the apparent damage. DO
NOT DISCARD THE BOX.
If the instrument itself has been damaged, a claim should be promptly
filed against the carrier by the customer. The selling agent will assist
the customer by supplying all pertinent shipping information;
however, the claim must be filed by the insured. If the instrument is
damaged beyond use, a new order should be placed with TSI while
awaiting reimbursement from the carrier for the damaged instrument.
Call TSI directly for assistance if necessary.

275 PROBE SPECIFICATIONS
Range
Air Velocity 20 to 6000 feet per minute fpm
Temperature 32 to 122°F
Resolution 0.001 below 1
0.01 from 1 to 10
0.1 from 10 to 100
1 above 100
Accuracy*
Standard Conditions ±5 fpm from 20 to 100 fpm
±3% of reading ±2 fpm from 101 to 700 fpm
±3% of reading ±20 fpm from 701 to 4000 fpm
±3% of reading ±200 fpm from 4001 to
6000 fpm
±1°F from 68 to 86°F
±5% of reading ±1.0°F from 32 to 68°F
and 86 to 122°F
Non-Standard
Conditions 20 to 200 fpm (0.1 to 1 m/s)
±0.1 fpm per °F (±0.001 m/s per °C)
201 to 6000 fpm (1 to 30 m/s)
±0.1% of reading per °F (±0.2% of reading
per °C)
Storage Temperature -40°F to 150 °F (-40°C to 65°C)
Dimensions 0.355” (9 mm) max. diameter
Handle—3 1/2” long x 1 1/2” wide
Length—20” closed, extendable to 45”
(508 mm extendable to 1143 mm)
Flexible cable 7 ft. (2.1 M) long
Pivoting section 4.5” (114 mm) long at tip end,
lockable in straight or either 90° position
Weight 12 oz (340 g)
Operating Temperature
of Heated Thermistor Approximately 194°F (90°C)
*With 8575, APM 150, or APM 360 meter.
Specifications subject to change without notice.

_____________________________________________________________
TSI Incorporated
Alnor Products
500 Cardigan Road
Shoreview, MN 55126 USA
Toll Free [phone] July 2002
Telephone [phone] Printed in USA
Fax [phone] Patent # 5,162,725
www.alnor.com Part No. 116-159-075 Rev. 4
[email protected] Copyright 1998-2002 TSI Incorporated