Kurz 490 series User manual

Series 490 Portable Velocity Meter
User Guide
368051B
Created by Robert Morpeth

Series 490 User’s Guideii
Copyrights and Trademarks
Copyright © 2017 Kurz Instruments, Inc.
All rights reserved.
No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical,
including photocopying, recording, or by any information storage and retrieval system without express written
permission from Kurz Instruments, Inc., 2411 Garden Road, Monterey, California 93940; Phone: [phone],
Fax: [phone], or www.kurzinstruments.com
The material in this manual is for information only and is subjectto change without notice. Every reasonable efforthas
been made to ensure that the information in this manual is complete and accurate. Kurz Instruments, Inc. makes no
representations or warranties of any kind concerning the contents of this publication, and therefore assumes no
liability, loss, or damages resulting from use, errors, or omissions in this publication or from the use of the information
contained herein. Kurz Instruments, Inc.,is not responsible for printing or clerical errors.
Kurz Instruments, Inc., reserves the right to make engineering changes, product improvements, and product design
changes without reservation and without notification to its users. Consult your Kurz Instruments, Inc. representative or
a factory applications engineer for information regarding current specifications.
Kurz Instruments, Inc. assumes no liability for damages or injuries (consequential or otherwise)caused by the improper
use and/or improper installation of this product or where this product is used in any application other than what it was
designed for and intended. Kurz Instruments, Inc. expressly denies any responsibility if this product has been modified
without Kurz Instruments, Inc. written approval or if this product has been subjected to unusual physical or electrical
stress, or if the original identification marks have been removed or altered.
Equipment sold by Kurz Instruments, Inc. is not intended for use in connection with any nuclear facility or activity
unless specifically sold for such applications and specific conditions for such usage are detailed. If the equipment is
used in a nuclear facility or activity without supporting quotation, Kurz Instruments, Inc. disclaims all liability for any
damage, injury, or contamination, and the buyer shall indemnify and hold Kurz Instruments, Inc., its officers, agents,
employees, successors, assigns, and customers, whether direct or indirect, harmless from and against any and all
losses, damages, or expenses of whatever form and nature (including attorneys fees and other costs of defending any
action) which they, or any of them, may sustain or incur, whether as a result of breach of contract, warranty, tort
(including negligence), strict liability or other theories of law, by reason of such use.
The Kurz logo is a trademark of Kurz Instrument, Inc., registered in the U.S. and other countries. Use of the Kurz logo for
commercial purposes without the prior written consent of Kurz Instruments, Inc. may constitute trademark
infringement in violation of federal and state laws. MetalClad, Series MFTB, Series 454FTB, Series 504FT, Series 534FTB,
and KBar-2000B are trademarks of Kurz Instruments, Inc.
Other company and product names mentioned herein are trademarks of their respective owners. Mention of third-
party products is for informational purposes only and constitutes neither an endorsement nor a recommendation.
Kurz Instruments, Inc., assumes no responsibility with regard to the performance or use of these products.
Kurz Instruments Inc. Kurz Technical Support
2411 Garden Road Customer Service
Monterey, CA 93940 800-424-7356 (toll free)
831-646-5911 (main) www.kurzinstruments.com
831-646-8901 (fax) [e-mail]

Series 490 User’s Guide iii
Table of Contents
Series 490 ................................................................................ 1
Overview ......................................................................................................... 1
Operating the Series 490 ................................................................................ 2
Application Tips .............................................................................................. 3
Large Duct Openings ................................................................................ 3
Changing Air Temperature ...................................................................... 3
Average Air Velocity ................................................................................ 3
HEPA Air Flow .......................................................................................... 4
Small Duct Flow Rates ............................................................................. 4
Standard vs. Actual Velocity ........................................................................... 5
Battery Replacement ...................................................................................... 6
Maintenance & Repair .................................................................................... 7

Series 490 User’s Guideiv

Series 490 User’s Guide 1
Series 490
Overview
The Kurz Series 490 provides reliable air flow measurement in a high-quality, portable velocity
meter. Each unit works up to 50 hours on a set of batteries. The low-power sensor exhibits
extraordinarysensitivitytoairflow.Thenonconductivegraphiteprobeshaftisextremelystrong.
Each model offers dual range capability, and is available in either standard or metric
measurements.

Series 490 User’s Guide2
Series 490
Operating the Series 490
Before taking a measurement:
•When the Series 490 is powered ON, a red indicator light illuminates.
•Check the battery voltage by sliding the power switch to BAT.
The needle must be to the right side of the scale in the BATT OK area.
•Slide the power switch to HIGH. Remove the protective shield
from the probe window. Ensure that air flow moves the needle
by blowing air through the window and across the sensor.
•Slide the power switch to LOW. Ensure thatair flow movesthe
needle by blowing air through the window and across
the sensor.
To use a Series 490, place the sensor near the vent so the vent air flows directly through the
sensor window opening and read the indicator.
The Series 490 is calibrated for use in air. Gas correction factors for gases other than air are
available fromthird-party sources. Note that gas correction factors can vary from meter to meter.
LO
HI
BAT
OFF
Air flow must go
directly through the
sensor window

Series 490 User’s Guide 3
Series 490
Application Tips
The Series 490 measures air velocities for a wide range of applications.
•Supply openings, return openings, and suction openings
•Wind speed for meteorological studies and sports activities (such as sailing,
golf, and track & field)
•Clean rooms
Output is relatively unaffected by angular rotation of the probe window until the angle approach
reaches approximately 30 degrees of the flow direction.
Large Duct Openings
The Series 490 allows you to conveniently obtain velocity and total flow of supply openings,
return openings, and suction openings. If a supply opening is covered by a grill, the probe should
be placed aboutone inch in front of a grill opening to obtain the average velocity reading. If an
opening is covered by a diffuser, refer to the manufacturer’s instructions.
To obtain greater accuracy, use a duct extension that is at least 10 percent of the largest
dimension of the grill. For example, a grill with dimensions 10” x 8” requires at least a one inch
extension. The duct extension is then placed against the grill.
Changing Air Temperature
For applications with changing air temperature, allow the probe toreach thermal equilibrium to
give the temperature-compensation feature time to respond.
Average Air Velocity
To determine the average air velocity:
1> Divide the opening into equal areas.
2> Take a velocity reading at the center of each area.
Traverse across the duct in both direction to determine the uniformity of the air
velocity. Only a few areas need to be measured if the velocity profile is relatively flat.
Severalareasshouldbeusedif the profile is non-uniform.Ifthevelocityisnotconstant
at one measuring point, use the mean velocity between the upper and lower readings.
3> Average the results.

Series 490 User’s Guide4
Series 490
HEPA Air Flow
ProperHEPAaircirculationensuresthatcleanairisefficientlyissuedfromaHEPA ceilingductand
contaminated air is expelled from the protected zone. The probe can be positioned at various
points in the clean room in a variety of orientations, establishing major flow lines and
investigating the differential pressure of various rooms.
The Series 490 can also be used to ensure the uniform laminar airflow through a HEPA filter and
to certify HEPA filters in accordance with environmental standards. HEPA certification readings
typically fall between 72 and 108 fpm.
Small Duct Flow Rates
The Series 490 can be used for velocity measurements with duct diameters less than 18 inches
andfairlyuniformvelocities.Wheneverpossible,chooseameasurementlocationat least10duct
diameters downstream from the nearest elbow, tee, bend, valve, or other flow obstruction. The
total flow rate within the duct can be determined only if the point velocity measurement
represents the average flow velocity, which requires an extremely smooth, uniform flow or a
multipoint traverse.
The Series 490 probe can be semi-permanently mounted in a duct wall using a Kurz duct
mounting bracket. The adapter is easily installed by drilling a 5/16” hole into the duct and
mounting the adapter plate with four sheet metal screws.

Series 490 User’s Guide 5
Series 490
Standard vs. Actual Velocity
The basic sensing element consists of a velocity sensor and a temperature sensor. The velocity
sensor is heated and operated at a constant temperature.
All Kurz air velocity metersare referencedto standardconditions:
•Temperature: 25ºC (77ºF)
•Barometric pressure: 760 mm Hg (101.32 kPa)
Thermal flow meters measure the mass velocity of the air. Most applications require only the
mass velocity, so no density calculation is required because the correction is small enough to be
neglected in most cases. However, you can use the following formula to obtain the actual
velocity:
Va= Vix(Ps/Pa) x(Ta/Ts)
where:
Va= actual air velocity
Vi= indicated velocity on the Kurz Series 490
Ps= air pressure at standard condition of 25ºC or 760 mm Hg
Pa= actual air or barometric pressure
Ta= actual air temperature, absolute units, Kelvin or Ranken
Ts= standard air temperature, absolute units, Kelvin (298ºK) or Ranken (536ºR)

Series 490 User’s Guide6
Series 490
Battery Replacement
The Series 490 requires newbatteries ormust be recharged when the needle is to the left of the
verticalline ofthebatteryindicator.Insufficientbattery voltagewill affectperformance,including
accuracyand potentialdeflection atzero.Usingahighervoltagebattery(above1.5VDCAA)voids
the safety approval, introduces calibration errors, and can damage the electronics.
Note Exceptforthe batteries,therearenouser-serviceablecomponentsinthe
meter.
To replace the four alkaline batteries:
1> Remove the screwsat the top and bottom of the meter case.
Important Do not remove the screws on the base plate.
2> Slide the case away fromthe base plate to expose the battery compartment.
3> Remove the four AA batteries. The batteries are spring-loaded and might need some
pressure to remove them.
4> Install four new AA alkaline batteries.
5> Re-install the meter case and secure it with the screws.
The unit is ready for operation.

Series 490 User’s Guide 7
Series 490
Maintenance & Repair
Although the sensors are generally immune to particulate contamination, continually using the
flow meter in dirty environments can require periodically cleaning the sensors. Power off and
gentlywavethe probesensorinanalcoholbathtoremovemostdustandgrime.Allowthesensor
to dry before resuming normal operation.
Important Do not use a brush or other harsh object to clean the sensor.
Also, protect the probe when not in use.
Field modifications or substitutions are not permitted and void the safety approval. Send the
meter to the factory for any repairs.
Annual recalibration is suggested based on the accuracy of the data requirements and the
amount ofuse. Before sending in your Series 490 unit, contact Kurz to obtain a return materials
authorization (RMA) number. This expedites the calibration/shipping process.
Contact Kurz Customer Service:
[phone]
[email protected]om
Series 490 flow meters can be returned to:
Kurz Instruments, Inc.
2411 Garden Road
Monterey, CA 93940
Have the following information readily available for your Customer Service Representative:
Series 490 Recalibration
RMA number
Model number
Serial number
Contact name
Contact phone number
Complete shipping address

Series 490 User’s Guide8
Series 490