ASTM E1258-88(2003)
(Test Method)Standard Test Method for Airflow Calibration of Fan Pressurization Devices
Standard Test Method for Airflow Calibration of Fan Pressurization Devices
SCOPE
1.1 This test method covers the airflow measurement calibration techniques for fan pressurization systems used for measuring air leakage rates through building envelopes.
1.2 This test method is applicable to systems used for air leakage measurement as described in Practice E779.
1.3 This test method involves the installation of the fan pressurization system in a calibration chamber. Use of the fan pressurization system in an actual building may introduce additional errors in the airflow measurement due to operator influence, interference of internal partitions and furnishings, weather effects, and other factors.
1.4 The proper use of this test method requires a knowledge of the principles of airflow and pressure measurement.
1.5 This standard includes two basic procedures, a preferred procedure, based on ASHRAE Standard 51/AMCA Standard 210, and an optional procedure based on a nonstandard airflow measurement technique, commonly used by manufacturers of fan pressurization devices, but which has not been compared with standard airflow measurement techniques.
1.6 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: E 1258 – 88 (Reapproved 2003)
Standard Test Method for
Airflow Calibration of Fan Pressurization Devices
This standard is issued under the fixed designation E 1258; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope ASHRAE 51/AMCA 210 Laboratory Methods for Testing
Fans for Rating
1.1 This test method covers the airflow measurement cali-
2.3 American Society of Mechanical Engineers Standard:
bration techniques for fan pressurization systems used for
ASME MFC-3M Standard Measurement of Fluid Flow in
measuring air leakage rates through building envelopes.
Pipes Using Orifice, Nozzle, and Venturi
1.2 This test method is applicable to systems used for air
leakage measurement as described in Practice E779.
3. Terminology
1.3 This test method involves the installation of the fan
3.1 Definitions—For definitions used in this test method,
pressurization system in a calibration chamber. Use of the fan
see Terminology E631.
pressurization system in an actual building may introduce
3.2 Descriptions of Terms Specific to This Standard:
additional errors in the airflow measurement due to operator
3.2.1 ambient conditions, n—conditions in the space from
influence, interference of internal partitions and furnishings,
which air is drawn into the calibration chamber and into which
weather effects, and other factors.
the chamber air is expelled.
1.4 Theproperuseofthistestmethodrequiresaknowledge
3.2.2 chamber, n—an enclosure of rectangular or circular
of the principles of airflow and pressure measurement.
cross section to simulate the entrance and exit conditions that
1.5 Thisstandardincludestwobasicprocedures,apreferred
the fan is expected to encounter in service.
procedure, based on ASHRAE Standard 51/AMCA Standard
3.2.3 fan air density, n—density of air at the fan inlet
210, and an optional procedure based on a nonstandard airflow
expressed in kilograms per cubic metre.
measurement technique, commonly used by manufacturers of
3.2.4 fan airflow rate, n—volumetric airflow rate at the fan
fan pressurization devices, but which has not been compared
air density expressed in cubic metres per second.
with standard airflow measurement techniques.
3.2.5 fan outlet area, n—gross inside area measured in the
1.6 This standard does not purport to address all of the
plane of the fan outlet opening expressed in square metres.
safety concerns, if any, associated with its use. It is the
3.2.6 fan pressure difference, n—the static pressure differ-
responsibility of the user of this standard to establish appro-
ence between two stations expressed in pascals, measured
priate safety and health practices and determine the applica-
usingthestaticpressuretapsdescribedinFig.1.Onestationis
bility of regulatory limitations prior to use.
located within the chamber between the fan and the nearest
2. Referenced Documents flow conditioners. The other station is outside the chamber.
3.2.7 fan pressurization system, n—a device for measuring
2.1 ASTM Standards:
the air leakage rate of a building envelope under controlled
E631 Terminology of Building Constructions
pressurization or depressurization of the building interior. The
E779 Test Method for Determining Air Leakage Rate by
system includes controllable air-moving equipment, an airflow
Fan Pressurization
ratemeasuringsystem,andadeviceformeasuringthepressure
2.2 American Society of Heating, Refrigerating, and Air-
difference across the building envelope. Such a system is often
Conditioning Engineers Standard:
referred to as a blower door.
3.2.8 fan signal, n—an output from a fan pressurization
This test method is under the jurisdiction of ASTM Committee E06 on system (other than fan speed) that is related to fan airflow rate
Performance of Building Constructions and is the direct responsibility of Subcom-
by the system calibration, such as the static pressure difference
mittee E06.41 on Infiltration Performances.
across a constriction that is integral to the system.
Current edition approved Oct. 1, 2003. Published October 2003. Originally
3.2.9 fan speed, n—speed of rotation of the fan impeller
approved in 1988. Last previous edition approved in 1998 as E1258–88 (1998).
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
expressed in inverse seconds.
contactASTM Customer Service at service@astm.org. ForAnnual Book ofASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
3 4
Available from American Society of Heating, Refrigerating, and Air- Available from American Society of Mechanical Engineers (ASME), ASME
Conditioning Engineers, 1791 Tullie Circle NE, Atlanta, GA 30329. International Headquarters, Three Park Ave., New York, NY 10016-5990.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
E 1258 – 88 (2003)
3.2.14 nozzle throat pressure difference, n—static pressure
differenceacrossthenozzleinaductmeasuredwiththroattaps
expressed in pascals (see Fig. 2).
3.2.15 orifice, n—a sharp-edged circular constriction used
in airflow measurement (see Fig. 3).
3.2.16 orifice pressure difference, n—static pressure differ-
ence measured across an orifice when the orifice is installed in
a chamber expressed in pascals.
3.2.17 revolution-per-minute (r/min) door, n—a fan pres-
surization system with a calibration that relates the fan airflow
rate to the fan speed.
3.2.18 signal door, n—a fan pressurization system with a
calibration that relates the fan airflow rate to an output signal
other than fan speed.
3.2.19 transformation piece, n—an element to connect a
FIG. 1 Static Pressure Tap Specifications
duct with a measuring station to a fan when the fan connection
is a different size than the duct (see Fig. 4).
4. Summary of Test Method
3.2.10 flow conditioners, n—a combination of screens or
perforated plates located within the calibration chamber to 4.1 Thistestmethodcontainstwoproceduresforcalibrating
reduce pressure disturbances within the chamber. fan pressurization devices, a preferred procedure based on
3.2.11 nozzle, n—a gradually tapered constriction, of very ASHRAE Standard 51/AMCA Standard 210, and an optional
precise elliptical shape, used in airflow rate measurement (see procedure employing an orifice in a chamber.
Fig. 2). 4.2 Both procedures involve the installation of the fan
3.2.12 nozzle chamber pressure difference, n—static pres- pressurization system in a chamber.
sure difference measured across a nozzle or bank of nozzles 4.3 The calibration consists of a comparison of the airflow
when nozzles are installed in a chamber expressed in pascals. rate through the fan pressurization system measured by the
3.2.13 nozzle throat diameter, n—diameter of nozzle dis- system itself, and the airflow rate measured in the calibration
charge end expressed in square metres. facility. In the preferred procedure, three modes of airflow
Nozzle with throat taps Nozzle without throat taps
NOTE 1—Nozzle throat dimension L shall be either 0.6 D 60.005 D (recommended) or 0.5 D 60.005 D .
n n n n
NOTE 2—Nozzle shall have elliptical section as shown. Two and three radii approximations to the elliptical form that do not differ at any point in the
normaldirectionmorethan1.5% D fromtheellipticalformmaybeused.Theoutletedgeofthenozzleshallbesquare,sharp,andfreefromburrs,nicks,
n
or roundings.
NOTE 3—The nozzle throat shall be measured (to an accuracy of 0.001 D ) at the minor axis of the ellipse and the nozzle exit. At each place, four
n
diameters, approximately 45° apart must be within 60.002 D of the mean.At the entrance to the throat the mean may be 0.002 D greater, but no less
n n
than the mean at the nozzle exit.
NOTE 4—The nozzle surface shall fair smoothly so that a straightedge may be rocked over the surface without clicking and the surface waves shall
not be greater than 0.001 D peak to peak.
n
NOTE 5—When nozzles are used in a chamber, either of the types shown above may be used. Where a nozzle discharges directly to a duct, nozzles
with throat taps shall be used, and the nozzle outlet should be flanged.
NOTE 6—Throat tap nozzles shall have four static pressure taps 90° apart connected to a piezometer ring.
FIG. 2 Nozzle Specifications
E 1258 – 88 (2003)
NOTE—Surfacefinishshallbe1µmorbetter.Thestaticorificesmaynot
exceed 1 mm in diameter. The minimum pitot tube stem diameter
recognized under this standard shall be 2.5 mm. In no case shall the stem
diameter exceed ⁄30 of the test duct diameter.
FIG. 5 Pitot Tube Specifications
Recommended Plate Thickness, b
MFC-3M) or constant injection tracer gas methods. In order
1.5mmfor d up to 150 mm
2.5mmfor d up to 300 mm
for an alternative airflow rate measurement technique to be
3.2mmfor d up to 600 mm
included as a preferred procedure, the errors introduced by the
4.5mmfor d up to 1200 mm
procedure must be demonstrated not to exceed those intro-
Recommended Edge Thickness, a
Less than 0.02 d
duced by a nozzle or pitot traverse. In the optional procedure,
the airflow is measured with a series of sharp-edged orifices
NOTE—For thin plates (b<0.02 d), there is no need for beveling the
installed in the wall of the chamber.
edge of the orifice.
FIG. 3 Sharp-Edged Orifice Design 4.4 The calibration must include measurement points that
cover a specific range in both fan pressure difference and fan
airflow rate.
5. Significance and Use
5.1 The fan pressurization procedure provides a relatively
fast evaluation of the airtightness of building envelopes. In
order for the accuracy of the test results to be known, the
airflow rate measurement technique of the fan pressurization
system must be calibrated.
5.2 This test method is applicable to fan pressurization
systems that are installed in an opening in the building
envelope, as opposed to pressurization techniques involving
the mechanical ventilation system of the building.
5.3 Thetechniqueofpressurizationtestingofbuildingsputs
specific requirements on the calibration of fan pressurization
systems. The calibration must cover the range of fan pressure
differences (approximately 12.5 to 75 Pa) that is induced
during pressurization tests. The calibration must also cover a
range in fan airflow rates corresponding to the range in
FIG. 4 Transformation Piece
buildingsizeandairtightnessthatthefanpressurizationsystem
will encounter in the field.
measurementareacceptable:(1)anozzleorbankofnozzlesin
thechamber,(2)atraverseinaductusingapitottube(seeFig.
5), and (3) a nozzle in a duct. Other airflow rate measurement 5
Persily, A. K., “Air Flow Calibration of Building Pressurization Devices,”
techniques in a duct can be used such as orifice plates (ASME NBSIR 84-2849, National Bureau of Standards, 1984.
E 1258 – 88 (2003)
5.4 Thefanpressurizationsystemmustbecalibratedinboth 7.1.1.2 Flow Conditioners—A combination of screens or
directions of airflow used to pressurize and depressurize a perforated plates located in the chamber to reduce pressure
buildingifthesystemairflowdirectionisreversible.Thesetwo disturbances within the enclosure. These air to be located
calibrations can be conducted using the various setups de- within the chamber in accordance with 7.1.2. Where a mea-
scribed in this test method; however some of the setups can be suring plane is located downstream of the flow conditioners,
combined such that a single calibration facility can be used to the flow conditioners are provided to ensure a substantially
calibrate the fan in both directions. Such a single setup may uniform flow ahead of the measuring plane. Where a measur-
involve moving the fan pressurization system from one end of ing plane is located upstream of the flow conditioners, the
the chamber to the other, reversing the orientation of the purposeofthesescreensistoabsorbsomeofthekineticenergy
system at the same end of the chamber, or it may not require of the upstream jet, and allow its normal expansion as if in an
moving the system at all. unconfined space. Screens of square-mesh round wire with
5.5 The calibration technique is applicable to the two basic openareasof50to60%aresuggestedandseveralwillusually
types of fan pressurization systems in use, r/min doors and be needed. Any combination of screens or perforated plates
signal doors. that provide this flow conditioning may be used.
5.6 For fan pressurization systems that operate in multiple 7.1.1.3 Airflow Rate Measurement System, for measuring
ranges of airflow rate, the system must be calibrated in each the fan airflow rate. Acceptable systems include a nozzle or
range. bank of nozzles within the chamber, a nozzle in a duct, or a
5.7 The calibration technique is intended to provide a pitot traverse in a duct in accordance with 7.1.2.
complete calibration of a fan pressurization system. After 7.1.1.4 Flow Straighteners, for straightening the flow up-
calibratingseveralsystemsofanidenticalorsimilardesign,the stream of the measuring stations when the airflow rate mea-
fan airflow rate may be found to be independent of certain surement system uses a nozzle in a duct or a pitot traverse in
parameters such as fan pressure difference. Other simplifying a duct. The downstream plane of the straightener shall be
relations between fan airflow rate and fan speed or fan signal located between 5 and 5.25 duct diameters upstream of the
may be observed. If these relations are observed, a manufac- plane of the pitot traverse or nozzle.Arecommended form for
turer or other calibrator may choose to simplify the calibration the straightener is shown in Fig. 6. The dimension D is the
procedure by reducing the number of calibration points. inside diameter of the duct. The dimension y, which is the
5.8 Theuseoffanpressurizationsystemsinactualbuildings thickness of the straightener elements, shall not exceed 0.005
introduces additional factors that may cause errors in the D.
airflow rate measurement that are not accounted for by the 7.1.1.5 VariableSupply/ExhaustSystem—Acontrollablefan
calibration. These factors include operator and weather effects or throttling device to enable variation in the fan pressure
andinterferencefrominternalpartitionsandotherobstructions. difference at a particular airflow rate.
7.1.1.6 Pressure Difference Measuring Device, for measur-
6. Hazards
ing the fan pressure difference, and if applicable the nozzle
6.1 Provide secure guards and cages for fans and motors to
chamber or nozzle throat pressure difference, with a maximum
prevent accidental
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.