ASTM E1258-88(2008)
(Test Method)Standard Test Method for Airflow Calibration of Fan Pressurization Devices
Standard Test Method for Airflow Calibration of Fan Pressurization Devices
SIGNIFICANCE AND USE
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.
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.
The technique of pressurization testing of buildings puts 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 building size and airtightness that the fan pressurization system will encounter in the field.
The fan pressurization system must be calibrated in both directions of airflow used to pressurize and depressurize a building if the system airflow direction is reversible. These two calibrations can be conducted using the various setups described in this test method; however some of the setups can be combined such that a single calibration facility can be used to calibrate the fan in both directions. Such a single setup may involve moving the fan pressurization system from one end of the chamber to the other, reversing the orientation of the system at the same end of the chamber, or it may not require moving the system at all.
The calibration technique is applicable to the two basic types of fan pressurization systems in use, r/min doors and signal doors.
For fan pressurization systems that operate in multiple ranges of airflow rate, the system must be calibrated in each range.
The calibration technique is intended to provide a complete calibration of a fan pressurization system. After calibrating several systems of an iden...
SCOPE
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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 E 779.
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 51/AMCA 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 concerns, 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.
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Standards Content (Sample)
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Designation:E1258 −88(Reapproved 2008)
Standard Test Method for
Airflow Calibration of Fan Pressurization Devices
This standard is issued under the fixed designation E1258; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2.2 American Society of Heating, Refrigerating, and Air-
Conditioning Engineers Standard:
1.1 This test method covers the airflow measurement cali-
ASHRAE51/AMCA210Laboratory Methods for Testing
bration techniques for fan pressurization systems used for
Fans for Rating
measuring air leakage rates through building envelopes.
2.3 American Society of Mechanical Engineers Standard:
1.2 This test method is applicable to systems used for air
ASME MFC-3MStandard Measurement of Fluid Flow in
leakage measurement as described in Practice E779.
Pipes Using Orifice, Nozzle, and Venturi
1.3 This test method involves the installation of the fan
3. Terminology
pressurization system in a calibration chamber. Use of the fan
3.1 Definitions—For definitions used in this test method,
pressurization system in an actual building may introduce
see Terminology E631.
additional errors in the airflow measurement due to operator
influence, interference of internal partitions and furnishings,
3.2 Definitions of Terms Specific to This Standard:
weather effects, and other factors.
3.2.1 ambient conditions, n—conditions in the space from
which air is drawn into the calibration chamber and into which
1.4 Theproperuseofthistestmethodrequiresaknowledge
the chamber air is expelled.
of the principles of airflow and pressure measurement.
3.2.2 chamber, n—an enclosure of rectangular or circular
1.5 Thisstandardincludestwobasicprocedures,apreferred
cross section to simulate the entrance and exit conditions that
procedure,basedonASHRAE51/AMCA210,andanoptional
the fan is expected to encounter in service.
procedure based on a nonstandard airflow measurement
3.2.3 fan air density, n—density of air at the fan inlet
technique, commonly used by manufacturers of fan pressur-
expressed in kilograms per cubic metre.
ization devices, but which has not been compared with
standard airflow measurement techniques.
3.2.4 fan airflow rate, n—volumetric airflow rate at the fan
air density expressed in cubic metres per second.
1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the 3.2.5 fan outlet area, n—gross inside area measured in the
responsibility of the user of this standard to establish appro-
plane of the fan outlet opening expressed in square metres.
priate safety and health practices and determine the applica-
3.2.6 fan pressure difference, n—the static pressure differ-
bility of regulatory limitations prior to use.
ence between two stations expressed in pascals, measured
usingthestaticpressuretapsdescribedinFig.1.Onestationis
2. Referenced Documents
located within the chamber between the fan and the nearest
flow conditioners. The other station is outside the chamber.
2.1 ASTM Standards:
E631Terminology of Building Constructions
3.2.7 fan pressurization system, n—a device for measuring
E779TestMethodforDeterminingAirLeakageRatebyFan
the air leakage rate of a building envelope under controlled
Pressurization
pressurization or depressurization of the building interior. The
system includes controllable air-moving equipment, an airflow
ratemeasuringsystem,andadeviceformeasuringthepressure
difference across the building envelope. Such a system is often
This test method is under the jurisdiction of ASTM Committee E06 on
PerformanceofBuildingsandisthedirectresponsibilityofSubcommitteeE06.41on referred to as a blower door.
Air Leakage and Ventilation Performance.
Current edition approved April 1, 2008. Published May 2008. Originally
approved in 1988. Last previous edition approved in 2003 as E1258–88(2003). Available from American Society of Heating, Refrigerating, and Air-
DOI: 10.1520/E1258-88R08. Conditioning Engineers, Inc. (ASHRAE), 1791 Tullie Circle, NE, Atlanta, GA
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 30329, http://www.ashrae.org.
contactASTM Customer Service at service@astm.org. ForAnnual Book ofASTM Available from American Society of Mechanical Engineers (ASME), ASME
Standards volume information, refer to the standard’s Document Summary page on International Headquarters, Three Park Ave., New York, NY 10016-5990, http://
the ASTM website. www.asme.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1258−88 (2008)
3.2.12 nozzle chamber pressure difference, n—static pres-
sure difference measured across a nozzle or bank of nozzles
when nozzles are installed in a chamber expressed in pascals.
3.2.13 nozzle throat diameter, n—diameter of nozzle dis-
charge end expressed in square metres.
3.2.14 nozzle throat pressure difference, n—static pressure
differenceacrossthenozzleinaductmeasuredwiththroattaps
expressed in pascals (see Fig. 2).
3.2.15 orifice,n—asharp-edgedcircularconstrictionusedin
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 pressur-
FIG. 1Static Pressure Tap Specifications
izationsystemwithacalibrationthatrelatesthefanairflowrate
to the fan speed.
3.2.8 fan signal, n—an output from a fan pressurization
3.2.18 signal door, n—a fan pressurization system with a
system (other than fan speed) that is related to fan airflow rate
calibration that relates the fan airflow rate to an output signal
by the system calibration, such as the static pressure difference
other than fan speed.
across a constriction that is integral to the system.
3.2.19 transformation piece, n—an element to connect a
3.2.9 fan speed, n—speed of rotation of the fan impeller
duct with a measuring station to a fan when the fan connection
expressed in inverse seconds.
is a different size than the duct (see Fig. 4).
3.2.10 flow conditioners, n—a combination of screens or
4. Summary of Test Method
perforated plates located within the calibration chamber to
reduce pressure disturbances within the chamber.
4.1 Thistestmethodcontainstwoproceduresforcalibrating
3.2.11 nozzle, n—a gradually tapered constriction, of very fan pressurization devices, a preferred procedure based on
precise elliptical shape, used in airflow rate measurement (see ASHRAE51/AMCA210, and an optional procedure employ-
Fig. 2). ing an orifice in a chamber.
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. 2Nozzle Specifications
E1258−88 (2008)
facility. In the preferred procedure, three modes of airflow
measurementareacceptable:(1)anozzleorbankofnozzlesin
thechamber,(2)atraverseinaductusingapitottube(seeFig.
5), and (3) a nozzle in a duct. Other airflow rate measurement
techniques in a duct can be used such as orifice plates (ASME
MFC-3M) or constant injection tracer gas methods. In order
for an alternative airflow rate measurement technique to be
included as a preferred procedure, the errors introduced by the
procedure must be demonstrated not to exceed those intro-
duced by a nozzle or pitot traverse. In the optional procedure,
the airflow is measured with a series of sharp-edged orifices
installed in the wall of the chamber.
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
Recommended Plate Thickness, b
systems that are installed in an opening in the building
1.5mmfor d up to 150 mm
envelope, as opposed to pressurization techniques involving
2.5mmfor d up to 300 mm
3.2mmfor d up to 600 mm the mechanical ventilation system of the building.
4.5mmfor d up to 1200 mm
5.3 Thetechniqueofpressurizationtestingofbuildingsputs
Recommended Edge Thickness, a
Less than 0.02 d
specific requirements on the calibration of fan pressurization
NOTE 1—For thin plates (b<0.02 d), there is no need for beveling the
systems. The calibration must cover the range of fan pressure
edge of the orifice.
differences (approximately 12.5 to 75 Pa) that is induced
FIG. 3Sharp-Edged Orifice Design
during pressurization tests. The calibration must also cover a
Persily, A. K., “Air Flow Calibration of Building Pressurization Devices,”
NBSIR 84-2849, National Bureau of Standards, 1984.
FIG. 4Transformation Piece
4.2 Both procedures involve the installation of the fan
NOTE 1—Surface finish shall be 1 µm or better. The static orifices may
pressurization system in a chamber.
not exceed 1 mm in diameter. The minimum pitot tube stem diameter
4.3 The calibration consists of a comparison of the airflow
recognized under this standard shall be 2.5 mm. In no case shall the stem
rate through the fan pressurization system measured by the
diameter exceed ⁄30 of the test duct diameter.
system itself, and the airflow rate measured in the calibration FIG. 5Pitot Tube Specifications
E1258−88 (2008)
range in fan airflow rates corresponding to the range in
thewidth Wshallbeatleast2.4m,and Misgivenby =4HW/π.
buildingsizeandairtightnessthatthefanpressurizationsystem
In the case of a circular cross section, the chamber diameter
will encounter in the field.
shall be at least 2.5 m and M is equal to the chamber diameter.
When multiple nozzles are used in a chamber, the chamber
5.4 Thefanpressurizationsystemmustbecalibratedinboth
must be large enough to accommodate all the nozzles as
directions of airflow used to pressurize and depressurize a
described in 7.1.2.1 and 7.1.2.2.
buildingifthesystemairflowdirectionisreversible.Thesetwo
calibrations can be conducted using the various setups de-
7.1.1.2 Flow Conditioners—A combination of screens or
scribed in this test method; however some of the setups can be
perforated plates located in the chamber to reduce pressure
combined such that a single calibration facility can be used to
disturbances within the enclosure. These air to be located
calibrate the fan in both directions. Such a single setup may
within the chamber in accordance with 7.1.2. Where a mea-
involve moving the fan pressurization system from one end of
suring plane is located downstream of the flow conditioners,
the chamber to the other, reversing the orientation of the
the flow conditioners are provided to ensure a substantially
system at the same end of the chamber, or it may not require
uniform flow ahead of the measuring plane. Where a measur-
moving the system at all.
ing plane is located upstream of the flow conditioners, the
purposeofthesescreensistoabsorbsomeofthekineticenergy
5.5 The calibration technique is applicable to the two basic
of the upstream jet, and allow its normal expansion as if in an
types of fan pressurization systems in use, r/min doors and
unconfined space. Screens of square-mesh round wire with
signal doors.
openareasof50to60%aresuggestedandseveralwillusually
5.6 For fan pressurization systems that operate in multiple
be needed. Any combination of screens or perforated plates
ranges of airflow rate, the system must be calibrated in each
that provide this flow conditioning may be used.
range.
7.1.1.3 Airflow Rate Measurement System, for measuring
5.7 The calibration technique is intended to provide a
the fan airflow rate. Acceptable systems include a nozzle or
complete calibration of a fan pressurization system. After
bank of nozzles within the chamber, a nozzle in a duct, or a
calibratingseveralsystemsofanidenticalorsimilardesign,the
pitot traverse in a duct in accordance with 7.1.2.
fan airflow rate may be found to be independent of certain
7.1.1.4 Flow Straighteners, for straightening the flow up-
parameters such as fan pressure difference. Other simplifying
stream of the measuring stations when the airflow rate mea-
relations between fan airflow rate and fan speed or fan signal
surement system uses a nozzle in a duct or a pitot traverse in
may be observed. If these relations are observed, a manufac-
a duct. The downstream plane of the straightener shall be
turer or other calibrator may choose to simplify the calibration
located between 5 and 5.25 duct diameters upstream of the
procedure by reducing the number of calibration points.
plane of the pitot traverse or nozzle.Arecommended form for
the straightener is shown in Fig. 6. The dimension D is the
5.8 Theuseoffanpressurizationsystemsinactualbuildings
inside diameter of the duct. The dimension y, which is the
introduces additional factors that may cause errors in the
thickness of the straightener elements, shall not exceed 0.005
airflow rate measurement that are not accounted for by the
D.
calibration. These factors include operator and weather effects
7.1.1.5 Variable Supply/Exhaust System—Acontrollablefan
andinterferencefrominternalpartitionsandotherobstructions.
or throttling device to enable variation in the fan p
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