ISO/FDIS 27327-1

• Abstract:

  ISO 27327-1:2009 establishes uniform methods for laboratory testing of air curtain units to determine aerodynamic performance in terms of airflow rate, outlet air velocity uniformity, power consumption and air velocity projection, for rating or guarantee purposes. ISO 27327-1:2009 is not applicable to the specification of test procedures to be used for design, production or field testing.

• Status: Not Published
• ICS: 23.120 - Ventilators. Fans. Air-conditioners
• Technical Committee: ISO/TC 117 - Fans
• Drafting Committee: ISO/TC 117 - Fans
• Current Stage: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 25-Aug-2026
• Completion Date: 25-Aug-2026

• Revises: ISO 27327-1:2009 - Fans — Air curtain units — Part 1: Laboratory methods of testing for aerodynamic performance rating
• Effective Date: 19-Aug-2023

Overview

ISO/FDIS 27327-1:2026 is the international standard developed by ISO/TC 117 for the laboratory testing of air curtain units (ACUs). This standard specifies uniform laboratory test methods to evaluate the aerodynamic performance of air curtain units. The evaluation is carried out in terms of key performance indicators such as airflow rate, outlet air velocity uniformity, power consumption, and air velocity projection. The objective is to provide consistent, reliable, and repeatable procedures to rate and guarantee the performance of air curtain units under controlled laboratory conditions. This standard does not address procedures for design, production, or field testing.

Key Topics

• Aerodynamic Performance Testing: Standardized laboratory procedures to assess and rate ACUs based on their airflow characteristics and efficiency.
• Airflow Rate Determination: Methods for measuring the volume of air delivered by the ACU through its discharge nozzle using reference methods (e.g., ISO 5801).
• Outlet Air Velocity Uniformity: Measurement and calculation of how evenly the air exits the ACU across its width to ensure effective barrier performance.
• Power Consumption: Procedures to measure the electrical power supplied to the unit under test, providing insights into energy efficiency.
• Air Velocity Projection: Techniques to determine how far and how consistently the air from the ACU projects from the discharge nozzle, crucial for the effective operation of air curtains.
• Terminology and Definitions: Precise definitions for terms including air curtain depth, discharge angle, discharge area, and other performance parameters for clarity in communication and reporting.

Applications

The methods specified in ISO/FDIS 27327-1 serve various stakeholders in the HVAC (Heating, Ventilation, and Air Conditioning) and building equipment industries:

• Manufacturers: Enables the development, performance evaluation, and product comparison of air curtain units in a controlled, comparable way.
• Testing Laboratories: Standardizes the testing process for ACUs, ensuring results are reliable, repeatable, and comparable across different labs and product types.
• Specifiers and Procurement Professionals: Provides a uniform basis for evaluating product claims, assessing suitability for specific installations, and ensuring regulatory and project compliance.
• Quality Assurance: Supports consistent documentation and verification for product warranties, certifications, and guarantees pertaining to the aerodynamic performance of air curtain units.
• Research and Product Development: Informs R&D activities by establishing clear test benchmarks for new and enhanced ACU designs, or alternative forms such as non-rectangular units.

The practical benefit of adhering to ISO/FDIS 27327-1 is improved confidence in performance ratings, easier compliance with procurement specifications, and enhanced marketability due to conformity with international standards.

Related Standards

A number of other international standards complement ISO/FDIS 27327-1:

• ISO 27327-2: Focuses on field testing methods for air curtain units, complementing the laboratory focus of Part 1.
• ISO 5801: Provides performance testing methods for fans using standardized airways, referenced within ISO/FDIS 27327-1 for airflow measurements.
• ISO/IEC Directives: General rules for drafting and maintaining ISO standards across industries.
• IEC Electropedia and ISO Online Browsing Platform: Authoritative sources for definitions and terminological consistency used in this and related standards.

By implementing ISO/FDIS 27327-1, stakeholders ensure that air curtain units are tested and rated in accordance with globally recognized best practices, supporting energy efficiency, indoor air quality, and environmental control objectives.

Keywords: ISO 27327-1, air curtain units, laboratory testing, aerodynamic performance, airflow rate, outlet air velocity, power consumption, air velocity projection, HVAC standards, ISO standards for fans.

FINAL DRAFT
International
Standard
ISO/TC 117
Fans — Air curtain units —
Secretariat: BSI
Part 1:
Voting begins on:
2026-08-25
Laboratory methods of testing for
aerodynamic performance rating
Voting terminates on:
2026-10-20
Ventilateurs — Rideaux d'air —
Partie 1: Méthodes d'essai en laboratoire des caractéristiques de
performance aérodynamique
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
International
Standard
ISO/TC 117
Fans — Air curtain units —
Secretariat: BSI
Part 1:
Voting begins on:
Laboratory methods of testing for
aerodynamic performance rating
Voting terminates on:
Ventilateurs — Rideaux d'air —
Partie 1: Méthodes d'essai en laboratoire des caractéristiques de
performance aérodynamique
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ii
Contents Page
Foreword .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions .1
3.2 Symbols .8
4 ACU airflow rate test . 10
4.1 Apparatus and instruments.10
4.1.1 General .10
4.1.2 Power .10
4.2 Preparation of ACU airflow rate test .10
4.3 Test procedure .10
4.3.1 Initial conditions .10
4.3.2 Data to be recorded.11
4.3.3 Airflow rate determination .11
4.4 Calculation .11
4.4.1 General .11
4.4.2 Static pressure as a function of airflow rate . 12
4.4.3 ACU Average outlet air velocity . 13
4.4.4 ACU input power . 13
4.5 Test report . 13
5 ACU outlet air velocity uniformity test . 14
5.1 Apparatus and instruments.14
5.1.1 General .14
5.1.2 Instrumentation.14
5.1.3 Air curtain core velocity measurement .14
5.2 ACU outlet air velocity uniformity test .14
5.3 Test procedure .14
5.3.1 Initial conditions .14
5.3.2 Data to be recorded.14
5.3.3 ACU outlet air velocity uniformity test . 15
5.3.4 Air curtain core velocity . . . 15
5.4 Calculation . 15
5.4.1 General . 15
5.4.2 Standard deviation .16
5.4.3 Average air curtain core velocity .16
5.4.4 ACU outlet air velocity uniformity .16
5.5 Test report .16
6 ACU velocity projection test . 17
6.1 Apparatus and instruments.17
6.1.1 Air curtain core velocity measurement .17
6.2 Equipment and organization.17
6.3 Test procedure .17
6.3.1 Initial conditions .17
6.3.2 Data to be recorded.17
6.3.3 Air curtain velocity projection test .18
6.4 Calculation .19
6.4.1 General .19
6.4.2 Air curtain core velocity . . .19
6.4.3 Air curtain average core velocity .19
6.4.4 ACU velocity projection .19
6.5 Test report .19
7 Illustration of tests .20

iii
7.1 ACU airflow rate test . 20
7.2 Determination of air discharge angle, θ . 22
7.3 Determination of Distance, A . 23
7.4 Calculation of test line space, C .24
d
7.5 Calculation of air curtain average core velocity, ν . 25
ca
7.6 Calculation of standard if deviation, s . 25
Annex A (Informative) Air curtain discharge area .29
Annex B (Informative) Air curtain depth and width .30
Annex C (Informative) Air curtain active and inactive depth and width .31
Annex D (Normative) Uncertainty in velocity determination using Pitot-static tube and
manometer due to manometer slope .33
Bibliography .35

iv
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 117, Fans.
This second edition cancels and replaces the first edition (ISO 27327-1:2009), which has been technically
revised.
The main changes are as follows:
— clarified definition between the dimensions of the air curtain and the air discharge nozzle;
— expanded definitions for air curtain and air discharge nozzle width and depth to address non-rectangular
constructions;
— added definitions for discharge nozzles that are not perpendicular to the opening or parallel to the floor
using a newly defined normal discharge plane;
— added minimum air curtain core velocity method to the air curtain velocity projection test to allow a
minimum core velocity to end the test resulting in a target distance based on projection.
A list of all parts in the ISO 27327-1 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
FINAL DRAFT International Standard ISO/FDIS 27327-1:2026(en)
Fans — Air curtain units —
Part 1:
Laboratory methods of testing for aerodynamic performance
rating
1 Scope
This document establishes uniform methods for laboratory testing of air curtain units to determine
aerodynamic performance in terms of airflow rate, outlet air velocity uniformity, power consumption and
air velocity projection, for rating or guarantee purposes.
This document does not specify test procedures to be used for design, production or field testing.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 5801, Fans — Performance testing using standardized airways
3 Terms, definitions and symbols
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1 Terms and definitions
3.1.1
absolute pressure
p
value of a pressure when the datum pressure is absolute zero
Note 1 to entry: This is always positive.
3.1.2
air curtain unit
ACU
air-moving device which produces an air curtain.

3.1.3
ACU airflow rate
q
airflow volume which leaves the ACU discharge nozzle (3.1.5), at standard air conditions, as measured in
accordance with ISO 5801
Note 1 to entry: This is given by Formula (1):
q = q (1)
Vsg1
where q is the volume flow rate at stagnation conditions
Vsg1
Note 2 to entry: This rate is expressed in cubic metres per second
3.1.4
ACU average outlet air velocity
ν
a
ACU airflow rate (3.1.3) produced by the ACU divided by the air curtain discharge area (3.1.20) on the air
curtain normal discharge plane (3.1.22) at free-air delivery
Note 1 to entry: See 4.4.3 for calculation of the value.
Note 2 to entry: Velocity is expressed in metres per second.
3.1.5
ACU discharge nozzle
component or an assembly in the ACU which directs and controls the airstream
Note 1 to entry: May include decorative (inactive) sections.
Note 2 to entry: May include adjustable vanes.
Note 3 to entry: Leading edge shall be the first point or edge where the airstream leaves the ACU discharge nozzle.
Note 4 to entry: Trailing edge shall be the last point or edge where the airstream leaves the ACU discharge nozzle.
Note 5 to entry: If only one ACU discharge nozzle is present, it is the primary ACU discharge nozzle.
Note 6 to entry: ACU discharge nozzles are considered “multiple” when they do not share a common airflow discharge
plane and are spaced more than two times the ACU discharge nozzle depth apart. The primary ACU discharge nozzle
on a system with multiple ACU discharge nozzles is that which is closest to the plane of the protected opening.
3.1.6
ACU discharge nozzle depth
h
n
inside short dimension of the ACU discharge nozzle (3.1.5) perpendicular to the airflow plane
Note 1 to entry: If a decorative (inactive) section exists between two active sections, it shall be considered active and
included in the dimension.
Note 2 to entry: If the ACU discharge nozzle is not rectangular, it shall be the largest measurement of the short
dimension.
Note 3 to entry: Depth is expressed in millimetres.
Note 4 to entry: Refer to Figures B.1 and C.1 for examples.
3.1.7
ACU discharge nozzle width
b
n
inside long dimension of the ACU discharge nozzle (3.1.5) parallel to the airflow plane
Note 1 to entry: If decorative (inactive) section exists between two active sections, it shall be considered active and
included in the dimension.
Note 2 to entry: If the ACU discharge nozzle is not rectangular, it shall be the largest measurement of the long side.
Note 3 to entry: Width is expressed in millimetres.
Note 4 to entry: Refer to Figures B.1 and C.1 for examples.
3.1.8
ACU inlet area
total inside net area of all surfaces where entering airflow first meets the ACU cabinet
3.1.9
ACU normal
vector declared by the sponsor that identifies the ACU cabinet orientation when the air curtain discharge
angle is 0° and parallel to the plane of the opening it is protecting
3.1.10
ACU outlet air velocity uniformity
u
ACU
indicator of the consistency of air velocities across the air curtain width
Note 1 to entry: The outlet air velocity uniformity is expressed as a percentage.
Note 2 to entry: See 5.4.4 for calculation of the value. See Figure 7.
3.1.11
ACU input power
power rating
P
e
electrical power supplied at the terminals of the ACU
Note 1 to entry: Includes electric motor(s) and drive(s).
Note 2 to entry: Input power is expressed in watts.
3.1.12
ACU pressure
p
ACU
difference between the stagnation pressure at the ACU outlet and the stagnation pressure at the ACU inlet
Note 1 to entry: This is determined using Formula (2):
p = p − p (2)
ACU sg2 sg1
Note 2 to entry: When the Mach number is less than 0,15, it is possible to use the relationship given in Formula (3):
p = p − p (3)
ACU t2 t1
Note 3 to entry: ACU pressure is expressed in pascals.
3.1.13
ACU static pressure
p
sACU
conventional quantity defined as the ACU pressure minus the ACU dynamic pressure corrected by the Mach
factor
Note 1 to entry: This is determined using Formula (4):
p = −p (4)
sACU sg1
Note 2 to entry: Static pressure is expressed in pascals.

3.1.14
ACU target distance
l
t
distance perpendicular to the air curtain normal discharge plane (3.1.22) specified by the sponsor of the test
to terminate an ACU velocity projection (3.1.15) test
Note 1 to entry: See 6.3.3.1 for definition of distances.
Note 2 to entry: Target distance is expressed in metres.
3.1.15
ACU velocity projection
set of average air curtain core velocities (3.1.17) measured along the air curtain width at specified distances
from the air curtain normal discharge plane (3.1.22)
Note 1 to entry: See 6.3.3.1 for definition of distances.
Note 2 to entry: Velocity is expressed in metres per second.
3.1.16
air curtain
directionally controlled airstream with a minimum width to depth ratio of 5:1
Note 1 to entry: When applied across the entire height and width of an opening, can reduce the infiltration or transfer
of air from one side of the opening to the other and/or inhibit the passage of moisture, insects, dust and debris.
3.1.17
air curtain average core velocity
ν
ca
average of air curtain core velocities (3.1.18) measured along the air curtain width at specified distances
from the air curtain normal discharge plane (3.1.22)
Note 1 to entry: See 6.3.3.1 for definition of distances.
Note 2 to entry: See 6.4.3 for determination.
Note 3 to entry: Velocity is expressed in metres per second.
3.1.18
air curtain core velocity
ν
cx
maximum air velocity of the air curtain at point x as measured across both the air curtain depth and width
at specified distances from the air curtain normal discharge plane (3.1.22)
Note 1 to entry: See 5.3.4 and 6.4.2 for determinations.
Note 2 to entry: See 6.3.3.1 for definition of distances.
Note 3 to entry: Velocity is expressed in metres per second.
3.1.19
air curtain discharge angle
θ
angle between the ACU normal (3.1.9) or plane of the protected opening and the direction in which the air
curtain leaves the ACU discharge nozzle (3.1.5)
3.1.20
air curtain discharge area
A
ac
true cross-sectional area of the air curtain on the air curtain normal discharge plane (3.1.22)
Note 1 to entry: Rectangular area is obtained by using the air curtain width and depth.

Note 2 to entry: This is determined using Formula (5).
()bh
ac ac
A  (5)
ac
11 0
Note 3 to entry: Discharge area is expressed in metre square.
Note 4 to entry: See Figure A.1 for examples.
3.1.21
air curtain depth
h
ac
short dimension of the air curtain measured on the air curtain normal discharge plane (3.1.22)
Note 1 to entry: If the ACU discharge nozzle’s entire depth is actively directing the airstream and is coplanar with the
air curtain normal discharge plane, it shall be equal to the ACU discharge nozzle depth.
Note 2 to entry: If the ACU discharge nozzle depth has decorative (inactive) sections and is coplanar with the air
curtain normal discharge plane, it shall be equal to the largest measurement of the short dimension of the active
section declared and located by the sponsor.
Note 3 to entry: If the ACU discharge nozzle’s entire depth is actively directing the airstream and is not coplanar
with the air curtain normal discharge plane, it shall be the largest short measurement from trailing edge of the ACU
discharge nozzle to the intersection of a line projected 5° from the leading edge of the ACU discharge nozzle and the air
curtain normal discharge plane.
Note 4 to entry: If the ACU discharge nozzle depth has decorative (inactive) sections and is not coplanar with the air
curtain normal discharge plane it shall be the largest short measurement from trailing edge of the ACU discharge
nozzle to the intersection of a line projected 5° from the leading edge of the active ACU discharge nozzle declared by
the sponsor and the air curtain normal discharge plane.
Note 5 to entry: Depth is expressed in millimetres.
Note 6 to entry: Refer to Figures 1, B.1, and C.1 for examples.
Key
1 air curtain normal discharge plane
2 airflow normal
3 leading edge of the active nozzle
4 trailing edge of the active nozzle
Figure 1 — Air curtain depth
3.1.22
air curtain normal discharge plane
plane perpendicular to the airflow normal (0° discharge angle) created by the cross section of the air curtain
Note 1 to entry: It is located at the trailing edge of the active ACU discharge nozzle.
Note 2 to entry: See Figure 2 for examples.

Key
1 air curtain normal discharge plane
2 airflow normal
Figure 2 — Air curtain normal discharge plane
3.1.23
air curtain width
b
ac
long dimension of the air curtain measured on the air curtain normal discharge plane (3.1.22)
Note 1 to entry: If the ACU discharge nozzle’s entire width is actively directing the airstream and is coplanar with the
air curtain normal discharge plane, it shall be equal to the ACU discharge nozzle width.
Note 2 to entry: If the ACU discharge nozzle width has decorative (inactive) sections and is coplanar with the air
curtain normal discharge plane, it shall be equal to the largest measurement of the long dimension of the active section
declared and located by the sponsor.
Note 3 to entry: If the ACU discharge nozzle’s entire width is actively directing the airstream and is not coplanar
with the air curtain normal discharge plane, it shall be the largest long measurement from trailing edge of the ACU
discharge nozzle to the intersection of a line projected 5° from the leading edge of the ACU discharge nozzle and the air
curtain normal discharge plane.
Note 4 to entry: If the ACU discharge nozzle width has decorative (inactive) sections and is not coplanar with the
air curtain normal discharge plane it shall be the largest long measurement from trailing edge of the ACU discharge
nozzle to the intersection of a line projected 5° from the leading edge of the active ACU discharge nozzle declared by
the sponsor and the air curtain normal discharge plane.
Note 5 to entry: Width is expressed in millimetres.
Note 6 to entry: Refer to Figures B.1 and C.1 for examples.
3.1.24
air density
ρ
a
mass per unit volume of air
Note 1 to entry: Air density is expressed in kilograms per cubic metre.
3.1.25
airflow rate
flow of air or an air current, specifically one that passes through a dimensionally defined plane
3.1.26
atmospheric pressure
p
a
absolute pressure of the free atmosphere at the mean altitude of the ACU
Note 1 to entry: Pressure is expressed in pascals.

3.1.27
barometric pressure
p
b
absolute pressure exerted by the atmosphere at a location of measurement
Note 1 to entry: Pressure is expressed in pascals.
3.1.28
determination
complete set of measurements for a particular point of operation for the parameter being determined
3.1.29
dry-bulb temperature
T
d
air temperature measured by a dry temperature sensor in the test enclosure, near the ACU inlet or airway
inlet
Note 1 to entry: Temperature is expressed in degrees Celsius.
3.1.30
dynamic pressure at a point
p
d
pressure calculated from the velocity and the density, ρ , of the air at a point
a
Note 1 to entry: The point is determined using Formula (6):
 
v
p     (6)
da
 
 
Note 2 to entry: Pressure is expressed in pascals.
3.1.31
free-air delivery
point of operation where the ACU operates against zero static pressure
3.1.32
gauge pressure
p
e
value of the pressure when the datum pressure is the atmospheric pressure at the point of measurement
Note 1 to entry: Gauge pressure can be negative or positive.
Note 2 to entry: Gauge pressure is determined using Formula (7):
pp p (7)
ea
Note 3 to entry: Pressure is expressed in pascals.
3.1.33
gauge stagnation pressure at a point
p
esg
difference between the absolute stagnation pressure, p , and the atmospheric pressure, p
sg a
Note 1 to entry: This pressure is calculated using Formula (8):
p = p − p (8)
esg sg a
Note 2 to entry: Pressure is expressed in pascals.

3.1.34
inlet stagnation volume flow r
...

SISO/DISFDIS 27327-1:2025(en)
ISO/TC 117
Secretariat: BSI
Date: 20252026-08-2111
Fans — Air curtain units — —
Part 1:
Laboratory methods of testing for aerodynamic performance rating
Ventilateurs — Rideaux d'air — —
Partie 1: Méthodes d'essai en laboratoire des caractéristiques de performance aérodynamique
FDIS stage
MUST BE USED
FOR FINAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
EmailE-mail: [e-mail]
Website: www.iso.orgwww.iso.org
Published in Switzerland
ICS 23.120
Price based on 29 pages
ii
ISO/DISFDIS 27327-1:20252026(en)
Contents
Foreword . iv
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions . 1
Figure 1 — Air Curtain Depth . 6
Figure 2 — Air Curtain Normal Discharge Plane . 7
3.2 Symbols . 9
4 ACU airflow rate test . 11
4.1 Apparatus and instruments . 11
4.1.1 General . 11
4.1.2 Power . 11
Figure 3 — ACU Input Power . 11
4.2 Preparation of ACU airflow rate test . 11
4.3 Test procedure . 12
4.3.1 Initial conditions . 12
4.3.2 Data to be recorded . 12
4.3.3 Airflow rate determination . 13
4.4 Calculation . 13
4.4.1 General . 13
4.4.2 Static pressure as a function of airflow rate . 13
4.4.3 ACU Average outlet air velocity . 14
4.4.4 ACU input power . 14
4.5 Test report . 14
5 ACU outlet air velocity uniformity test . 15
5.1 Apparatus and instruments . 15
5.1.1 General . 15
5.1.2 Instrumentation . 15
5.1.3 Air curtain core velocity measurement . 15
5.2 ACU outlet air velocity uniformity test . 15
5.3 Test procedure . 16
5.3.1 Initial conditions . 16
5.3.2 Data to be recorded . 16
5.3.3 ACU outlet air velocity uniformity test . 17
5.3.4 Air curtain core velocity . 17
5.4 Calculation . 17
5.4.1 General . 17
5.4.2 Standard deviation . 17
5.4.3 Average air curtain core velocity . 17
5.4.4 ACU outlet air velocity uniformity . 17
5.5 Test report . 18
6 ACU velocity projection test . 18
6.1 Apparatus and instruments . 18
6.1.1 Air curtain core velocity measurement . 18
MUST BE USED
6.2 Equipment and organization . 18
6.3 Test procedure . 19
6.3.1 Initial conditions . 19
FOR FINAL
6.3.2 Data to be recorded . 19
iii
6.3.3 Air curtain velocity projection test . 20
6.4 Calculation . 20
6.4.1 General . 20
6.4.2 Air curtain core velocity . 21
6.4.3 Air curtain average core velocity . 21
6.4.4 ACU velocity projection . 21
6.5 Test report . 21
7 Illustration of tests . 21
7.1 ACU airflow rate test . 21
7.2 Determination of air discharge angle, θ . 24
Figure 5 — ACU airflow rate vs. static pressure curve . 25
Figure 6 — Outlet air velocity uniformity and air curtain velocity projection test method . 25
7.3 Determination of Distance, A . 25
Figure 7 — Outlet air velocity uniformity test method (dimensions in millimetres) . 27
7.4 Calculation of test line space, C . 27
d
7.5 Calculation of air curtain average core velocity, νca . 27
7.6 Calculation of standard if deviation, s . 27
Figure 8 — Air curtain velocity projection test method (dimensions in millimetres) . 28
Figure 9 — Typical ACU airflow rate performance chart. 29
Annex A (Informative) Air curtain discharge area . 32
Annex B (Informative) Air curtain depth and width . 33
Annex C (Informative) Air curtain active and inactive depth and width . 34
Annex D (Normative) Uncertainty in velocity determination using Pitot-static tube and
manometer due to manometer slope . 35
Bibliography . 36

Foreword . vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions . 1
3.2 Symbols . 10
4 ACU airflow rate test . 12
4.1 Apparatus and instruments . 12
4.2 Preparation of ACU airflow rate test . 13
4.3 Test procedure . 13
4.4 Calculation . 14
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ISO/DISFDIS 27327-1:20252026(en)
4.5 Test report . 16
5 ACU outlet air velocity uniformity test . 17
5.1 Apparatus and instruments . 17
5.2 ACU outlet air velocity uniformity test . 17
5.3 Test procedure . 18
5.4 Calculation . 19
5.5 Test report . 20
6 ACU velocity projection test . 20
6.1 Apparatus and instruments . 20
6.2 Equipment and organization . 21
6.3 Test procedure . 21
6.4 Calculation . 23
6.5 Test report . 23
7 Illustration of tests . 24
7.1 ACU airflow rate test . 24
7.2 Determination of air discharge angle, θ . 28
7.3 Determination of Distance, A . 31
7.4 Calculation of test line space, C . 33
d
7.5 Calculation of air curtain average core velocity, νca . 34
7.6 Calculation of standard if deviation, s . 34
Annex A (Informative) Air curtain discharge area . 41
Annex B (Informative) Air curtain depth and width . 43
Annex C (Informative) Air curtain active and inactive depth and width . 45
Annex D (Normative) Uncertainty in velocity determination using Pitot-static tube and
manometer due to manometer slope . 48
Bibliography . 50

MUST BE USED
FOR FINAL
v
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of
ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents.www.iso.org/patents. ISO shall not be held responsible for identifying any or all such
patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.htmlwww.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 117, Fans.
This second edition cancels and replaces the first edition (ISO 27327-1:2009), which has been technically
revised.
The main changes are as follows:
— Addedclarified definition clarity between the dimensions of the air curtain and the air discharge nozzle.;
— Expandedexpanded definitions for air curtain and air discharge nozzle width and depth to address non -
rectangular constructions.;
— Addedadded definitions for discharge nozzles that are not perpendicular to the opening or parallel to the
floor using a newly defined normal discharge plane.;
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ISO/DISFDIS 27327-1:20252026(en)
— Added Minimumadded minimum air curtain core velocity method to the Airair curtain velocity projection
test to allow a minimum core velocity to end the test resulting in a target distance based on projection.
A list of all parts in the ISO 27327-1 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.htmlwww.iso.org/members.html.
MUST BE USED
FOR FINAL
vii
DRAFT International Standard ISO/DIS 27327-1:2025(en)

Fans — Air curtain units —
Part 1:
Laboratory methods of testing for aerodynamic performance rating
1 Scope
This document establishes uniform methods for laboratory testing of air curtain units to determine
aerodynamic performance in terms of airflow rate, outlet air velocity uniformity, power consumption and air
velocity projection, for rating or guarantee purposes.
This document does not specify test procedures to be used for design, production or field testing.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 5801, Fans — Performance testing using standardized airways
3 Terms, definitions and symbols
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— — ISO Online browsing platform: available at https://www.iso.org/obphttps://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/https://www.electropedia.org/
3.1 Terms and definitions
3.1.1 3.1.1
absolute pressure
p
value of a pressure when the datum pressure is absolute zero
NOTE Note 1 to entry: This is always positive.
3.1.2
Air Curtain Unit
3.1.2
air curtain unit
ACU
air-moving device which produces an air curtain.
3.1.23.1.3 3.1.3
ACU airflow rate
q
airflow volume which leaves the ACU discharge nozzle [3.1.5],(3.1.5), at standard air conditions, as measured
in accordance with ISO 5801
Note 1 to entry: This is given by Formula (1): Error! Reference source not found.:
q = q (1)
Vsg1
where qVsg1 is the volume flow rate at stagnation conditions
Note 2 to entry: This rate is expressed in cubic metres per second
3.1.33.1.4 3.1.4
ACU average outlet air velocity
ν
a
ACU airflow rate [3.1.3](3.1.3) produced by the ACU divided by the air curtain discharge area [3.1.20](3.1.20)
on the air curtain normal discharge plane [3.1.22](3.1.22) at free-air delivery
NOTE 1 Note 1 to entry: See 4.4.34.4.3 for calculation of the value.
NOTE Note 2 to entry: Velocity is expressed in metres per second.
3.1.43.1.5 3.1.5
ACU discharge nozzle
component or an assembly in the ACU which directs and controls the airstream
Note 1 to entry: May include decorative (inactive) sections.
Note 2 to entry: May include adjustable vanes.
Note 3 to entry: Leading edge shall be the first point or edge where the airstream leaves the ACU discharge nozzle.
Note 4 to entry: Trailing edge shall be the last point or edge where the airstream leaves the ACU discharge nozzle.
Note 5 to entry: If only one ACU discharge nozzle is present, it is the primary ACU discharge nozzle.
Note 6 to entry: ACU discharge nozzles are considered “multiple” when they do not share a common airflow discharge
plane and are spaced more than two times the ACU discharge nozzle depth apart. The primary ACU discharge nozzle on
a system with multiple ACU discharge nozzles is that which is closest to the plane of the protected opening.
3.1.53.1.6 3.1.6
ACU discharge nozzle depth
h
n
inside short dimension of the ACU discharge nozzle (3.1.5)(3.1.5) perpendicular to the airflow plane
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Note 1 to entry: If a decorative (inactive) section exists between two active sections, it shall be considered active and
included in the dimension.
Note 2 to entry: If the ACU discharge nozzle is not rectangular, it shall be the largest measurement of the short
dimension,.
Note 3 to entry: Depth is expressed in millimetres.
Note 4 to entry: Refer to Figures B.1Figure B.1 and C.1Figure C.1 for examples.
3.1.63.1.7 3.1.7
ACU discharge nozzle width
bn
inside long dimension of the ACU discharge nozzle [3.1.5](3.1.5) parallel to the airflow plane
Note 1 to entry: If decorative (inactive) section exists between two active sections, it shall be considered active and
included in the dimension.
Note 2 to entry: If the ACU discharge nozzle is not rectangular, it shall be the largest measurement of the long side.
Note 3 to entry: Width is expressed in millimetres.
Note 4 to entry: Refer to Figures B.1Figure B.1 and C.1Figure C.1 for examples.
3.1.73.1.8 3.1.8
ACU inlet area
total inside net area of all surfaces where entering airflow first meets the ACU cabinet
3.1.83.1.9 3.1.9
ACU normal
vector declared by the sponsor that identifies the ACU cabinet orientation when the air curtain discharge angle
is 0° and parallel to the plane of the opening it is protecting
3.1.93.1.10 3.1.10
ACU outlet air velocity uniformity
u
ACU
indicator of the consistency of air velocities across the air curtain width
Note 1 to entry: The outlet air velocity uniformity is expressed as a percentage.
Note 2 to entry: See 5.4.45.4.4 for calculation of the value. See Figure 7.Figure 7 .
3.1.103.1.11 3.1.11
ACU input power
power rating
P
e
electrical power supplied at the terminals of the ACU
Note 1 to entry: Includes electric motor(s) and drive(s).
Note 2 to entry: Input power is expressed in watts.
3.1.113.1.12 3.1.12
ACU pressure
MUST BE USED
p
ACU
difference between the stagnation pressure at the ACU outlet and the stagnation pressure at the ACU inlet
FOR FINAL
Note 1 to entry: This is determined using Formula (2): Error! Reference source not found.:
pACU = psg2 − psg1 (2)
Note 2 to entry: When the Mach number is less than 0,15, it is possible to use the relationship given in Formula (3):
Error! Reference source not found.:
pACU = pt2 − pt1 (3)
Note 3 to entry: ACU pressure is expressed in pascals.
3.1.123.1.13 3.1.13
ACU static pressure
p
sACU
conventional quantity defined as the ACU pressure minus the ACU dynamic pressure corrected by the Mach
factor
Note 1 to entry: This is determined using Formula (4): Error! Reference source not found.:
p = −p (4)
sACU sg1
Note 2 to entry: Static pressure is expressed in pascals.
3.1.133.1.14 3.1.14
ACU target distance
l
t
distance perpendicular to the air curtain normal discharge plane [3.1.22](3.1.22) specified by the sponsor of
the test to terminate an ACU velocity projection [3.1.15](3.1.15) test
Note 1 to entry: See 6.3.2.56.3.3.1 for definition of distances.
Note 2 to entry: Target distance is expressed in metres.
3.1.143.1.15 3.1.15
ACU velocity projection
set of average air curtain core velocities [3.1.17](3.1.17) measured along the air curtain width at specified
distances from the air curtain normal discharge plane [3.1.22](3.1.22)
Note 1 to entry: See 6.3.2.56.3.3.1 for definition of distances.
Note 2 to entry: Velocity is expressed in metres per second.
3.1.153.1.16 3.1.16
air curtain
directionally controlled airstream with a minimum width to depth ratio of 5:1
Note 1 to entry: When applied across the entire height and width of an opening, can reduce the
infiltration or transfer of air from one side of the opening to the other and/or inhibit the passage of moisture, insects,
dust and debris.
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3.1.163.1.17 3.1.17
air curtain average core velocity
νca
average of air curtain core velocities [3.1.18](3.1.18) measured along the air curtain width at specified
distances from the air curtain normal discharge plane [3.1.22](3.1.22)
Note 1 to entry: See 6.3.2.56.3.3.1 for definition of distances.
Note 2 to entry: See 6.4.36.4.3 for determination.
Note 3 to entry: Velocity is expressed in metres per second.
3.1.173.1.18 3.1.18
air curtain core velocity
ν
cx
maximum air velocity of the air curtain at point x as measured across both the air curtain depth and width at
specified distances from the air curtain normal discharge plane [3.1.22](3.1.22)
Note 1 to entry: See 5.3.45.3.4 and 6.3.46.4.2 for determinations.
Note 2 to entry: See 6.3.2.56.3.3.1 for definition of distances.
Note 3 to entry: Velocity is expressed in metres per second.
3.1.183.1.19 3.1.19
air curtain discharge angle
θ
angle between the ACU normal [3.1.9](3.1.9) or plane of the protected opening and the direction in which the
air curtain leaves the ACU discharge nozzle [3.1.5](3.1.5)
3.1.193.1.20 3.1.20
air curtain discharge area
Aac
true cross-sectional area of the air curtain on the air curtain normal discharge plane [3.1.22](3.1.22)
Note 1 to entry: Rectangular area is obtained by using the air curtain width and depth.
Note 2 to entry: This is determined using Formula (5). (5).
()bh 
ac ac
A = (5)
ac
110
(𝑏 × ℎ )
𝑎𝑐 𝑎𝑐
𝐴 =
𝑎𝑐
1 × 10
(5)
Note 3 to entry: Discharge area is expressed in metre squaredsquare.
Note 4 to entry: See Figure A.1Figure A.1 for examples.
3.1.203.1.21 3.1.21
air curtain depth
hac
MUST BE USED
short dimension of the air curtain measured on the air curtain normal discharge plane [3.1.22](3.1.22)
Note 1 to entry: If the ACU discharge nozzle’s entire depth is actively directing the airstream and is coplanar with the air
FOR FINAL
curtain normal discharge plane, it shall be equal to the ACU discharge nozzle depth.
Note 2 to entry: If the ACU discharge nozzle depth has decorative (inactive) sections and is coplanar with the air curtain
normal discharge plane, it shall be equal to the largest measurement of the short dimension of the active section declared
and located by the sponsor.
Note 3 to entry: If the ACU discharge nozzle’s entire depth is actively directing the airstream and is not coplanar with
the air curtain normal discharge plane, it shall be the largest short measurement from trailing edge of the ACU discharge
nozzle to the intersection of a line projected 5° from the leading edge of the ACU discharge nozzle and the air curtain
normal discharge plane.
Note 4 to entry: If the ACU discharge nozzle depth has decorative (inactive) sections and is not coplanar with the air
curtain normal discharge plane it shall be the largest short measurement from trailing edge of the ACU discharge nozzle
to the intersection of a line projected 5° from the leading edge of the active ACU discharge nozzle declared by the sponsor
and the air curtain normal discharge plane.
Note 5 to entry: Depth is expressed in millimetres.
Note 6 to entry: Refer to Figures 1, B.1,Figure 1 , Figure B.1 , and C.1Figure C.1 for examples.

Key
1 air curtain normal discharge plane
2 airflow normal
3 leading edge of the active nozzle
4 trailing edge of the active nozzle
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Figure 1 — Air Curtain Depthcurtain depth
3.1.213.1.22 3.1.22
air curtain normal discharge plane
plane perpendicular to the airflow normal (0° discharge angle) created by the cross section of the air curtain
Note 1 to entry 1: : It is located at the trailing edge of the active ACU discharge nozzle.
Note 2 to entry 2: : See Figure 2Figure 2 for examples.

Key
1 air curtain normal discharge plane
2 airflow normal
Figure 2 — Air Curtain Normal Discharge Planecurtain normal discharge plane
3.1.223.1.23 3.1.23
air curtain width
bac
long dimension of the air curtain measured on the air curtain normal discharge plane [3.1.22](3.1.22)
Note 1 to entry: If the ACU discharge nozzle’s entire width is actively directing the airstream and is coplanar with the air
curtain normal discharge plane, it shall be equal to the ACU discharge nozzle width.
Note 2 to entry: If the ACU discharge nozzle width has decorative (inactive) sections and is coplanar with the air curtain
normal discharge plane, it shall be equal to the largest measurement of the long dimension of the active section declared
and located by the sponsor.
Note 3 to entry: If the ACU discharge nozzle’s entire width is actively directing the airstream and is not coplanar with
the air curtain normal discharge plane, it shall be the largest long measurement from trailing edge of the ACU discharge
MUST BE USED
nozzle to the intersection of a line projected 5° from the leading edge of the ACU discharge nozzle and the air curtain
normal discharge plane.
FOR FINAL
Note 4 to entry: If the ACU discharge nozzle width has decorative (inactive) sections and is not coplanar with the air
curtain normal discharge plane it shall be the largest long measurement from trailing edge of the ACU discharge nozzle
to the intersection of a line projected 5° from the leading edge of the active ACU discharge nozzle declared by the sponsor
and the air curtain normal discharge plane.
Note 5 to entry: Width is expressed in millimetres.
Note 6 to entry: Refer to Figures B.1Figure B.1 and C.1Figure C.1 for examples.
3.1.233.1.24 3.1.24
air density
ρa
mass per unit volume of air
Note 1 to entry: Air density is expressed in kilograms per cubic metre.
3.1.243.1.25 3.1.25
airflow rate
flow of air or an air current, specifically one that passes through a dimensionally defined plane
3.1.253.1.26 3.1.26
atmospheric pressure
p
a
absolute pressure of the free atmosphere at the mean altitude of the ACU
Note 1 to entry: Pressure is expressed in pascals.
3.1.263.1.27 3.1.27
barometric pressure
p
b
absolute pressure exerted by the atmosphere at a location of measurement
Note 1 to entry: Pressure is expressed in pascals.
3.1.273.1.28 3.1.28
determination
complete set of measurements for a particular point of operation for the parameter being determined
3.1.283.1.29 3.1.29
dry-bulb temperature
Td
air temperature measured by a dry temperature sensor in the test enclosure, near the ACU inlet or airway
inlet
Note 1 to entry: Temperature is expressed in degrees Celsius.
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ISO/DISFDIS 27327-1:20252026(en)
3.1.293.1.30 3.1.30
dynamic pressure at a point
pd
pressure calculated from the velocity and the density, ρ , of the air at a point.
a
Note 1 to entry: The point is determined using Formula (6): (6):

v 𝑣
p =  𝑝 = 𝜌 ( )

da d a
 2

(6)
NOTENote 2 to entry: Pressure is expressed in pascals.
3.1.303.1.31 3.1.31
free-air delivery
point of operation where the ACU operates against zero static pressure
3.1.313.1.32 3.1.32
gauge pressure
p
e
value of the pressure when the datum pressure is the atmospheric pressure at the point of measurement
Note 1 to entry: Gauge pressure can be negative or positive.
Note 2 to entry: Gauge pressure is determined using Formula (7): (7):
p =−p p 𝑝 = 𝑝 − 𝑝
e a
ea
(7)
Note 3 to entry: Pressure is expressed in pascals.
3.1.323.1.33 3.1.33
gauge stagnation pressure at a point
p
esg
difference between the absolute stagnation pressure, p , and the atmospheric pressure, p
sg a
Note 1 to entry: This pressure is calculated using Formula (8): Error! Reference source not found.:
p = p − p (8)
esg sg a
Note 2 to entry: Pressure is expressed in pascals.
3.1.333.1.34 3.1.34
inlet stagnation volume flow rate
q
Vsg1
mass flow rate divided by the inlet stagnation density
Note 1 to entry: This is determined using Formula (9): (9):
q 𝑞
m m
q = 𝑞 =
Vsg1 Vsg1
𝜌
sg1

sg1
MUST BE USED
(9)
Note 2 to entry: Volume flow rate is expressed in cubic metres per second.
FOR FINAL
3.1.343.1.35 3.1.35
point of operation
relative position on the air curtain performance curve corresponding to a particular airflow rate, pressure,
power and efficiency
3.1.353.1.36 3.1.36
pressure loss
decrease in pressure caused by friction and turbulence
3.1.363.1.37 3.1.37
standard air
air with a standard density of 1,2 kg/m at a standard barometric pressure of 101,325 kPa
3.1.373.1.38 3.1.38
static pressure
pressure that exists by degree of compression only
Note 1 to entry: If expressed as gauge pressure, it may be positive or negative.
3.1.383.1.39 3.1.39
test
series of determinations of various characteristics at a single point of operation of an ACU
3.1.393.1.40 3.1.40
velocity pressure
pressure that exists by virtue of rate of motion only
3.1.403.1.41 3.1.41
wet-bulb temperature
Tw
air temperature measured by a temperature sensor covered by a water-moistened wick and exposed to air in
motion
Note 1 to entry: When properly measured, it is a close approximation to the temperature of adiabatic saturation.
Note 2 to entry: Temperature is expressed in degrees Celsius.
3.2 Symbols
Symbol Term Unit
Aac Air Curtain cross-sectional area m
b Air curtain width mm
ac
b ACU discharge nozzle width mm
n
C The calculated test line spacing mm
d
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E ACU energy effectiveness 1
ACU
h Air curtain depth mm
ac
hn ACU discharge nozzle depth mm
l ACU target distance m
t
n Number of data points 1
N ACU speed (rotational) r/min
p Absolute pressure Pa
p ACU pressure Pa
ACU
p Atmospheric pressure Pa
a
p Barometric pressure Pa
b
pd Dynamic pressure at a point Pa
p Gauge pressure Pa
e
p Gauge stagnation pressure at a point Pa
esg
psg Absolute stagnation pressure Pa
p Stagnation pressure at the ACU inlet Pa
sg1
p Stagnation pressure at the ACU outlet Pa
sg2
p ACU static pressure Pa
sACU
Pe ACU input power W
q ACU airflow rate m /s
q Mass flow rate kg/s
m
q Inlet stagnation volume flow rate m /s
Vsg1
ρa Air density kg/m
ρ Inlet stagnation density kg/m
sg1
s Standard deviation 1
θ Air discharge angle degrees
T Dry-bulb temperature °C
d
T Wet-bulb temperature °C
w
u Outlet air velocity uniformity %
ACU
ν velocity m/s
ν ACU average outlet air velocity m/s
a
ν Air curtain average core velocity m/s
ca
ν air curtain core velocity at section x m/s
cx
MUST BE USED
FOR FINAL
4 ACU airflow rate test
4.1 Apparatus and instruments
4.1.1 General
Instruments and methods of measurement shall be in conformance with ISO 5801, except where specifically
noted.
4.1.2 Power
Power shall be measured with a wattmeter having a certified accuracy of ±1 % of the observed reading. See
Figure 3.See Figure 3 .
Air Curtain Unit Drive
W
c Wm W
1 2 3
Key
W shall designate electrical input power.
Wc indicates a test where motor control input power is measured (if include)
W indicates a test where motor input power is measured
m
1 Mainsmains
2 Motormotor control (e.g. VSD)
3 Motormotor
Figure 3 — ACU Input Power
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4.2 Preparation of ACU airflow rate test
The ACU shall be mounted with its inlet sealed to the test chamber in conformance with the requirements of
Figure 4a).Figure 4 . The seal shall be sufficient to minimize leakage. The primary ACU discharge nozzle or
adjustable vanes in the primary ACU discharge nozzle shall be set to 0° ± 3°. Additional tests may be run at
discharge angles other than 0°. If there are multiple ACU discharge nozzles, additional ACU discharge nozzles
shall be set to the manufacturer’s specifications that meet the requirements dictated by the primary nozzle
setting.
4.3 Test procedure
4.3.1 Initial conditions
The unit under test shall be energized and operated for not less than 15 min to allow equilibrium conditions
to become established before the first determination. If the unit is equipped with a heating and/or cooling
accessory (i.e. hydronic coil, electric coil and gas furnace), it shall be attached as catalogued. The accessory
shall not be powered or activated during any part of the test unless it contributes to the active generation of
airflow. In such cases, only the fan section(s) shall be energized.
4.3.2 Data to be recorded
4.3.2.1 ACU under test
The following information shall be recorded:
a) a) the initial conditions;
b) b) the name and address of the manufacturer;
c) c) the trade name;
d) d) the model number;
e) e) the impeller diameter;
f) f) the inlet and outlet areas;
g) g) the number of fans;
h) h) the air discharge angle;
i) i) the number of motors and type;
j) j) the data on the motor nameplate;
k) k) the accessories attached;
l) l) the accessories which are energized.
4.3.2.2 Test method
The description of the test setup shall be recorded, including specific dimensions, as required by Figures 4, 6,
MUST BE USED
7 and 8.Figure 4 , Figure 6 , Figure 7 and Figure 8 . Alternatively, an annotated photograph of the arrangement
shall be attached to the recorded data.
FOR FINAL
4.3.2.3
...