National foreword

This British Standard is the UK implementation of ISO 22484:2024.

The UK participation in its preparation was entrusted to Technical Committee MCE/8/-/1, Compressors - Safety.

A list of organizations represented on this committee can be obtained on request to its committee manager.

Contractual and legal considerations

This publication has been prepared in good faith, however no representation, warranty, assurance or undertaking (express or implied) is or will be made, and no responsibility or liability is or will be accepted by BSI in relation to the adequacy, accuracy, completeness or reasonableness of this publication. All and any such responsibility and liability is expressly disclaimed to the full extent permitted by the law.

This publication is provided as is, and is to be used at the recipient’s own risk.

The recipient is advised to consider seeking professional guidance with respect to its use of this publication.

This publication is not intended to constitute a contract. Users are responsible for its correct application.

Compliance with a British Standard cannot confer immunity from legal obligations.

This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 November 2024.

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.

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This document was prepared by Technical Committee ISO/TC 118, Compressors and pneumatic tools, machines and equipment, Subcommittee SC 6 Air compressors and compressed air systems.

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.

Introduction

This document was developed in response to a recognized need to provide a methodology to correct performance of a low-pressure air compressor to guarantee conditions for positive displacement and dynamic compression types.

In dynamic compression, air is drawn between the blades on a rapid rotating compression impeller1 and accelerates to high velocity. The gas is then discharged through a diffuser, where the kinetic energy is transformed into static pressure. Dynamic low-pressure compressors are of a radial flow design, with the following typical examples:

single-stage centrifugal (aka high speed “turbo”) compressors;
multi-stage centrifugal compressors without intercooling.

Positive displacement low-pressure compressors work on the principle of trapping a volume of air and reducing its volume, internally or externally. Two basic types are typical, as follows:

Rotary screw positive displacement compressor where air is drawn into a compression chamber formed by intermeshing rotors¹. As the rotors turn, the cavity between the rotors becomes smaller, reducing the volume of the trapped air and increasing its pressure;
Rotary lobe positive displacement compressor where air is drawn into the case and is trapped between the rotor and the case wall. These air pockets are progressively moved to the discharge port. At the discharge port, a back flow of air into the pocket from the higher-pressure discharge line produces a constant volume pressure rise.

Existing standards (e.g. ISO 1217, ISO 5389, ISO 18740) for positive displacement compressors and dynamic compressors, do not provide clear and concise means of comparing different technologies.

This document provides simplified wire to air performance test methods that measure true performance of low-pressure air compressor packages.

1 Scope

This document specifies the performance test method of electrically driven low-pressure air compressor packages, where the compression is performed by positive displacement or dynamic compression; utilising atmospheric air as the compression gas. Low-pressure air compressor packages are often referred to as “blowers”.

NOTE Throughout this document, the term ‘low-pressure compressor’ is used to describe a low-pressure air compressor (“blower”) package

Low-pressure compressors with and without means of controlling flow (control may be electrical (e.g. with a variable frequency drive) or mechanical or both) are covered.

This document applies to low-pressure compressors meeting all the following limits:

Atmospheric inlet air pressure between 0,5 bar and 1,1 bar.
Discharge vs inlet pressure differential between 0,1 bar and 2,5 bar.
Discharge vs inlet pressure ratio between 1,1 and 3,5.

This document is not applicable to:

positive displacement low-pressure compressors with a liquid in the compression element (such as liquid ring pumps and liquid injected low-pressure compressor of screw type)
multi-stage low-pressure compressors other than multistage centrifugal compressors comprised of multiple, identical or very similar uncooled sections along a single shaft (repeating stages).
single shaft, multistage centrifugal compressors are treated from the point of measurement and calculation as a single stage

2 Normative references

3 Terms and definitions

4 Units

5 Guarantee and measurement

5.1 Packaged compressor

5.2 Preconditions of the guarantee

5.3 Object of the guarantee

5.4 Low-pressure compressor to be tested

5.5 Low-pressure compressor specifications to be provided prior to testing

6 Measuring equipment, methods and accuracy

6.1 General

6.2 Measurement of pressure

6.3 Measurement of temperature

6.4 Measurement of humidity

6.5 Measurement of rotational frequency

6.6 Measurement of flow rate

6.7 Measurement of external coolant flow rate

6.8 Measurement of power and energy

6.9 Calibration of instruments

7 Test

7.1 General test process

7.2 Allowed deviation of rotational speed between test and guarantee

7.3 Allowed deviation of ambient conditions

7.4 Allowed deviation of preconditions

7.5 Allowed deviation of machine Mach number

7.6 Selection of test flow

7.7 Selection of test pressure

7.8 Allowed deviation of flow and work coefficient

7.9 Fluctuations on the specific test readings/results during test at steady state

7.10 Two-speed test

8 Correction of test results

8.1 General

8.2 Correction of measured flow (variable speed packaged compressors, only)

8.3 Correction of measured pressure

8.4 Correction of specific energy demand

8.5 Corrected packaged compressor power consumption

8.6 Power correction of the two-speed test

8.7 Calculated package isentropic efficiency

8.8 Comparison of corrected values with guaranteed values

8.9 Examples of calculations

9 Test report

9.1 Test report content

9.2 Test results summary

Bibliography

BS ISO 22484:2024

Displacement and dynamic compressors. Performance test code for electric driven low-pressure air compressor packages

Current

Published:

30 Nov 2024