kSIST prEN ISO 18623-1:2015

SLOVENSKI STANDARD
oSIST prEN ISO 18623-1:2014
01-oktober-2014
Kompresorji za zrak in sistemi na stisnjen zrak - Kompresorji za zrak - 1. del:
Varnostne zahteve (ISO/DIS 18623-1:2014)
Air compressors and compressed air systems - Air compressors - Part 1: Safety
requirements (ISO/DIS 18623-1:2014)
Compresseurs à air et systèmes à air comprimé - Compresseurs à air - Partie 1:
Prescriptions de sécurité (ISO/DIS 18623-1:2014)
Ta slovenski standard je istoveten z: prEN ISO 18623-1 rev
ICS:
23.140 .RPSUHVRUMLLQSQHYPDWLþQL Compressors and pneumatic
VWURML machines
oSIST prEN ISO 18623-1:2014 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN ISO 18623-1:2014
oSIST prEN ISO 18623-1:2014
DRAFT INTERNATIONAL STANDARD
ISO/DIS 18623-1
ISO/TC 118/SC 6 Secretariat: SIS
Voting begins on: Voting terminates on:
2014-04-14 2014-07-14
Air compressors and compressed air systems — Air
compressors —
Part 1:
Safety requirements
Compresseurs à air et systèmes à air comprimé — Compresseurs à air —
Partie 1: Prescriptions de sécurité
ICS: 23.140
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENT AND APPROVAL. IT IS
THEREFORE SUBJECT TO CHANGE AND MAY
NOT BE REFERRED TO AS AN INTERNATIONAL
STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
Reference number
NATIONAL REGULATIONS.
ISO/DIS 18623-1:2014(E)
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 SUPPORTING DOCUMENTATION. ISO 2014

oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1:2014(E)
Copyright notice
This ISO document is a Draft International Standard and is copyright-protected by ISO. Except as
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ii © ISO 2014 – All rights reserved

oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
Contents Page
Foreword . v
Introduction . vi
1 Scope . 1
2 Normative References . 1
3 Terms and definitions . 3
4 Safety requirements and/or protective measures . 4
4.1 General . 4
4.2 Mechanical safety . 4
4.2.1 Guards . 4
4.2.2 Fluid injection . 5
4.2.3 Loss of stability . 6
4.2.4 Slip, trip and fall . 6
4.3 Electrical safety . 6
4.3.1 Generally applicable . 6
4.3.2 Protection from overload . 7
4.3.3 Protection from live parts . 7
4.3.4 Portable and skid-mounted compressor units . 7
4.4 Control systems . 7
4.4.1 General . 9
4.4.2 Manual reset function . 9
4.4.3 Start/restart function . 9
4.4.4 Emergency stop . 10
4.4.5 External influences on electrical equipment . 10
4.4.6 Pneumatic and/or hydraulic control systems . 10
4.4.7 Pressure or fluid level drops . 10
4.5 Thermal safety . 11
4.6 Noise . 11
4.7 Materials and substances processed, used or exhausted . 11
4.7.1 Micro-organisms, biological and microbiological substances . 11
4.7.2 Breathing difficulties . 11
4.8 Fire and explosion . 12
4.8.1 Electrostatic phenomena . 12
4.8.2 Oil-flooded rotary air compressor units . 12
4.8.3 Oil-lubricated reciprocating air compressor units . 13
4.8.4 Oil-lubricated reciprocating compressor units operating above 50 bar . 13
4.8.5 Compressor units driven by combustion engines. 13
4.9 Ergonomic principles . 13
4.9.1 General . 13
4.9.2 Manual handling of compressor units . 14
4.9.3 Portable and skid-mounted compressor units . 14
4.10 Breaking down of machinery parts and other functional disorders . 14
4.10.1 Break-up during operation . 14
4.10.2 Low temperature operation . 15
4.10.3 Liquid shock . 15
4.10.4 Coolant system . 15
4.11 Pressure relief – fragmentation . 15
4.11.1 General . 15
4.11.2 Design specifications of pressure relief devices . 16
4.11.3 Turbo compressor units . 16
oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
4.11.4 Multi stage compressor units . 16
4.11.5 Application of pressure relief devices at the cooling medium side . 16
4.12 Information and warning devices . 16
5 Verification of safety requirements and/or protective measures . 17
5.1 Pressure testing . 17
5.2 Noise . 17
5.2.1 General . 17
5.2.2 Sound power level of compressor units for use outdoors . 17
5.3 Stability of portable compressor units . 17
5.4 Structure of verification . 18
6 Information for use . 20
6.1 General requirements . 20
6.2 Accompanying documents (in particular, instruction handbook) . 20
6.2.1 Instruction handbook . 20
6.2.2 Information relating to the use of the compressor/compressor unit . 22
6.3 Specific types of compressors . 23
6.3.1 General . 23
6.3.2 Portable and skid-mounted air compressor units . 23
6.3.3 Entry to inlet ducts and enclosures . 23
6.4 Service instructions . 24
6.4.1 General . 24
6.4.2 Precautions for service/maintenance . 24
6.5 Markings, signs and written warnings . 25
6.5.1 Generally applicable . 25
6.5.2 Compressor unit enclosures . 25
6.5.3 Off-road portable and skid-mounted air compressor units . 25
6.5.4 Markings (in particular, data plate) . 25
6.6 Noise . 26
6.6.1 A-weighted emission sound pressure level and A-weighted sound power level declaration . 26
6.6.2 Hearing protection . 27
6.7 Dismantling . 27
Annex A (informative) Labels, signs and tags . 28
Annex B (informative) List of significant hazards . 33

iv © ISO 2014 – All rights reserved

oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 18623-1 was prepared by Technical Committee ISO/TC 118, Compressors and pneumatic tools, machines and
equipment, Subcommittee SC 6, Air compressors and compressed air systems.
This second/third/. edition cancels and replaces the first/second/. edition (), [clause(s) / subclause(s) / table(s)
/ figure(s) / annex(es)] of which [has / have] been technically revised.
ISO 18623 consists of the following parts, under the general title Air compressors and compressed air systems — Air
compressors:
 Part 1: Safety requirements
 Part 2: Good practice
oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
Introduction
This document is a type-C standard as stated in ISO 12100.
The machinery concerned and the extent to which hazards, hazardous situations or hazardous events are covered
are indicated in the Scope of this document.
When requirements of this type-C standard are different from those which are stated in type-A or B standards, the
requirements of this type-C standard take precedence over the requirements of the other standards for machines
that have been designed and built according to the requirements of this type-C standard.
This International Standard classifies and makes available general information on practices, specific
requirements, and recommendations covering safety for air compressors, their drives, and auxiliaries. Safety
requirements, recommendations, and suggestions described in this Standard provide guidance to those who
design, produce, install, maintain, and/ or operate air compressors.

vi © ISO 2014 – All rights reserved

oSIST prEN ISO 18623-1:2014
COMMITTEE DRAFT ISO/DIS 18623-1

Air compressors and compressed air systems — Air
compressors — Part 1: Safety requirements
1 Scope
This part of ISO 18623 is applicable to compressors and compressor units having an operating pressure greater
than 0,5 bar and designed to compress air, nitrogen or inert gases. This standard deals with all significant hazards,
hazardous situations and events relevant to the design, installation, operation, maintenance, dismantling and
disposal of compressors and compressor units, when they are used as intended and under conditions of misuse
which are reasonably foreseeable by the manufacturer (see Clause 4).
This part of ISO 18623 includes under the general term compressor units those machines which comprise:
 the compressor;
 a drive system;
 any component or device which is necessary for operation.
This part covers compressors driven by any power media, including battery powered and which are fitted in or
used with motor vehicles.
The significant hazards dealt with in the standard are identified in Annex A.
It does not cover requirements for compressors and compressor units used in potentially explosive atmospheres.
It is not applicable to compressors and compressor units which are manufactured before the date of publication of
this standard.
It does not cover compressors and compressor units for processing petroleum, petrochemicals, or chemicals
within the scope of ISO TC67.
2 Normative References
The following referenced documents are indispensable for the application 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 2151:2008, Acoustics. Noise test code for compressors and vacuum pumps. Engineering method (Grade 2)
ISO 3857-1:1977, Compressors, pneumatic tools and machines. Vocabulary – Part 1 - General
ISO 3857-2:1977, Compressors, pneumatic tools and machines. Vocabulary – Part 2 – Compressors
ISO 4126-1:2013, Safety devices for protection against excessive pressure - Safety valves
ISO 4413:2010, Pneumatic fluid power. General rules and safety requirements for systems and their components
oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
ISO 4414:2010, Hydraulic fluid power. General rules and safety requirements for systems and their components
ISO 8573-1:2010, Compressed air — Part 1: Contaminants and purity classes
ISO 8573-2:2007, Compressed air — Part 2: Test methods for oil aerosol content
ISO 8573-3:1999, Compressed air — Part 3: Test methods for measurement of humidity
ISO 8573-4:2001, Compressed air — Part4: Test methods for solid particle content
ISO 12100:2010, Safety of machinery - General principles for design – Risk assessment and risk reduction
ISO 13849-1:2006, Safety of machinery — Safety-related parts of control systems — Part 1: General principles for
design
ISO 13850:2006, Safety of machinery – Emergency stop – Principles for design
ISO 13857:2008, Safety of machinery - Safety distances to prevent hazard zones being reached by upper and lower
limbs
ISO 14120, Safety of machinery. Guards. General requirements for the design and construction of fixed and movable
guards
ISO 14122-1:2001, Safety of machinery — Permanent means of access to machinery — Part 1: Choice of fixed means
of access between two levels
ISO 14122-2:2001, Safety of machinery — Permanent means of access to machinery — Part 2: Working platforms
and walkways
ISO 14122-3:2001, Safety of machinery — Permanent means of access to machinery — Part 3: Stairs, stepladders
and guard-rails
ISO 14122-4:2004, Safety of machinery — Permanent means of access to machinery — Part 4: Fixed ladders
ISO 15534-1:2000, Ergonomic design for the safety of machinery - Part 1: Principles for determining the dimensions
required for openings for whole-body access into machinery
IEC 60204-1:2005+A1:2008, Safety of machinery - Electrical equipment of machines - Part 1: General requirements
IEC 60204-11: 2000, Safety of machinery - Electrical equipment of machines - Part 11: Requirements for HV
equipment for voltages above 1 000 V a.c. or 1 500 V d.c. and not exceeding 36 kV
IEC 61310-2:2007, Safety of machinery. Indication, marking and actuation - Requirements for marking
EN 626-1:1994+A1:2008, Safety of machinery. Reduction of risks to health from Hazardous substances emitted by
machinery - Principles and specifications for machinery manufacturers
EN 1005-2:2003+A1:2008, Safety of machinery. Human physical performance - Manual handling of machinery and
component parts of machinery
EN 13445-5:2009 +A4:2013: Unfired pressure vessels - Inspection and testing

2 © ISO 2014 – All rights reserved

oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 12100:2010 apply. Terms and
definitions specifically needed for compressors are listed below and in ISO 3857-1:1977 and ISO 3857-2:1977.
3.1.1
compressor
part of a compressor unit that compresses a gas or vapour media to a pressure higher than that at the inlet
3.1.2
compressor unit
unit that comprises the compressor, a drive system and any component or device which is necessary for operation
3.1.3
drive system
system that consists of a prime mover and coupling mechanism
Note 1 to entry: Prime mover may be an electric motor, steam engine (turbine), etc.
Note 2 to entry: Coupling mechanism may be a drive belt, shaft, gears, etc.
3.1.4
inert gas
chemically inactive gas which retains this characteristic even at elevated pressures
3.1.5
pressure
pressure relative to atmospheric pressure, i.e. gauge pressure
Note 1 to entry: In many cases, this is referred to as effective pressure.
Note 2 to entry: The unit bar for pressure is used. 1 bar = 100 kPa.
3.1.6
liquid shock
excessive force resulting from an attempt to compress incompressible media
3.1.7
maximum allowable pressure
maximum pressure for which the compressor or compressor unit is designed, as specified by the manufacturer
Note 1 to entry: This is also identified as maximum allowable working pressure.
3.1.8
normal operating conditions
conditions considered to be when the compressor is properly maintained and operated within admissible limits in
particular ambient temperature, as specified by the manufacturer when compressing the specified media
3.2 Specific terms
3.2.1
air compressor
compressor intended for compression of air, nitrogen or inert gases
3.2.2
compressor assembly
assembly of compressor units and ancillary equipment to provide a compression facility that functions as an
integrated whole
Note 1 to entry: The limits of the assembly are as defined by the manufacturer.
oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
3.2.3
portable and skid mounted compressor
3.2.3.1
portable compressor unit
compressor unit which is wheel-mounted and can be towed on- and off-site
3.2.3.2
skid-mounted compressor unit
compressor unit which is mounted on skids and which can be towed short distances on-site or transported
3.2.3.3
gross mass
maximum specified mass of a skid-mounted or portable compressor unit (including tools, equipment and fuel)
Note 1 to entry: Tools and equipment includes for example concrete breakers, picks and hoses likely to be carried for a typical
working application.
3.2.4
process compressor
compressor intended for compression of all gases other than air, nitrogen or inert gases
3.2.5
water-injected compressor
compressor design in which the compressed media and the water are mixed
4 Safety requirements and/or protective measures
4.1 General
The machine shall comply with the following safety requirements and/or protective measures and be verified in
accordance with Clause 5. In addition, the machine shall be designed according to the principles of ISO 12100 for
relevant but not significant hazards, which are not dealt with by this document.
When choices are necessary for the application of type B standards referred to in this Standard, i.e. listed in Clause
2, the manufacturer shall carry out an appropriate risk assessment for making these choices.
The measures adopted to comply with the requirements of this clause shall take account of the state-of-the-art
when more effective technical means become available.
4.2 Mechanical safety
4.2.1 Guards
4.2.1.1 General
When fixed guards have to be removed for periodic maintenance or repair their fixing systems shall remain
attached to the guard or machinery when the guards are removed.
4.2.1.2 Cutting and severing, friction and abrasion
All moving parts shall be enclosed within the permanent compressor casing or compressor unit cover, enclosure
or canopy. When this is not possible, separate guards shall be provided to prevent contact with all rotating and
reciprocating parts to minimize the risk of cutting and severing, friction and abrasion to personnel in accordance
with Clause 5 of ISO 14120 and ISO 13857 for safety distances.
4 © ISO 2014 – All rights reserved

oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
4.2.1.3 Bodily contact
Guards shall be sufficiently rigid so as not to deflect excessively as a result of bodily contact. Such deflections shall
not result in contact with moving parts, or that the deflection should not result in permanent deformation of the
guard. The provisions for rigidity of guards shall be in accordance with 5.4.3 of ISO 14120.
4.2.1.4 Ejection of parts
Moving parts shall be designed and mounted in such a way that in all foreseeable modes of operation the risk of
ejection of parts is minimised. Where the risk assessment identifies a remaining risk of ejection, e.g. a drive belt
from a belt driven compressor, then the impact resistance for guarding shall be in accordance with 5.4.2 of ISO
14120.
4.2.1.5 Entry to inlet ducts and enclosures
Atmospheric inlets and inspection openings in inlets shall be provided with protective devices, so that persons
cannot be drawn in or danger zones reached when the compressor is running. For this purpose, any openings
shall comply with Table 4 of ISO 13857:2008 for upper limbs and Table 7 of ISO 13857:2008 for lower limbs,
when applicable.
Openings giving access to moving parts creating a risk of trapping or shearing shall be prevented by either:
 total enclosure with an interlocked means of access, e.g. door, cover, etc. such that the compressor is shut
down when the access is opened and cannot be started until the access is closed; or
 total enclosure without interlock when access to moving parts, e.g. fan belts, barring gear, timing marks, etc.,
shall be prevented by local guarding; or
 without total enclosure when access to moving parts, e.g. fan belts, barring gear, timing marks, etc., shall be
prevented by local guarding.
Where service, maintenance or inspection activities require access within the enclosure doors whilst the
compressor is still operational, consideration shall be given to the additional hazards created and the measures
taken shall be in accordance with 6.3.2.4 of ISO 12100:2010. The provisions of 6.3.3 shall also be applied.
Where whole body access is required to inlet ducts and enclosures for service, maintenance or inspection the
provisions of ISO 15534-1 shall be followed when determining the minimum dimensions of openings for such
whole body access.
Where whole body access is required to inlet ducts for service, maintenance or inspection, a guard shall be fitted
to prevent unauthorised access. The guard shall be:
 interlocked such that when the guard is opened the compressor is shut-down and cannot be restarted until
the guard is closed; and
 unintentional closure of the guard is prevented by the use of a trapped key interlock or a padlock where the
only key for the trapped key or the padlock is retained by the person entering the inlet duct.
Where it is foreseeable that the compressor will remain operational during whole body access to the inlet duct for
service, maintenance or inspection, the design of the inlet duct shall be such that the air flow at the entrance to the
inlet duct shall be ≤ 2,5m/s and in addition a protective grid shall be installed inside the duct to prevent personnel
being drawn into the compressor.
A safe system of work shall also be identified in accordance with 6.4.1.
4.2.2 Fluid injection
The risk of fluid (gas or liquid) injection into the human body shall be minimized by:
oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
 designing and supporting integral pipework, hoses and auxiliaries to withstand vibration, thermal expansion
and their own mass, foreseeable external forces, influence of contaminants and external chemical substances;
 ensuring that all piping which is in a position likely to be damaged is protected, robust and sufficiently
supported, but shall be free to move with changing temperature;
 ensuring that the design of oil/coolant filler plugs does not allow the dangerous release of fluid, e.g. by means
of preventing the removal of the filler plug under pressure or an effective warning system;
 the design and location of pressure vents and drains, shall take account of the velocity of air, gas, vapour or
liquid likely to be discharged.
4.2.3 Loss of stability
4.2.3.1 Generally applicable
Compressor units shall be in accordance with 6.2.6 of ISO 12100:2010.
4.2.3.2 Portable and skid-mounted compressor units
The centre of gravity, mainly associated with the engine/compressor combination shall be low enough to ensure
that the compressor unit remains stable, without tipping or slipping, when used within intended limits.
The provisions of 7.3.2 d) shall be applied to indicate the intended limits.
Tyres of a portable compressor unit shall be rated to carry the maximum gross mass of the portable compressor
unit at the highest towing speed the compressor unit is intended for. All tyres shall be of the same construction.
The support leg or jockey wheel shall be capable of supporting the gross nose weight of the portable compressor
unit as defined in the instruction handbook. It shall be possible to securely lock it in the support and towing
positions by, for example, a clamping system or removable pin in locating holes.
The jockey wheel device shall be positively retained in the draw bar in the event of the operator leaving it
unlocked.
NOTE Portable compressor units used on-road are also subject to regulations related to motor vehicles and their trailers.
4.2.4 Slip, trip and fall
If access to elevated areas around a compressor unit is necessary and is an integral part of a compressor unit then
these access areas shall be in accordance with 6.3.5.6 of ISO 12100:2010. Where such access is provided,
permanent means of access to working platforms, walkways, fixed ladders and stairways shall be in accordance
with ISO 14122-1, ISO 14122-2, ISO 14122-3 and ISO 14122-4.
If access to elevated areas is required and is not an integral part of the compressor unit, appropriate installation
instructions shall be given in the instruction handbook.
4.3 Electrical safety
4.3.1 Generally applicable
The electrical equipment of a compressor unit shall be in accordance with IEC 60204-1:2005+A1:2008 and/or IEC
60204-11: 2000 as appropriate.
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oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
4.3.2 Protection from overload
Where the compressor unit is not fitted with an over-current protection of the power circuit due to it being
installed outside the compressor enclosure on site, the provisions of 6.2.1.3.1 shall be followed.
4.3.3 Protection from live parts
Where the compressor unit is not fitted with an electrical disconnecting device, the provisions of 6.2.1.3.2 shall be
followed.
Electrical and instrument cabling shall:
 be adequately secured and protected;
 not be in contact with hot surfaces;
 have adequate electrical insulation.
Cabling and cabling practices shall be in accordance with Clauses 12 and 13 of IEC 60204-1:2005+A1:2008.
4.3.4 Portable and skid-mounted compressor units
4.3.4.1 General
A suitable over-current protection device, e.g. fuse, shall be provided in the electrical installation to protect the
wiring harness and the electric equipment. This excludes the pre-heat, starting and charging circuits. Where fuses
are provided as over-current protection devices, a type readily available in the country of use shall be selected, or
arrangements made for the supply of spare parts.
4.3.4.2 Fluid, corrosive action
Batteries shall be of the type with lifting handles or with lifting points. They shall be mounted and firmly secured
so there is no risk of electrolyte splashing on personnel and surrounding equipment.
4.4 Control systems
The design of safety related parts of control systems (SRP/CS) shall be established by the application of the risk
reduction process identified in 4.2.2 of ISO 13849-1, and the application of the iterative process indicated in
Figure 3 of ISO 13849-1,. This logic is to be applied to each function individually. The ability of SRP/CS to perform a
safety function under foreseeable conditions is allocated one of five levels, called performance levels (PL). These
performance levels are defined in terms of probability of dangerous failure per hour, see Table 1.
Table 1 — Performance levels (PL)
Average probability of dangerous failure per hour
PL
1/h
− −
5 4
a ≥ 10 to < 10
− −
6 5
b
≥ 3 υ 10 to < 10
− −
6 6
c
≥ 10 to < 3 x 10
− −
7 6
d ≥ 10 to < 10
− −
8 7
e ≥ 10 to < 10
NOTE Besides the average probability of dangerous failure per hour other measures are also necessary to achieve the PL.
oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
The determination of the performance level requires knowledge of the severity of the injury (S) and the frequency
and/or the exposure time (F) to the hazard. ISO 13849-1, Annex A provides guidance to determine the required
performance level which is summarised in Figure 1.

H
a
P1
F1
P2
S1
b
P1
F2
P2
c
P1
F1
P2
S2
d
P1
F2
P2 e
L
Figure 1 Risk graph for determining required PLr for safety function
ISO 13849-1 employs the principle of performance level (PL) for safety functions there are however other
standards, notably IEC 61508 which utilise the safety integrity level (SIL). To provide guidance on the relationship
between the two systems ISO 13849-1 gives the following tabulated comparison in Table 2.
Table 2 — Relationship between performance level (PL) and safety integrity level (SIL)
SIL
PL (IEC 61508-1, for information)
high/continuous mode of operation
a No correspondence
b 1
c 1
d 2
e 3
The probability of dangerous failure of the safety function depends on several factors, including hardware and
software structure, the extent of fault detection mechanisms [diagnostic coverage (DC)], reliability of components
[mean time to dangerous failure (MTTFd), common cause failure (CCF)], design process, operating stress,
environmental conditions and operation procedures. These categories are allocated one of five levels, termed
Categories B, 1, 2, 3 and 4.
8 © ISO 2014 – All rights reserved

oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
Meant time to dangerous failure is given three levels of severity in ISO 13849-1 as summarised in Table 3.
Table 3 – Meant time to dangerous failure
MTTFd
Denotation of each channel Range of each channel
Low 3 years ≤ MTTFd < 10 years
Medium 10 years ≤ MTTFd < 30 years
High 30 years ≤ MTTFd ≤ 100 years
NOTE 1 The choice of the MTTF ranges of each channel is based on failure rates found in the field as state-of-the-art,
d
forming a kind of logarithmic scale fitting to the logarithmic PL scale. An MTTFd value of each channel less than three years is
not expected to be found for real SRP/CS since this would mean that after one year about 30 % of all systems on the market
will fail and will need to be replaced. An MTTFd value of each channel greater than 100 years is not acceptable because SRP/CS
for high risks should not depend on the reliability of components alone. To reinforce the SRP/CS against systematic and
random failure, additional means such as redundancy and testing should be required. To be practicable, the number of ranges
was restricted to three. The limitation of MTTF of each channel values to a maximum of 100 years refers to the single channel
d
of the SRP/CS which carries out the safety function. Higher MTTFd values can be used for single components (see Table D.1).

Where the performance level of non-complex safety related part of a control system is to be determined then the
following simplified procedure may be adopted, see Table 4. See also 4.5.4 of ISO 13849-1,.
Table 4 — Simplified procedure for evaluating PL achieved by SRP/CS
Category B 1 2 2 3 3 4
DCavg none none low medium low medium high

MTTFd of each channel
Low a Not covered a b b c Not covered
Medium b Not covered b c c d Not covered
High Not covered c c d d d e
Note 'PL' as identified in this table is that as given in Table 1

4.4.1 General
Effective control system design shall be in accordance with 6.2.11 of ISO 12100:2010, 9.4 of IEC 60204-
1:2005+A1:2008 and ISO 13849-1 for the safety related parts of control systems.
Safety-related stop function
Compressor units fitted with safety related stop function(s) shall follow the requirements of Table 8 and 5.2.1 of
ISO 13849-1. Examples of such functions are an interlock fitted to an access door to a packaged compressor unit
or a high air temperature sensor fitted to an oil-injected rotary compressor unit.
4.4.2 Manual reset function
The requirements for a manual reset after a stop command has been initiated shall be in accordance with Table 8
and 5.2.2 of ISO 13849-1:2008 and 9.2.5.3, 9.2.5.4 of IEC 60204-1:2005+A1:2008.
4.4.3 Start/restart function
The requirements for a start and restart shall be in accordance with Table 8 and 5.2.3 of ISO 13849-1:2008.
Compressor units that are fitted with automatic or remote start controls shall follow the provisions of 7.2.2 b) and
c).
oSIST prEN ISO 18623-1:2014
ISO/DIS 18623-1
4.4.4 Emergency stop
The need for and provision of an emergency stop shall be in accordance with 6.3.5.2 of ISO 12100:2010.
Where an emergency stop is identified as a requirement, then this and the stop category shall be in accordance
with ISO 13850.
In addition to the 'stop categories' identified in ISO 13850 the performance level of ISO 13849-1 shall also be
determined for the emergency stop function
The emergency stop device shall be coloured in accordance with 4.4.5 of ISO 13850:2006 and as shown in A.14 of
this standard.
4.4.5 External influences on electrical equipment
The safety system and other electrical equipment shall be so designed and constructed that they cannot give rise
to a hazardous situation in case of disturbances such as:
 short circuiting;
 external impacts;
 interruptions or variations in the supply voltage;
 earthing faults.
Failure of the power supply to the control system shall employ an "oriented failure mode system" in accordance
with 6.2.12.3 of ISO 12100:2010 having a known failure mode, e.g. bring the machine to a stop.
4.4.6 Pneumatic and/or hydraulic control systems
4.4.6.1 General
Where pneumatic and hydraulic equipment forms part of a control system of a compressor unit this shall be in
accordance with 6.2.10 of ISO 12100:2010 and the following shall apply.
4.4.6.2 Conditioning
Compressed air for measuring, control and safety systems shall be conditioned for the purpose and shall be in
accor
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