EN ISO 7494:1997
(Main)Dental units (ISO 7494:1996)
Dental units (ISO 7494:1996)
Migrated from Progress Sheet (TC Comment) (2000-07-10): This WI went to PQ in 89 and to FV in 9001; negative. New procedure decided by ++ BTS3 72/1994.
Should be withdrawn as ISO 7494:1996 was withdrawn (NT/041213)
Zahnärztliche Behandlungsgeräte (ISO 7494:1996)
Die ISO 7494 ist eine Norm aus einer Serie von Internationalen Normen, die auf der IEC 601-1 basieren. In der IEC 601-1 ("Allgemeine Norm") wird diese Art einer Internationalen Norm als "Spezielle Norm" benannt. Im Abschnitt 1.3 der IEC 601-1:1988 wird dargelegt, daß die Anforderungen dieser Internationalen Norm Vorrang vor denen der IEC 601-1 haben. Diese Internationale Norm legt Anforderungen und Prüfmethoden für zahnärztliche Behandlungsgeräte unabhängig von ihrer Konstruktion fest und unabhängig davon, ob sie elektrisch oder nicht-elektrisch betrieben werden.
Units dentaires (ISO 7494:1996)
Dental units (ISO 7494:1996)
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 7494:2000
01-januar-2000
Dental units (ISO 7494:1996)
Dental units (ISO 7494:1996)
Zahnärztliche Behandlungsgeräte (ISO 7494:1996)
Units dentaires (ISO 7494:1996)
Ta slovenski standard je istoveten z: EN ISO 7494:1997
ICS:
11.060.20 =RERWHKQLþQDRSUHPD Dental equipment
SIST EN ISO 7494:2000 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 7494:2000
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SIST EN ISO 7494:2000
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SIST EN ISO 7494:2000
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SIST EN ISO 7494:2000
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SIST EN ISO 7494:2000
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SIST EN ISO 7494:2000
IS0
INTERNATIONAL
7494
STANDARD
Second edition
1996-03-I 5
Dental units
Units den takes
Reference number
IS0 7494:1996(E)
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SIST EN ISO 7494:2000
IS0 7494:1996(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work
of preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
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.
International Standard IS0 7494 was prepared by Technical Committee
ISO/TC 106, Dentistry, Subcommittee SC 6, Dental equipment.
This second edition cancels and replaces the first edition
(IS0 7494:1990), of which it constitutes a technical revision.
Annex A forms an integral part of this International Standard.
0 IS0 1996
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronic or mechanical, including photocopying and
microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzer *land
I
Printed in Switzerland
II
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SIST EN ISO 7494:2000
IS0 7494:1996(E)
INTERNATIONAL STANDARD 0 Iso
Dental units
I EC 601-I : 1988, Medica/ electrical equipment -
1 Scope
Part 1: General requirements for safety.
IS0 7494 is one of a series of International Standards
based on IEC 601-I; in IEC 601-I (the “General Stan-
3 Definitions
dard ”), this type of International Standard is referred
to as a “Particular Standard ”. As stated in 1.3 of For the purposes of this ‘International Standard, the
IEC 601-I :I 988, the requirements of this International
definitions given in IEC 601-I apply, as appropriate,
Standard take precedence over those of IEC 601-I. and the following definitions from IS0 1942-4.
This International Standard specifies requirements
3.1 dental equipment: Furniture, machines, appar-
and test methods for dental units, regardless of their
atus and accessories thereto, specially manufactured
construction and regardless of whether or not they
and/or presented for the use of authorized persons in
are electrically powered.
the practice of dentistry and/or its associated pro-
cedures. [ISO 1942-41
It also specifies requirements for manufacturer ’s in-
structions, marking and packaging.
3.2 dental unit: Item of dental equipment consist-
ing of an assembly of interconnected sub-units of
NOTE 1 For dental patient chairs see IS0 6875, and for
dental equipment and instruments providing a func-
dental operating lights see IS0 9680.
tional unit for dental use. [ISO 1942-41
4 Classification
2 Normative references
4.1 According to type of protection against
The following standards contain provisions which,
electric shock
through reference in this text, constitute provisions
of this International Standard. At the time of publi-
Dental units may be classified as follows:
cation, the editions indicated were valid. All standards
are subject to revision, and parties to agreements
a) Class I equipment
based on this International Standard are encouraged
Equipment in which protection against electric
to investigate the possibility of applying the most re-
shock does not rely on basic insulation only, but
cent editions of the standards indicated below.
which includes an additional safety precaution in
Members of IEC and IS0 maintain registers of cur-
such a way that means are provided for the con-
rently valid International Standards.
nection of accessible conductive parts to the pro-
IS0 1942-4: 1989, Dental vocabulary - Part 4: Dental tective (earth) conductor in the fixed wiring of the
equipment. installation so that accessible conductive parts
cannot become live in the event of a failure of the
IS0 6875: 1995, Dental patient chair.
basic insulation.
IS0 9680:1993, Dental operating light.
b) Class II equipment
Equipment -in which protection against electric
IS0 9687:1993, Dental equipment - Graphical sym-
shock does not rely on basic insulation only, but
bols.
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SIST EN ISO 7494:2000
0 IS0
IS0 7494:1996(E)
These requirements cannot be objectively assessed.
in which additional safety precautions such as
They are considered as fulfilled if all the following
double insulation or reinforced insulation are pro-
tests are passed.
vided, there being no provision for protective
earthing or reliance upon installation conditions.
5.1.1.2 Dental units shall have the strength and
rigidity necessary to resist the stresses to which they
4.2 According to degree of protection
may be subjected in normal dental practice without
against electric shock
risk of introducing fire, electric shock or accident haz-
ard.
Dental units may be grouped by type as follows:
These requirements cannot be objectively assessed.
a) Type B equipment
They are considered as fulfilled if all the following
tests are passed.
Class I or II equipment or equipment with an
internal electrical power source providing an ad-
Any item of equipment recommended by the
5.1.1.3
equate degree of protection against electric
manufacturer for use in conjunction with the dental
shock, particularly regarding:
unit shall not render the unit unsafe.
- allowable leakage currents;
These requirements cannot be objectively assessed.
They are considered as fulfilled if all the following
- reliability of the protective earth connection (if
tests are passed.
present).
5.1.1.4 Edges and corners of components and parts
Type B equipment is, for example, suitable for in-
of the unit accessible to the patient or personnel shall
tentional external and internal application to the
be finished so as to avoid injury to the patient or op-
patient, excluding direct cardiac application.
erator.
b) Type BF equipment
Compliance shall be checked by visual inspection.
Type B equipment with an F-type isolated (float-
Instrument hoses connected to the unit shall
ing) applied part. 5.1.1.5
be disconnectable for cleaning and disinfection.
4.3 According to mode of operation
The disconnectability shall be checked by manual in-
spection.
Dental units are a type of equipment with intermittent
operation.
5.1.2 Moving parts
5 Requirements and recommendations
Moving parts that may constitute a hazard under
normal working conditions shall be covered to prevent
the risk of injury to the patient and personnel.
5. I General requirements
The distance between power-activated moving parts
5.1 .I Design
and counterparts accessible to patient ’s and person-
nel’s hands and fingers shall be less than 10 mm (i.e.
Electrical requirements given in 5.3 are only applicable
0 to < 10 mm) when fully opened or a minimum of
to electrically powered dental units. The general re-
20 mm (i.e. 3 20 mm) when fully closed.
quirements referred to in IEC 601-I :I 988, are appli-
cable to non-electrical dental units as well.
Safety features shall be provided to protect the
patient and personnel from accessible power-
If the dental unit is an integral part of the dental
activated moving parts. These can include safety
patient chair, then IS0 6875 applies in addition.
switches, limit switches or controls requiring continu-
ous activation.
5.1.1.1 Dental units shall be designed, constructed
and manufactured so that when properly transported,
All electrical cables and hydraulic tubes shall be ad-
stored, installed, used and maintained according to
equately protected against wear, fracture and damage
the manufacturer ’s instructions, they cause no
due to rubbing or strain incurred during normal oper-
reasonably foreseeable danger to the patient, to the
ation of the unit.
operating personnel or to the surroundings in normal
Testing shall be carried out in accordance with 7.2.2.
use and in single-fault condition.
2
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SIST EN ISO 7494:2000
IS0 7494:1996(E)
0 IS0
Testing shall be carried out in accordance,with 7.2.4.
5.1.3 Operating controls
Controls should be located to comply with ergonomic
5.2.5 Pressure relief
conditions and in such a position or be of such design
that they cannot be accidentally activated.
Dental units shall be equipped with a means for safe
pressure relief for all parts in which pressure might
Operating symbols in accordance with IS0 9687 shall
be generated in the event of fire.
be used where applicable.
Pressure-relief devices, fused plugs, soldered joints,
Testing shall be carried out in accordance with 7.2.1.
non-metal tubing or other suitable pressure-relief
means or the equivalent may be employed to comply
5.1.4 Cleaning and disinfection
with this requirement.
All exterior parts including instrument hoses shall be Testing shall be carried out in accordance with 7.2.1.
cleanable and disinfectable, without deterioration of
the surface or markings, by using agents rec-
5.2.6 Stability in normal use
ommended by the manufacturer.
The requirements given in clause 24 of
Testing shall be carried out in accordance with 7.1.8.
I EC 601-I : 1988 apply.
5.1.5 Excessive temperatures
5.3 Electrical requirements
clause 42 of
The requirements given in
IEC 601-I:1988 ap
5.3.1 Failsafe device
IPlY.
In case of a single-fault condition, e.g. failure of a limit
5.2 Mechanica I requirements
switch, additional protective means shall be provided
such as mechanical limits to prevent injury to the
5.2.1 Cuspidors
patient and/or operating personnel.
Cuspidor bowls, if provided, shall be of a material that The failsafe device shall also offer protection against
is capable of undergoing repeated cleaning and disin-
hazards which might arise from any type of con-
fection in accordance with instructions provided by
.nection with a dental patient chair.
the manufacturer without signs of deterioration.
Testing shall be carried out in accordance with 7.3.2.
Testing shall be carried out in accordance with 7.2.3.
5.3.2 Power input
5.2.2 Solids collector
The requirements given in clause 7 of IEC 601-I :I 988
Dental units shall contain a solids collector in the
apply.
waste system. The solids collector should be capable
of retaining anything having a diameter of > 2 mm.
5.3.3 Single-fault conditions
Testing shall be carried out in accordance with 7.2.1.
The requirements given in subclause 3.6 of
I EC 601-I : 1988 apply.
5.2.3 Amalgam separator device
5.3.4 Protection against electrical shock hazards
Dental units shall be capable of being equipped with
or connected to an amalgam separator device in the
The requirements given in clause 13 of
waste system.
I EC 601-I : 1988 apply.
Testing shall be carried out in accordance with 7.2.1.
5.3.5 Requirements related to classification
5.2.4 Bursting pressure
5.3.5.1 Class I equipment
Pressure systems used in dental units shall be strong
The requirements given in subclause 14.1 of
enough to withstand without bursting or leaking the
IEC 601-I:1988 apply.
pressures specified by the manufacturer.
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SIST EN ISO 7494:2000
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IS0 7494:1996(E)
5.3.10 Separation
5.3.5.2 Class II equipment
The requirements given in subclause 14.2 of
The requirements given in clause 17 of
IEC 601-I :I 988 apply.
IEC 601-I :I 988 apply, with the following addition:
Electrical non-insulated heating devices, e.g. hot-
5.3.5.3 Classes I and II equipment
water syringes, which are in direct contact with
The requirements given in subclause 14.4 of
water, as well as electrically operated low-voltage
IEC 601-I :I988 apply, limited to classes I and II.
motors in the handpiece with basic insulation, shall
be operated with safety extra-low voltage (SELV).
5.3.5.4 Types B and BF equipment
5.3.11 Protective earthing, functional earthing
The requirements given in subclause 14.6 of
and potential equalization
IEC 601-I:1988 apply, limited to types B and BF.
The requirements given in clause 18 items a) to g) of
5.3.6 Limitation of voltage and/or energy
I EC 601-I : 1988 apply.
The requirements given in clause 15 of
5.3.12 Continuous leakage currents and patient
IEC 601-I :I 988 apply with the following additions:
auxiliary currents
Voltage shall not exceed a nominal value of 25 V
5.3.12.1 General requirements
a.c. or 60 V d.c. safety extra-low voltage (SELV) at
a rated supply voltage on the transformer or con-
The requirements given in subclause 19.1 of
verter, between conductors in an earth-free circuit
I EC 601-I : 1988 apply.
which is isolated from the supply mains by a
safety transformer or by a device with an equiv-
alent separation. 5.3.12.2 Single-fault conditions
The requirements given in subclause 19.2 of
Parts of the unit generating internal voltages
IEC 601-I :I 988 apply, with the following additions:
higher than SELV shall be separated electrically
from SELV. The measures required for this, such
In low-voltage electrical motors that do not fulfill
as protective shield or insulation, are an integral
the requirement according to 5.3.19, bridging over
part of the unit and are tested together with this.
the working insulation against the housing is con-
sidered a first fault. In this case the values for the
Parts of the unit that are fed at SELV may not
generate any internal voltage higher than SELV, patient leakage current given in table 1 shall not
unless these voltages are separated electrically be exceeded.
safe from SELV.
In syringes providing hot water in which the non-
insulated heating element is in direct contact with
5.3.7 Enclosures and protective covers
water, one-sided grounding of the SELV is con-
The requirements given in clause 16 of
sidered a first fault. In this case the values for the
I EC 601-I : 1988 apply.
patient leakage current given in table 1 shall not
be exceeded.
5.3.8 Spillage and ingress of liquids
Testing shall be carried out in accordance with 7.3.3.
The requirements given in subclauses 44.3 and 44.6
of IEC 601-I:1988 apply.
5.3.12.3 Allowable values
5.3.9 Leakage
The maximum allowable current values shal I be as
specified in table 1.
The requirements given in subclause 44.4 of
Testing shall be carried out in accordance witt -I 7.3.3.
IEC 601-I :I 988 apply.
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SIST EN ISO 7494:2000
IS0 7494: 1996(E)
0 IS0
Maximum allowable values of continuous leakage currents and patient auxiliary currents
Table 1 -
Values in milliamperes
Type BF
Current path Type B
NC ’) SFC 2) NC 1) SFC 2)
1 3) 1 3)
Earth leakage current 0,5 0,5
a1 0,5
Enclosure leakage current O,l 0,5
Patient leakage current 81 015 Ql 015
Patient leakage current (mains voltage
5
on the signal input part or signal output
pa t-t)
Patient leakage current (mains voltage
5
on the applied part)
dc. 0,Ol 0,05 0,Ol 0,05
Patient auxiliary current
a.c. a1 0,5 OrI 015
1) NC: Normal condition.
2) SFC: Single-fault condition.
3) The only single-fault condition for the earth leakage current is the interruption of one supply conductor at a time; see
subclause 19.2 a) and figure 16 of IEC 601-I :1988.
5.3.13 Dielectric strength B-g) Parts standing in direct conductive contact
with water must be insulated as if they had direct
contact to the ground or protective ground wire.
5.3.13.1 General requirements for all types of
This does not apply to parts for
...
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