Halma Apollo XP95 I.S. User manual

Intrinsically safe
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CERTIFICATION
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© Apollo Fire Detectors Ltd 2021
PP1095/2021/Issue 6
Page 1 of 8
About XP95 I.S.
Introduction to intrinsic safety
There are many places where an explosive mixture of air and gas
or vapour is or may be present continuously, intermittently or as a
result of an accident. These are defined as hazardous areas by BS
EN , the code of practice for installation and maintenance of
electrical apparatus in potentially explosive atmospheres.
Hazardous areas are common in petroleum and chemical
engineering plants and in factories processing and storing gases,
solvents, paints and other volatile substances.
Electrical equipment for use in these areas needs to be designed
so that it cannot ignite an explosive mixture, not only in normal
operation but also in fault conditions. There are a number of
methods available to achieve this, oil-immersion, pressurised
apparatus and powder filling, for example, but the two in most
common use are flameproof enclosures and intrinsic safety.
Flameproof equipment is contained in a box so strong that an
internal explosion will neither damage the box nor be transmitted
outside the box. The surface must remain cool enough not to ignite
the explosive mixture.
When flameproof equipment is interconnected, flameproof wiring
must be used. This method is most valuable when high power
levels are unavoidable but is not acceptable for areas in which an
explosive gas ⁄ air mixture may be continuously present or present
for long periods.
For this reason Apollo fire detectors are made intrinsically safe
rather than flameproof. Intrinsically safe equipment operates at
such low power and with such small amounts of stored energy
that it is incapable of causing ignition:
• In normal conditions
• With a single fault (for Ex ib classification)
• With any combination of two faults (for Ex ia classification)
In any of these conditions every component must remain cool
enough not to ignite the gases for which it is approved.
Classification of hazardous areas
BS EN -- defines a hazardous area as one in which
explosive gas/air mixtures are, or may be expected to be, present
in quantities such as to require special precautions for the
construction and use of electrical apparatus.
The degree of risk in any area is a function of:
• The probability of an explosive mixture being present
• The type of gas which may be present
• The temperature at which a gas might ignite spontaneously
These are defined in Table , Zone Classification, Table , Sub-
division of Group II Gases.
Table 1: Zone classification
Zone Definition
Intrinsically safe
equipment approval
required
0
In which an explosive gas/air
mixture is continuously present
or present for long periods
Ex ia
1
In which an explosive gas/
air mixture is likely to occur in
normal operation
Ex ia or Ex ib
2
In which an explosive gas/air
mixture is not likely to occur in
normal operation and if it occurs
will exist only for a short time
Ex ia or Ex ib
Table 2: Subdivision of Group II gases
Zone Definition
Intrinsically safe
equipment approval
required
Acetylene Carbon Disulphide, Hydrogen IIC
Ethylene Butadiene, Formaldehyde,
Diethyl-ether IIB or IIC
Propane
Acetaldehyde, Acetone,
Benzene, Butane, Ethane,
Hexane, Heptane, Kerosene,
Naptha, Petroleum, Styrene,
Xylene
IIA or IIB or IIC
XP95 Intrinsically Safe communications protocol
The standard XP95 communications protocol is designed to be
very robust and to give the maximum flexibility to designers of loop
driver circuits. The current and voltage levels used are chosen to
be well above noise levels and to operate in adverse conditions
with the minimum of errors. The maximum voltage and current
levels used are, however, outside the limits of intrinsically safe
(I.S.) systems and it has been necessary to apply lower limiting
values for both current and voltage in the I.S. range.
Related Apollo Product Ranges
Product Publication Type PP Number
XP95 Range Engineering Product Guide PP1039
General Sales Brochure PP1040
XP95 I.S. Sales Leaflet PP1094
Orbis I.S. Engineering Product Guide PP2147
MiniDisc Remote Indicator Datasheet PP2074
Bases and Accessories Brochure PP1089
Mounting Accessories Datasheet PP5068

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PP1095/2021/Issue 6
Page 2 of 8
The voltage limitation arises because of the need for safety
barriers. The barriers used with Apollo I.S. detectors are rated
at 28 volts, the highest rating that is commercially available.
These are used to limit the voltage inside the hazardous area to a
(practical) maximum of about 26 V dc. Although this is within the
standard XP95 protocol specification, it is lower than that provided
by most loop drivers.
The safety barrier is also responsible for the current limitation
because the 28 V barriers have a series resistance of at least
300 ohms. This resistance results in unacceptable voltage drops
if the normal 20 mA current pulses are used. It has therefore
been necessary to reduce the amplitude of the current
pulses to 10 mA.
XP95 Protocol Translator
In order to enable the use of standard control and indicating
equipment in intrinsically safe systems, Apollo has developed
a device to ‘translate’ voltage levels from any loop driver
operating within the XP95 limits to levels compatible with the
I.S. requirements. The translator also ‘boosts’ the current pulses
returned by the I.S. detectors from 10 mA to 20 mA, thereby
ensuring compatibility with standard loop driver thresholds. For
more information regarding the XP95 Protocol Translator refer to
PP5034.
System design
The design of an intrinsically safe fire detection system should
only be undertaken by engineers familiar with codes of practice
for detection systems and hazardous area electrical systems.
In the UK the relevant standards are BS5839-1 and BS EN 60079-
14 respectively.
The fire detection performance of the XP95 I.S. range is the same
as that of its standard counterparts. Performance information is
given in the XP95 I.S. products data sheets.
The BASEEFA certification of the I.S. devices covers their
characteristics as components of an intrinsically safe system and
indicates that they can be used with a margin of safety in such
systems. The precise way in which the system can be connected
and configured is covered by an additional, ‘system’ certification.
The System Diagram, Z20982, see Figure 6, details cable
parameters and permissible configurations of detectors, manual
call points and safety barriers which are certified by BASEEFA. Any
user wishing to install a system outside the parameters given on
this system diagram cannot make use of the Apollo certification
and should seek independent certification from a competent
certification body.
The BASEEFA system Certificate Number is BAS21Y0069 / IECEx
BAS21.0014
Any system installed within the parameters specified in Z20982
should be marked in accordance with BS EN 60079-25. The
marking should include at least ‘Apollo XP95 I.S. Fire Detection
System, BASEEFA No BAS21Y0069 / IECEx BAS21.0014
In safe area (standard) applications it will be normal practice to
connect the wiring as a loop, with both ends terminated at the
control panel. In the event of an open-circuit fault it is then possible
to drive both ends simultaneously. In a hazardous area it is not
possible to use a loop configuration because the potential to feed
power from each end of the loop would double the available energy
in the hazardous area and contravene the energy limitations of the
I.S. certification. All XP95 I.S. circuits must therefore be connected
as spurs from the safe area loop or as radial connections from the
control panel.
It is recommended, for the highest system integrity, that each I.S.
circuit be restricted to a single zone and that the connection from
the safe area loop to the I.S. spur be protected on each side by XP95
isolators. The DIN-Rail dual isolator (55000-802) is particularly
suited to this application. This configuration, shown in Figure 1 will
conform fully with the requirements of BS5839-1 and with local
codes since a single wiring fault will result in the loss of only one
zone of detection.
Figure 1: Schematic wiring diagram of XP95 I.S. circuit
to BS5839
XP95 Loop
in Safe Area
2 core
IS Zone n+2
IS Zone n+1
IS Zone n
Key
XP95 IS Isolator
XP95 IS Protocol Translator
Safety barrier
XP95 IS Detector
In certain circumstances it may be possible for the simpler
configuration, shown in Figure 2 to be used. This arrangement
may include single or dual-channel translators, housed, together
with the critical wiring, in a robust mechanical housing such as
the Apollo DIN-Rail enclosures part no. 29600-239 (1 x I.S. circuit)
or part no. 29600-240 (up to 5 x I.S. circuits). For further advice,
please contact the Technical Support Team at Apollo.

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PP1095/2021/Issue 6
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Types of safety barriers
The certified system configurations allow for two types of safety
barrier, each of which has its own advantages and disadvantages.
A brief outline of their characteristics is given below.
Single Channel 28 V/300 Ω Barrier
This is the most basic type of barrier and therefore the lowest
in cost. Being passive devices, they also impose the minimum of
restrictions on the operation of the fire detectors. Thus, single
channel barriers are available either as positive or negative
polarity where the polarity refers to the polarity of the applied
voltage relative to earth.
The significance of this is that one side of the barrier must be
connected to a high-integrity (safety) earth. Although this earth
connection has no eect on the operation of the XP95 I.S. devices and
is not needed for their correct operation, it may not be acceptable
to the operation of the control and indicating equipment. This is
particularly true if the control equipment incorporates earth-
leakage monitoring and even without this feature the earthing of
the loop may cause unwanted cross-talk between loops.
If the earth connection is not acceptable then the isolating barriers
should be used.
Galvanically Isolated Barrier
Galvanically isolated barriers (also known as transformer isolated
barriers) dier from conventional shunt zener barriers in that
they provide electrical isolation between the input (safe area) and
the output (hazardous area). This is achieved by the use of a dc
converter on the input side which is connected to the hazardous
area through a voltage-and power-limiting resistor/zener
combination similar to a conventional barrier.
The galvanic isolation technique means that the circuit does
not need a high integrity (safety) earth and that the intrinsically
safe circuit is fully floating. Earth leakage problems for control
and indicating equipment are therefore eliminated if this type of
interface is used.
Note: Although the circuit does not require a high-integrity earth, it
is permissible to earth either polarity of the hazardous area circuit if
required by other system considerations.
Although galvanically isolated barriers are widely used with
conventional fire detectors the pulse response of standard products
has been too slow to allow their use in analogue addressable
systems. Apollo has worked closely with Pepperl + Fuchs in the
development of a special galvanically isolated barrier which freely
transmits the XP95 protocol pulses without introducing severe
voltage drops.
This interface is available as single or dual channel versions
and is recommended for any application in which direct earth
connections are not acceptable. The Pepperl + Fuchs type numbers
are KFD0-CS-Ex1.54 (Apollo part no. 29600-098) and KFD0-CS-
Ex2.54 (available from Pepperl + Fuchs) for the single and dual
Figure 2: Schematic wiring diagram of XP95 I.S. circuit
using a dual channel protocol translator
I.S. Zones n n + 1 n + 2 n+ 3
Sealed enclosure to IP54 or higher
2 core
Key
XP95 I.S. Isolator XP95 I.S. single channel
Protocol Translator
XP95 I.S. dual channel
Protocol Translator
Safety Barrier XP95 I.S.
Detector
High -integrity
wiring
Figure 3: Detail of wiring diagram for XP95 I.S. Zone
+R
L1+ L2–
+R
L1+ L2–


Optional
Remote
LED
XP95 Loop
+–
–+
P & F KFD0 barrier
(view from top)
–+
Protocol translator
(view from top)


7 8 9
10 11 12
1 2 3
4 5 6

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PP1095/2021/Issue 6
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channel devices respectively. Both versions are BASEEFA certified
under Certificate Number BAS00ATEX7087.
The galvanically isolated barrier is a two-wire device which does
not need an external power supply. Current drawn from the XP95
loop by the barrier itself is less than 2mA when loaded as specified
by the manufacturer. The housing is a DIN-Rail mounting, identical
to that used for the protocol translator.
Approved safety barriers
The system certification includes a generic specification for
barriers, two additional, individually approved barriers and two
transformer isolated current repeaters (galvanic barriers).
The generic specification is:
Any shunt zener diode safety barrier certified by BASEEFA or any
EU approved certification body to
E Ex ia IIC
Having the following or lower output parameters:
Uz = 28 V
I max:out = 93.3 mA
W max: out = 0.67 W
In any safety barrier used the output current must be limited by a
resistor ‘R’ such that
I max: out = Uz
R
Wiring and cable types
It is not permitted to connect more than one circuit in the hazardous
area to any one safety barrier and that circuit may not be connected
to any other electrical circuit.
Both separate and twin cables may be used. A pair contained in a
type ‘A’ or ‘B’ multicore cable (as defined in clause 12.2.2 of BS EN
60079-14) may also be used, provided that the peak voltage of any
circuit contained within the multicore does not exceed 60 V.
The capacitance and either the inductance or the inductance
to resistance (L/R) ratio of the hazardous area cables must not
exceed the parameters specified in Table 4. The reason for this
is that energy can be stored in a cable and it is necessary to use
cable in which energy stored is insucient to ignite an explosive
atmosphere.
To calculate the total capacitance or inductance for the length of
cables in the hazardous area, refer to Table 3, which gives typical
per kilometre capacitance and inductance for commonly used
cables. (Note: All XP95 I.S. devices have zero equivalent capacitance
and inductance).
Table 3: Examples of electrical characteristics of cables commonly used in fire protection systems
Cable Type Core Size mm Conductor Resistance
Ohm/km/Core
Inductance
mH / km
Capacitance F / km Sheath
Resistance
Ohm / km
Core to
Core
Core to
Sheath
MICC Pyrotenax Light Duty 2 1.5 12.1 0.534 0.19 0.21 2.77
MICC Pyrotenax Heavy Duty 2 1.5 12.1 0.643 0.13 0.17 1.58
Pirelli FP200 all 1.5 12.1 - 0.08 0.15 -
PVC Sheathed and Insulated to
BS 6004
all 1.5 12.1 0.77 0.09 - -
Table 4: Limits for energy stored in cables
Group Capacitance
F
Inductance
mH L/R Ratio H / Ohm
IIC 0.083 4.2 55
IIB 0.65 12.6 165
IIA 2.15 33.6 440

Intrinsically safe
PP1095/2021/Issue 6
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Safety earth
Shunt zener safety barriers must be connected to a high integrity
earth by at least one and preferably two copper cables, each of
cross sectional area of four mmor greater. The connection must
be such that the impedance from the connection point to the main
power system earth is less than one ohm.
Intrinsically safe circuits in the hazardous area should be insulated
from earth and must be capable of withstanding a 500V RMS ac
test voltage for at least one minute. When using armoured or
copper sheathed cables, the armour or sheath is normally isolated
from the safe area busbar.
Remote LED connection
A drive point is provided on each of the XP95 I.S. detectors for
a remote LED indicator. For connection details see Figure 3. The
indicator must be a standard high-eciency red LED and does not
require a series limiting resistor since current is limited within
the detector to approximately 1 mA. The remote LED cannot, as
in the standard XP95 range, be controlled independently from the
integral LED since it is eectively connected in series with the
integral LED. The benefit of this configuration is that illumination of
the remote LED does not increase the current drawn from the loop.
The system certification allows for the use of any LED indicator
having a surface area between 20 mmand 10 cmwhich
covers all commonly used case styles from T1 (3 mm) upwards
but would exclude some miniature and surface mounted types.
Additional requirements of the certification are that the LED and
its terminations must be aorded a degree of protection of at least
IP20 and must be segregated from other circuits and conductors
as defined in BS EN 60079-14.
The Apollo MiniDisc Remote Indicator (53832-070) is suitable
using connections B(+) and C(-).
Installation
It is important that the XP95 I.S. detectors are installed in such a
way that all terminals and connections are protected to at least
IP20 when the detector is in the base. Special care must be taken
with the rear of the mounting base where live metal parts (rivets)
may be accessible. Flush mounting of the base on a flat surface
will provide the required degree of protection.
If the base is mounted on a conduit box (e.g. BESA box or similar)
whose diameter is less than 85 mm then the base should be fitted
with a XP95 Backplate (Apollo part number 45681-233). Use
of the backplate will prevent access to the metal parts and will
also protect the rear of the base from water ingress. The conduit
box available from Apollo, part no. 45681-204, is also acceptable
for mounting I.S. bases. Apollo also supply a range of deckhead
mounting boxes.
Figure 4 shows permissible methods of installing intrinsically safe
detector bases.
Note: The earth terminal in the base is provided for convenience
where continuity of a cable sheath or similar is required. It is not
necessary for the correct operation of the detector nor is it provided
as a termination point for a safety earth.
Figure 4: Permissible methods of mounting I.S. detector
bases
Base fitted flush to sot
I.S. Base
Part No. 45681-215
Base with backplate and BESA box
Standard
BESA box
Backplate
Part No. 45681-233
I.S. Base
Part No. 45681-215
I.S. Base
Part No. 45681-215
Conduit box
Part No. 45681-204
Base fitted to conduit box
Maximum loading of an I.S. circuit
The safety barrier is a mandatory part of an I.S. system, but the
high series impedance limits the number of I.S. detectors that may
be fitted to the circuit. Typically an I.S. circuit will have a maximum
load of about 15 detectors depending on the barrier type, the
type of devices fitted and the number of detector LEDs allowed to
illuminate concurrently by the Control and Indicating Equipment.
When calculating the detector load to ensure the I.S. detection
zone is not overloaded two components of the current drain must
be considered, namely the standing current of the devices by
themselves and the maximum drain caused by alarm LEDs being
illuminated.
The standing current of the devices can be calculated by taking the
sum of the individual device currents on the circuit, as given in the
section ‘Technical data’ for each product.
The maximum number of LEDs that can be illuminated
simultaneously should be limited by the panel software.
Table 5 and Table 6 show the maximum device current which can
be supported for varying numbers of LEDs illuminated for zener
and galvanic barriers respectively.

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PP1095/2021/Issue 6
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Table 5: Maximum loading 28 V/300 Ω single channel
barrier
Max. No of LEDs illuminated Max. (Total) device load (mA)
0 8.0
1 7.0
2 6.0
3 5.0
4 4.0
5 3.0
Table 6: Maximum loading 28 V Galvanic Isolator Single
Channel Barrier
Max. No of LEDs illuminated Max. (Total) device load (mA)
0 4.0
1 3.0
2 2.0
Table 7: Loading of the fire loop from a Translator and
Barrier pair
Characteristic Zener Barrier Galvanic
Barrier
Min Loading
Current (mA) 1 5
Capacitance
(nF) 1 90
Max Loading
Current (mA) 10 10
Capacitance
(nF) 80 170
Using Galvanically Isolated Barriers
Whilst the cable parameters in Table 4 specify the allowable limits
for energy storage in the Hazardous area wiring these values do
not generally allow reliable XP95 protocol transmission. This is
particularly true when using Galvanically Isolated Barriers. Due
to their design, these barriers present a relatively high capacitive
load on the main fire loop. Therefore, the main fire loop capacitive
loading and the I.S. spur capacitive loading must be carefully
considered when designing a fire system.
The maximum impedance allowed on the I.S. spur is 15 ohms and
80nF, which is typical of 500m of FP200 cable.
The maximum capacitive load that can be tolerated on the fire loop
will be defined by the Control Panel manufacturer. The capacitive
load of the IS zone includes 90nF for the galvanic barrier and the
total cable capacitance (80nF maximum). This should be added to
the main fire loop capacitance and compared with the fire panel
specification.
Additionally, a galvanic barrier will add 5mA to the system load
which should be added to the loop loading calculations.
The loop calculations for each I.S spur often use the maximum
load of 10mA and 200nF as the equivalent load on the fire main
loop. Any calculation must ensure that the translator has at least
19V at the translator input.
Servicing
Servicing of I.S. fire detectors may be carried out only by a
BASEEFA authorised body. In practical terms this means that
Apollo XP95 I.S. fire detectors may be serviced only by Apollo at its
factory. Servicing of the fire protection system should be carried
out as recommended by the code of practice BS 5839-1 or other
local regulations in force. For more information on servicing Apollo
detectors, please refer to the care, service and maintenance guide,
PP2055.
Approvals
XP95 I.S. detectors have been approved by LPCB to EN54 and the
XP95 I.S. Manual Call Point, Part No 55100-940, is LPCB approved
to EN54-11. These products have also been approved for marine
use by the following bodies:
• American Bureau of Shipping
• Bureau Veritas
• DNV GL
• Lloyds Register of Shipping
• China Classification Society
• Korean Register of Shipping
Details of approvals held are available on request.
The product certification technical files for the XP95 I.S. range are
held by BASEEFA in accordance with the requirements of the ATEX
Directive 2014/34/EU. All detectors and manual call points are
marked.

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PP1095/2021/Issue 6
Page 7 of 8
Figure 5: Functional earthing and wiring (Sheathed and Unsheathed)
50mm
(Minimum)
10 11 12
7 8 9
1 2 3
4 5 6
Non-hazardous area Hazardous area
AB
Cable
sheath
Cable
sheath
Cable
sheath
Cable
sheath
CI.S
Detector Base
I.S
Detector Base
Functional earth
A
B
C
Dual-channel Isolator
Protocol Translator
DIN-Rail enclosure
Galvanic Barrier
All mounted within
the DIN-Rail enclosure
Drain / Shield
CIE Wiring in accordance to TSDxxx, BS5839-1 or local codes,
BS EN 60014-xx, and CIE manufacturers recommendation
Loop
wiring
1 2 3
4 5 6
10 11 12
7 8 9
1 2 3
4 5 6
10 11 12
7 8 9
Ch 1
Ch 2
Functional earth
+
-
50mm
(Minimum)
10 11 12
7 8 9
1 2 3
4 5 6
Non-hazardous area Hazardous area
AB
CI.S
Detector Base
I.S
Detector Base
Functional earth
This is optional for a shielded cable in the hazardous area
A
B
C
Dual-channel Isolator
Protocol Translator
DIN-Rail enclosure
Galvanic Barrier
All mounted within
the DIN-Rail enclosure
Loop
wiring
1 2 3
4 5 6
10 11 12
7 8 9
1 2 3
4 5 6
10 11 12
7 8 9
Ch 1
Ch 2
Functional earth
Wiring in accordance to TSDxxx, BS5839-1 or local codes,
BS EN 60014-xx, and CIE manufacturers recommendation

Intrinsically safe
Figure 6: XP95 I.S. System drawing
PP1095/2021/Issue 6
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