EXPO MiniPurge D829/ET User manual

ML538 | v8 19 January 2024
D829/ET MiniPurge®
Manual
ML538
Important Note:
It is essential for safety that the installer and user of the Expo system follow these
instructions.
Please refer to the standard for principles and definition.
These instructions apply only to the pressurizing system. it is the responsibility of the
manufacturer of the pressurized enclosure to provide instructions for the enclosure.

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System Specification .................................................................................................................1
MiniPurge® Control Unit Data .................................................................................................2
Pressure Relief/Outlet Valve with Integral Spark Arrestor .......................................................3
Quick User Guide .......................................................................................................................3
Installation ...............................................................................................................................3
Operation of the System ..........................................................................................................3
Application Suitability ................................................................................................................4
Description and Principle of Operation ....................................................................................5
Main Components ......................................................................................................................6
Air Supply Filter / Regulator .....................................................................................................6
Logic Air Supply Regulator ......................................................................................................6
Minimum Pressure Sensor ......................................................................................................6
Purge Flow Sensor ..................................................................................................................6
Electronic Purge Timer ............................................................................................................7
Purge Complete Valve .............................................................................................................7
Purge Inhibit Sensor ................................................................................................................7
OR Gate ..................................................................................................................................7
Alarm Only Circuit (/AO) ..........................................................................................................7
Power Interlock Switch ............................................................................................................7
Alarm / Pressurized Switch ......................................................................................................8
System Purging Switch (Optional) ...........................................................................................8
Purge Valve .............................................................................................................................8
Purge Flow Restrictor ..............................................................................................................8
CLAPS Sensor ........................................................................................................................8
CLAPS Regulator ....................................................................................................................8
Visual Indicators ......................................................................................................................8
Relief Valve Unit ......................................................................................................................8
/PA Terminal Box .....................................................................................................................9
Installation of the System ..........................................................................................................9
Relief Valve Unit ......................................................................................................................9
Air Supply Quality ....................................................................................................................9
Pipe Work ..............................................................................................................................10
Multiple Enclosures ...............................................................................................................10
Provision and Installation of Alarm Devices ..........................................................................10
Power Supplies and their Isolation ........................................................................................10
Power Interlock Switch ..........................................................................................................11
Commissioning ........................................................................................................................11
Commissioning the System ...................................................................................................11
Maintenance of the System .....................................................................................................13
General maintenance ............................................................................................................13
Additional maintenance checks .............................................................................................14
Maintenance of Electronic Timer ...........................................................................................14
Re-calibration of the Relief Valve Unit ...................................................................................15
Re-calibration of the Pressure Sensors .................................................................................15
Fault Finding ............................................................................................................................16
General Information ...............................................................................................................16
System purges correctly but trips and auto re-purges at the end of the purge time ..............16
Relief Valve opens (continuously or intermittently) ................................................................17
System enters purging but purge indication does not occur ..................................................17
Recommended Spare List .......................................................................................................17
Glossary ....................................................................................................................................18
Drawings and Diagrams ..........................................................................................................18
Certificates ................................................................................................................................18

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Section 1: System Specification
3 X LC / ss / ET / OV / PC / PA / D829
Size
3 = MiniPurge® Purge
Flow Rate:
1000 - 1500 NI/min
Approval / Certification
Sira 01ATEX1295X
2813 II 2(2) G
Ex [pxb] ia IIC T5 Gb
Tamb -20ºC to +55ºC
IECEx SIR07.0027X
Ex [pxb] ia IIC T5 Gb
Tamb -20ºC to +55ºC
TÜV 12.1462X
Ex [pxb] ia IIC T5 Gb
Tamb -20ºC to +55ºC
PC = Pressurized Control. Automatic
leakage compensation (CLAPS)
OV = Purge Outlet Valve is pneumatically
operated
Timing Method
ET = Electronic Timer
MiniPurge® Housing
ss = Stainless Steel 316L
Pressurization Method
LC = Leakage Compensation
ATEX Certificate:
IECEx Certificate:
TÜV INMETRO Certificate:
PA = Power and Alarm. Integral Ex e
Terminal Box
For limitations and conditions of use refer to the applicable certificates on ML497
2020312304000830
Ex [pxb] ia IIC T5 Gb
Tamb -20ºC to +55ºC
CCC Certificate:
ЕАЭСRU С-RU.АЖ58.В.00906/20
1Ex [px] ia IIC T5 Gb
-20ºC ≤ Tamb ≤ +55ºC
EAC Certificate:

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MiniPurge® Control Unit Data
Action on Pressure Failure: Alarm and Trip (isolate power to pressurized enclosure), user adjusta-
ble Alarm Only.
Type of Operation: Automatic leakage compensation using the Closed Loop Automatic
Pressurization System (CLAPS System).
Leakage Compensation Capacity: 500Nl/min @ 4barg inlet pressure
Leakage Compensation Over Ca-
pacity:
+40% (minimum) of the normal enclosure leakage
Enclosure Material: Stainless Steel 316L.
Temperature Limits: -20oC to +55oC
Compressed Air Supply: Clean, dry, oil free air or inert gas. Refer to Air Supply Quality section
in Installation of the System.
Supply Pressure: 4 to 8 barg (60 to 120 psi).
Main Regulator: Set at 5 barg, 40 mm automatic drain supply inlet filter.
Logic Regulator and Gauge: Fitted and set to 2.3 barg (33 psi).
Process Connections: Purge supply and outlet to pressurized enclosure ½” NPT female.
Minimum supply line 13mm (½”) ID tube, inlet sized appropriately for
flow rate.
Reference points & signals 1/8” NPT female, minimim 6mm pipe to be
used.
Visual Indicators: Alarm (Red ) / Pressurized (Green ).
System Purging: 4 LEDs that flash sequentially to indicate elapsed
time (black when not purging).
/PA Terminal Box: Stainless Steel, Ex e IIC T5 Gb Tamb: -20ºC to +60ºC with terminals,
front access cover & lower removable gland plate.
Stainless Steel, Ex e IIC T4 Gb Tamb: -20ºC to +60ºC with terminals,
front access cover & lower removable gland plate.
Power Interlock Switch: DPNO switch, contact ratings 250 Vac 4A (AC-15) / 24V DC 4A,
Ex d IIC T6 IP66.
Alarm Switch: SPCO switch, contact ratings 250 Vac 4A (AC-15) / 24V DC 4A,
Ex d IIC T6 IP66.
System Purging Switch (Optional): SPCO switch, contact ratings 250 Vac 4A (AC-15) / 24V DC 4A,
Ex d IIC T6 IP66.
Minimum Pressure Sensor: Minimum: 0.5 mbarg.
Maximum: 5.0 mbarg.
Default Setting: 1.5 mbarg.
Tolerance -0, +0.7 mbarg.
Purge Inhibit Settings: Minimum: 2.0 mbarg.
Maximum: 12 mbarg.
Default Setting: 12 mbarg.
Tolerance -0, +10%.
Purge Flow Sensor: Set at 6.4 mbarg (Tolerance: -0, +10%).
CLAPS Sensor: Minimum: 5.0 mbarg.
Maximum: 15 mbarg.
Default Setting: 10 mbarg.
Tolerance: -0, +10%

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Pressure Relief/Outlet Valve with Integral Spark Arrestor
Section 2: Quick User Guide
Installation
The MiniPurge® System must be installed by a competent engineer, in accordance with relevant standards, such
as IEC / EN 60079-14 and any local codes or practice.
• Mount the purge system in accordance with the hook-up drawing.
• Ensure the system is installed according to the full instructions in the “Installation of the System” section
of this manual.
• All piping must be clean and free of dirt, condensation and debris prior to connection to the purge system
or pressurized enclosure.
• It is strongly recommended that a local isolation valve is installed on the air supply upstream of the purge
system.
Note: Most faults are due to restricted air supply, inadequate supply pipe work or drop in air supply
pressure during the purge process.
Operation of the System
Once the system is installed correctly, turn on the air supply. Refer to Commissioning section.
The purge system commences the purge cycle:
• The purge air will enter the enclosure.
Purge Time: User selectable, in 1 minute intervals, up to 99 minutes (tolerance -0,
+3 seconds).
Default Setting 99 minutes.
Weight: 16 kg (35lb).
Type RLV52/ss/FS, Design number D779RLV
Bore: Purge Outlet Valve Ø 52 mm, Relief Valve Ø 52 mm.
Relief Valve Lift-Off Pressure: Minimum: 20 mbarg.
Maximum: 50 mbarg.
Default: 30 mbarg (+0, -20%).
Flow Rate: Range: 1000 or 1500 NI/min.
Default: 1500 NI/min.
Material: Housing: Stainless steel 316L.
Gasket: Neoprene.
Spark arrestor: Stainless steel mesh.
Mounting Method: Rectangular cut-out and fixing holes as per drawing.
Weight: 4 kg (8.8lb)
Indicator Colour Status
Alarm / Pressurized Red Low pressure alarm (enclosure pressure too low)
Purging Black Purge flow too low or not in purge mode

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• The pressurized enclosure will obtain a positive pressure.
• The Purge Outlet Valve will open within the Relief Valve Unit.
• The air will then exit the Relief Valve Unit housing via the spark arrestor.
Open the Purge Flow Restrictor Valve until the air flow reaches the required rate; the system will initiate the
timed purge cycle. Start a stopwatch when the purging indicator flashes yellow.
On completion of an uninterrupted purge cycle of the required length, the system will indicate purge complete.
Stop the stopwatch when the purging indicator stops flashing.
Check stopwatch timing to verify that the actual purge time is equal to or greater than the required purge time.
Note: The recorded purge time must never be less than the required purge time.
The system is now operating correctly in leakage compensation mode.
If the system has not performed as expected, check the installation thoroughly and ensure it has been carried
out according to the instructions.
If an obvious problem has not been highlighted and corrected, follow the procedures in the Fault Finding
section.
If all checks have been carried out and the system still does not perform as expected, contact your local
distributor or Expo Technologies.
Section 3: Application Suitability
MiniPurge® systems are certified for use in hazardous locations, where the hazardous location is non-mining
(above ground) and the hazard is caused by flammable gasses, vapours or dust. Depending on the model the
systems may be used in IECEx and ATEX Zone 1 and/or Zone 2 - Categories 2 and 3 respectively.
MiniPurge® systems may be used for hazards of any gas group. Apparatus associated with the MiniPurge®
system, such as intrinsically safe signalling circuits and flameproof enclosures containing switching devices
may be limited in their gas group. The certification documentation supplied with any such devices must be
checked to ensure their suitability.
This system is primarily designed for use with compressed air. Where other inert compressed gasses are used
(Nitrogen, for example) the user must take suitable precautions so that the build up of the inert gas does not
present a hazard to health. Consult the Control of Substances Hazardous to Health (COSHH) data sheet for the
gas used. Where a risk of asphyxiation exists, a warning label must be fitted to the pressurized enclosure.
Indicator Colour Status
Alarm / Pressurized Green Pressurized (minimum enclosure pressure achieved)
Purging Black Purge flow too low
Indicator Colour Status
Alarm / Pressurized Green Pressurized
Purging Sequential flashing
Yellow
Purge flow rate above minimum
Indicator Colour Status
Alarm / Pressurized Green Pressurized and in leakage compensation mode
Purging Black No longer in purge mode

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The following materials are used in the construction of MiniPurge® systems. If
substances that will adversely affect any of these materials are present in the surrounding environment,
please consult Expo Technologies for further guidance.
Section 4: Description and Principle of Operation
The MiniPurge® system is pneumatic in operation, with electrical interfaces.
Purge and pressurization is a method of protection used in Zone 1 (21) and/or Zone 2 (22) hazardous locations
to ensure that the interior of an enclosure is free of flammable gas. Addition of a MiniPurge® system allows the
electrical equipment within the enclosure to be used safely in a hazardous location.
The principle of purge and pressurization is as follows:
• Clean compressed air or inert gas is drawn from a non-hazardous location.
• The interior of the pressurized enclosure is flushed to remove any hazardous gas or dust.
• This is introduced into the pressurized enclosure to keep the internal pressure at least 0.5 mbarg above the
external pressure.
• Whilst pressurized, flammable gas cannot enter the enclosure from the environment.
Prior to switching on the power to the electrical equipment, the enclosure must be purged to remove any
flammable gas that might have entered the enclosure before pressurization. Purging is the process of removal
contaminated air and replacement with air (or inert gas) known to be free from flammable gas. The duration of
this purge process is normally ascertained by performing a purge test.
At the end of the purge cycle the system automatically switches to leakage compensation mode. The Purge
Outlet Valve is closed and the airflow is reduced but remains high enough to compensate for the leakage of air
from the enclosure whilst maintaining the minimum over pressure state.
In the event of pressure failure within the pressurized enclosure the system will raise an alarm in the form of
visual indicators and a volt free contact depending on the specification of the system. The default action on
loss of pressurization is alarm and automatic disconnect of power (A&T - Alarm and Trip). This can be changed
by the customer to Alarm Only (/AO), please refer to section titled Main Components.
The MiniPurge® system incorporates a Closed Loop Automatic Pressurization System (CLAPS). This allows the
system to detect a rise or fall of the enclosure’s internal pressure and adjust the leakage compensation rate
accordingly. Pressure variations are more likely during sudden start up of large rotating electrical machines but
can also be caused by changes in running temperature. This system has been specifically designed to maintain
a stable internal pressure within the enclosure.
Materials of Construction
Stainless Steel ABS Polyurethane Silicone
Mild (Carbon) Steel Aluminium Polycarbonate Neoprene
Brass Nylon Acrylic Polyester (glass filled)

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Pressure characteristics during purge and pressurization of a pressurized enclosure
using a MiniPurge® system that incorporates a CLAPS system:
Section 5: Main Components
Air Supply Filter / Regulator
The unit is provided with a 50 mm liquid / dust filter element as a precaution. The user of the MiniPurge® sys-
tem must ensure that air supply is to the quality stated in Air Supply Quality paragraph found in the Installation
of the System section. The regulator is factory set to 4 barg (60 psig) and regulates the pressure of an air sup-
ply between 4 and 8 barg (60 to 120 psig). A pressure gauge is fitted down stream of the filter; this should
indicate no less than 4 barg (60 psig). During the purge cycle a pressure drop will be indicated on the gauge.
Logic Air Supply Regulator
This device provides the system with a stable air supply pressure to the logic system and allows consistent
operation. The pressure level is factory set to 2.5 barg (36 psig) and can be verified by means of the integral
pressure gauge.
Minimum Pressure Sensor
This monitors the pressure inside the pressurized enclosure. When the pressure is below the minimum required
for safe operation, the pressure sensor causes the system to reset and the Alarm / Pressurized indicator turns
Red . The sensor is factory calibrated and set to operate in falling pressure at or above the minimum specified
pressure.
Purge Flow Sensor
The Purge Flow Sensor monitors flow through the Purge Outlet Valve. At correct purge flow rates, above the
minimum specified for purging, the sensor sends a signal that activates the purge timer. This sensor is factory
calibrated to operate on falling flow rate at or above the minimum specified purge flow rate.
Intermediate Pressure
Sensor Pressure
Power Interlock switch
Alarm &Trip
Purge Time Machinery Start Normal Operation
CLAPS Regulator
Pressure
Intermediate switch contacts
open. Intermediate sensor
sends falling pressure signal
Fault Condition - loss of pressure
outside of CLAPS regulation
Minimum Pressure
Sensor Pressure
Purging Pressure
Minimum pressure switch contacts
open. Minimum pressure sensor sends
a low pressure signal.
Alarm indicator shows red (alarm only)
Alarm indicator shows red and power
is disconnected (Alarm and Trip)
Minimum
pressure switch
Intermediate
pressure switch
Power Interlock switch
Alarm Only
Contacts
Active
Inactive

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Electronic Purge Timer
When both the enclosure pressure and the purge flow rate are correct, the Purge Flow Sensor activates the
timer and the electronic timer starts. The timing period is selected using switches mounted on the timer
module.
Note: Setting the timer to 00 minutes will cause infinite purging; the cycle will never complete.
During timing, the percentage of the purge cycle is indicated by four LEDs which flashes sequentially while the
timer is running.
The Electronic Timer contains an intrinsically safe battery pack that needs regular replacement. See
Commissioning section.
Purge Complete Valve
This valve receives a signal from the purge timer that indicates the completion of the purge cycle and verifies
that the pressurization signal is still present. If both conditions are satisfied a signal is sent to indicate that the
purge is complete. This performs two functions: to turn on the electrical supply to the pressurized enclosure
and to reduce the high purge flow rate to leakage compensation mode. It also provides a hold-on signal that
maintains the leakage compensation mode with the power switch on, even when the purge timer has reset
ready for the next purge cycle.
Purge Inhibit Sensor
This sensor interlocks the purge cycle with an auxiliary purge air circulation fan or other device i.e where
forced circulation of purge air is required. The purging sequence will only commence once a pre-set differential
across the sensor has been reached.
OR Gate
This device provides the Purge Complete Valve with the hold-on function referred to previously. When either
the timed-out signal or the purge complete signal is present it allows the pilot signal to be sent to the purge
complete valve.
Alarm Only Circuit (/AO)
If the pressure in the pressurized enclosure is too low the system will normally cut off electrical power to it. In
certain circumstances, where local codes of practice allow, the system can be altered to provide a hold-on
circuit that will maintain the electrical power supply to the pressurized enclosure while also providing a
pressure failure alarm. The user must respond to the alarm and either restore the pressure to the pressurized
enclosure or otherwise make the installation safe; for example, cut off the electrical supply. The decision to
use the Alarm Only facility, and the allowable length of time for non-pressurized operation, is the responsibility
of the user.
Warning: It is potentially dangerous to energise the pressurized enclosure in an non-pressurized
condition when it is known that there is potentially explosive gas or dust in the hazardous location.
Power Interlock Switch
This flameproof power switch is activated by the signal from the Purge Complete Valve. This activation can be
used to turn on the electrical supply to the pressurized enclosure. The cable from the switch is terminated in
the /PA terminal box.
LED 1
LED 2LED 3
LED 4 LED 1
LED 2LED 3
LED 4 LED 1
LED 2LED 3
LED 4 LED 1
LED 2LED 3
LED 4
0 to 25%
of purge time
26 to 50%
of purge time
51 to 75%
of purge time
76 to 100%
of purge time

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Alarm / Pressurized Switch
This flameproof switch is operated by the pressurized signal. It allows a remote electrical system status
indicator to show either pressurized or a pressure failure alarm. The cable from the switch is terminated in the
/PA terminal box.
System Purging Switch (Optional)
This switch is operated by the purge flow signal that allows a remote electrical system status indicator to
signal that the system is purging; sometimes referred to as “purge-in-progress”. The cable from the switch is
terminated in the /PA terminal box.
Purge Valve
This changeover valve selects between purge air flow or leakage compensation. It is sized to allow sufficient
air into the enclosure during purging based on: the specified air supply pressure range, the minimum specified
purging outlet flow rate +10% and the expected leakage rate from the pressurized enclosure. At the end of the
purge cycle, the purge valve closes in response to the “Purge Complete” signal; it remains in the closed position
until the next purge cycle is initiated.
Purge Flow Restrictor
This valve restricts the purge flow to the minimum required flow rate. The Purge Flow Restrictor must be
readjusted during commissioning.
CLAPS Sensor
This sensor monitors the pressure within the pressurized enclosure and sends a control signal to the CLAPS
Regulator. The normal running pressure must be determined prior to system start-up so that the CLAPS Sensor
may be set to the level required to control the CLAPS Regulator.
CLAPS Regulator
This is the regulator that controls the leakage compensation air flow into the enclosure after the purging is
complete. It either increases or decreases the air flow into the enclosure as appropriate to maintain a stable
running pressure. The CLAPS Regulator must be set at the time of commissioning.
Visual Indicators
Visual indicators are fitted to provide status information to the operator.
* The Green / Black combination indicates normal operation of the pressurized enclosure after the initial
purging cycle has been completed.
Relief Valve Unit
The Relief Valve Unit allows the purge air to exit the enclosure safely via a built-in spark arrestor. This spark
arrestor is designed to prevent the emission of arcs, sparks and incandescent particles produced within the
pressurized enclosure.
Alarm / Pressurized Indicator
Green* Pressurized
Red Pressure Alarm (enclosure pressure low)
System Purging Indicator
Black* Purge flow too low (not in purge mode)
Yellow (flashing) Purging (flow above minimum)