EXPO MiniPurge D770/ET User manual

ML564 | v3 26-June-18
D770/ET MiniPurge®
Manual
ML 564
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.
Expo Technologies reserves the right to replace any component, with one of the equivalent functionality.

ML564 | v3 i
Section 1: System Specification................................................................................................1
MiniPurge® Control Unit Data...................................................................................................2
Vortex Cooling Assembly .........................................................................................................3
Relief Valve Unit and Purge Outlet Valve with integral spark arrestor......................................3
Section 2: Quick User Guide......................................................................................................4
Installation ................................................................................................................................4
Operation of the System...........................................................................................................4
Section 3: Application Suitability ..............................................................................................6
Section 4: Description and Principle of Operation ..................................................................7
Section 5: Main Components.....................................................................................................9
Air Supply Filter / Regulator......................................................................................................9
Logic Air Supply Regulator .......................................................................................................9
Minimum Pressure Sensor .......................................................................................................9
Purge Flow Sensor ...................................................................................................................9
Intermediate Sensor .................................................................................................................9
Electronic Purge Timer .............................................................................................................9
Purge Complete Valve..............................................................................................................9
OR Gate .................................................................................................................................10
Alarm Only Circuit (/AO) .........................................................................................................10
Visual Indicators .....................................................................................................................10
Power Interlock Switch ...........................................................................................................10
Alarm / Pressurized Switch.....................................................................................................10
System Purging Switch (Optional)..........................................................................................10
Intermediate Switch ................................................................................................................11
Purge Valve ............................................................................................................................11
Purge Flow Restrictor .............................................................................................................11
CLAPS Sensor .......................................................................................................................11
CLAPS Regulator ...................................................................................................................11
Relief Valve Unit .....................................................................................................................11
/PA Terminal Box....................................................................................................................11
Pneumatic Vortex Cooling Assembly .....................................................................................11
Vortex Cooler Activation Thermostat......................................................................................12
Logic Isolation Thermostat .....................................................................................................12
Section 6: Installation of the System.......................................................................................13
Relief Valve Unit .....................................................................................................................13
Air Supply Quality ...................................................................................................................13
Pipe Work ...............................................................................................................................14
Multiple Enclosures ................................................................................................................14
Provision and Installation of Alarm Devices ...........................................................................14
Power Supplies and their Isolation .........................................................................................14
Power Interlock Switch ...........................................................................................................14
Section 7: Commissioning .......................................................................................................16
Commissioning the System ....................................................................................................16
Normal Operation ...................................................................................................................17
Section 8: Maintenance of the System....................................................................................18
General maintenance .............................................................................................................18
Additional maintenance checks ..............................................................................................18
Maintenance of Electronic Timer ............................................................................................18
Re-calibration of the Relief Valve Unit....................................................................................18
Re-calibration of the Pressure Sensors..................................................................................19
Section 9: Fault Finding............................................................................................................20
General Information................................................................................................................20
System purges correctly but trips and auto re-purges at the end of the purge time...............20
Relief Valve opens (continuously or intermittently).................................................................21
System enters purging but purge indication does not occur...................................................21
System begins purging but cycles fail to complete.................................................................21

ii ML564 | v3
Section 10: Recommended Spares List..................................................................................22
Section 11: Glossary.................................................................................................................22
Section 12: Drawings and Diagrams .......................................................................................22
Section 13: Certifications .........................................................................................................23

ML564 | v3 Page
1
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[email protected]
Expo Technologies China
T: [phone]
E: [email protected]
Section 1: System Specification
5 X LC / ss / ET / OV / H7 / PC / PA
Size
5 = MiniPurge®
Purge flow rate:
6000 NI/min
Approval / Certification
Sira 01ATEX1295X
0518 II 2(2) G
Ex [pxb] ia IIC T4 Gb
Tamb -20ºC to +60ºC
IECEx SIR07.0027X
Ex [pxb] ia IIC T4 Gb
Tamb -20ºC to +60ºC
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:
PA = Power and Alarm Switches.
Integral /PA Terminal Box
For limitations and
conditions of use refer to
the applicable certificates.
High Temperature =
Tamb: -20ºC to +60ºC
Purge air Temp: max 70ºC
INMETRO CERTIFICATE:
TÜV 12.1462X
Ex [pxb] ia IIC T4 Gb
Tamb -20ºC to +60ºC

Page
2
ML564 | v3
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[e-mail]
Expo Technologies China
T: [phone]
E: [e-mail]
MiniPurge® Control Unit Data
Action on Pressure Failure: Alarm and Trip (isolate power to pressurized enclosure), user adjustable
Alarm Only.
Type of Operation: Automatic leakage compensation using the Closed Loop Automatic
Pressurization System (CLAPS System).
Leakage Compensation
Capacity
1000 NI/min initial maximum pressurized enclosure leakage.
1900 NI/min maximum as leakage increases.
Enclosure Material: Stainless Steel 316L.
Mounting Method: Wall mounting straps. Fixing holes as per drawing.
Temperature Limits: Ambient -20oC to +60oC
Purge air temperature max = 70oC
Compressed Air Supply: Clean, dry, oil free air or inert gas. Refer to Air Supply Quality section in
Installation of the System.
Supply Pressure: 5 to 16 barg (73 to 232 psi).
Main Regulator: Set at 5 barg, 40 μm 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 1” NPT female.
Minimum supply line 25 mm (1”) ID tube, inlet sized appropriately for flow
rate.
Reference points & signals 1/8” NPT female, minimum 6 mm 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 T4 Gb Tamb : -20ºC to +60ºC with terminals,
front access cover & lower removable gland plate.
Power Interlock Switch: DPNO switch, contact ratings 250 Vac 4 Amps (AC-15) / 24V DC 4A,
Ex d IIC T6 Gb / Ex tb IIIC T80ºC Db.
Alarm Switch: SPCO switch, contact ratings 250 Vac 4 Amps (AC-15) / 24V DC 4A,
Ex d IIC T6 Gb / Ex tb IIIC T80ºC Db.
Intermediate Switch: SPCO switch, contact ratings 250 Vac 4 Amps (AC-15) / 24V DC 4A,
Ex d IIC T6 Gb / Ex tb IIIC T80ºC Db.
System Purging Switch
(Optional):
SPCO switch, contact ratings 250 Vac 4 Amps (AC-15) / 24V DC 4A,
Ex d IIC T6 Gb / Ex tb IIIC T80ºC Db.
Minimum Pressure Sensor: Minimum: 0.5 mbarg.
Maximum: 5.0 mbarg.
Default Setting: 1.5 mbarg.
Tolerance -0, +0.7 mbarg.
Intermediate Sensor: Minimum: 2.0 mbarg.
Maximum: 10 mbarg.
Default Setting: 5.0 mbarg.
Tolerance: -0, +10%.
Note: There must be a 1.5 mbarg difference between the minimum pressure and intermediate sensors.
Purge Flow Sensor: Set at 6.4 mbarg (Tolerance: -0, +10%).
CLAPS Sensor: Minimum: 5.0 mbarg.

ML564 | v3 Page
3
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[email protected]
Expo Technologies China
T: [phone]
E: [email protected]
Vortex Cooling Assembly
Relief Valve Unit and Purge Outlet Valve with integral spark arrestor
Maximum:15 mbarg.
Default Setting: 10 mbarg.
Tolerance: -0, +10%
Note: there must be a 2.5 mbarg difference between the intermediate and CLAPS sensor calibration point.
For example: Minimum pressure = 5 mbarg, intermediate pressure = 6.5 mbarg, CLAPS sensor = 9 mbarg.
Purge Time: User selectable, in 1 minute intervals, up to 99 minutes (tolerance -0, +3
seconds).
Default Setting 99 minutes.
Weight: 26 kg (57lb).
Air Consumption during
Operation:
Approx. 200Nl/min.
Noise during Operation: Approx. 92dB.
Type: RLV104/ss/FS, Design number D770RLV.
Bore: Purge Outlet Valve Ø 104 mm, Relief Valve Ø 75 mm.
Relief Valve Lift-Off Pressure: Minimum: 20 mbarg.
Maximum: 50 mbarg.
Default: 30 mbarg (+0, -20%).
Flow Rate: Range: 2000, 3000, 4000, 5000, or 6000 NI/min.
Default: 2000 NI/min.
Material: Housing: Stainless steel 316L.
Gasket: Silicone foam.
Spark arrestor: Stainless steel mesh.
Mounting Method: Rectangular cut-out and fixing holes as per drawing.
Weight: 7 kg (15.4 lb).

Page
4
ML564 | v3
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[e-mail]
Expo Technologies China
T: [phone]
E: [e-mail]
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 pipings 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 pres-
sure 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.
• 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.
Indicator Colour Status
Alarm / Pressurized Red Low pressure alarm (enclosure pressure too low)
Purging Black Purge flow too low or not in purge mode
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

ML564 | v3 Page
5
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[email protected]
Expo Technologies China
T: [phone]
E: [email protected]
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.
Indicator Colour Status
Alarm / Pressurized Green Pressurized and in leakage compensation mode
Purging Black No longer in purge mode

Page
6
ML564 | v3
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[e-mail]
Expo Technologies China
T: [phone]
E: [e-mail]
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(21) and/or Zone 2(22) - 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.
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.
Materials of Construction
Stainless Steel Aluminium Acrylic
Mild (Carbon) Steel Nylon Silicone
Brass Polyurethane Neoprene
ABS Polycarbonate Polyester (glass filled)

ML564 | v3 Page
7
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[email protected]
Expo Technologies China
T: [phone]
E: [email protected]
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 and/or Zone 2 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.

Page
8
ML564 | v3
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[e-mail]
Expo Technologies China
T: [phone]
E: [e-mail]
Pressure characteristics during purge and pressurization of a pressurised enclosure using a
MiniPurge® system that incorporates a CLAPS system:
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

ML564 | v3 Page
9
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[email protected]
Expo Technologies China
T: [phone]
E: [email protected]
Section 5: Main Components
Air Supply Filter / Regulator
The unit is provided with a 40 μm liquid / dust filter element as a precaution. The user of the MiniPurge® system
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 5 barg (73 psig) and regulates the pressure of an air supply
between 5 and 16 barg (73 to 232 psig). A pressure gauge is fitted downstream of the filter; this should indicate
no less than 5 barg (73 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 2.3 barg (33 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 Sensor
This sensor monitors the pressure inside the pressurized enclosure. It senses when the pressure is drops and
provides early warning before the low pressure sensor trips the system. The setting on this is user selectable.
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
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

Page
10
ML564 | v3
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[e-mail]
Expo Technologies China
T: [phone]
E: [e-mail]
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.
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.
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.
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.
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.
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)

ML564 | v3 Page
11
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[email protected]
Expo Technologies China
T: [phone]
E: [email protected]
Intermediate Switch
This is a flameproof switch which is activated by the signal from the Intermediate Sensor. 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.
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.
Purge air passes through the Relief Valve Unit; the preset pressure differential across the appropriate orifice
ensures that the purge flow sensor is activated once the selected purge flow has been attained.
During the purge cycle a pneumatic cylinder operates the Purge Outlet Valve that lets the air from inside the
enclosure exhaust through the Relief Valve Unit. When the system changes to leakage compensation mode, the
Purge Outlet Valve is closed and the enclosure sealed.
The Relief Valve Unit has an in-built relief valve. This is sized to ensure that, if the air supply pressure rises up
from the specified maximum, the internal enclosure pressure will not exceed the specified maximum working
pressure of the pressurized enclosure.
/PA Terminal Box
The Terminal Box is increased safety (Ex e) certified and incorporates the terminal connection points for the
alarm and interlock switches. All contacts provided are volt free (dry).
Cable entry methods (for example conduit or cable glands) must be certified to IECEx, ATEX or INMETRO stand-
ards. The main requirement is that IP66 (or better) ingress protection must be provided by use of seals or wash-
ers.
Pneumatic Vortex Cooling Assembly
The pneumatic vortex cooling assembly is an automatic cooling system that allows the purge control unit to be
used in areas with an ambient temperature of up to +60°C. The Vortex Cooling Assembly comprises of the Pneu-

Page
12
ML564 | v3
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[e-mail]
Expo Technologies China
T: [phone]
E: [e-mail]
matic Vortex Cooler and two capillary thermostats; the Vortex Cooler Activation Thermostat and the
Logic Isolation Thermostat. These two thermostats are connected to the Pneumatic Vortex Cooler in a parallel
configuration and work independently to each other. The Vortex Cooling assembly uses a vortex tube to split the
compressed air supply allow the cold stream to ventilate the MiniPurge® housing to lower the ambient tempera-
ture for the sensitive logic components and exhaust the hot stream directly outside of the housing. Warning! The
hot exhaust protruding through the MiniPurge® housing can reach surface temperatures of +55°C above ambient
temperature; caution should be used when placing sensitive components near the exhaust or physical handling
during cooling operation.
Vortex Cooler Activation Thermostat
A capillary tube thermostat with pneumatic signal output that is used to activate the Pneumatic Vortex Cooler
when the enclosure’s internal temperature exceeds a pre-determined set point of 50°C. The temperature set
point is slightly lower than the Logic Isolation Thermostat to prevent constant isolation at 60°C.
Logic Isolation Thermostat
A capillary tube thermostat with pneumatic signal output that will isolate the logic supply when the ambient tem-
perature inside of the MiniPurge® housing reaches above the pre-set value that has been set in accordance to
ATEX and IECEx certification. The Logic Isolation Thermostat will cut the supply to the logic circuit to protect the
operation of the sensitive logic components under high ambient temperatures and will maintain the supply isola-
tion until the temperature within the has dropped below the falling switch point of the thermostat.

ML564 | v3 Page
13
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[email protected]
Expo Technologies China
T: [phone]
E: [email protected]
Section 6: Installation of the System
The MiniPurge® is designed for use under normal industrial conditions of ambient temperature, humidity and
vibration. Please consult Expo before installing this equipment in conditions that may cause stresses beyond
normal industrial conditions.The MiniPurge® system must be installed by a competent person in accordance with
relevant standards, such as IEC / EN 60079-14, and any local codes of practice.
The MiniPurge® control unit should be installed either directly on, or close to the pressurized enclosure. It should
be installed such that the system indicators and certification labels are in view.
All parts of the system carry a common serial number. If installing more than one system, ensure that this
commonality is maintained within each system installed.
Relief Valve Unit
To achieve effective purging, the points where air enters and exits the pressurized enclosure should normally be
at opposite ends of the enclosure. The RLV unit must be mounted vertically and there should be a minimum
clearance of 300 mm (12") around the spark arrestor (purge outlet).
It is important that the interior and exterior of the spark arrestor is kept clean and debris is not allowed to
accumulate; this might affect the calibration of the device. In particular the exterior of the spark arrestor should
not be painted or blocked in any way.
Air Supply Quality
The MiniPurge® system should be connected to a protective gas supply, which is suitable for purging and
pressurization.
The supply pipe connection to the MiniPurge® must be appropriate for the maximum input flow rate for the
application.
The air supply must be regulated at a pressure less than the maximum stated inlet pressure.
The air supply must be: clean, non-flammable and from a non-hazardous location. The air should be of
Instrument Air Quality. Although the purge control system will operate with lower air quality, its operational life
will be adversely affected. The equipment that is being protected by the MiniPurge® may also suffer because of
poor air quality.
With reference to BS ISO 8573-1: 2010, Instrument Air is typically specified as:
Particle Class 1
In each cubic metre of compressed air, the particulate count should not exceed 20,000 particles in the 0.1 to 0.5
micron size range, 400 particles in the 0.5 to 1 micron size range and 10 particles in the 1 to 5 micron size range.
Humidity or pressure dew point
The dew point, at line pressure, shall be at least 10 °C below the minimum local recorded ambient temperature
at the plant site. In no case, should the dew point at line pressure exceed +3 °C.
Oil Class 2
In each cubic metre of compressed air, not more than 0.1mg of oil is allowed. This is a total level for liquid oil, oil
aerosol and oil vapour.
When an inert gas is being used to supply the purge system, risk of asphyxiation exists. Refer to Application
Suitability section.

Page
14
ML564 | v3
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[e-mail]
Expo Technologies China
T: [phone]
E: [e-mail]
Before connection of the air supply to the purge system, the supply pipe work should be flushed through
with instrument quality air to remove any debris that may remain in the pipes. This must be carried out for at least
10 seconds for every meter of supply pipe.
Unless a supply shut-off valve has been fitted to the MiniPurge® system, an external shut-off valve with the same,
or larger, thread size as the Control Unit inlet fitting should be fitted by the installer to prevent any restriction of
purge flow.
The purge air from the MiniPurge® Control Unit should be piped within the pressurized enclosure to ensure
purging of potential dead air spots.
The purge system is fitted with an internal regulator factory set to 3 bar feeding the logic.
Pipe Work
If the MiniPurge® is not connected directly to the pressurized enclosure, pipe work and fittings used to connect
the Control Unit to the pressurized enclosure should be either metallic or appropriate to the environment into
which the system is installed. No valve may be fitted in any signal pipe connecting the Control Unit to the
pressurized enclosure. This pipe work must be fitted in accordance with local codes of practice where relevant.
Multiple Enclosures
This system is suitable for the purge and pressurization of the primary pressurized enclosure and its associated
terminal boxes.
Provision and Installation of Alarm Devices
When the pressure inside the pressurized enclosure is above the minimum, the Minimum Pressure Sensor re-
turns a positive (pressurized) signal causing the alarm indicator on the control unit to change from red to green.
When the pressure falls below the minimum permissible the positive (pressurized) signal is removed. This ab-
sence of signal indicates a low pressure alarm condition and causes the alarm indicator on the control unit to
go from green to red.
There are volt free (dry) contacts available within the terminal box for remote usage.
The user must make use of this alarm facility in accordance with the local code of practice for Action on Pressure
or Flow Failure. Most codes include the following recommendations:
•Zone 1 Installations: Alarm and Automatic Trip of Power.
•Zone 2 Installations: Alarm Only on pressure or flow failure with power being removed manually.
Power Supplies and their Isolation
All power entering the pressurized enclosure should have a means of isolation. This requirement also applies to
any external power sources that are connected to the equipment such as volt-free (dry) contacts within the
pressurized enclosure. This is commonly achieved using the Power Interlock Switch.
Power Interlock Switch
This switch is a Double Pole Normally Open, double-break switch: it provides two independent contacts that
should be connected in series and used to isolate the power. This can be achieved using switchgear or other
suitable switching device. These contacts are terminated and accessible to the user in the Ex e terminal box.
It is the responsibility of the user to ensure that the switch is only operated within appropriate technical limits.
The switch must be replaced after any short circuit that occurs within the main circuit; the switch is a piece of
encapsulated equipment and as such it is not possible to check the state of the contacts. Technical modifications
to the switch are not permitted.

ML564 | v3 Page
15
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[email protected]
Expo Technologies China
T: [phone]
E: [email protected]
Prior to commissioning, check that the Ex e terminal box is clean, the connections have been made
properly, the cables laid correctly and all screws in the terminals are secure.
In all cases the application and isolation of power must be controlled by the MiniPurge® system using the power
interlock signal.
No switches are permitted between the power switch and the MiniPurge® system other than an authorized
manual override circuit.
The safe use of this switch is the responsibility of the user, all electrical installations must conform to local codes
of practice.
Exception
Power to apparatus that is already suitable for use in hazardous locations need not be isolated by the MiniPurge®
system.

Page
16
ML564 | v3
Expo Technologies UK
T: [phone]
E: [email protected]
Expo Technologies US
T: [phone]
E:[e-mail]
Expo Technologies China
T: [phone]
E: [e-mail]
Section 7: Commissioning
Commissioning the System
Note: The steps 11 and 15 to 21 represent detailed commissioning tests. The commissioning of this system
must be performed in an ambient temperature of less than +50°C to prevent the Vortex Cooling Assembly
offsetting the calibration of the sensors.
The following equipment is needed for this process:
• Continuity meter
• Gauge manometer (0 to 200 mbarg)
• Differential manometer
If, after commissioning, the system does not perform as expected, refer to the Fault Finding Section.
Follow the steps as outlined:
1. Check all connections and that the Relief Valve Unit is fitted correctly with an unobstructed path to the purge
exhaust.
2. Close the Purge Flow Restrictor Valve.
3. Fully open external supply shut-off valve where fitted.
4. Check that the internal logic pressure gauge reads 2.3 barg / 33 psi / 230 kPag.
5. Check that the pressure gauge on main air supply reads 5 barg / 73 psi / 500 kPag.
6. Check that the Pressure Relief Valve is correctly set by disconnecting the minimum pressure sensing pipe at
the bulkhead fitting on the input to the MiniPurge®. This will disable all of the pressure sensors.
• Using a 4 mm nylon tube, connect a manometer to the bulkhead fitting from which the minimum pressure
sensing pipe was removed.
• Open the Purge Flow Restrictor Valve very slowly, until the Pressure Relief Valve opens
• Check the opening pressure is within calibration limits.
• This test can be carried out several times to ensure repeatability and compliance.
Refer to the Maintenance of the System section if the Relief Valve needs recalibrating.
7. Close the Purge Flow Restrictor Valve.
8. Remove the manometer and reconnect the minimum pressure sensing pipe to the bulkhead fitting.
9. Remove red plug from the top of the Minimum Pressure Sensor and connect a gauge manometer.
10.Connect a differential manometer to the test points on the flow sensor.
11.To check sensor calibration
• The internal pressure in the pressurized enclosure must be below Relief Valve lift off pressure and above
the CLAPS pressure
• At this time the pressurized indicator should be green.
• gradually open Purge Flow Restrictor Valve until purging indicator flashes yellow.
Note: For large volumes it may take a long time for the purge flow to start.
• very slowly close Purge Flow Restrictor Valve until the purging indicator stops flashing yellow.
• Take a reading from pressure gauge.
12.To set the purge flow rate:
• Turn on the compressed air to the MiniPurge®.
• Gradually open the Purge Flow Restrictor Valve until the black / yellow indicator changes to yellow
(flashing).