Data sheet: D779 MotorPurge System
The Motor Purging and Pressurization control system has been designed for use on large electrical machines located in a hazardous location.
The system delivers a high purge rate for a given duration (as defined by machine designer and Notified Body) prior to start-up, to purge any potentially explosive gases from the machine. After purge, the system automatically switches to leakage compensation mode for normal operation. The Closed Loop Automatic Pressurization System (CLAPS) automatically compensate for pressure variations in the machine during start-up or through temperature variations during operation. The system enables the machine to continuously operate at a set over-pressure, saving considerable time during test and commissioning, and simplifying normal operation.
The system comprises the Control Unit (CU) and the Relief Valve (RLV). The Control Unit contains the pneumatic logic to monitor and control air flow, pressure and purge timing, and provides the system outputs. The RLV measures purge flow at the outlet and provides over-pressure protection for the machine through a patented magnetically-set exhaust valve with integrated spark arrestor.
In operation, the system provides local indication of ventilation condition and progress, plus volt-free contacts for external indication (see Technical Specification).
- Simple Order Code
One model number defines Control Unit (CU) and
Relief Valve (RLV)
- User Selectable Settings(* default)
Pre-set selectable purge flow rates (1000 and *1500)
1 -99* minute purge time (-0/+3 seconds tolerance)
Suits a wide variety of machine frames sizes
- Clear Visual Status Indication
Local indicators for “Alarm/Pressurized” and “Purging”
- Continuous Operation through Closed Loop Automatic Pressurization System (CLAPS) Eliminates spurious trips on start-up or load change
- 316L Stainless Steel enclosure & fittings Excellent resistance to corrosion for harsh environments
- Full Compliance with Standards
Direct purge flow measurement at Relief Valve exhaust orifice
- Global Approvals
IECEx & ATEX certified Ex [px] to IEC/EN 60079-2.
IECEx & ATEX certified Ex [p] to IEC/EN 61241-4 for dust applications.
INMETRO certified Ex [px] & Ex [p] to ABNT NBR IEC 60079-2.
Hazardous Area classification
IECEx, INMETRO Zone 1 (21), Group IIC T6 Gb ATEX Category 2 G D, Zone 1 (21), Group IIC T6 Gb
-20°C to +55°C (4°F to 131°F)
|Fitting||f||W’ NPT (F)|
Purge Supply: 1/2″ NPT (F), recommended supply pipe: 1″ I.D min. Purge outlet to machine: 1″ NPT (F). Reference point & signals: 1/8″ NPT (F).
Compressed Air Supply
Clean Dry Air or Inert Gas. Minimum supply pressure 4 barg, Max 16 barg. Supply inlet filter 40and regulator fitted.
Enclosure & Mounting
Wall mounting lugs & spacer provided for fitting to machine.
Order Code: D779MOTORSYS-E Description: 3XLC/ss/ET/OV/PA/PC/D779
Purge flow rate, user selectable to
1,000 and 1,500
Leakage Compensation Capacity
Up to 500 Nl/min @ 4 barg inlet pressure.
Intrinsically safe Electronic Timer, range 1-99 mins. battery powered
System outputs are volt-free contact closures terminated on Ex e Junction Box, with
Power= 250 Vac 4 Amp (AC15) DPNO Ex d IIC T6
Alarm = 250 Vac 4 Amp (AC15) SPCO Ex d IIC T6
Minimum pressure sensor default set at 1.5 mbarg
0.5 to 5 mbarg
CLAPS sensor default set at 10 mbarg
5.0 mbarg to 15 mbarg
IEC Zone 1 Ex [px] ia IIC T6 Gb
ATEX II 2 (2) G D Ex [px] ia IIC T6 Gb
INMETRO/TUV Zone 1 Ex [px] ia IIC T6 Gb
Relief Valve Lift-Off pressure setting
Minimum: 20mbarg, Maximum: 50mbarg
- Air Inlet // Ball Valve for local isolation of the system.
Order Code: D779BALLVV.
- Air Inlet “Ex” approved 1 Solenoid Valve for remote isolation of the system. Order Code: D779SOLW.