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Z Purge & Pressurization 1ZLC/PM/IS

Purge Type Z inert gas or air purge
Area: Class I Div 2, Zone 2 Equipment Content: Unclassified
Purging Action Leakage Compensation High flow rate during purge.
Then compensation for leakage
Enclosure Size up to 60 cu ft up to 1.35m3
Mounting Style Panel Mount Mounts externally through enclosure wall. Minimal piping.
Alarm Output Integral Switch – IS or NI Volt free, Dry contact
Z-Purge unit. Inert gas or air purge. For enclosures to 60 cu.ft, 1.35 cu.m, Leakage Compensation, Panel Mount, Ex i Integral Signal hermetically sealed volt free dry contact for Unclassified equipment in Class I Div 2 location.1ZLC/PM/IS


Install any equipment in a Class I Div 2  Gp A-D,  Zone 2 IIC  Ex [pz] and Zone 22  Ex [pD] hazardous area.

Leakage compensation operates by:

  • Initially providing high air or inert gas volumes to rapidly purge hazardous gas from the enclosure;
  • Then providing low air or inert gas volumes,  sufficient to maintain a higher pressure inside the enclosure than the surrounding hazardous area, and to compensate for leaks from the enclosure.

Leakage compensation improve equipment uptime, and reduces running costs. It:

  • Improves equipment uptime, by reducing downtime caused by purging;
  • Reduces costs, by minizing compressed air or inert gas consumption during operation.

Note:  The enclosure size assumes a 30 minute purge period and:

  • 4 volume changes for ft3  i.e. required by NFPA 496;
  • 5 volume changes for m3  i.e. required by IEC 60079-2.

The standards do not specify a minimum or maximum purge time. Select an appropriate Purge Flow sensor for your enclosure size, and desired purge time.

Z Purge units are:

  • Complete with:
    • Control unit: controls air flow, monitors flow & pressure. Saves installation time & money, as mounts directly on enclosure with no costly interconnecting pipework;
    • Relief valve: Open during purging, and measures the gas or air flow through the enclosure.  Closes after purging, when in leakage compensation mode.
  • Compact: Gain full use of enclosure’s internal space;
  • Series Purging: Purge multiple enclosures with 1 unit. N.B application specific.
  • Certified: Fully compliant as direct purge flow measurement at Relief Valve exhaust, required by IEC/EN 60079-2, NFPA 496:
    • ATEX,
    • cFMus,
    • cULus,
    • IECEx,
    • INMETRO.

Common Specifications of Z Purge units

Typical specifications:

  • Purge Sensor: Select size:
    • Size 1: 8 scfm, 225 Nl/min for enclosures 60 cu ft, 1.35m3;
    • Size 2: 16 scfm, 450 Nl/min for enclosures 120 cu ft, 2.7m3;
    • Size 3: 32 scfm,  900 Nl/min for enclosures 240 cu ft, 5.4m3;
    • 1/4″, 6mm pipe required between Control Unit and Relief Valve, installed inside the purged enclosure.
  • Supply Pipe: Provide:
    • Size 1 & 2: 1/2″, 15mm O/D;
    • Size 3: 3/4″, 20mm;
    • Max length: 20ft, 6 m.
  • Control Unit: Inert gas or compressed air, clean, dry, free of flammable gases.
    • Supply Pressure: 4 – 8 bar, 60 – 115 psi;
    • Temperature Range: -20°C to 55°C, -4°F to 131°F;
  • Relief Value: RLV 25  – Full 1″ bore
    • Patented Magnetic Operation with integral spark arrestor;
    • Opening Pressure: 1KPa, 10 mbar 4″ WC.
  • Manual Purge Flow: ON/OFF lever.
  • Mounting: Panel Mount:
    • Fits directly onto the enclosure with minimum external space.
  • Alarm Indicators:
    • Red: “Alarm”indicates low pressure;
    • Green: “Pressurized”  indicates pressure ok;
    • Yellow: “Purge Flow” purging the enclosure;
    • Low pressure sensor alarm setting: 2.5 mbar, 1″ WC.
  • Permissible Enclosure Leakage: 2 scfm, 60Nl/min
  • Excellent corrosion resistance: 316L stainless steel, suitable for:
    • Offshore;
    • Corrosive environments.

Data Sheet