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Purge Controls for Pressurization Systems

Controls for Pressurization Systems

Photo of Exloc instruments Model EX301 purge and pressurization controller

Problem: there are times when electrical equipment must be installed in a classified hazardous location but protection methods such as intrinsic safety or explosion-proof boxes are unsuitable or impractical.

Solution: applying a source of clean air or inert gas at a positive pressure to an equipment enclosure prevents the ingress of flammable gases and dust. Thus, the hazard classification of the atmosphere inside the enclosure may be reduced. Standards have been established which determine the degree of reduction, and stipulate initial purging volume changes, minimum maintained pressure differential, and system status indication. Alarm initiation and power interruption in the event of pressure loss are mandated for some situations.

System Design Considerations:
Type X pressurization reduces the hazard classification from Division 1 to non-classified.
Type Y pressurization reduces the hazard classification from Division 1 to Division 2.
Type Z pressurization reduces the hazard classification from Division 2 to non-classified.
Systems for leakage compensation are designed to maintain a minimum positive pressure.
Continuous flow systems are for enclosures with internal gas releases, e.g. analysers.
Enclosure volume must be checked against the flow capability of the purge control system.
A fast purge feature expedites the required number of air changes for system initialization.
Choose Type X Type Y Type Z Leakage Continuous Max. Volume Initial
Model Compensation Flow cu.ft. / m³ Fast Purge
EX300 2 / 0.057 None
EX301 15 / 0.42 Manual
EX302 75 / 2.12 Manual
EX303 300 / 8.5 Manual
1XLC 60 / 1.7 Auto
2XLC 120 / 3.4 Auto
3XLC 240 / 6.8 Auto
1XCF 17 / 0.48 Auto

EX300 Purge Control System

Photo of Exloc Instruments Model EX300 Type Z purge and pressurization controller

  • FM approved for Type Z purging (only)
  • Complies with NFPA 496
  • Front panel pressure adjustmentFM Logo
  • Large easy view pressure indicator
  • Stainless steel panel
  • Optional pressure switch for alarm
  • Optional relief vent for enclosure
  • For enclosures up to 2 cu.ft. in volume

EX301/302/303 Purge Control Systems

EX301 for enclosures up to 15 cu. ft in volume. EX302 for enclosures up to 75 cu.ft. in volume. EX303 for enclosures up to 300 cu.ft. in volume.

FM Logo

Photo of Exloc Instruments Models EX301, EX302, EX303 Type Y and Z purge and pressurization controllers

  • FM approved for both Type Y & Z purging
  • Complies with NFPA 496
  • Front panel pressure adjustment
  • Large easy view pressure indicator
  • Fast purge function with separate gauge
  • Stainless steel panel
  • Optional pressure switch for alarm
  • Optional relief vent for enclosure

 

 

FM Logo

Photo of Exloc Instruments relief vent valve for use with Model XLC purge and pressurization controllers

Photo of Exloc Instruments Model XLC Type X, Y and Z purge and pressurization controllerPhoto of Exloc Instruments optional Model MIU power contactor for use with Model XLC purge and pressurization controllers

XLC Purge Control Systems

1XLC — enclosures up to 60 cu. ft in volume. 2XLC — enclosures up to 120 cu.ft. in volume. 3XLC — enclosures up to 240 cu.ft. in volume.

  • FM approved for Type X, Y & Z purging
  • Provides leakage compensation
  • Complies with NFPA 496
  • Direct mounting to pressurized enclosure without the need for separate piping
  • Automatic fast purge with flow verification
  • Status indicators
  • Pneumatic logic – independent of electrical power supply
  • Stainless steel housing & fittings
  • Choice of I.S. contact or pneumatic alarm output
  • Optional explosion-proof power contactor
  • Includes relief vent valve for enclosure

 

 

FM Logo

Photo of Exloc Instruments relief vent valve for use with Model XCF purge and pressurization controllers

Photo of Exloc Instruments Model XCF Type X, Y and Z purge and pressurization controller

Photo of Exloc Instruments optional Model MIU power contactor for use with Model XCF purge and pressurization controllers

XCF Purge Control Systems

  • FM approved for Type X, Y & Z purging
  • For continuous flow applications
  • Complies with NFPA 496
  • Direct mounting to pressurized enclosure without the need for separate piping
  • Automatic purge with flow verification
  • Status indicators
  • Pneumatic logic – independent of electrical power supply
  • Stainless steel housing & fittings
  • Choice of I.S. contact or pneumatic alarm output
  • Optional explosion-proof power contactor
  • Includes relief vent valve and calibrated orifice
  • For enclosures up to 17 cu.ft in volume