Controls for Pressurization Systems
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 Compensation | Continuous Flow | Max. Volume | Initial |
| Model | cu.ft. / m³ | Fast Purge | |||||
| AP-01Z-02 | • | • | 2 / 0.057 | None | |||
| AFP-01Z-15 | • | • | • | 15 / 0.42 | Manual | ||
| AFP-02Z-75 | • | • | • | 75 / 2.12 | Manual | ||
| AFP-03Z-300 | • | • | • | 300 / 8.5 | Manual | ||
| 1XLC | • | • | • | • | 60 / 1.35 | Auto | |
| 2XLC | • | • | • | • | 120 / 2.7 | Auto | |
| 3XLC | • | • | • | • | 240 / 5.4 | Auto | |
| 1XCF | • | • | • | • | 17 / 0.39 | Auto |
AP-01Z-02 Purge Control System
More AP-01Z-02 Information
AFP-01Z-15 / AFP-02Z-75 / AFP-03Z-300 Purge Control Systems
AFP-01Z-15 for enclosures up to 15 cu. ft in volume. AFP-02Z-75 for enclosures up to 75 cu.ft. in volume. AFP-03Z-300 for enclosures up to 300 cu.ft. in volume.
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 and UL Listed 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
- Electronic purge timer
- Stainless steel housing & fittings
- Choice of I.S. contact or pneumatic alarm output
- Optional explosion-proof power contactor
- Includes relief vent valve for enclosure
XCF Purge Control Systems
- FM approved and UL Listed 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
