Hazardous Area Pressurization Systems by EKG M&E Sdn Bhd
In the oil and gas refineries of Pengerang and the chemical plants of Shah Alam, not every piece of essential equipment can be built as "Explosion Proof" (Ex d). For complex control systems, computers, and large analyzer houses, we use Hazardous Area Pressurization (Ex p). This technique creates a "Safe Island" within a dangerous zone by maintaining a constant internal overpressure of clean air or inert gas, physically preventing flammable mixtures from ever entering the enclosure.
EKG M&E Sdn Bhd provides turnkey design and certification for Ex p systems in compliance with IEC 60079-2, IEC 60079-13 (for rooms), and NFPA 496.
1. The Ex p Protection Mechanism
As an HVAC and Clean Air Specialist, we implement the pressurization cycle in two distinct phases to ensure the equipment is never energized in a dangerous atmosphere:
Phase A: The Purge Cycle
Before power is applied, the system must flush out any potentially trapped gases.
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Volume Exchange: We program the control unit to pass at least 5 times the internal volume of the enclosure with clean air.
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Flow Monitoring: The system times this purge based on a confirmed flow rate. If the flow drops, the timer resets to zero, ensuring no "pockets" of gas remain.
Phase B: Positive Pressure Maintenance
Once purged, the system enters "Operational Mode."
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Differential Pressure: We maintain a minimum overpressure of at least 50 Pa (0.5 mbar). This ensures that even if there is a minor seal leak, air moves outward, preventing gas from moving inward.
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Leakage Compensation: To save energy and instrument air, we use Variable Frequency Drives (VFDs) or leakage compensation valves that only provide enough air to maintain the pressure setpoint.
2. Standardized Classification (pxb, pyb, pzc)
We select the pressurization type based on the risk level of your location and the type of equipment inside:
| Type | Hazardous Zone | Equipment Inside | Safety Action on Pressure Loss |
| Ex pxb | Zone 1 | Standard (Non-Ex) | Immediate Automatic Power Shutdown. |
| Ex pyb | Zone 1 | Zone 2 Rated | Alarm only (Equipment must be Zone 2 safe). |
| Ex pzc | Zone 2 | Standard (Non-Ex) | Local & Remote Alarm to operators. |
3. Critical System Components
A compliant Ex p system is more than just a fan; it is an integrated safety loop:
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Purge Control Unit (PCU): The "brain" that manages the timing, pressure sensors, and power interlocks.
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Spark Arrestors: Installed on the exhaust vents to ensure that if a rare internal spark occurs during the purge, it cannot exit into the hazardous zone.
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Flameproof (Ex d) Interlock Switches: The switches that physically cut the main power must themselves be explosion-proof, as they operate in the hazardous zone even when the internal pressure is lost.
4. JKKP (DOSH) Compliance and Maintenance
In Malaysia, pressurized rooms and enclosures are subject to JKKP (DOSH) safety audits. Our maintenance services ensure your "Certificate of Fitness" remains valid:
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Integrity Testing: We perform "Leakage Rate" tests to ensure your enclosure hasn't developed gaps that exceed your air supply capacity.
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Vibration Health Check: For the pressurization blowers, we use Vibration Analysis to prevent mechanical failure. A fan failure in an Ex p system leads to an immediate plant shutdown in Zone 1.
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Air Source Audit: We ensure the intake air is pulled from a "Guaranteed Safe Area," far from any potential gas release points or exhaust stacks.
Why Choose EKG M&E Sdn Bhd?
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Turnkey MEP Execution: We design the airtight enclosures, specify the VFD-driven blowers, and integrate the safety PLC logic for a seamless JKKP approval.
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Cost-Effective Engineering: By using Ex p, we allow you to use standard, high-performance PLCs and HMIs instead of buying multiple, expensive Ex d components.
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Strategic Support: Based in Kuala Lumpur, we provide 24/7 support for Analyzer Shelter maintenance and emergency sensor recalibration.
