Pacbrake PowerHalt PH3 Mk II Emergency Air Intake Shut-Off Valve

Name: Pacbrake PowerHalt PH3 Mk II Emergency Air Intake Shut-Off Valve
Brand: Pacbrake

The PowerHalt PH3 Mk II is an electronically controlled emergency shutdown system, engineered to force a diesel engine to stop by instantly blocking its air intake path. Built for heavy-duty applications, it offers a smart, maintenance-free solution to prevent catastrophic engine runaway. Ideal for both automatic overspeed protection and manual override in critical situations.

1.5″ – 4.0″ Valve Sizes Available

Electronic Actuation

Auto/Manual Control Options

IP66/IP67 Ingress Protection

The Pacbrake PowerHalt PH3 Mk II is a positive air shut-off valve designed to provide fail-safe protection against dangerous diesel engine runaway. By mounting directly into the engine's air intake system, the valve remains open during normal operation. However, in the event of an overspeed condition or external emergency, the electronically controlled butterfly valve snaps shut, cutting off combustion air and forcing an immediate shutdown. This maintenance-free system is available in various configurations, including fully automatic overspeed sensing models and manual activation versions.

Key Features

The PowerHalt PH3 Mk II delivers advanced electronic control combined with robust mechanical design, providing reliable emergency engine shutdown for heavy-duty applications.

12 and 24 VDC System Compatibility: The PowerHalt PH3 Mk II is engineered to seamlessly integrate into both 12-volt and 24-volt electrical systems, ensuring flexibility across diverse equipment fleets and heavy-duty truck platforms.
Reliable Emergency Shut Down for Diesel Engines: This valve provides a robust safety net by physically blocking the air supply to the cylinders. This is the only proven method to safely stop an engine that has begun to run away on external fuel sources like oil or gas vapors.
Fully Automatic Operation with Manual Override: The intelligent controller monitors engine speed and automatically triggers the valve if a pre-set overspeed limit is exceeded. Operators can also manually activate emergency shutdown at any time via a cab-mounted switch.
Smart Control & Low Power Consumption: Featuring PID, PWM, and H-Bridge control methods, the system ensures precise valve actuation. The controller draws minimal current when idle, preserving vehicle battery life while remaining ready to respond instantly.
Configurable Automatic or Manual Reset: The system can be programmed to automatically reset after a shutdown or to remain closed until manually reset. The manual reset mode is crucial for meeting safety regulations that require operator intervention before engine restart.
High Temperature & Corrosion Resistant Design: Built with an aluminum flap and housing, the valve is tested for extreme thermal ranges and validated against ASTM B117 standards (96 hours of salt fog testing), ensuring reliability in harsh environments.
Advanced Speed Signal Compatibility: The PowerGuard controller is compatible with multiple speed sensing methods including Hall Effect sensors, Variable Reluctance (VR) sensors, CAN Bus (J1939 & ISO 15765-4 OBDII), and generator alternator taps.

Applications

Class 6-8 Heavy Duty Trucks: Provides critical overspeed protection for commercial trucks, preventing catastrophic engine failure and safeguarding drivers on the road.
Oil & Gas Refinery Processing: Installed on pumping units and support vehicles operating in volatile hydrocarbon environments where the risk of ingesting flammable vapors is high.
Fire Trucks & Emergency Vehicles: Ensures reliable engine shutdown in hazardous zones, protecting high-value assets and personnel during critical operations.
Stationary Diesel Power Generators: Offers automatic overspeed protection for backup and prime power generators, complying with safety regulations for unattended or remote installations.
Mining & Off-Highway Equipment: Designed to withstand high vibration levels typical of underground loaders, haul trucks, and drilling rigs found in rugged mining environments.
Work Boats & Barges: Marine-rated design provides emergency air shut-off for auxiliary engines and gen-sets on vessels, preventing runaway in engine rooms.

Technical Specifications

Detailed specifications for the PowerHalt PH3 Mk II emergency air intake shut-off valve. The valve is available in multiple bore sizes and includes an electronic controller with multiple configuration options.

Parameter	Specification
Product Series	PowerHalt PH3 Mk II
Valve Operation	Electronically Controlled, Spring Return
Resting Position	Normally Open (Engine Run)
Valve Sizes (Bore)	1.5" to 4.0" (38mm to 101.6mm)
Ingress Protection	IP66 (1.5"-3.0") / IP67 (3.5"-4.0")
Temperature Range	-40°C to +120°C (-40°F to +248°F)
Max Intake Boost	50 psig (3.45 bar gauge)
Vibration Rating	Up to 18.6 G_RMS
Voltage Compatibility	12 / 24 VDC (9 to 32 VDC)
Controller Compliance	CSA B621-14, B622-14

Technical FAQ

Common Questions Answered

Can't find your answer? Contact our engineers →

In Automatic Reset Mode, the valve electronically returns to the open position when the shutdown signal is removed, preparing the engine for restart. In Manual Reset Mode, the valve remains closed after a trip and requires a deliberate manual command (press of a button) to reset. Manual reset is often preferred for CSA B621/B622 compliance to ensure an operator confirms safety before restarting.

The system includes a manual activation button on the controller. Pressing this button simulates a shutdown command, allowing you to verify valve function and observe the linkage and indicator lights without running the engine.

Yes. The PowerGuard controller provides an auxiliary output signal that activates when the valve is closed. This can be connected to external indicator lights, alarms, or other supervisory systems.

Yes, the PH3 Mk II is rigorously tested for vibration resistance. It is rated for up to 18.6 G_RMS vibration, making it suitable for high-shock applications like mining haul trucks and drilling equipment.

The controller is compatible with Hall Effect (5V square wave), Variable Reluctance (VR) sine wave, CAN Bus (J1939 and ISO 15765-4 OBDII), and generator alternator (Gen-End) signals, providing flexible installation options.