Pacbrake PowerHalt PH2 Emergency Air Intake Shut-Off Valve

Name: Pacbrake PowerHalt PH2 Emergency Air Intake Shut-Off Valve
Brand: Pacbrake

The PowerHalt PH2 is an emergency air intake shut-off valve that provides a reliable and safe method of stopping a diesel engine during a runaway event. Designed for extreme environments, this valve is the positive air shut-off solution of choice for the heavy-duty diesel industry.

2.8″ – 5.5″ Valve Sizes Available

3 Activation Manual / Electric / Pneumatic

12/24 VDC Electric Solenoid

-40°C to +70°C Operating Temperature

The Pacbrake PowerHalt PH2 is a positive air shut-off valve engineered to prevent catastrophic damage from diesel engine runaway by instantly cutting off the engine's air supply. Utilizing a robust butterfly valve design with a spring-loaded valve plate, the PH2 installs directly into the engine's intake hose and remains in a normally open (engine run) position until activated. This emergency shut-off valve is available with manual, electric (12/24 VDC), or pneumatic activation, and in sizes ranging from 2.8 to 5.5 inches. The PowerHalt PH2 is the ideal safety solution for Class 3-5 pickup trucks, Class 6-8 commercial vehicles, and stationary diesel equipment.

Key Features

The PowerHalt PH2 combines robust engineering with multiple activation options to deliver reliable emergency engine shutdown. Its durable construction and smart design ensure protection in the harshest operating conditions.

Positive Air Shut-Off Butterfly Valve Design: The PH2 utilizes a reliable butterfly valve mechanism with a spring-loaded valve plate. Upon activation, the valve instantly closes to cut off the engine's air supply, ensuring a rapid and complete shutdown during a diesel runaway event.
Multiple Activation Options: Choose from manual pull cable, 12/24 VDC electric solenoid, or pneumatic activation to best suit your application. For hands-free operation, automatic activation models are available with the PowerGuard controller, which monitors engine speed and automatically shuts down the engine when a user-set overspeed condition is detected.
Wide Range of Valve Sizes: Available in nominal sizes from 2.8 to 5.5 inches, the PowerHalt PH2 can be matched to the intake hose diameter of virtually any medium-duty or heavy-duty diesel engine, from pickup trucks to commercial trucks and industrial generators.
Durable Construction for Extreme Environments: Built to withstand the toughest conditions, the PH2 is designed for extreme temperatures, vibration, and contamination. Its robust construction ensures reliable operation when you need it most.
Manual Latching with Spring Return: The valve features a manual latching system with a spring-loaded valve plate in the normally open (engine run) position. After activation, the valve requires a manual reset, ensuring the engine cannot be restarted until the valve is returned to its open position.
PowerGuard Smart Overspeed Limiter (Automatic Models): The available PowerGuard controller provides smart overspeed protection. It can be programmed to a specific trip speed and features a test mode to ensure the system's automatic function is working as intended.

Applications

Class 3-5 Pickup Trucks (Dodge/RAM, Ford, GMC/Chevrolet): A critical safety upgrade for diesel pickup trucks, the PH2 protects against engine runaway that can cause catastrophic failure and endanger personnel.
Class 6-8 Commercial Heavy-Duty Trucks (Kenworth, Volvo/Mack): For over-the-road and vocational trucks, the PowerHalt PH2 ensures compliance with safety regulations and protects expensive engine assets from runaway damage.
Stationary Diesel Generators & Industrial Equipment: Protect critical standby and prime power generators with the PH2. Automatic models can monitor engine speed and shut down the generator in an overspeed condition.
Construction & Mining Equipment: Off-highway vehicles operating in dusty or hazardous environments are at risk of diesel engine runaway. The PowerHalt PH2 provides a reliable emergency shutdown solution for excavators, loaders, haul trucks, and drills.
Marine Diesel Engines: For marine vessels with large diesel engines, the PH2 offers a critical safety measure to stop an engine in the event of a runaway, preventing damage to the vessel and ensuring crew safety.
Agricultural Tractors & Harvesters: Protect valuable farm equipment from the dangers of diesel engine runaway caused by seal failure or flammable vapor ingestion with an easy-to-install PH2 shut-off valve.

Technical Specifications

Detailed specifications for the PowerHalt PH2 emergency air intake shut-off valve. All models are 12 VDC unless otherwise stated. Electric actuators feature a 10-second on / 90-second off duty cycle.

Parameter	Specification
Valve Type	Positive Air Shut-Off Butterfly Valve
Nominal Valve Sizes (OD)	2.8″, 3.0″, 3.5″, 4.0″, 5.0″, 5.5″
Activation Methods	Manual (Pull Cable), Electric (12/24 VDC Solenoid), Pneumatic
Control / Reset	Manual / Manual (Standard); Auto / Manual (Optional with PowerGuard)
Electric Motor Resistance (12 VDC)	1.7 Ω +/- 10%
Electric Motor Resistance (24 VDC)	3.9 Ω +/- 10%
Duty Cycle	10 sec ON / 90 sec OFF
Electrical Connector	Metri-Pack 280 Series, Female, 2-Pin (Delphi #15300027)
Actuator Weight	0.84 kg (1.9 lb)
Pull Cable Activation Force	90 N (20.2 lbf)
Minimum Pull Cable Stroke	12 mm (0.47 in)
Default Position	Normally Open (Engine Run)
Power Supply	12 VDC or 24 VDC
Operating Temperature (Solenoid)	-40°C to +70°C (-40°F to +158°F)
Pneumatic Activation Supply Pressure	4.1 bar(g) [60 psig] min, 10 bar(g) [145 psig] max

Technical FAQ

Common Questions Answered

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Diesel engine runaway is an uncontrolled acceleration of the engine caused by an external fuel source, such as engine oil from a blown turbo seal or flammable vapors. The engine continues to run even when the key is turned off, leading to catastrophic mechanical failure, fire, or explosion.

The PowerHalt PH2 is a positive air shut-off valve. When activated, it instantly blocks the engine's air intake, cutting off the oxygen supply required for combustion. This action forces the engine to stop quickly and safely, preventing damage.

Manual activation requires an operator to trigger the valve (pull cable or press a button). Automatic activation uses the PowerGuard controller, which monitors engine RPM and automatically shuts down the engine if it exceeds a user‑set trip speed.

The PH2 is designed for minimal maintenance. Regular visual inspections of the valve, intake hoses, and clamps are recommended. The valve can be tested by activating it at low idle to ensure proper operation and then manually resetting it.

The PowerHalt PH2 is available in nominal sizes from 2.8″ to 5.5″. You should select the size that matches the inner diameter of your engine's intake hose. If you are unsure, our team can help you identify the correct size based on your engine make and model.