Fluid Power Journal

Valve Adds Fire Safety to Pneumatic Control Systems

When fire occurs in refineries or producers of alcohol, perfumes, and any product that uses flammables, process valves need to quickly shutdown. Any pneumatic valve equipped with a FireChek® will shut down without the need for any external signal or power, as its shape-memory alloy responds to the ambient temperature.

When working with flammable and hazardous materials, pneumatically actuated quarter-turn valves are preferred over electrical or motorized actuators, reducing the potential for electrical sparks. And now, Assured Automation, Roselle, NJ, provides another safety level to pneumatically driven processes.

The FM-approved FireChek thermal shutoffs with resettable memory shape alloy quickly respond to heat in the event of a fire and automatically exhaust pressure in the actuator to close the supply line.

When the ambient temperature reaches 135, 150, or 165°F, the FireChek’s memory shape alloy undergoes a phase induction change, and rapidly produces the force and motion to shift the valve – no other power source is involved.

When the FireChek senses excessive heat from a nearby fire, it immediately closes the air supply line, preventing the air from feeding the fire. It simultaneously vents the spring return actuator to allow the return to fail-safe. The FireChek triggers quickly, securing pneumatically operated process line valves in their fail-safe position for both on/off and throttling applications. Because FireChek responds to heat, not flame, it offers dramatically improved protection compared with conventional plastic tubing burn-through.

The element is 100% reliable because the shape memory effect is intrinsic to the alloy. Shape memory alloys have performed successfully for decades in military, industrial, and consumer product applications.

The testability and reset-ability of the FireChek makes it a preferred choice over emergency isolation valves that rely on fusible links or plastic burn-through tubing.

FireChek’s manual reset allows routine performance testing for safety maintenance programs. The FireChek is available in four different configurations:

1.    FireChek®

The single FireChek is directly mounted between the pneumatic supply and spring return actuator via two NPT threaded connections. While the FireChek itself is extremely well suited for the vast majority of pneumatic actuators with ¼” air supply input ports, the FireChek with Quick Exhaust or a FireChek with High Flow Pilot valve can be used very effectively on larger pneumatic actuators.

2.    FireChek® with Quick Exhaust 

The FireChek with Quick Exhaust provides a larger exhaust port. When the emergency operation is triggered by excessive heat, the actuator exhaust air is diverted to a larger port by the Quick Exhaust valve. This allows for the spring return actuator to move to the failsafe position much faster.

3.    FireChek® with High Flow Pilot Valve

For local activation on large valve actuators, the FireChek with a SIL III High Flow Pilot Valve is recommended. This assembly increases both the inlet and exhaust Cv for large pneumatic actuators. Here, the FireChek is pre-installed on a high flow pilot valve. The assembly is easily installed inline on the actuator’s air supply line via two compression fittings or female NPT ports. Plate mounted and NAMUR styles are available. This configuration does not provide for actuator control, but can be placed before or after the control solenoid. On these models, the FireChek® is installed to shut off the pilot air and vent the air of the pilot valve rather than the actuator itself. The FireChek® vents the air from the pilot valve, the valve spool springs to the exhaust position allowing the actuator to exhaust through the higher Cv pilot valve.

  • FireChek® with High-Flow Solenoid Operated Pilot Valve
    These models operate just like the Pilot Valve models above, with the addition of an explosion proof solenoid that can be used for actuator control, and/or emergency shutoff which can be initiated electrically from any type of sensor, local or remote. These models are also available as NAMUR mount, plate mount, or inline.

The FireChek is used in both batch and continuous process systems as found in oil refining, paper manufacturing, chemicals, pharmaceutical and power plants.  Upgrades to the more efficient, more economical, and testable FireChek thermal shutoffs do not affect normal plant operations or the normal function of the control valve. Upgrades are simply achieved by installing the FireChek components into the existing control valve’s pneumatic air line.

FEATURES

  • FM approved
  • Easy to test and reset
  • Rapidly responds to temperature rise, not flames
  • Vents actuator air pressure
  • Closes actuator air supply line
  • Needs no power source, self-activates
  • Compatible with most pneumatic actuators
  • No contact with process fluids
  • Reliable, intrinsic triggering
  • Easy to retrofit, installs in minutes

Assured Automation, www.assuredautomation.com

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