Category Archive: Fusible Links

What is a Fire-Safety Valve with a Fusible Link and How Does It Work?

A fire-safety shut-off valve, also known by thermal shut-off valve or simply a fusible link valve, is a safety device designed to provide automatic valve shut-off in the event of a fire. Fire-safety valves of this type are designed for facilities that utilize flammable or toxic gases and chemicals in their production or for fuel systems of all types.

The fusible link is an FM and/or UL approved two-part linkage held together by a specialized heat-sensitive solder. These link(s) hold the fire safety valve open by keeping tension on a spring pack through a trigger assembly.

How Does a Fire-Safe Valve Work with a Fusible Link?

A fire safety shut-off valve is comprised of five main components – API 607 fire-safe valve, spring pack, mounting hardware, trigger assembly, and fusible link. The last four of these components work in unison to close the API 607 valve should a fire be detected within a facility.

The fusible link portion is the linchpin of the assembly and keeps the fire safety valve open by keeping tension on a spring pack through the trigger assembly. When a fire breaks out, the link separates when its rated temperature is met, releasing the spring pack and allowing it to close the valve.

The API 607 standard is a specification for the fire testing of quarter-turn valves. For fire-safety valve with fusible links, this means that the valves have a primary drop-tight seat, typically made of TFE, along with a secondary seat made of metal for isolation in a fire. The secondary seat is coupled with graphite seals for further protection. This means the top works of the shut-off valve can be paired with any quarter-turn API 607 fire safe valve – ball valve, butterfly valve, or plug valve.

Where are Fusible Links Used?

Fusible link fire-safety valves are used in a variety of industries within an organization’s overall fire safety system for widespread fire protection. Most modern facilities have at diesel generators and day tanks that that requires this type of safety valve at a minimum. Other locations where flammable or toxic media are part of the production process,  this valve type is placed at strategic locations throughout facilities including storage tanks, pumps, entryways into a building, and at key piping junctions. Entryways into buildings are especially key so that have employees, customers, and patients have as much time for notification and evacuation as possible.

Applications that use Fire-Safety Shut-off Valves include:

  • Backup generator systems
  • Chemical plants
  • Refineries
  • Storage or day tanks
  • Solvent or paint lines
  • Biofuel plants
  • Fuel systems (diesel or natural gas)
  • Hospitals

Choose BI-TORQ Valve Automation

A fire safety valve should be used as a safety precaution on any system that utilizes flammable or hazardous media. Designed to save lives and enable quick resumption of operations after a fire has been handled, fusible link assemblies are necessary for the safe daily operations of many commercial operations, plants, and manufacturing facilities. Many of these operations will find that insurance for their business is not available without a fire safety valve with fusible link.

BI-TORQ has been designing this type of assembly for over two decades. Let’s have a conversation about your fire safety needs and how our products can provide safety for your workers and operation. Contact us for more information on fire safety valves with fusible links, or to discuss any of our wide range of valve solutions.

Gold just isn’t for fall leaves

BI-TORQ was recently specified and has received an order for several thermal shut-off valve assemblies to ship in early November. The valve packages range in size from ½” through 6” and are for a large gold mine in Central Asia.

The carbon steel ANSI 150#  assemblies are going to be installed in a diesel system to offer complete emergency shut-off protection in areas such as the main fuel storage tanks; inlets and outlets of generators; day tanks; the fire pump diesel tank; boiler fuel inlets; and fuel feeds to the mill and screening areas. This approach offers maximum protection with a product of this type.

If you take a look at the image below, you can see how the strategic placement of our thermal shut-off valves maximizes plant safety. This is accomplished 3 major ways. First, it allows for fuel lines to be shut down at critical junctures in the event of a fire. Our assemblies will stop flow into buildings or at branch points to keep flammable media from feeding a fire due to ruptured pipes, broken fittings or other leak points in the system. The thermal shut-off valves will also isolate tanks at their source, keeping the bulk of the flammable material safely in a tank. Additionally, they can also be used on top of tanks in a fail-open configuration as tank vacuum protection. Lastly, they can be used to shut down pumps when a localized fire breaks out. This is done by using the position feedback option to send a signal to the PLC.

FLP Placement - Diesel System

Whether your protection needs are simply for a small day tank in a commercial building or for a comprehensive fuel system at a industrial facility, you can count on our FM approved thermal shut-off valves.

Fusible Link Application – Lubricants



SKF combo2

SOLUTION: FM approved FLP series fusible link valves (also known as thermal shut-off valves) were mandated on all lubricant lines feeding the EDM machines. The plant currently has 4 EDM machines with several lines feeding various portions of the machines.

FOLLOW UP: The company’s safety department has decided to be more comprehensive with their fire safety requirements. They have determined that FLP series fusible link valves should be installed on all lubricant lines.

Our Fusible Link Assemblies are the Real Deal

As the leader in the fusible link (or thermal shut-off) valve market, BI-TORQ Valve Automation takes pride in knowing that every valve assembly we send out the door is built to our own exacting standards and meets all current product standards and approvals. We’d like to think that not only do we provide you with the best product of its type in the market, but also the most versatile as well. Let’s take a look at 5 reasons why.


Some safety shutdown products on the market promote the fact that their links are FM approved. That’s great, but who wants a partially approved safety product? All our FM approved fusible link assemblies are approved as a whole unit (topworks) and designed to fit just about any quarter-turn fire safe valve. While Factory Mutual has not dictated that the complete package, valve included, be FM approved yet, we have taken the proactive step and had most of our FLP packages approved to include the valve.

Our complete Fusible Link Package (FLP) includes an API 607 certified valve not one “designed by” as other companies offer. We can provide a fire test certificate for the valve and its applicable size range per API 607 section 4.4 whereas a “designed to” valve might have fire tested at one time, but not necessarily in the size range or pressure class in accordance with API 607 section 4.4.

We treat these devices as engineered products not a commodity type product so every unit we ship has its own serial number for maximum traceability. We can also supply Certified Material Test Reports (CMTRs) and functional test reports upon request.

Size Range

The “Single Source for Valve Automation” model that we use for automated valve packages is very fitting here. While some of our competitors are limited to 2” and 3” valve sizes, we can provide the largest automatic shut-off  valve of its type in the industry, up to 21,000 inch pounds of torque. Whether insurance mandated or an internal safety driven requirement, our unparalleled size range makes outfitting a full facility easier from a cost, purchasing, training, and documentation standpoint.


All of our fusible link assemblies have manual operation capability. Ball valves in the smaller LT & MT Series (typically ¼” through 2”) allow for manual operation even while armed with a simple turn of the lever. This saves having to install a manual isolation valve in the process line. HT & BT Series and all butterfly valve assemblies utilize a declutchable manual override with a handwheel to manually operate the valve.

Designing the assemblies to be field resettable was one of the main goals when this product was originally designed twenty some years ago. No long complicated process and no special tools are needed to replace the links with the valve in line. We even have Video IOMs to visually walk you through the process.

As a safety device for containing flammable or toxic media, the inline valve portion should be taken into consideration. With our assemblies designed around a quarter-turn valve and not a check valve type, you can operate our assemblies under pressure and use them as a “block valve”.  No need for periodic inspection to ensure functionality either. We do recommend annual link replacement as part of an overall plant maintenance program.


While the FLP Series is a full thermal shut-off device including our valve, we also offer the FL Series which is used to mount on top of customer-owned valves. This allows for API 607 fire safe valves on an Approved Manufacturer’s List (AML), particularly important in the Oil & Gas industry, to be mounted to our topworks.

Additional customization options include anti-vibration hardware (used in maritime applications), special coatings for tough environments, proximity switches for remote indication, and thermo-electric links for remote firing.


Our Product Configurator is a unique resource designed to help get our fusible link assemblies incorporated into a plant design or written specification. The Product Configurator offers the ability to search by different criteria such as valve type, size, link temp, or end connection.  Model specific sales drawings, sample specifications, and data sheets can also be downloaded here.  Additionally, with a simple online registration, you can download 2D line drawings or 3D models in various formats to integrate into a plant design.

Bottom line: Don’t get fooled by the competition