If you are looking at the TR300FK-S and wondering how it differs from the standard TR300FK, the answer is one component: the integrated pressure switch built into the end fitting of the tube assembly.
That single addition changes what the system can do after a discharge, and whether you need it depends entirely on what you want to happen when the system activates. This guide covers the difference between the two models, what the pressure switch connects to, which applications make the most sense for the S version, and how to decide which one is right for your situation.
What the Standard TR300FK Does
The TR300FK is a 3-meter BlazeCut T Series tube, pre-charged with FK-5-1-12 clean suppression agent. It routes through an enclosed space, responds to heat without any electrical connection, and discharges at the hottest point in the enclosure when temperature reaches approximately 248 degrees Fahrenheit.
It requires no power, no wiring, and no connection to anything. It is a fully passive and self-contained system. After a discharge, you replace the tube.
The standard TR300FK covers enclosure volumes up to approximately 3 cubic feet depending on the application type. It is suited to truck and SUV engine compartments, larger electrical enclosures, mid-size CNC machining centers, larger boat engine bays, and similar applications in that volume range.
What the TR300FK-S Adds
The TR300FK-S is the same 3-meter tube with an integrated pressure switch built into the end fitting. The tube itself is identical. The suppression agent, the activation temperature, the coverage volume, and the installation process are all the same.
What the S adds is an electrical output. When the tube discharges, the drop in internal pressure triggers the pressure switch, which sends a signal to whatever device is connected to it. That signal can trigger a beacon, a sounder, a warning buzzer, an alarm panel, or a relay that performs an equipment shutdown.
Without the S, you get suppression. With the S, you get suppression plus the ability to notify someone or trigger an action at the moment of discharge.
What You Can Connect to the Pressure Switch
The pressure switch output is a simple electrical signal that can drive a range of notification and control devices:
Indoor-outdoor beacon. A red xenon strobe light that activates when the system discharges, providing a visible indication that something happened in the protected space. Useful in workshops, garages, facilities with multiple machines, or any location where a person might not be present at the time of discharge but needs to know about it shortly after.
Sounder and beacon combined. An audio-visual unit that produces both a flashing light and an audible alarm at the moment of discharge. Useful where ambient noise levels are high or where someone might not be looking toward the beacon location.
Warning buzzer. A compact 25mm unit with an LED ring, 12V DC, designed for vehicle cab installations. If you are protecting a truck, a UTV, or a boat engine compartment and you want an alert in the cab when the system discharges, the warning buzzer connects to the pressure switch output and mounts in the vehicle interior.
Equipment shutdown relay. The pressure switch signal can be wired to a relay that cuts power to the protected equipment at the moment of discharge. This is particularly useful for CNC machines, electric forklifts, and other equipment where stopping the machine the moment a fire suppression event occurs is the safest response.
Alarm panel. For installations where continuous system monitoring is needed, the BlazeCut alarm panel connects to the pressure switch and provides OK, FAULT, and FIRE status indication. It tells you the system is functioning normally before any discharge event occurs, not just after.
Which Applications Are the Best Fit for the TR300FK-S
The S version makes the most practical sense in specific scenarios. Here is how to think through whether it applies to your situation.
You want to know when the system has discharged and you will not be present. If your truck is parked overnight, your boat is at a dock, your CNC machine is running a lights-out shift, or your electrical panel is in an unoccupied utility room, knowing that the system has activated is not just convenient. It determines what you do next. A beacon or sounder connected to the TR300FK-S provides that notification.
You want to stop the equipment when the system fires. If you are protecting a CNC machine, a vehicle engine compartment, or any piece of equipment where continued operation after a suppression event could worsen the situation, a relay connected to the pressure switch can kill power to the equipment at the moment of discharge. This requires the S version.
You have an alarm panel or building management system to integrate with. Facilities that want suppression events logged, monitored, or integrated into an existing alarm infrastructure need the pressure switch output to make that connection.
You are protecting a vehicle cab where the operator should be alerted immediately. A warning buzzer in the cab connected to the TR300FK-S protecting the engine compartment or battery bay gives the driver immediate notification of a discharge event while they are operating the vehicle.
If none of these scenarios apply to your installation, the standard TR300FK does everything you need. The S version is not more effective at suppression. It is the same tube with an added notification capability that is only worth paying for if you will actually use it.
What the TR300FK-S Does Not Do Differently
A few common misconceptions worth addressing.
The S version does not activate faster or suppress more aggressively. The suppression tube is identical to the standard model. The only difference is the pressure switch in the end fitting.
The S version does not activate any connected devices on its own. The pressure switch provides a signal, but whatever is connected to it requires its own power supply. The beacon, sounder, and other accessories are not powered by the tube. They need an external power source and are wired to the pressure switch output as a trigger.
The S version does not provide continuous system monitoring by itself. The pressure switch only sends a signal when the tube discharges. Continuous monitoring, including fault detection and OK status indication, requires the BlazeCut alarm panel connected to the pressure switch.
Installation Differences Between the Two Models
The TR300FK-S installs the same way as the standard TR300FK. The tube routes through the enclosure, mounts with zip ties or one-hole straps, and requires no connection to any electrical system for the suppression function to work.
The pressure switch adds two wires coming out of the end fitting. Those wires connect to whatever notification or control device you are using. If you are not connecting anything to the pressure switch, those wires can be left disconnected and capped. The suppression function works regardless of whether anything is connected to the switch.
Sizing: Is the TR300FK-S the Right Length for Your Application?
The TR300FK and TR300FK-S are both 3-meter tubes covering enclosure volumes up to approximately 3 cubic feet. If you need a different tube length with a pressure switch, the S versions are available across the T Series range: TR025FK-S, TR050FK-S, TR100FK-S, TR200FK-S, TR300FK-S, and TR400FK-S.
To determine whether a 3-meter tube is the right length for your enclosure, measure the interior of the space you are protecting (length x width x height), calculate the volume, and compare it to the coverage chart on the product page. If your enclosure is larger or smaller than the TR300FK-S range, the same S functionality is available in the correct tube length.
FAQ: TR300FK-S
Can I add a pressure switch to a standard TR300FK after I have already purchased it? No. The pressure switch is integrated into the tube assembly at the factory. It cannot be added to a standard tube after purchase. If you want notification or shutdown capability, you need to order the S version from the start.
Does the pressure switch require power to function? The pressure switch itself does not require external power to send its signal. However, the notification devices it connects to, the beacon, sounder, buzzer, and alarm panel, all require their own power source. The pressure switch is a trigger, not a power source.
What voltage and current does the pressure switch output? Check the product specifications on the TR300FK-S product page for the exact electrical ratings. The output is compatible with the BlazeCut beacon, sounder, and alarm panel accessories, and can be used to trigger external relays within its rated parameters.
If I connect a beacon but nothing happens at discharge, what should I check? First confirm that the beacon has its own power supply connected and functioning. Then confirm the wiring between the pressure switch output and the beacon input is correctly connected. The pressure switch signal is only a trigger. If the beacon has no power, it will not activate regardless of whether the pressure switch fires correctly.
Does the pressure switch affect the warranty or certifications of the tube? No. The TR300FK-S carries the same ANSI/UL 521 certification, LPS 1666 certification, and NFPA 2001 compliance as the standard TR300FK. The pressure switch is an integrated factory component, not a modification.
What is the coverage volume of the TR300FK-S? The same as the TR300FK: up to approximately 3 cubic feet for standard enclosure applications. The S designation refers only to the pressure switch feature and does not change the tube length or agent capacity.
Shop the TR300FK-S and Accessories
BlazeCut TR300FK-S on Modern Fire Suppression
If you need a different tube length with the pressure switch feature, the full S series is available on the site. For help deciding between the S and standard versions for your specific application, reach out through the contact page before you order.