N2-BLAST® FPS-1650, FPS-3250 & FPS-5000 — Safety Guidelines – South-Tek Systems

Applies to: South-Tek Systems N2-BLAST® FPS-1650, FPS-3250, and FPS-5000 fire protection nitrogen generators.

Does NOT apply to: FPS-500 and FPS-900 (see FPS-500 and FPS-900 Safety Guidelines) or FPS-10000, FPS-16500, and FPS-22500 (see FPS-10000, FPS-16500, and FPS-22500 Safety Guidelines). The hazards overlap but the isolation procedures do not.

This article is the safety reference for installing, operating, and maintaining the FPS-1650, FPS-3250, and FPS-5000. It covers who may work on the equipment, the hazards it actually presents, how to isolate and verify each energy source before mechanical work, and what to do when something goes wrong. Read the O&M manual before performing any work on the system, and for external air compressors and dryers follow those manufacturers' own safety instructions as well.

⚠ Warning — this is a pressurized system on a life-safety application The generator holds compressed air and nitrogen under pressure, is connected to an energized electrical panel, and supervises a fire sprinkler system. Only trained, competent, authorized personnel may install, operate, maintain, or repair it. Isolate and depressurize before any mechanical work — including a filter change — following the isolation procedure and the depressurizing procedure below. Use only approved replacement parts that meet or exceed the original specification. Do not tamper with the equipment, and do not operate it outside its published specifications.

Who may do what

Most of the incidents on this equipment come down to the wrong person doing the right task. The owner is responsible for keeping the unit in safe working condition; the split below is the practical version of that.

Task	Who	Why it matters
Reading the screen, noting an alarm, reporting it	Anyone briefed on the system	No hazard, and the sooner an alarm is reported the smaller the problem.
Starting and stopping the unit at the touchscreen	Trained operator	Stopping the unit takes the riser off active nitrogen replenishment — that is a fire protection impairment. A trained operator may work the controls, but the impairment has to be declared and tagged with the building owner or their impairment coordinator first.
Filter changes and preventive maintenance	Qualified service technician	Requires isolating and depressurizing a live pressure system, and correct sequencing to avoid venting the riser.
Electrical connection, panel work, three-phase rotation checks	Qualified electrician	Live panel work. Supply voltage is factory configured and must match the incoming service.
Changing setpoints, control programming, internal repairs	South-Tek, or with South-Tek's written consent	The control program is proprietary and password-protected. Unauthorized changes void the performance specification and the warranty.
Anything on the external compressor or dryer	Per that manufacturer's instructions	Separate equipment with its own hazards, its own lockout points, and its own manual.
Closing the AMD, draining or refilling a riser section	Licensed fire-sprinkler contractor	This is sprinkler-system work under the site's impairment program, not generator work, and the section is full of nitrogen.
Declaring, tagging, and clearing an impairment	The person in charge of the work, with the building owner or their impairment coordinator	Every valve closure in this article removes supervisory gas from a live sprinkler system.

The hazards on this equipment

Hazard	Where it comes from	How it is controlled
Oxygen displacement asphyxiation	Nitrogen vented from the generator, the purity sample port, a relief valve lifting, or an open line. Nitrogen is not poisonous, but it pushes oxygen out of a space — and it is colorless, odorless, and gives no warning. You do not smell it, and the first symptom can be collapse.	Install in a well-ventilated room that is not sealed off from normal air changes. Vent exhaust gas outside or into a large ventilated space. Never enter a confined space downstream of a vent without confirming at least 19.5% O₂ with a calibrated oxygen meter.
Stored pressure	On the FPS-3250 and FPS-5000 the cabinet inlet regulator is factory set at 120–125 PSIG — but the feed line upstream of that regulator sits at whatever the compressor cuts out at, around 175 PSIG on a South-Tek-supplied compressor. Nitrogen in the internal storage tank stays at its cut-out pressure with the machine stopped, protected by an ASME safety relief valve, and pressure stays trapped in the filter bodies, the interconnecting piping, and — on the FPS-3250 and FPS-5000 — the feed receiver. The vessel rating and the relief setting are stamped on the tank data plate and the valve tag — read them off the unit in front of you, and do not calibrate your caution to the regulated number.	Isolate, vent, and verify zero on every section before opening it — except the nitrogen tank, which has no field bleed and is isolated rather than emptied. See Isolation and lockout below.
Whipping hose	A pressurized hose that is not secured, or one that bursts in service.	Secure both ends before pressurizing, and confirm the restraint before opening any valve. Never let pressurized gas exhaust from an unsecured hose. If one bursts, close the isolation valves if it is safe to do so and shut the unit down — do not try to grab the hose.
Electrical	The control panel and, on the FPS-3250 and FPS-5000, the external compressor's motor circuit, which may be three-phase.	Disconnect supply power before any electrical work. The panel is an open-type industrial control panel, so the cabinet is its enclosure — do not run the unit with the panel exposed.
Automatic start	The generator starts and stops on its own, on tank pressure. A unit sitting quietly in Standby is not a unit that is off.	Stopping at the touchscreen is a control action, not an energy isolation. Open the disconnect before working inside the cabinet.
Noise	Under 90 dBA at the cabinet, plus the external compressor on the FPS-3250 and FPS-5000.	Wear hearing protection while the equipment is running; on the FPS-3250 and FPS-5000 the feed compressor is usually the louder source.
Weight and handling	A tall, narrow cabinet at roughly 223–303 lb depending on model, delivered in a crate.	Keep it upright, move it with a floor jack, and never stack anything on top of it.
Loss of supervision the life-safety hazard	Valving the generator off, leaving a valve shut after a test, or leaving a system on air instead of nitrogen.	Treat it as an impairment — see Fire protection impairment below. This is the hazard that hurts a building rather than a technician.

Personal protective equipment

PPE	When
Safety glasses (ANSI Z87.1)	Any time the cabinet door is open with the machine running, and any time you are opening a pressurized component or leak-checking.
Hearing protection	While the equipment is running — the generator and, on the FPS-3250 and FPS-5000, the feed compressor.
Calibrated oxygen meter	Before entering any confined or poorly ventilated space downstream of a vent, or any space where nitrogen may have accumulated. Confirm at least 19.5% O₂ before entry.
Gloves	Handling the cabinet, crate, or sheet metal edges, and when working around a compressor that has been running.
Electrical PPE per site policy	Any work at the panel, at the disconnect, or on the compressor motor circuit.

Isolation and lockout — before any mechanical work

This equipment has six separate energy sources, and stopping the unit at the touchscreen isolates none of them. Stopping is a control action: on every model it leaves the nitrogen storage tank charged and the cabinet energized, and on the FPS-1650 the air side is the only energy it touches. Isolate each one and then verify it, in pairs — an isolation you have not verified is an assumption.

Order matters. Work through it like this:

Declare the impairment before you touch a valve. This work stops nitrogen reaching the riser. Notify the building owner or their impairment coordinator and the alarm monitoring company — they will see a genuine supervisory alarm — meet any AHJ and property-insurer requirements, and tag the system under the site's impairment program, separately from your personal lockout tag. If the work will reach the alarm contact terminals, arrange at the same time for the fire alarm or BMS technician to disconnect and lock that circuit — it is powered from their panel, not from this cabinet.
Stop the unit at the touchscreen — hold the Start/Stop button on the home screen until the status reads Off. On the FPS-1650 this is also what relieves the air side; on every model the nitrogen storage tank stays charged.
Close the isolation valves — the N2 OUT ball valve, the main air input ball valve (FPS-3250 / FPS-5000), the bypass air inlet ball valve where auto air bypass is fitted, and, where you will open riser piping, the air maintenance device (AMD) upstream of that section. Leave the nitrogen tank ball valves open for now — closing them blinds the panel gauge to the tank. All of these fall under the impairment declared in step 1.
Vent each section you intend to open, at the vent point named in the depressurizing table for your model. If the section you need to open is not in that table, stop — see the nitrogen row.
Drain the isolated riser section, if you are opening riser piping, per the site procedure — venting outdoors or into a large, well-ventilated space.
Open the disconnect and lock it out, at the generator and, on the FPS-3250 and FPS-5000, at the external feed compressor. The FPS-1650 has no external compressor — its compressor is internal and comes off the generator's own disconnect. Venting the air side comes before the generator disconnect: on the FPS-1650 the unit has to be running-then-stopped for the air side to relieve at all, and on the FPS-3250 and FPS-5000 the vent valve has to be opened against a closed inlet while the unit is still stopped rather than locked out.
Close the tank ball valves last, and only if the work requires the tank itself isolated — see the stored nitrogen row for what you can and cannot prove once they are shut.
Verify against every row of the isolation table — absence of voltage proved with a meter at the point of work, absence of voltage at the alarm terminals if your work reaches them, 0 PSIG on the air-section gauge for your model, the nitrogen tank pressure read and recorded on the panel gauge and the nitrogen side treated as charged for the rest of the job, 0 PSIG on a gauge on the riser section you are actually opening, and the panel given time to discharge. Only then begin work.
When the work is done, restore in reverse order and close the impairment — the full restore-and-verify list is in Fire protection impairment below. Do not leave site until every item on it is confirmed.

Do not open a vent before the isolation valves are shut, and do not pull the disconnect on a running FPS-1650 — that skips the stop-and-depressurize and leaves the air side charged.

Energy source	Isolate	Verify
Electrical	Open the disconnect feeding the generator and lock it out. If the unit is cord-and-plug connected and there is no lockable local disconnect, either lock the upstream branch-circuit breaker or unplug it and keep the plug under your exclusive control — the cabinet's power entry module is not a lockable energy-isolating device. On the FPS-3250 and FPS-5000 the external feed compressor is a separate circuit with its own disconnect: open and lock that too. A dryer may be a stand-alone unit on its own circuit or the cabinet-mounted option running from the generator's own supply — establish which is fitted rather than assuming it is separately fed, and test for absence of voltage at its terminals either way.	Test for absence of voltage with a meter at the point of work, and prove the meter before and after. A dark display tells you the screen lost power; it does not prove the conductors you are about to touch are dead.
Compressed air	FPS-3250 / FPS-5000: close the main air input ball valve. That leaves the feed compressor, any air receiver, and the piping between them at full pressure — isolate and bleed those at the compressor if your work reaches them. FPS-1650: stop the unit first (that is what relieves the air side), then open the disconnect. On any model with auto air bypass, also close the bypass air inlet ball valve.	Vent the section and read 0 PSIG at its gauge — see the depressurizing procedure below. Closing a valve stops the supply; it does not empty what is already downstream of it.
Stored nitrogen	Close the N2 OUT ball valve on top of the cabinet. Leave both nitrogen tank ball valves open at this stage — the panel gauge reads the tank only through the tank's upper (outlet) ball valve, so closing that valve blinds you to the vessel you are working near. There is no field bleed for the nitrogen side on these models, so the tank does not come down to zero in a normal lockout — it is isolated, not emptied. The filter vent valve does not touch it: that vents the filter bowls on the air side only. Closing these valves on a system in service is a fire protection impairment — see below.	This is the one energy source you isolate but cannot empty. Read and record the tank pressure on the cabinet's 0–160 PSIG panel gauge while the tank's upper (outlet) ball valve is still open — that is the only condition in which that gauge reads the storage tank. Then treat the tank, its manifold, and everything between it and the N2 OUT ball valve as fully charged for the whole job. Closing the tank valves and the N2 OUT valve also leaves nitrogen trapped in the run between them, and once the tank's upper valve is shut nothing on the machine reads the tank at all. Do not open the tank, its manifold, its relief valve, or any fitting between them — that work is a South-Tek job.
Riser pressure	The N2 OUT ball valve isolates the generator from the riser — it does not relieve riser pressure. To work downstream of it, close the air maintenance device (AMD) upstream of that section and drain the section per the site procedure. Closing an AMD and draining a section removes fire protection from it — that is an impairment in its own right and must be covered by the notification and the tag from step 1. The section is full of nitrogen: drain and vent it outdoors or into a large, well-ventilated space, never into a closed valve room, closet, or pit, and treat that space as oxygen-deficient until it has been ventilated and reads at least 19.5% O₂ on a calibrated meter.	0 PSIG on a gauge on the riser section you are actually opening. The panel gauge sits upstream of the N2 OUT ball valve: with that valve shut it reads the generator side only, and it can never prove that a riser section isolated behind a closed AMD has been drained. This is the isolation most often missed — closing the N2 OUT valve leaves full supervisory pressure sitting on the downstream side of it. And do not rely on a check valve for isolation — there are check valves in the nitrogen path and none of them is an isolation device.
Stored electrical energy	Open and lock the disconnect, then wait before opening the panel — the power supply and the panel components hold charge after the supply is removed. Treat the panel as live until it is proved otherwise at the point of work.	After opening the disconnect, confirm the display is dark and allow the panel to discharge before opening it — then test for absence of voltage at the point of work.
Foreign voltage alarm contacts	The common alarm and purity dry contacts are wired out to the fire alarm panel or BMS, which supplies its own control voltage from outside this cabinet. Opening the generator's disconnect does not de-energize them. If your work reaches those terminals, have the fire alarm or BMS technician disconnect and lock that circuit first — arrange it when you make the step 1 notification, not when you get to the terminals.	Test for absence of voltage at the alarm terminals with a meter, proving the meter before and after. The generator being locked out proves nothing about this circuit.

⚠ Warning — Standby is not Off, and Stop is not isolation The generator starts on its own whenever tank pressure falls to the cut-in setpoint — 60 PSIG on all three models, confirmed on the controller's N2 Pressure Settings screen. A unit that has been silent for twenty minutes can start while your hands are inside it. Holding the Stop button is a control action; it does not isolate any energy source. Open the disconnect, lock it out, and verify absence of voltage before working inside the cabinet.

Depressurizing before opening a pressure component

Isolate first, then vent, then verify — and the order of the valves matters.

Model / build	Procedure
FPS-1650	Stop the unit — hold the Start/Stop button until the status reads Off. The air side self-relieves on stop, and the internal compressor is the generator's only process-air source, so opening and locking the disconnect completes the air-side isolation — where auto air bypass is fitted, close the bypass air inlet ball valve as well. Confirm the gauge after the copper coil reads 0 PSIG before opening any filter body. This relieves the air side only — the nitrogen storage tank stays at cut-out pressure after the unit stops, on every model.
FPS-3250 / FPS-5000 current white-bowl build	Stop the unit, close the main air input ball valve first, then open the tagged filter vent valve on the filter assembly on the bracket in the middle of the cabinet, then open the disconnect and lock it out. That valve order matters — opening the vent while the inlet is still open just dumps live feed air and depressurizes nothing. It vents the filter bowls together; it does not relieve the nitrogen storage tank. Confirm 0 PSIG at the filter/regulator gauge and that venting has stopped. Leave it open while you work, and close it before returning the unit to service. This is a manual vent, not a safety relief valve — safety relief valves are never opened, blocked, or adjusted.
FPS-3250 / FPS-5000 legacy black-bowl build	Stop the unit, close the main air input ball valve, then open the air service valve after the regulator slowly to relieve to 0 PSIG, then open the disconnect and lock it out. Leave the service valve open while you work and close it before returning to service.
Nitrogen side all three models	There is no field bleed point for the nitrogen storage tank on these models, and no field procedure that brings it to zero. Isolate it at the N2 OUT ball valve, record the pressure on the panel gauge before you close the tank's upper ball valve, and work on the assumption that the tank stays at cut-out pressure throughout. If the work requires opening the tank, its manifold, its relief valve, or any fitting between the tank and the N2 OUT ball valve, stop and contact South-Tek Service — do not improvise a bleed, and do not crack a fitting to test it.

⚠ Warning — never use a component as a bleed Do not crack a filter bowl, a fitting, or a body clamp to find out whether a section is still pressurized. If you cannot positively identify the vent point for a section, stop and contact South-Tek. Loosening a retained component under pressure is how people get hurt on this equipment.

Fire protection impairment

This generator is part of a fire protection system. Anything that stops nitrogen reaching the riser — closing the N2 OUT ball valve, closing the tank valves for a leak test, taking the unit out of service for a filter change — is a system impairment, even though the sprinkler piping itself is untouched.

▲ Attention — before you close a valve on a system in service Follow the site impairment procedure: tag it under the site's impairment program; notify the building owner or their impairment coordinator and the alarm monitoring company — that is the notification that stops a false dispatch when the supervisory signal trips — and, where required, the authority having jurisdiction and the property insurer. Keep the window as short as the work requires, and restore and verify before you leave. Restore in reverse order and confirm all of it before you leave: the filter vent valve or air service valve closed, the main air input ball valve reopened on the FPS-3250 and FPS-5000, the bypass air inlet ball valve reopened where auto air bypass is fitted, both tank ball valves and the N2 OUT ball valve reopened, the AMD reopened and the riser section refilled, locks removed and power restored, the tank recovered to its cut-out setpoint — 70 PSIG on the FPS-1650, 100 PSIG on the FPS-3250 and FPS-5000, confirmed on the controller's N2 Pressure Settings screen for the unit in front of you — the panel gauge following, the riser back at supervisory pressure, the unit returned to Standby with no active alarm, and the impairment tag cleared with everyone you notified, including confirmation from the monitoring company that the supervisory point reads normal. A diagnostic that ends with the nitrogen supply valved off is worse than the fault you went to investigate — the riser bleeds down with nobody watching.

A system sitting in bypass is a related case: it is supervised, but with air rather than nitrogen, so it is not protected from corrosion. Automatic bypass during the 30-minute fire protection piping fill test is expected and self-clearing, and is not an impairment. Bypass at any other time means the riser is being supervised with compressed air and corrosion protection is suspended: treat it as an active impairment — notify the building owner or their impairment coordinator and the alarm monitoring company, tag it under the site's impairment program, find the cause, and confirm the unit is back on nitrogen and in Run or Standby before closing it out. Alarm meanings are in Operation and Alarms.

Pressurized gas and relief valves

Never disable, plug, adjust, or bypass a safety relief valve. The nitrogen storage tank carries an ASME safety relief valve, and on the FPS-1650 the internal compressor side carries a second one. On the FPS-3250 and FPS-5000 the feed compressor is separate equipment with its own relief protection and its own manual. Settings and flow ratings are stamped on the valve tag — read them off the valve in front of you, and never carry a figure over from another unit. If a relief valve is lifting, the cause is upstream — investigate it, do not restrain the valve.
Never let pressurized gas exhaust from an unsecured hose. A loose hose whips. If one bursts in service, close the isolation valves if it is safe to reach them and shut the unit down.
FPS-3250 and FPS-5000 — the cabinet inlet regulator is factory set at 120–125 PSIG and is not a field adjustment. A South-Tek-supplied feed compressor is preset to cut out around 175 PSIG and the cabinet regulator brings that down to the pressure the machine runs on; neither is something to retune in the field. Feed air outside specification can damage the generator, and that damage is not covered under warranty. If the compressor was not bought from South-Tek, confirm the selection with South-Tek before it is installed. The FPS-1650 makes its own process air and has no feed-air connection — but where auto air bypass is fitted, the bypass air supply is still an external connection and still has to be isolated.
The purity sample port vents nitrogen into the room. Ventilate the space, open it only for the reading, and close it immediately afterwards.
Use approved replacement parts that meet or exceed the original specification. Non-factory filter elements and fittings are a warranty and a safety issue.

Electrical safety

Disconnect supply power before any electrical work — and verify absence of voltage at the point of work with a meter, not by looking at the display.
Land incoming power at the cabinet's power entry module on the left side of the cabinet, not directly onto the internal power supply. That module carries the generator's built-in 15 A over-current protection, which protects the machine: it is not the branch-circuit protection and it is not a disconnecting means. Provide a lockable disconnecting means ahead of the cabinet so the machine can be locked out for service, and size and protect the branch circuit to the unit nameplate. Final connection is a qualified electrician's work.
Supply is 120–240 VAC, 50/60 Hz, single phase — under 8 A on the FPS-1650, under 5 A on the FPS-3250 and FPS-5000. Each unit is built for one supply voltage within that range and it cannot be changed in the field. Read the configured voltage on the product information label and confirm the incoming service matches before energizing. Run an equipment grounding conductor with the branch circuit and land it on the cabinet ground terminal.
The control panel is a UL 508A open-type industrial control panel on the cabinet's left side, and the sheet metal is its enclosure — never run the unit with that face open, and close it up before restoring power. The front door is the maintenance access; running with it open is a defined observation task only, with eye protection and nothing in your hands.
FPS-3250 and FPS-5000: the external feed compressor is a separate circuit with its own disconnect. A dryer may be a stand-alone unit on its own circuit or the cabinet-mounted option running from the generator's own supply — establish which is fitted rather than assuming it is separately fed. If the compressor is three-phase, verify rotation before first start — running it backwards damages it.
Keep the touchscreen and panel area clear. Do not spray soapy leak-check solution on or near electrical components.

Environment, handling, and installation

Install indoors in a nonhazardous, well-ventilated location at 40–100°F, on a hard flat surface rated for the weight with margin. The room must not be sealed off from normal air changes.
Store the unit before installation at 60–80°F, dry, upright or in its crate as shipped. Never place or stack objects on top of it.
Unbolt the unit from the crate before lifting it out, set it down, and move it with a floor jack. Do not walk a tall cabinet on its corners.
FPS-1650: remove the four painted bolts underneath the cabinet before startup — they lock the compressor's vibration isolators for shipping, and running the unit with them in place transmits vibration into the cabinet.
Keep gas lines dry during hook-up so moisture does not enter the generator. Water carried into the PSA beds is permanent damage and is not covered under warranty.
Leave 36" at the front and at the left side for maintenance access and 6" minimum on all sides for ventilation, plus NEC 110.26 working space at the electrical face — which is the left side, where the power entry module and the panel are. Full detail is in Site and Utility Requirements.

If something goes wrong

Situation	What to do
A hose bursts or a line lets go while running	Stay clear of the loose end. Close the isolation valves only if you can reach them safely, shut the unit down, and let the section vent before approaching it.
Audible leak inside the cabinet	Hold Start/Stop until the status reads Off. Close the N2 OUT ball valve, then isolate and depressurize the air side using the procedure for your model in the depressurizing table, and verify 0 PSIG before opening anything. Do not chase a leak with the system live. You have now impaired the system — notify the building owner or their impairment coordinator and the alarm monitoring company, tag it, and restore and verify before you leave.
Someone feels dizzy or breathless in the room	Most fatalities in oxygen-deficient atmospheres are would-be rescuers. Do not enter a suspected oxygen-deficient space to attempt a rescue without self-contained breathing apparatus and trained assistance. Call emergency services, ventilate the area from outside, and shut off the gas supply only if that can be done safely from a safe location. If the casualty is already out, move them to fresh air and keep them there until help arrives; if they are not breathing, begin rescue breathing or CPR if you are trained. Get medical attention even if they appear to recover completely — that is standard after an oxygen-deficiency exposure and it is the step most often skipped.
A relief valve is lifting	Do not restrain or plug it. Shut the unit down, isolate, and find the upstream cause before restarting. Shutting the unit down impairs the system — notify the building owner or their impairment coordinator and the alarm monitoring company, tag it under the site's impairment program, and restore and verify before you leave.
You are not sure the system is depressurized	Then it is not. Stop, and contact South-Tek before opening anything.
The system has been left valved off or in bypass	Treat it as an active impairment. Restore supervision and verify the unit returns to Standby. If a tag exists, notify whoever holds it; if none exists, declare the impairment now — notify the building owner or their impairment coordinator and the alarm monitoring company and tag it under the site's impairment program until nitrogen supply is confirmed restored.

Warranty and unauthorized modifications

Do not modify the equipment, defeat a safety device, or operate it outside its published specifications.
Do not change the cut-in and cut-out setpoints or the control programming without South-Tek's written consent. The program is proprietary and password-protected, and unauthorized changes void the performance specification and the warranty.
Use only approved replacement parts. Non-factory filter elements and fittings void the warranty and are a safety issue.
Damage from feed air outside the supply arrangement South-Tek specifies — the wrong compressor, high temperature, or a dew point that lets moisture reach the PSA beds — is not a warranty repair. If the compressor was not bought from South-Tek, confirm the selection with South-Tek before it is installed.
Only the designed purpose. These units make nitrogen for fire protection systems; do not repurpose them.

Manual download

FPS-1650, FPS-3250, and FPS-5000 O&M Manual

Need help? South-Tek Systems Service — Phone: (910) 415-1880 · Open a support ticket at support@southteksystems911.zendesk.com or through the Help Center. Remote startup and troubleshooting support is available.