N2-BLAST® FPS-500 & FPS-900 — Safety Guidelines – South-Tek Systems

Applies to: South-Tek Systems N2-BLAST® FPS-500 and FPS-900 fire protection nitrogen generators.

Does NOT apply to: FPS-1650, FPS-3250, and FPS-5000 (see their safety guidelines) or FPS-10000, FPS-16500, and FPS-22500 (see their safety guidelines). The hazards overlap but the isolation procedures do not.

This article covers the safety requirements for installing, operating, and maintaining the FPS-500 and FPS-900. All personnel and their supervisors must read and fully understand the O&M manual before installing, operating, or maintaining the system, and must follow OSHA and local health and safety regulations alongside it. For equipment used with the generator, also refer to that manufacturer's safety guidelines.

Two things set this equipment apart from ordinary shop machinery, and between them they drive nearly everything below. First, it produces a gas that displaces oxygen and gives you no warning that it is doing so. Second, it is part of a life-safety system — work on the generator can impair the fire protection it supports, and a building can be left unprotected without anyone noticing.

Hazards at a glance

Hazard	Why it matters on this equipment	The control
Oxygen displacement	Nitrogen is colorless, odorless, and tasteless. There is no smell, no irritation, and no breathlessness to warn you.	Well-ventilated room, never sealed. Vent exhaust outdoors or to a large, well-ventilated area. Confirm at least 19.5% O₂ with a calibrated meter before entering any confined space downstream of a vent.
Fire protection impairment	Draining, venting, or isolating the piping can leave the building without sprinkler protection, and a unit left in bypass supervises with air instead of nitrogen.	Follow the site impairment procedure: notify the building owner or their impairment coordinator and the alarm monitoring company, meet AHJ and insurer requirements, tag the system, keep the impairment short, and verify full restoration and supervisory pressure before closing out.
Stored pressure	The storage tank, cabinet, and sprinkler piping all hold pressure — and the piping stays at supervisory pressure even with the generator switched off.	Isolate and fully depressurize the section being worked on, and verify 0 PSIG on a gauge reading the section you are actually opening. Never trust a valve position.
Hose whip	An unsecured pressurized hose whips violently. This is a documented cause of serious and fatal injury.	Secure both ends before pressurizing. If a hose bursts, immediately close all isolation valves if it is safe to do so, then shut the unit off.
Electrical	Live supply inside the cabinet, and an internal compressor that can start automatically without warning whenever the unit is energized.	Disconnect supply power before any electrical work. Qualified electrician for the final connection. Keep the working clearance in front of the panel clear.
Falling equipment	The cabinet weighs about 84 lb and vibrates while the internal compressor runs. The nitrogen storage tank is a separate wall-mounted pressure vessel — a 100 lb-size cylinder (part 800-111-FPS), roughly 15" across and 50" tall, held by a strap and clip. “100 lb” is the cylinder size designation, not the tank's weight, which is not published. Handle it as a two-person or mechanical lift in every case, and call South-Tek Service if you need a figure for a lifting plan.	Two people or mechanical assistance to lift. Confirm the wall or rack carries the load. Secure the cabinet at both top and bottom flanges, and secure the tank D-ring to the wall with 1/4" hardware.
Automatic start	The internal compressor starts on its own whenever tank pressure calls for it. A unit that has been silent for twenty minutes is not a unit that is off.	The On/Off toggle is a control action, not an energy isolation. Open the disconnect and lock it out before working inside the cabinet.
Noise	These units are rated under 60 dB — quiet for the class, and quieter than the larger floor-standing models. The rating carries no measurement distance, and the cabinet is often installed alongside noisier equipment, so judge hearing protection on the noise level of the room rather than on the generator alone.	Hearing protection per site policy while the equipment runs. Bear in mind the level is low enough that the machine is easy to forget about while it is running.

The 3-way outlet / bypass valve — one handle, two jobs

These models bypass manually, with a single 3-way ball valve on the lower left of the cabinet that is also the generator's nitrogen outlet. That matters for safety in three ways.

What to know	Why it matters
It is 3-way, not on/off	The alternate position does not isolate — it feeds the riser with compressed air. “Closing” a 3-way handle can silently put a fire protection system on air, or leave it mid-travel.
There is one, and it does two jobs	A single 3-way ball valve on the lower left of the cabinet is both the nitrogen outlet and the bypass — the same handle that sends nitrogen to the riser sends compressed air to it in the other position. Neither position isolates the tank or the riser — the bypass position only takes the generator off the line, and the riser keeps receiving gas either way. Never treat a handle position as an isolation. On the FPS-500 the panel legend lists an Air Bypass Top and an Air in Bottom 3-way ball valve: those are the upper and lower ports of that one valve, not two valves. If you find more than one 3-way handle on a unit, turn none of them until South-Tek Service has confirmed which one is the outlet/bypass.
Its position is sensed magnetically	A magnet on the valve and a proximity sensor beside it drive the bypass alarm and the common alarm contact. Turn the handle and the display should respond. If the alarm state and the handle disagree, do not trust the handle — check that the magnet and the sensor enclosure are seated, and confirm what the riser is actually receiving before signing off. A displaced magnet silently defeats the only indication that the system is on air. Neither the handle nor the display alone proves what the riser is receiving — confirm the handle, the bypass alarm on the display and the red bypass indicator all agree, then confirm the gas itself before you sign off: a nitrogen reading at a zone sample port, or the generator cycling and holding the riser at supervisory pressure.

ℹ Note — bypass is a tool, not just a mistake Bypass is the designed way to hold the riser during the 30-minute fire protection piping fill test, and the normal way to keep the riser supervised while the generator is serviced — better than leaving it with no make-up gas at all. Two things to know before you rely on it. It only supervises if an air supply is actually piped to the bypass inlet and running; with nothing connected there, the bypass position leaves the riser with no make-up gas at all. And bypass does not stop or de-energize the generator — it stays online, the compressor still starts on its own, so bypass is never a substitute for shutting down and locking out. Use it deliberately: declare the impairment, notify the building owner or their impairment coordinator and the alarm monitoring company, tag it under the site's impairment program, do the work, then return the handle to Nitrogen Out, confirm the bypass alarm and indicator have cleared, and confirm the riser is back on nitrogen at supervisory pressure before you leave. What is not acceptable is a system found in bypass that nobody put there on purpose.

Fire protection system impairment

The generator is part of a life-safety system. Working on the generator alone does not always impair the sprinkler system, but draining, venting, or isolating the piping does. When in doubt, treat it as an impairment.

Follow the site's impairment procedure and comply with the requirements of the authority having jurisdiction and the property insurer.
Notify the building owner or their impairment coordinator and the alarm monitoring company before you begin, and tag the system under the site's impairment program.
Keep the impairment as short as practical, and confirm the system is fully restored and back at supervisory pressure before closing out the work.
Where the work takes the generator out of service, put the system on air bypass to hold supervision rather than leaving the riser with no make-up gas — and tag it.
Before leaving site, verify the unit is supplying nitrogen and is not left in air bypass. A system left in bypass is supervised with compressed air and is no longer protected from corrosion.

Nitrogen and asphyxiation

These systems produce nitrogen at a low flow rate that dissipates quickly into open air. Nitrogen is not poisonous — it already makes up about 78% of the atmosphere — but it displaces oxygen, and in an enclosed space that is genuinely dangerous.

⚠ Warning — nitrogen has no warning properties Nitrogen is colorless, odorless, and tasteless. There is no smell, no irritation, and no sensation of breathlessness to warn you — oxygen deficiency can cause confusion, loss of consciousness, and death with little or no warning. Never rely on your senses to detect it.

Install the unit in a well-ventilated room that is not sealed off from normal air changes. Never install it in a closed closet or a sealed enclosure.
Do not directly inhale the gas, and do not vent nitrogen into an occupied or confined space.
When changing filters or performing other maintenance, vent exhaust gas outdoors or to a large, well-ventilated area.
Never enter a confined space downstream of a vent without confirming the oxygen level is at least 19.5% with a calibrated oxygen meter.

Pressurized gas

⚠ Warning Components operate under pressure. Pressurized gas is dangerous and can cause serious injury or death if handled incorrectly. Never crack a fitting, loosen a filter bowl, or open a connection under pressure.

Before any mechanical work — including filter changes — isolate the incoming and outgoing pressure and fully depressurize the section being serviced, venting to atmosphere outdoors or into a large, well-ventilated space and never into a closet, pit, or sealed room. Verify zero pressure on the gauge reading that section; do not rely on a valve position. Isolating the outgoing pressure stops nitrogen makeup to the riser and is a fire protection impairment — notify, tag, and restore per the impairment section above.
Never allow pressurized gas to exhaust from an unsecured hose. Secure both ends before pressurizing.
If a hose bursts during operation, immediately close all isolation valves if it is safe to do so, then shut off the unit.
Never disable, plug, adjust, or bypass a safety relief valve. These units carry a 115 PSI safety relief on the pressure-switch assembly, a further relief valve on the filter assembly, and a safety relief on the nitrogen storage tank manifold — three in all, so do not assume the section you are working on has none. If a relief valve is lifting, the cause is upstream — investigate it, do not restrain the valve. Replace like-for-like only; never substitute a different rating.
Remember that the sprinkler piping remains at supervisory pressure even when the generator is switched off.

Electrical safety

Always disconnect the generator from supply power before any electrical work.
Final electrical connection must be made by a qualified electrician in accordance with local code and site requirements.
Land incoming power on the field terminal strip, on the line side of the 15 A breaker — not directly onto the internal power supply. Supply is 120–240 VAC, 50/60 Hz, single phase, under 8 A; confirm the incoming voltage matches what the unit was built for before energizing.
Keep the working clearance at the front of the panel clear at all times — 36", and whatever the electrical code requires at the disconnect.
The control panel is a UL 508A open-type industrial control panel. The cabinet door is the guard — energized terminals are exposed whenever it is open. Do not open the door on an energized unit except for a defined live-observation task carried out under the site's energized-work authorization, with electrical PPE, and never with a tool in hand.
When leak checking, use a soapy-water spray bottle on non-electrical components only. Never spray near the panel or any electrical connection.
Opening the disconnect trips the alarm contact. These units provide a single voltage-free common alarm contact that pools bypass, BlastOff, filter and power loss — so cutting power reports to the panel as an alarm. That is why the first step of any lockout here is notifying the monitoring company. Work from the terminal numbers on the unit's own schematic when landing that wiring, and function-test the contact end to end after any work on it — terminal states, the test procedure, and its impairment handling are in Fire Alarm & BMS Wiring for FPS Generator Dry Contacts.

Lockout / tagout

Isolate every energy source before servicing, and verify each one separately. Two points that catch people out on this equipment: de-energizing does not depressurize it — the compressor head, PSA beds, filter bowls, and interconnecting tube stay under pressure after the disconnect is opened — and a dark display is not proof the supply is dead.

Energy source	How to isolate it	How to verify zero energy
1. Electrical supply	Open and lock the branch-circuit disconnect feeding the unit. If the unit is cord-and-plug connected and there is no lockable local disconnect, either lock the upstream breaker or unplug it and keep the plug under your exclusive control. The unit's own 15 A breaker switch — which is also the On/Off toggle — is not a lockable energy-isolating device and must never be used in place of the branch-circuit disconnect.	Test for absence of voltage with a meter, proving the meter live-dead-live. A dark display is not a voltage test — it can be dark from a blown fuse or a failed controller while the terminals are still live.
2. Control power	Control power follows the supply once the disconnect is open. The common alarm contact does not. It is wired out to the fire alarm panel or BMS, which supplies its own voltage from outside this cabinet, so those terminals stay live with the generator locked out. Have that circuit disconnected and locked by the panel technician before touching the contact terminals.	Display dark and no compressor cycling. Treat this as a secondary confirmation only, never as the electrical test.
3. Compressed air in the cabinet	The generator makes its own process air with an internal compressor — there is no external feed compressor supplying the PSA beds. The air side still holds pressure after shutdown. Stop the unit at the On/Off toggle, then open and lock the disconnect. Do not assume the filter section self-vents. Watch the filter assembly's own gauge and confirm it falls to zero. If it will not fall, the section is still being fed or the vent path is blocked — re-check that the unit is off, that the disconnect is open, that the 3-way valve is off Nitrogen Out, and that no bypass air supply is feeding the cabinet. If it still holds after that, contact South-Tek rather than cracking anything to find out.	0 PSIG on the filter assembly's own gauge, inside the cabinet behind the front cover — not the panel gauge, which reads storage tank pressure and tells you nothing about the filter section. Powering the unit down does not depressurize it.
4. Stored nitrogen	Close both ball valves on the nitrogen storage tank manifold — the inlet valve and the upper outlet valve. Those are the isolation for stored nitrogen. Closing them stops all make-up gas to the riser, so this is a fire protection impairment — it must be covered by the notification and the tag from step 1 of the sequence below. The 3-way valve at the cabinet does not isolate the tank: the tank sits downstream of it, so turning that handle isolates the generator and puts the riser on bypass air (see the 3-way outlet / bypass valve, above). Then bleed the tank and cabinet to atmosphere in a well-ventilated space — never into a closet, pit, or valve room.	0 PSIG on the storage tank's own gauge at the tank manifold. The cabinet gauge normally reads tank pressure, but only through the tank inlet valve — once you close that valve the cabinet gauge is cut off from the tank and reads the generator side instead, so it cannot prove the tank is empty.
5. Sprinkler system pressure	Close the air maintenance device (AMD) feeding the section you are opening, then drain that section per the site procedure. This is a fire protection impairment — it must be covered by the notification and the tag from step 1 of the sequence below. The section is full of nitrogen, so drain and vent it to a well-ventilated space or outdoors, never into a closed valve room, closet, or pit, and treat the room as oxygen-deficient until it has been ventilated and reads 19.5% O₂ or better on a calibrated meter. The 3-way outlet valve at the cabinet isolates the generator from the riser — it does not relieve riser pressure.	0 PSIG on a gauge on the riser section you are actually opening. The cabinet gauge reads the generator side and tells you nothing about the riser. This is the isolation most often missed — closing the outlet valve at the generator leaves full supervisory pressure sitting on the downstream side of it.
6. Bypass air supply	Where an air supply is piped to the bypass inlet at the lower port of the 3-way valve, close and lock its isolation valve and lock out the compressor feeding it. Turning the 3-way valve off Nitrogen Out opens that air supply into the riser — it is not a safe parking position. Isolating it removes the last make-up gas the riser has, so this is part of the same impairment.	0 PSIG downstream of the bypass isolation valve, and the bypass compressor locked and proved dead.

⚠ Warning — power down for all maintenance Power the system down before any maintenance, not just electrical work. The internal compressor starts automatically on tank pressure whenever the unit is energized, with no warning. Never crack a filter bowl, a fitting, or a drain to find out whether a section is still pressurized — work the isolations in the table above, and if a gauge will not fall to zero after them, stop and contact South-Tek. The control panel is a UL 508A open-type panel, which means the cabinet door is the guard — energized terminals are exposed whenever it is open. Do not open the door on an energized unit except for a defined live-observation task carried out under the site's energized-work authorization, and never with a tool in hand.

Recommended sequence

Treat this work as a fire protection impairment. Notify the building owner or their impairment coordinator and the alarm monitoring company before you begin — the monitoring company will see a genuine alarm the moment you open the disconnect — and meet any AHJ and property-insurer requirements. Tag the system under the site's impairment program, separately from your personal lockout tag. If the work will reach the common alarm terminals, arrange at the same time for the fire alarm panel technician to disconnect and lock that circuit — it is powered from the panel, not from this cabinet, and your disconnect does not kill it.
With the unit still energized, turn the 3-way outlet valve off Nitrogen Out and confirm the bypass alarm appears on the display and the red bypass indicator lights. This is your only chance to prove the valve state — both go dark the moment you open the disconnect, and handle position on its own proves nothing. Then stop the unit: move the On/Off toggle to Off. There is no start/stop function on the keypad, and letting the unit reach cut-out only puts it in Standby, from which the compressor restarts on its own. Then open and lock the branch-circuit disconnect.
Apply your personal lock and tag.
Close the remaining isolation valves before you open any bleed, and lock and tag each one as you close it — both ball valves on the nitrogen storage tank manifold (the inlet valve and the upper outlet valve), any bypass air supply piped to the lower port of the 3-way valve — close and lock its isolation valve and lock out the compressor feeding it, and the AMD upstream of the section you are working on. The 3-way valve itself was already turned and proved in step 2. Closing the tank valves and the bypass supply stops all make-up gas to the riser, and closing the AMD and draining a section removes protection from it — all of it falls under the impairment declared in step 1. Do not open a bleed before these are shut, or you will vent the sprinkler system's supervisory gas through the generator.
Bleed the stored nitrogen in the tank and cabinet to atmosphere in a well-ventilated space, and confirm the filter assembly's gauge has fallen to zero.
Drain the isolated riser section to atmosphere per the site procedure, venting to a well-ventilated space or outdoors.
Verify zero energy against every row of the table above — absence of voltage proved with a meter, display dark, filter section at 0 PSIG on its own gauge, storage tank at 0 PSIG on the tank's gauge, the bypass air supply locked out and 0 PSIG downstream of its isolation valve, and riser at 0 PSIG where the riser was isolated.
Only then begin work.
Restore in reverse order, with a second person verifying. Before you leave, confirm all of it: the 3-way valve back in Nitrogen Out, the bypass alarm and indicator cleared, both tank ball valves reopened, the riser back at supervisory pressure with the unit supplying nitrogen, the panel showing no active alarm from the generator, and the impairment tag cleared with everyone you notified in step 1.

▲ Attention — documentation is part of the job Sign in and out of the customer's lockout/tagout log, record zero-energy verification on the work order, and photograph applied locks. Good documentation protects the technician as much as it protects the equipment.

Personal protective equipment

Equipment	When it is required
ANSI Z87.1 safety glasses	Whenever the cabinet door is open while the machine is running, and during any pressurized work.
Hearing protection	Per site policy while the equipment runs, and wherever the overall noise level in the room requires it.
Gloves	Filter changes — wet particulate and coalescing bowls, sharp sheet-metal edges, and O-ring handling.
Calibrated oxygen meter	Before entering any confined space downstream of a vent. Do not enter below 19.5% O₂.
Electrical PPE per site policy	Any work at the panel or the disconnect, and any live-observation task with the door open. That task also needs site energized-work authorization — it is not something to decide on your own at the cabinet.
No loose clothing, jewelry, or untied long hair	Any time you are near running equipment.

Installation and mounting safety

Install indoors, upright, in a nonhazardous location, with ambient temperature between 40°F and 100°F (4–38°C).
Do not install near a heat source, or anywhere steam or water may contact the unit.
The cabinet weighs approximately 84 lb. Use two people or mechanical assistance to lift and position it, and confirm the wall or rack can carry the load.
Maintain at least 6" of clearance on both sides — the ventilation intake is on the left — and 36" at the front for access to the control panel, the connections, and the front cover. Allow 55" of height for the 50" tank plus its manifold.
Mount the cabinet on the A05-TYP1-RD wall bracket kit, to studs at standard 16" centres. If the studs are not 16" on centre, back the mounting area with 1/2" or thicker plywood before hanging the unit. All mounting holes take 1/4" screws or anchors, not supplied.
Secure the nitrogen tank upright to the wall: strap around the tank with the plastic clip, and the D-ring assembly bolted to the wall with 1/4" hardware (not supplied). Handle the tank as a two-person or mechanical lift.
Plumb the 1/4" OD drain port at the bottom right of the cabinet, and both filter auto-drains, to a site drain or floor sink, open to atmosphere. Unpiped auto-drains discharge condensate and a jet of air at floor level without warning.
Never place or stack objects on top of the unit.
Remove the four painted shipping bolts under the cabinet before first power-up. Left in, they transmit compressor vibration straight into the mounting. See Installation and Startup.
An optional floor-mounting kit is available. Where it is used, the load-bearing and securing requirements above apply to the floor mounting instead of the wall.
Improper installation may cause bodily harm or equipment damage, and voids the system warranty.

⚠ Warning — secure both flanges Secure the cabinet at both the top and bottom flanges. Failure to secure both points can allow the unit to fall, causing injury or damage — the cabinet vibrates while the internal compressor runs, so the mounting has to hold under vibration, not just static load.

If someone is overcome

⚠ Warning — do not become a second casualty 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 of the space, 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. And if you yourself start to feel dizzy, confused, or short of breath near this equipment, leave the area immediately and tell someone — do not stay to finish the task or to close a valve. Confusion is an early symptom, which is exactly why you cannot rely on your own judgement once it starts.

Unauthorized modifications and qualified personnel

Only competent, trained, and authorized individuals may install, operate, maintain, or repair this equipment. Unqualified people should not work on it.
Do not alter factory controls, instrumentation, or controller settings without prior written approval from South-Tek Systems. All programs are proprietary and password-protected from the factory, and unauthorized changes void all warranties and may cause system damage or malfunction.
Do not adjust the factory-preset cut-in and cut-out pressures without consulting South-Tek.
Use only approved replacement parts that meet or exceed the original specification.
Do not tamper or experiment with the equipment, and do not exceed its technical specifications. Use the unit only for its designed purpose.
The owner is responsible for keeping the unit in safe working condition at all times.

Manual downloads

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