AutoPurge and Quick-Check Overview for N2-BLAST Systems – South-Tek Systems

Applies to: The AutoPurge System (APS2 and APS4) and the Quick-Check accessories, used with South-Tek N2-BLAST fire protection nitrogen generators on dry and pre-action sprinkler systems.

This article provides a general overview of AutoPurge and Quick-Check accessories used with supported South-Tek N2-BLAST fire protection systems.

The APS purges trapped air out of a zone. The Quick-Check accessories show what the purity in that zone actually is, and a PowerSaver manifold also cuts the generator runtime spent holding it there.

What is the AutoPurge System?

The AutoPurge System (APS) removes oxygen-rich trapped air from a zone so nitrogen from the generator can replace it. Filling a system with nitrogen does not by itself clear the air already in the pipe and fittings — the two mix, and the trapped air has to be vented out before the zone reaches its purity setpoint.

Unlike a fixed vent, the APS is adjustable, so each zone can be tuned to purge at the rate that zone needs. That is what keeps a zone from purging too little to reach its setpoint, or purging so much that it drives unnecessary generator and compressor runtime.

The APS is supplied in two models, APS2 and APS4. Tuning one is a field procedure with a defined target — see APS Field Tuning Instructions.

AutoPurge System features

One AutoPurge System per zone.
Fully pneumatic. No electrical power required.
An adjustable flow dial with a float bead. The tuning target is the lettered setting on the label on the back of that APS. Where a PowerSaver manifold is installed the setting is taken from the APS model instead.
A ball valve that shuts the APS off from the sprinkler piping. It does not depressurize the tubing or the manifold downstream. The APS also carries a ball check valve that closes on a rush of pressure or water — a backstop, not a substitute for closing the ball valve.
Site each APS as far from the riser as reasonably possible, and where water will not accumulate. A remote endpoint of the zone is preferred; a low point is an option only where no reasonable remote location exists, and is not preferred. Water reaching a pressurized APS puts it out of service and it has to be stripped and cleaned.

What is Quick-Check?

Quick-Check is not one device. It is a family of three purity-verification accessories, and the difference between them matters: one measures purity and acts on it, one purges on time alone, and one is read by hand.

Accessory	What it does
Portable Quick-Check	Handheld. Spot-checks a zone at an APS or a sample port and displays the result as % nitrogen. Read and recorded by a person.
Quick-Check PowerSaver Manifold 1, 6, 10 and 20 port	Samples each zone automatically, displays its purity and raises an alarm when a zone is out of specification. It stops purging a zone that has reached its setpoint, and returns that zone to normal purging if it drifts back out. Single-port units are also found under the retired name Purity Sampling Manifold — the same device under a name South-Tek no longer uses. The name on the unit does not tell you which program it runs — identify that from the screen, under Quick-Check PowerSaver manifold below.
Quick-Check PowerSaver Timer 6 port	Purges on a fixed timer, then closes the purge valve at the end of the cycle. It does not measure purity, does not display purity and raises no alarms — purity is checked separately. Reset it after the system is tripped and refilled, after compressed air is introduced into the nitrogen system, after repairs to the sprinkler piping, or if a separate purity check on any zone reads above 2.0% oxygen.

Match the port count to the number of zones monitored — a one-port manifold monitors one zone. Quick-Check PowerSaver manifold below covers the manifold at every port count; the PowerSaver Timer has none of the sampling, display or alarm functions described there.

Quick-Check portable purity sensor

The portable Quick-Check reads one point in the system and displays the result as % nitrogen, derived by subtracting the measured oxygen from 100. Use it at an APS port or a sample port on service visits, inspections and troubleshooting.

Regulate the sample through a regulator or metering valve to 3 psig or less and no more than 2 liters per minute. Never take the sample straight off a port at supervisory pressure — over-pressure destroys the sensor and voids its warranty.
Calibrate before use, and weekly while in service. Hold the calibration key for three seconds to calibrate to room air, and recalibrate after a significant change in elevation or temperature. An uncalibrated reading, or one taken in Over Range Mode, is not evidence of a zone's purity — recalibrate and read again rather than recording it.
Convert before comparing. This meter reads in % nitrogen and most Quick-Check setpoints are configured in % oxygen — a 2.00% O₂ setpoint is 98.0% N₂. Read the setpoint on the manifold, and check which unit it is in, before judging any reading.

⚠ Warning — sample in a well-ventilated space only The port discharges nitrogen, which displaces oxygen with no smell, taste or warning. Sample only in a ventilated, non-hazardous location. Never sample in a closet, pit, shaft or sealed room.

Quick-Check PowerSaver manifold

The manifold connects to the outlet of each APS and samples the zones in turn. It is the same device at every port count — 1, 6, 10 and 20 — and behaves the same way on each.

Some single-port units in the field run an earlier program. If the menu offers a PowerSaver Option screen rather than Zone Setup, and the setpoint reads in % nitrogen, the sampling and communication settings below do not apply — see the note under What the purity setpoint is.

Zone-by-zone purity on the display: green means that zone's most recent sample was within setpoint, red that it was not. A zone whose sample path is closed or blocked can hold a green reading, so green is not confirmation that a zone is being sampled now.
A zone that reaches its setpoint stops purging, and resumes normal purging if it drifts back out of specification. That is what cuts generator and compressor runtime.
The time of day for sampling, the sample frequency and the length of purge after a sample are settings under Zone Setup. The factory default samples each zone daily and purges a zone that is out of specification until the next sample.
A history screen records, for each zone, the last day it was out of specification and how many consecutive days it has been out.
A dry contact carries purity and flow alarms out to the supervisory circuit it is wired to, so a zone out of specification is seen remotely rather than at the next inspection. Modbus over Ethernet is available as an option.
Separate purity, flow and filter alarms. The flow alarm covers too little or no sample flow from a zone. Purity and flow are the two alarms that drive the dry contact, so disabling either removes remote reporting of that condition indefinitely — unlike an Initial System Purge, it never expires. Do not disable one to quiet a nuisance condition; call South-Tek Tech Support. If one must be disabled, treat it as an impairment: notify the building owner or their impairment coordinator and the alarm monitoring company, tag it under the site's impairment program, and re-enable it and confirm the zone reads green before leaving site.

Each APS connects to the manifold with ¼ in. OD tubing; sites with no manifold have no such tubing.

⚠ Warning — mount the manifold where it can vent A manifold vents nitrogen in normal operation. Mount it in a ventilated, non-hazardous location, never in a closet, pit, shaft or sealed room. It also stays pressurized after it is switched off — depressurize before opening any fitting or removing a filter bowl.

ℹ Note — what a zone reading is, and is not A manifold reading is the gas at that zone's sample point — not the purity of the whole system, and not the generator's output. A zone in a partly purged network can read poorly while the generator is producing normally. Judge a zone against its setpoint, and judge the generator at the generator.

What the purity setpoint is

Two purity figures apply to a nitrogen-supervised system and they measure different things. Keep them apart.

98.5+% nitrogen is the generator's output purity, measured at the generator outlet.
The purity setpoint is a separate, adjustable value in the Quick-Check, and it is what each zone is judged against — not the generator's 98.5+%. It is entered as % oxygen, factory default 2.00% O₂, and the alarm raises when a zone's oxygen rises above it.

▲ Attention — some single-port manifolds read the setpoint in % nitrogen A single-port manifold running the earlier program takes its setpoint as % nitrogen: a value of 95 raises the alarm when nitrogen falls below 95%. A current unit takes it as % oxygen, where 2.00 raises the alarm when oxygen rises above 2.00%. Those are the same purity read in opposite directions — 2.00% O₂ is 98.0% N₂ — so read the setpoint on the screen and confirm which unit it is in before deciding whether a zone is in specification. Tell the two apart by the screen, not by the name on the unit: the earlier program offers a PowerSaver Option menu screen and its sample timers are factory set, while a current unit offers Zone Setup. A unit on the earlier program also has no Modbus and no Initial System Purge, so a newly filled zone on one purges and alarms until it comes within setpoint — there is nothing to suppress the alarm during the fill.

Initial System Purge

A newly filled system takes time to vent its trapped air, and until it does, zones read out of specification — correctly. Initial System Purge covers that period on the PowerSaver manifold: purging continues without raising a purity alarm. The factory default is 40 days, it is adjustable, and it switches itself off when the days remaining reach zero. On the PowerSaver Timer the equivalent is the timed purge cycle, restarted by toggling the power switch off and on. A single-port manifold on the earlier program has neither, so a newly filled zone alarms until it comes within setpoint.

⚠ Warning — an Initial System Purge suppresses purity supervision Purity is one of the two alarms that drive the dry contact, so while an Initial System Purge runs, an out-of-specification zone is reported neither locally nor to the alarm monitoring company — for as many days as the setting allows. Turning one on changes how the system is supervised: notify the building owner or their impairment coordinator and the alarm monitoring company first, tag it under the site's impairment program, and record the date enabled and the days set. Turn it off as soon as purity is satisfactory rather than letting it run to term, and confirm every zone reads within its setpoint with the purge off before closing the work out.

▲ Attention — run it again after the system has been open If the generator or any part of the system has been open to atmosphere or to water, that air and moisture have to be purged back out before zones will hold their setpoint, and another Initial System Purge is advised. Run it under the conditions above — the purity alarms it silences are real until the zones come back within setpoint.

Before water enters the sprinkler piping

Trip tests, flow tests, pressure and hydro testing, and pipe work all put water into the sprinkler piping. Water that reaches an AutoPurge System puts it out of service. An APS left open during a pressure test also bleeds a slow purge that distorts the test result.

Close the ball valve at each APS before water is introduced. That work is a fire protection impairment in its own right, carried out under the site's impairment program — isolating the APS is a step inside it, not a substitute for it. Closing the valve also stops that zone's sample flow, which raises the flow alarm and trips the dry contact, so notify the building owner or their impairment coordinator and the alarm monitoring company before closing, and tag each closed valve.

Restore every valve before leaving. Once the piping is drained and back in service, reopen each APS ball valve slowly and confirm, zone by zone: the flow alarm has cleared, the APS is back at the setting it was tuned to, and the zone is reading back toward its setpoint. A zone whose valve is still shut does not purge, and nothing on the manifold will tell you the valve is the reason. Where no manifold is installed, or at a PowerSaver Timer site, there is no flow alarm or zone reading to check — confirm each valve is fully open and each APS is back at its tuned setting, and at a Timer site restart the purge cycle by toggling the power switch off and on.

Water that does reach an APS has to be recovered, not just drained: the red anodized section is stripped, drained, cleaned and dried, the wye strainer is cleaned, the full length of tubing to the manifold is cleared, and the sample flow is retuned. Close the APS ball valve, then depressurize the manifold and the tubing run, before opening any fitting — the ball valve shuts off the riser side only, and the manifold stays pressurized after it is switched off. That zone is impaired until the flow is retuned and it holds its setpoint. If the flow will not hold, or the zone will not come back, leave it tagged, keep the owner and the monitoring company informed, and call South-Tek Tech Support before closing out.

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