APS Flow Settings Reference (APS2 and APS4) – South-Tek Systems

This article provides a general reference for AutoPurge System (APS) flow settings used with supported South-Tek N2-BLAST fire protection systems.

APS flow settings are used during field tuning to establish a controlled purge at each riser. The correct setting depends on the APS model and the size of the associated zone or riser.

This article is intended as a reference only. The APS should be properly installed, and the fire protection system should be at supervisory pressure before any setting is adjusted.

APS model types

APS flow settings vary by APS model. The most common settings references are for APS2 and APS4 configurations.

Always confirm that the setting being used matches the installed APS model and the applicable South-Tek label or setup information on the device.

How APS settings are used

During setup, the APS flow dial is turned from the closed position until the center of the float bead reaches the applicable alphabetical setting. That alphabetical setting corresponds to the zone or riser volume for the installed APS model.

If the system includes a Quick-Check or PowerSaver connection, refer to the applicable setup guidance before finalizing the adjustment.

APS2 flow settings

APS2 units use alphabetical flow settings based on the associated zone gallon range.

50 gallons: 1/4
100 gallons: 1/2
150 gallons: 3/4
200 gallons: A
250 gallons: A+1/2
300 gallons: A+3/4
350 gallons: B
400 gallons: B+1/4
500 gallons: B+1/2
550 gallons: B+3/4
600 gallons: C
650 gallons: C+1/4
750 gallons: C+1/2
800 gallons: C+3/4
850 gallons: D
900 gallons: D+1/4
950 gallons: D+1/2
1000 gallons: D+3/4
1050 gallons: E

APS4 flow settings

APS4 units use alphabetical flow settings based on the associated zone gallon range.

1100-1250 gallons: A
1250-1500 gallons: A+1/4
1550-1700 gallons: A+1/2
1750-1900 gallons: A+3/4
1950-2050 gallons: B
2100-2300 gallons: B+1/4
2350-2550 gallons: B+1/2
2600-2750 gallons: B+3/4
2800-3050 gallons: C
3100-3300 gallons: C+1/4
3350-3600 gallons: C+1/2
3650-3850 gallons: C+3/4
3900-4000 gallons: D

Special note for Quick-Check and PowerSaver installations

If a Quick-Check or PowerSaver manifold is connected to the APS, the 1/4" tubing should be removed from the APS adapter during adjustment and reconnected after the float bead has stabilized at the intended setting.

Depending on the installed configuration, the target setting used during setup may differ from a standard APS-only installation. Refer to the applicable setup guidance for those configurations.

Best practices

Confirm the installed APS model before using any settings reference
Start with the APS flow dial fully closed before making adjustments
Tune the APS only after the fire protection system is at supervisory pressure
Use the setting label on the APS as the primary field reference
Verify all tubing connections are restored after setup if optional accessories are installed

Need additional support?

Phone: (910) 415-1880
Email: support@southteksystems911.zendesk.com