UNITED Nitrogen Pac SC-W Guide

M O D E L S C –W
INSTALLATION, COMMISSIONING,
AND MAINTENANCE MANUAL
SERIAL NUMBER: ___________________________________________________________
DATE OF INSTALLATION: ____________
DATE OF COMMISSIONING: ____________
UNITED Fire Systems
Division of UNITED Fire Protection Corporation
1 Mark Road
Kenilworth, NJ USA 07033
908-688-0300
Unitedfiresystems.com
Manual Part Number 30-NPWICM-000
Revision 1.01
Mar 2021

(THIS SURFACE DELIBERATELY LEFT BLANK)

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
i
INDEX
Section
Description
Page
INDEX
List Of Figures
iv
List Of Tables
v
List Of Abbreviations
vi
Safety Information
vii
Foreword
ix
1.
GENERAL INFORMATION
1
1.1
Glossary
1
1.2
System Purpose
2
1.3
Functional Description
3
1.4
Model SC-W Assembly –Internal Arrangement
5
1.5
Model SC-W Assembly –External Arrangement
7
1.5.1
Connections
7
1.5.2
Indicators
7
1.5.3
Controls
7
1.5.4
Other
7
1.6
Nitrogen Receiver –Model NR-5
9
1.7
Nitrogen Receiver –Model NR-10
10
1.8
Nitrogen / Air Maintenance Device –Model NAMD-1
11
1.9
Purge Vent Assemblies
12
1.9.1
Purge Vent Assembly –Model PVA-4 (For Manual Purging)
12
1.9.2
Purge Vent Assembly –Model PVA-2 (For TRUE ADVANCED PURGE (TAP) Device)
13
1.10
N2Purity Analyzer –Hand-Held –Model NA-2
14
1.11
(Optional) TRUE ADVANCED PURGE (TAP) Device –Model TAP-G3
15
1.12
(Optional) Corrosion Monitor Assembly –Model CMA-1
16
2.
EQUIPMENT SELECTION
17
2.1
Introduction
17
2.2
Basis for Equipment Selection
17
2.3
Steps to Follow
17
2.4
Information To Be Obtained During Survey
17
2.5
System Arrangements
19
2.5.1
Type IArrangement
19
2.5.2
Type II Arrangement
20
2.6
Ensuring the NITROGEN-PAC™ Model SC-W is Appropriate for the Sprinkler System in Use
21
2.6.1
Maximum Number Of Risers
21
2.6.2
Determining Volume (In Gallons) Of Each Sprinkler Riser
21
2.6.3
Maximum Volume Of Single Largest Riser
22
2.6.4
Maximum Volume Of All Risers
22
2.6.5
Required Supervisory Pressure
22
2.6.6
Type I Arrangements –Model SC-W Assembly for Initial-Fill with Air
22
2.6.7
Type II Arrangements –External Air Compressor for Initial-Fill with Air
22
2.6.8
Are Sprinkler Systems NEW or EXISTING?
22
2.6.9
Are Sprinkler Systems Equipped with Quick-Opening Devices (Dry Accelerators)?
23
2.6.10
Nitrogen Receiver
23
2.6.11
Nitrogen / Air Maintenance Device –Model NAMD-1
23

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
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2
EQUIPMENT SELECTION (continued)
2.6.12
Nitrogen Purging and Sensing
23
2.6.12 (a)
Purge Vent Assembly (Model PVA)
23
2.5.12 (b)
Hand-Held Nitrogen Purity Analyzer –Model NA-2
23
2.5.12 (c)
(Optional) TRUE ADVANCED PURGE (TAP) Device –Model TAP-G3
24
2.6.13
(Optional) Corrosion Monitor Assembly –Model CMA-1
24
2.7
Equipment Selection Examples
24
3.
INSTALLATION
30
3.1
General Installation Information
31
3.1.1
Unpacking
31
3.1.2
Equipment Locations
31
3.2
Model SC-W Assembly
31
3.2.1
Location
31
3.2.2
Mounting
32
3.2.3
N2Purity Analyzer Connection
34
3.2.4
Outlet Connection
35
3.2.5
Drain Connection
36
3.2.6
Electrical Connections
36
3.2.6.1
General
36
3.2.6.2
Using Top Entry Raceway Attachment Point
37
3.2.6.3
Using Left-Side Raceway Attachment Point
39
3.3
Piping Requirements
40
3.4
Model NR-5 Nitrogen Receiver
41
3.4.1
Wall Mounting With or Without Strut Channel
42
3.4.2
Riser Mounting
43
3.4.3
Inlet, Outlet, and Drain Connections
44
3.5
Model NR-10 Nitrogen Receiver
45
3.5.1
Mounting –Floor-Mount
45
3.5.2
Inlet, Outlet, and Drain Connections
46
3.6
Nitrogen / Air Maintenance Device –Model NAMD-1
47
3.7
Purge Vent Assembly –Model PVA
47
3.7.1
Choice of Model PVA To Use
47
3.7.2
Location
47
3.7.3
Connection to Vertical Piping
47
3.7.4
Connection to Horizontal Piping
48
3.8
N2Purity Analyzer –Hand-Held Model NA-2
49
3.9
(Optional) TRUE ADVANCED PURGE (TAP) Device Model TAP-G3
49
3.10
(Optional) Corrosion Monitor Assembly Model CMA-1
50
3.10.1
Attachment To Sprinkler Piping
50
3.10.2
Vertical Installation
50
3.10.3
Horizontal Installation
50
3.10.4
Electrical Connection
52
4.
COMMISSIONING
53
4.1
Preliminary
57
4.2
Startup
58
4.3.1
30 Minute Initial Fill (Type I System)
58
4.3.2
30 Minute Initial Fill (Type II System)
58
4.4
Purging
59
4.5
Final Acceptance
60

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
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5.
MAINTENANCE
62
5.1
Monthly Inspection
64
5.1.1
Objective
64
5.1.2
Personnel
64
5.1.3
Instructions
64
5.2
Specific Procedures –Monthly Inspection
64
5.2.1
Use of Model NA-2 N2Purity Analyzer to Measure Nitrogen Purity at Model SC-W Assembly
64
5.2.2
Inspection of Enclosure Inlet Filter Element –Model SC-W Assembly
64
5.2.3
Inspection of Exhaust Fan Filter Element –Model SC-W Assembly
64
5.2.4
Use of Model NA-2 N2Purity Analyzer to Measure Nitrogen Purity at Model PVA-2
64
5.3
Annual Maintenance
65
5.3.1
Objective
65
5.3.2
Personnel
65
5.3.3
Instructions
65
5.4
Specific Procedures –Annual Maintenance
65
5.4.1
Replacement of Compressor Intake Filter –Model SC-W Assembly
65
5.4.2
Replacement of Enclosure Inlet Filter Element –Model SC-W Assembly
65
5.4.3
Replacement of Exhaust Fan Filter –Model SC-W Assembly
65
5.4.4
Replacement of Filter Elements –Model SC-W Assembly
66
5.4.5
Drainage of Accumulated Water at Model PVA Purge Vent Assembly
67
5.4.6
Replacement of Strainer at Model PVA Purge Vent Assembly
67
5.5
Maintenance Parts
67
6.
TROUBLESHOOTING
68
APPENDICES
A
N2Purity Analyzer –Hand-Held Model NA-2
B
Installation –Model NAMD-1 Nitrogen / Air Maintenance Device (UFS-710)
C
Checklist –Commissioning –Model SC-W System (UFS-622)
D
Checklist –Monthly Inspection –Model SC-W System (UFS-623)
E
Checklist –Annual Maintenance –Model SC-W System (UFS-624)
F
Coalescing and Particulate Filters
G
Water Separator
H
Limited Warranty –NITROGEN-PAC™ Model SC Systems
J
Limited Warranty –TRUE ADVANCED PURGE™ Model TAP-G3 Device
K
Limited Warranty –SPRINKLER ACCESSORIES Model NAMD-1 Device

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
iv
LIST OF FIGURES
Figure
No.
Description
Page
SECTION 1 –GENERAL INFORMATION
1
Functional Description and General Arrangement
4
2
Model SC-W Assembly –Internal Arrangement
6
3
Model SC-W Assembly –External Arrangement
8
4
Nitrogen Receiver –Model NR-5
9
5
Nitrogen Receiver –Model NR-10
10
6
Nitrogen / Air Maintenance Device –Model NAMD-1
11
7
Purge Vent Assembly, Manual –Model PVA-4
12
8
Purge Vent Assembly (For TRUE ADVANCED PURGE Device) –Model PVA-2
13
9
N2Purity Analyzer, Hand-Held –Model NA-2
14
10
TRUE ADVANCED PURGE (TAP) Device –Model TAP-G3
15
11
Corrosion Monitor Assembly –Model CMA-1
16
SECTION 2 –EQUIPMENT SELECTION
12
Type IModel SC-W System Arrangement
19
13
Type II Model SC-W System Arrangement
20
14
Model SC-W with Model NR-5 Wall-Mount
27
15
Model SC-W with Model NR-5 Riser-Mount
28
16
Model SC-W with Model NR-10 Floor-Mount
29
SECTION 3 –INSTALLATION
17
Dimensions –Model SC-W Assembly
32
18
Strut Channel Mounting –Model SC-W Assembly
33
19
N2 Purity Analyzer Connection –Model SC-W Assembly
34
20
Outlet Connection –Model SC-W Assembly
35
21
Using Top Entry Raceway Attachment Point –Model SC-W Assembly
38
22
Using Left-Side Raceway Attachment Point –Model SC-W Assembly
39
23
Dimensions –Model NR-5 Nitrogen Receiver
41
24
Wall-Mounting with Strut Channel –Model NR-5 Nitrogen Receiver
42
25
Riser-Mounting –Model NR-5 Nitrogen Receiver
43
26
Connections –Model NR-5 Nitrogen Receiver
44
27
Dimensions –Model NR-10 Nitrogen Receiver
45
28
Mounting –Model NR-10 Nitrogen Receiver
45
29
Connections –Model NR-10 Nitrogen Receiver
46
30
Purge Vent Assembly Model PVA –Dimensions and Installation in Vertical Piping
48
31
Purge Vent Assembly Model PVA –Installation in Horizontal Piping
49
32
Installation –Corrosion Monitor Assembly Model CMA-1
51
33
Electrical Connection –Corrosion Monitor Assembly Model CMA-1
52
SECTION 4 - COMMISSIONING
34
Model SC-W Assembly –Valve Locations and Numbers
54
35
Bypass Valve and Indicator Operation
55
36
Model SC-W Assembly –External Indicators and Controls
56
37
Packaging Material –Air Compressor
57
SECTION 5 - MAINTENANCE
38
Model SC-W Assembly Components
63
39
Model PVA Purge Vent Assembly (Model PVA-2 Shown)
66

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
v
LIST OF TABLES
Table
No.
Description
Page
SECTION 2 –EQUIPMENT SELECTION
1
Information To Be Obtained During Survey
17
2
Maximum Limits - NITROGEN-PAC™ Model SC-W Assembly
21
3
Gallons Per Foot Of Pipe Based On Nominal Pipe Size And Pipe Schedule
22
4
Purge Vent Assemblies
23
5
Equipment Selection Examples
24
SECTION 3 - INSTALLATION
6
Minimum Wire Size for Model SC-W Assembly 120 VAC Power
37
7
Piping Limitations
40
8
PVAs for Use with Model SC-W Systems
47
SECTION 4 - COMMISSIONING
9
Valve Numbers and Purposes
54
10
Example –Setting of Model NAMD-1 Connected to External Air Compressor (Type II System)
59
11
Quick Reference Valve Position Table
61
SECTION 5 - MAINTENANCE
12
Maintenance Parts
67

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
vi
LIST OF ABBREVIATIONS
The following is an explanation of abbreviations used in this manual.
MEASUREMENT UNITS
ABBREVIATION
UNIT
PARAMETER BEING MEASURED
A
Amperes
Electric current
°F
Degrees Fahrenheit
Temperature
Hz
Hertz
Frequency (cycles per second)
in
Inches
Length
lbs.
Pounds
Weight
PSI
Pounds per Square Inch
Pressure (reference not specified)
PSIG
Pounds per Square Inch, Gauge
Pressure (referenced to normal atmospheric
pressure)
VAC
Volts, Alternating Current
Electrical voltage (electromotive force)
v/v
Volume / Volume
Concentration expressed as a ratio of volumes
OTHER MEASUREMENT TERMS
ABBREVIATION
MEANING
H
Height
L
Length
W
Width
NITROGEN-PAC™ EQUIPMENT
ABBREVIATION
MEANING
NAMD
Nitrogen / Air Maintenance Device
NA
Nitrogen Analyzer
PVA
Purge Vent Assembly
SC-W
“Self-Contained Wall-mount” (refers to self-contained, wall-mounted NITROGEN-PAC™Model
SC-W assemblies)
TAP
True Advanced Purge device
MISCELLANEOUS TERMS
ABBREVIATION
MEANING
MIC
Microbiologically Influenced Corrosion
N2
Nitrogen (2 represents two atoms of nitrogen in a naturally-occurring diatomic molecule)
NFPA
National Fire Protection Association
NPT
National Pipe Thread - Tapered
Sch.
Schedule (refers to standard expression of pipe wall thickness)

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
vii
SAFETY INFORMATION
This manual contains safety information that is important to know and understand. This information is provided for the
safety of installers, operators, and users of the UNITED Fire Systems NITROGEN-PAC™ equipment. Carefully read,
understand, and follow instructions identified by these symbols.
DANGER
RISK OF ELECTROCUTION
The use of the words “DANGER” and “RISK OF ELECTROCUTION” with the lightning symbol identifies an
immediate electrical hazard with a likelihood of death or serious personal injury if instructions, including
recommended precautions, are NOT followed.
DANGER
The use of the word “DANGER” identifies an immediate hazard with a likelihood of death or serious personal injury if
instructions, including recommended precautions, are not followed.
WARNING
The use of the word “WARNING” identifies the presence of hazards or unsafe practices that could result in death,
personal injury, or serious property damage if instructions, including recommended precautions, are not followed.
CAUTION
The use of the word “CAUTION” identifies possible hazards or unsafe practices that could result in personal injury or
property damage if instructions, including recommended precautions, are not followed.
IMPORTANT
The use of the word “IMPORTANT” identifies special instructions, not related to hazards that should be followed.

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
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IMPORTANT NOTICES TO INSTALLERS AND USERS
This manual must be read thoroughly and completely understood before installation and operation of UNITED Fire
Systems NITROGEN-PAC™ equipment. All appropriate safety standards for handling of gases as determined by local or
national laws and regulations should be followed at all times.
WARNING
Do not operate assembly if damage occurred during shipping, handling, or use. Contact UNITED Fire Systems
immediately. Failure to do so could result in death, personal injury, or serious property damage.
General Safety Information
IMPORTANT
Read all of the safety information in this manual before operating this equipment. Use of the equipment in a manner not
specified within this manual may impair the protection provided by the equipment and could result in an unplanned
release of pressure, which may cause serious injury or damage. Only competent personnel, who have been trained,
qualified, and approved by UNITED Fire Systems should perform commissioning, servicing, and repair procedures.
When handling, installing, or operating this equipment, personnel must employ safe engineering practices and observe all
related local regulations, health, and safety procedures, and legal requirements for safety.
Ensure that the equipment is depressurized and electrically isolated before carrying out any of the scheduled
maintenance instructions specified in this manual.
Nitrogen is not a poisonous gas. However, in a concentrated form, there is a risk of asphyxiation. The Model SC-W
assembly produces both a flow of nitrogen and a flow of oxygen enriched air which quickly disperses in the atmosphere.
However, do not directly inhale the output gas from the outlet pipe.
NITROGEN-PAC™ Model SC-W equipment is classified as non-hazardous for transportation purposes and as non-
flammable for fire regulations. This equipment is for indoor use only. Do not operate outdoors.
Specific procedures must be followed for maintenance of the NITROGEN-PAC™ Model SC-W system and the equipment
to which the assembly is connected. Appropriate labels must be continuously displayed in all areas where personnel
might be exposed to a nitrogen atmosphere.

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
ix
FOREWORD
This manual is written for those who install, operate and maintain UNITED Fire Systems NITROGEN-PAC™ Model SC-
W sprinkler corrosion inhibiting systems. The manual contains installation, operation, and maintenance information for
these assemblies.
IMPORTANT
UNITED Fire Systems assumes no responsibility for the installation, operation, or maintenance of any systems other
than those addressed in this manual. The data contained in this manual is for information purposes only. UNITED Fire
Systems believes this data to be accurate at the time of publication, but the data is published and presented without
any guarantee or warranty whatsoever. UNITED Fire Systems disclaims any liability for any use that may be made of
the data and information contained in this manual by any and all parties.
IMPORTANT
UNITED Fire Systems NITROGEN-PAC™ Model SC-W sprinkler corrosion inhibiting systems are a vital part of the
fire protection of any facility where these units are installed. Life safety and property protection depends on continuing
proper operation of these assemblies. The owner of the Model SC-W equipment is responsible for its condition and
continued proper operation. UNITED Fire Systems strongly recommends that all owners of Model SC-W systems
engage the services of qualified, trained fire protection professionals to design, install, commission, and maintain the
equipment.
UNITED Fire Systems NITROGEN-PAC™ Model SC-W sprinkler corrosion inhibiting systems are to be installed and
maintained by qualified, trained personnel in accordance with:
This Installation, Operation, and Maintenance Manual P/N 30-NPWICM-000.
National Fire Protection Association No. 13, “Standard for the Installation of Sprinkler Systems.”
National Fire Protection Association No. 25, “Standard for the Inspection, Testing, and Maintenance of
Water-Based Fire Protection Systems.”
National Fire Protection Association No. 70, “National Electrical Code®”.
Any questions on the information in this manual should be addressed to:
UNITED Fire Systems
Division of United Fire Protection Corporation
1 Mark Road
Kenilworth, NJ USA 07033
908-688-0300
www.unitedfiresystems.com

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
1
1. GENERAL INFORMATION
1.1. GLOSSARY. All glossary terms are defined in reference to their use in this manual. Refer to this glossary for
definitions of unfamiliar terms encountered when reading and using this manual.
Air. Air is the naturally occurring gas making up Earth’s atmosphere. Air consists of a mixture of gases, of which two
predominate (refer to the glossary terms Nitrogen and Oxygen).
Compressed Air. Compressed air refers to the output of the NITROGEN-PAC™ compressor. This air has NOT
been conditioned for filtering and nitrogen separation.
Pressure Dew Point. The temperature at which the water in a compressed gas at given pressure condenses into
liquid water at the same rate at which it evaporates. At temperatures below the pressure dew point, liquid water will
leave the gas.At temperatures above the pressure dew point, liquid water will be taken up by the gas.
Dried Compressed Air. Dried compressed air refers to the output of the NITROGEN-PAC™ Model SC-W assembly
intercooler. This compressed air has been conditioned for entry into the separator membrane.
Microbiologically Influenced Corrosion (MIC). Microbiologically influenced corrosion (also known as MIC)
occurs inside steel dry and preaction sprinkler pipes in the presence of certain microbes. This form of corrosion
causes thinning of pipe walls, possibly leading to failure under water pressure. Pinhole leaks can occur, leading to
water damage. Roughening of the internal pipe surface leads to unpredictable hydraulics, impairing the effectiveness
of the sprinkler system. The tubercles formed by the microbes can loosen, clogging sprinkler heads and impairing or
preventing the discharge of water onto a fire. MIC microbes can be aerobic, growing in the presence of oxygen, or
anaerobic, not needing oxygen but growing in the presence of water. Prevention of MIC results in longer life and
better functionality of the sprinkler system. MIC can be inhibited by using nitrogen to displace oxygen and dry out the
inside of the pipe.
Nitrogen (N2). Nitrogen is a naturally occurring diatomic gas present in Earth’s atmosphere at a concentration of
approximately 78% (v/v). All references to “nitrogen” in this manual are the output from the nitrogen outlet of the
Model SC-W assembly. This outlet delivers gas that is at least 98% (v/v) nitrogen, at a pressure dew point of
approximately -40°F. The pressure dew point of nitrogen is much lower than of compressed air, making nitrogen
much more effective at drying out the inside of a sprinkler pipe.
Oxidation Corrosion. Oxidation corrosion (also known as rust) occurs inside steel dry and preaction sprinkler pipes
in the presence of oxygen and water. This form of corrosion causes thinning of pipe walls, possibly leading to failure
under water pressure. Pinhole leaks can occur, leading to water damage. Roughening of the internal pipe surface
leads to unpredictable hydraulics, impairing the effectiveness of the sprinkler system. Loose rust particles can clog
sprinkler heads, impairing or preventing the discharge of water onto a fire. Prevention of oxidation corrosion results in
longer life and better functionality of the sprinkler system. Oxidation corrosion can be inhibited by using nitrogen to
displace oxygen and dry out the inside of the pipe.
Oxygen (O2). Oxygen is a naturally occurring diatomic gas present in Earth’s atmosphere at a concentration of
approximately 21% (v/v). Oxygen is vented from the Model SC-W assembly after being separated from dried
compressed air by the separator membrane.
Purging. Because of its low dew point, the nitrogen introduced into the sprinkler piping by the NITROGEN- PAC™
system absorbs liquid water. To ensure complete drying of the pipe interior, saturated nitrogen within the pipe must
be replaced by dry nitrogen. Purging ensures that this process occurs.

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
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1.2. SYSTEM PURPOSE. The FM Approved UNITED Fire Systems NITROGEN-PAC™ Model SC-W Sprinkler
Corrosion Inhibiting System is a fully integrated nitrogen generating system designed to introduce high-purity
nitrogen into preaction or dry sprinkler piping. NITROGEN-PAC™ replaces the existing air compressor, providing
the necessary supervisory pressure in the form of nitrogen instead of air. NITROGEN-PAC™ occupies minimal
space, operates quietly, and can be installed near the sprinkler system riser(s).
The interior of preaction and dry sprinkler piping is subject to corrosion, which can lead to clogged sprinkler heads,
leaks, and pipe failure. This corrosion can be of two distinct types. Oxidation corrosion takes place in the presence
of oxygen, and is accelerated by the presence of water. Microbiologically influenced corrosion (MIC) takes place in
the presence of certain microbes that attack metal, again in the presence of water and in many cases oxygen.
Reducing the damaging effects of corrosion is best accomplished by greatly reducing or eliminating the amount of
water and oxygen left in the pipe. Ordinary air compressors used to provide supervisory pressure keep the oxygen
concentration inside the pipe the same as normal air –ideal for oxidation corrosion to take place. Ordinary
compressors also do not dry the air –residual water from system testing remains in low points, and moist air can
actually increase standing water within pipes from condensation. The introduction of high-purity dry nitrogen with a
low dew point reduces or eliminates these two problems. The interior of the pipe remains dry, with very little oxygen
remaining to attack the metal.

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
3
1.3. FUNCTIONAL DESCRIPTION. Refer to Figure 1.
Model SC-W Assembly. This assembly generates either 98% pure nitrogen for protection or air for initial-fill of the
sprinkler piping
Outlet Hose. Vibration from the air compressor inside the Model SC-W assembly is damped by the outlet hose,
minimizing transmission of the vibration to the piping.
Nitrogen Receiver. Compressor runtime and the number of start / stop cycles are minimized by having a reservoir of
nitrogen stored in the nitrogen receiver.
Nitrogen / Air Maintenance Device. Air and nitrogen pressure is properly regulated and delivered to the sprinkler
valve by this device.
Preaction or Dry-Pipe Sprinkler Valve. The trim of the sprinkler valve receives the gas pressure from the nitrogen /
air maintenance device.
Sprinkler Piping. The interior of the sprinkler piping is protected against oxidation corrosion and MIC by the 98%
purity N2generated by the NITROGEN-PAC™ Model SC-W assembly.
Purge Vent Assembly. Air is purged from the sprinkler piping and replaced by 98% pure nitrogen by the Purge Vent
Assembly.
(Optional) Flexible Tubing. Optional) Flexible tubing connects the Purge Vent Assembly to the True Advanced
Purge (Model TAP-G3) device.
(Optional) TRUE ADVANCED PURGE™ Device Model TAP-G3 with ADC. The True Advanced Purge (Model
TAP-G3) device provides automatic control of system purging and includes permanently-connected nitrogen purity
monitoring.

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
4
Figure 1
Functional Description and General Arrangement
MODEL SC-W
ASSEMBLY
OUTLET
HOSE
NITROGEN RECEIVER
(MODEL NR-5)
PRESSURE MAINTENANCE DEVICE
(MODEL NAMD-1)
PREACTION OR DRY-PIPE
SPRINKLER VALVE
SPRINKLER
PIPING
TRUE ADVANCED PURGE™
(MODEL TAP-G3)
FLEXIBLE
TUBING
PURGE VENT ASSEMBLY
(MODEL PVA-2)

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
5
1.4. Model SC-W Assembly –Internal Arrangement. Refer to Figure 2.
Air Compressor. The air compressor supplies compressed air for either nitrogen separation or sprinkler system
initial fill, depending on the position of the Bypass Valve. The compressor's inlet filter is an important periodic
maintenance item (refer to Section 5 - Maintenance).
Intercooler. The intercooler lowers the temperature of the compressed air, condensing water vapor into liquid water
for removal by the water separator. A fan draws external air across the intercooler coils. The fan filter is an important
periodic maintenance item (refer to Section 5 - Maintenance).
Water Separator. The water separator consists of a rugged cast aluminum housing and a filter element with a
stainless steel support core and high performance separator media. The water separator removes condensed water
from the compressed air, allowing the water to drain.
Pressure Regulator. The regulator is factory-adjusted to provide the proper compressed air pressure for nitrogen
separation. THIS IS NOT A USER-ADJUSTABLE COMPONENT. DO NOT attempt to adjust the regulator unless
instructed to do so by UNITED Fire Systems!
Particulate Filter. The particulate filter consists of a rugged cast aluminum housing and a filter element with a
stainless steel support core and high performance filter media. The particulate filter separates particulate matter from
the dried compressed air stream, with the air flowing from the outside of the element to the inside. Periodic
replacement of the filter element is an important maintenance item to protect the separator membrane from
contamination (refer to Section 5 - Maintenance).
Coalescing Filter. The coalescing filter consists of a rugged cast aluminum housing and a filter element with a
stainless steel support core and high performance filter media. The coalescing filter separates oil from the dried
compressed air stream, with the air flowing from the inside of the element to the outside. Periodic replacement of the
filter element is an important maintenance item to protect the separator membrane from contamination (refer to
Section 5 - Maintenance).
Nitrogen Separator Membrane. When dried compressed air is supplied to the inlet of the nitrogen separator
membrane, the smaller oxygen and other gas molecules permeate through the walls of hollow fiber membranes. The
larger nitrogen molecules flow through the fibers, exit the ends of the fibers, and then discharge 98% purity nitrogen
from the outlet of the separator membrane.
Needle Valve. The needle valve is factory-adjusted to provide back pressure to the separator membrane. Proper
back pressure results in the production of 98% pure nitrogen. THIS IS NOT A USER-ADJUSTABLE COMPONENT.
DO NOT attempt to adjust the needle valve unless instructed to do so by UNITED Fire Systems!
Bypass Valve. The Bypass Valve is used to place the Model SC-W assembly into NORMAL or BYPASS mode.
NORMAL mode sends the dried compressed air to the separator membrane, resulting in 98% pure nitrogen being
sent to the sprinkler system piping. BYPASS mode sends the dried compressed air directly to the sprinkler system
piping for 30 minute initial fill as required by NFPA 13.
Outlet Valve. The outlet valve is used to turn on and shut off the gas flow from the outlet of the Model SC-W
assembly.
Enclosure Inlet Filter. The enclosure inlet filter traps dust from entering the cabinet. Periodic replacement of the
filter element is an important maintenance item to protect the separator membrane from contamination (refer to
Section 5 - Maintenance).

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
6
Cooling Fan. The cooling fan draws air through the cabinet, keeping the air compressor cool.
Enclosure Vent. The enclosure vent permits exhaust of compressor cooling air and oxygen from the nitrogen
separator membrane.
Electrical Connection Enclosure. The 115 VAC power connection is made inside the electrical connection
enclosure.
Drain Connection. Water removed from the compressed air exits at the drain connection.
Figure 2
Model SC-W Assembly - Internal Arrangement
ELECTRICAL
ENCLOSURE
BYPASS VALVE
PARTICULATE
FILTER
NEEDLE VALVE
OUTLET VALVE
PRESSURE
REGULATOR
AIR COMPRESSOR
COOLING FAN
ENCLOSURE VENT
N2SEPARATOR
MEMBRANE
COALESCING
FILTER
INTERCOOLER
ENCLOSURE
AIR FILTER
WATER
SEPARATOR
DRAIN
CONNECTION

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
7
1.5. Model SC-W Assembly –External Arrangement. Refer to Figure 3.
1.5.1. Connections.
AC Power Raceway Connection Point. This is the location where raceway is attached to the Model SC-W
enclosure for the three (3) conductors carrying 115 VAC 60 Hz single-phase device power.
Alternate AC Power Raceway Connection Point. This is an alternate location where raceway can be attached to
the Model SC-W enclosure for the three (3) conductors carrying 115 VAC 60 Hz single-phase device power. Refer to
Section 3 –Installation for specific information on the use of this connection point.
Outlet Connection Point. This is the point where the Model SC-W assembly is connected to the nitrogen receiver.
The outlet hose (UFS P/N 32-000038-000 –included with assembly) should be connected to the outlet connection
point at installation. Refer to Section 3 - Installation for information on connecting to this point.
N2Purity Analyzer Connection Point. The Model NA-2 N2Purity Analyzer (qty. (1) included with each Model SC-W
assembly –refer to Appendix A) may be connected here to verify that the Model SC-W assembly is producing 98%
pure nitrogen.
Drain Connection Point. This is the connection point for pipe or tubing to drain away water condensed and
separated from the compressed air.
1.5.2. Indicators.
Power On Visual Indicator. This GREEN indicator is illuminated when 115 VAC 60 Hz single phase power is
applied to the device and the ON / OFF Selector Switch (refer to Figure 3) is in the ON position.
Bypass Visual Indicator. This indicator flashes RED to indicate that the Model SC-W assembly is in BYPASS
mode, capable of delivering compressed air to the sprinkler system for 30 minute initial fill.
Compressor Runtime Monitor. This is a digital display that monitors the total hours and minutes that the
compressor motor has run. This information can be used to evaluate the condition of the sprinkler system.
Pressure Gauges. These pressure gauges monitor the gas pressure upstream and downstream of the separator
membrane (refer to Figure 3). This information can be used to evaluate the condition of the Model SC-W assembly,
and to verify that the assembly is properly de-pressurized for maintenance (refer to Section 5 - Maintenance).
1.5.3. Controls.
ON / OFF Selector Switch. This switch selects device power ON or OFF.
Outlet Valve. This quarter-turn ball valve is used to open and close the Model SC-W assembly outlet.. Refer to
Section 4 - Commissioning, Section 5 - Maintenance, and Section 6 - Troubleshooting for information on when this
valve should be used.
1.5.4 Other.
Enclosure Ventilation Inlet. This location is where fresh air enters the Model SC-W assembly enclosure. A foam
filter (refer to Section 5 –Maintenance) reduces dust accumulation inside the enclosure. It is vitally important that this
vent be kept clear to permit unimpeded airflow.
Enclosure Vent. Vent slots are built-in to the Model SC-W assembly enclosure to permit venting of heated air and
oxygen. An exhaust fan inside the enclosure forces the heated air and oxygen out. It is vitally important that this vent
be kept clear to permit unimpeded airflow.
Mounting Ears. Refer to Section 3 –Installation for use of the four (4) mounting ears to attach the Model SC-W
assembly to the mounting surface.

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
8
Figure 3
Model SC-W Assembly –External Arrangement
BYPASS
VISUAL INDICATOR
MOUNTING TABS
ALTERNATE POWER
CONNECTION POINT
ENCLOSURE VENT
DRAIN CONNECTION
POWER CONNECTION
POINT
POWER ON
VISUAL INDICATOR
ON / OFF SWITCH
RUNTIME MONITOR
PRESSURE GAUGES
N2 PURITY ANALYZER
CONNECTION POINT
OUTLET BALL VALVE
OUTLET
CONNECTION POINT
ENCLOSURE VENT

UNITED FIRE SYSTEMS - NITROGEN-PAC™ MODEL SC-W
INSTALLATION, COMMISSIONING, AND MAINTENANCE MANUAL
REVISION 1.01 MAR 2021 - P/N 30-NPWICM-000
9
1.6. Nitrogen Receiver, 5 Gallon, Wall-Mount or Riser-Mount –Model NR-5. Refer to Figure 4. The Model NR-5
Wall-Mount or Riser-Mount 5 Gallon Nitrogen Receiver is a steel tank for receiving and storing nitrogen from the
Model SC-W assembly, and minimizes the Model SC-W assembly compressor runtime by providing a reservoir of
nitrogen for the sprinkler system. The nitrogen receiver is designed to be mounted vertically on the wall near the
Model SC-W assembly, near the sprinkler system valve(s), or on a sprinkler riser. The tank is manufactured to ASME
Section VIII Division I. The device includes an inlet fitting at the top, an outlet fitting on the side, and a manual drain
valve at the bottom. Integral brackets permit easy mounting. The device is required to be mounted vertically as
shown, so that water drainage can be accomplished.
Figure 4
Nitrogen Receiver –Model NR-5
INLET
(1/2 NPT FEMALE)
PRESSURE GAUGE
MANUAL DRAIN VALVE
PRESSURE RELIEF
DEVICE
OUTLET
(1/2 NPT FEMALE)