Model AMD-3 Automatic Nitrogen Maintenance
Device High Pressure (Cylinder) Reducing Type
with Field-Adjustable Pressure Regulator
Page 1 of 4
AUGUST 2018
TFP1241
Worldwide
Contacts
www.tyco-fire.com
IMPORTANT
Refer to Technical Data Sheet
TFP2300 for warnings pertaining to
regulatory and health information.
General
Description
The TYCO Model AMD-3 Automatic
Nitrogen Maintenance Device is an
automatic, field-adjustable, nitrogen
maintenance device of the high pres-
sure reducing type. The Model AMD-3
Device is utilized in conjunction with a
cylinder of high pressure to control the
pressure in a dry pipe sprinkler system,
preaction system, or dry pilot line
system of a dry pilot actuated deluge
or preaction valve.
The Model AMD-3 Device features
a two-stage pressure regulator that
maintains a constant outlet pressure,
as the cylinder pressure decreases to
the set point.
Use of the Model AMD-3 Device is
typically specified in applications for
which a dependable plant or local
air supply is not available; the system
piping requires pneumatic pres-
sure having a maximum dewpoint as
shown in Graph A; or, the presence of
potentially explosive vapors prohib-
its the installation of an automatic air
compressor.
The Model AMD-3 Device is a re-desig-
nation for the Gem Model F328.
NOTICE
The Model AMD-3 Automatic Nitrogen
Maintenance Devices described herein
must be installed and maintained in
compliance with this document and
with the applicable standards of the
NATIONAL FIRE PROTECTION ASSO-
CIATION, in addition to the standards
of any authorities having jurisdiction.
Failure to do so may impair the perfor-
mance of these devices.
The owner is responsible for main-
taining their fire protection system
and devices in proper operating con-
dition. Contact the installing contrac-
tor or product manufacturer with any
questions.
Technical
Data
Approvals
UL and C-UL Listed
FM Approved
NYC Approved under MEA 206-02-E
Maximum Inlet Nitrogen Supply
Pressure
3000 psi (200 bar)
Field-Adjustable Outlet Pressure
Range
4 to 60 psi (0,4 to 4,1 bar)
Inlet Gauge Range
200 to 4000 psi (1000 to 28000 kPa)
Outlet Gauge Range
4 to 100 psi (30 to 700 kPa)
Cylinder Outlet Connection
C.G.A. No. 580
Assembly
Major components illustrated in Figure
1 are factory-assembled, galvanized
steel nipples and malleable iron pipe
fittings. Connection to the system is via
copper tubing and brass tubing fittings.
Design
Criteria
Unless otherwise specified, nitrogen
cylinders with Outlet Connection No.
580 are supplied with nitrogen having
a dewpoint equal to or less than
-60° F (-51°C) at atmospheric pressure.
Graph A illustrates the maximum dew-
point of the supply nitrogen as a func-
tion of the system pressure.
The approximate volume “N” of free
nitrogen (that is, at atmospheric pres-
sure) in cubic feet, required to fill a
system having a capacity of “V” in U.S.
gallons, to a pressure “P” in pounds
per square inch gauge, can be deter-
mined using the formula:
N=0.009VP
A typical cylinder volume is 242 cubic
feet of free nitrogen, but the actual
figure varies depending on the supplier.
The approximate time “T” in minutes to
fill a system having a capacity of “V”
in U.S. gallons, as a function of system
pressure, can be determined using the
formula:
T=CV
where “C” is a constant determined
from the following table:
System Pressure
PSI
“C”
20
0.0400
30
0.0424
40
0.0440
50
0.0451
60
0.0457
