User Guide
Intelligent Purger System (IPS) for Ammonia
Technical data, installation, and use
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User Guide | Intelligent Purger System (IPS) for Ammonia - Technical data, installation, and use
2 | BC297731816824en-000101 | 148R9643
Contents Page
Introduction........................................................................................3
Features
............................................................................................3
Working principle
..................................................................................4
Working cycle
......................................................................................5
Air traps
............................................................................................6
Connection locations
...............................................................................7
Connection points
..................................................................................9
Installation
....................................................................................... 10
Electrical wiring ..................................................................................12
Light Indicators................................................................................... 14
Display ...........................................................................................15
Programming/Configuration...................................................................... 16
Technical data.................................................................................... 18
Ordering
......................................................................................... 18
© Danfoss | DCS (hhr) | 2019.02
User Guide | Intelligent Purger System (IPS) for Ammonia - Technical data, installation, and use
© Danfoss | DCS (hhr) | 2019.02
BC297731816824en-000101 | 148R9643 | 3
The Danfoss Intelligent Purger System (IPS)
is a stand-alone, self-contained purging unit
designed to remove non-condensable gases
(NC gases = air and other unwanted foreign
gases) from industrial ammonia refrigeration
systems.
The ingress of NC gases into a refrigeration
system is inevitable, regardless of the refrigerant,
pressures, or temperatures. NC gases in the
system will result in a decrease in system
efficiency, both in terms of an increase in power
consumption and reduced cooling capacity.
Due to having a different density than ammonia,
the ingressed air will accumulate in specific areas
of the system, where it can be removed using the
Danfoss IPS.
The accumulation areas are identified in the
Connection locations section, along with
recommended connection principles.
The purger unit is an electronic-controlled, selfemployed R404A refrigerant system that runs
independent of the main ammonia system and
with only one flange connection to the ammonia
plant.
This flanged opening allows access of the
ammonia gas/NC gas mix to the purger
evaporator, where it is divided into ammonia
condensate and NC gases. The ammonia
condensate is returned by gravity to the main
plant, while the NC gases are purged to the
atmosphere through a water bath.
Through the flanged opening, the purger unit
has access to all parameters from the ammonia
plant required for full electronic control.
The unit runs automatically in 24-hour cycles,
checking for the presence of NC gases and, if
present, removed.
To regain the design capacity of the main
ammonia system and prevent future air
accumulation, it is highly recommended to install
the Danfoss IPS.
Introduction
Features
• State-of-the-art electronic controlled unit
based on the Danfoss MCX controller platform.
• Reduced power consumption.
• Automatic purging response to NC gases in the
refrigeration system.
• Continuous monitoring of differential pressure
between system refrigerant and purger
refrigerant.
• Electronic purging that minimizes refrigerant
(ammonia) relief to the environment.
• Self-contained unit operation, which functions
independently from the main plant.
• An operation log for easy purging cycle data
monitoring.
• Self-diagnostics for unit and system operation
to shut down in case of malfunction of air
purger components.
• Cost-effective installation with few mechanical
and electrical connection interfaces.
• A hermetic internal cooling system, which
minimizes leakage risks.
• A plug-and-play stand-alone design, which
eases installation and commissioning with low
risk of potential errors.
• No need for advanced settings.
• A compact and easy-to-handle design.
• Patent pending on IPS.
User Guide | Intelligent Purger System (IPS) for Ammonia - Technical data, installation, and use
4 | BC297731816824en-000101 | 148R9643
Working principle The Danfoss IPS is factory-tested and ready for
use in ammonia plants with a condenser pressure
of more than 6 bar (87 psi). The purger is charged
with 500 gram (17.637 oz) of R404A.
Only 2 mechanical connections are needed for
the purger (see fig. 1). The exchange of ammonia/
NC gases with the main plant is done through
the flange for ammonia access (see 11 in figure
below), while the NC gas purge is done through
the blow-off pipe after the purge solenoid valve
(15)
Through the flange for ammonia access (11), a
mixture of ammonia gas and NC gases enters the
evaporator (10) of the purger.
This ammonia/NC mix is cooled down below
the condensing temperature of the ammonia
by the R404A circuit. At this point, ammonia gas
condenses and returns to the ammonia plant via
gravity, whereas the NC gases accumulates in the
evaporator (10) for subsequent purging.
By condensing the ammonia gas, a new
ammonia/NC gases mix is naturally pulled
through. This new mix is separated through a
continuous process.
While the NC gas concentration in the evaporator
(10) increases, the R404A evaporator pressure
and temperature will continuously lower.
The controller monitors R404A evaporator
pressure and ammonia pressure and temperature
and when R404A pressure reaches a predefined
pressure differential to the ammonia pressure/
temperature, it prepares to purge the NC gases
through the solenoid valve (15). The blow-off
is activated by the solenoid (15) and through
appropriate piping/hosing, it is led into a water
bath. This process is done to retain small amounts
of ammonia (see Installation section).
1 Compressor R404A
2 Safety Switch
3 Condenser coil
4 Fan
5 Fan control
6 Liquid reciever
7 Filter
8 Sight glass
9 Expansion valve
10 Evaporator R404A
11 Flange for ammonia access
12 Pressure transmitter R404A
13 Pressure transmitter - Ammonia
14 Temperature sensor - Ammonia
15 Purge solenoid valve
R404A charge 500 gram (17.637 oz)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Fig. 1 - Purger R404A lay-out
© Danfoss | DCS (hhr) | 2019.02
User Guide | Intelligent Purger System (IPS) for Ammonia - Technical data, installation, and use
© Danfoss | DCS (hhr) | 2019.02
BC297731816824en-000101 | 148R9643 | 5
Working cycle The Danfoss IPS operates in 24-hour cycles, of
which 45 minutes are dedicated to a R404A pull
down. At power on, the pull down is initiated
immediately. If no NC gases are detected during
the 45 minute pull down, the system will stand
by for 23 hours and 15 minutes before another
pull down is performed.
To identify NC gases, the controller utilizes
upper and lower thresholds for R404A
evaporating temperature. If, during pull down,
the temperature continues decreasing and the
lower threshold is passed, the controller consider
this to be a high concentration of NC gases
and opens the purge solenoid valve. The purge
valve will stay open until sufficient condensing
ammonia is present to lift the R404A evaporating
temperature above the upper threshold.
The compressor will continue running and if the
temperature again decreases below the lower
threshold, a new purging will be performed. This
process will be repeated until the evaporator
temperature stays above the lower threshold
for 45 minutes after the previous closing of the
purge valve.
Fig. 2 - Power on & Cycle at no NC gases present: CST (compressor start time) and PDT (pull down time) are configurable
Fig. 3 - Purging procedure - Low R404A evap. temperature detected during PDT: Tresholds are configurable.
* If low evaporator temperature is detected (passing lower threshold), the purging procedure will be repeated immediately.
Cycle (CST). 24 hours
Purger Pull down
(PDT): 45 min
Cycle (CST). 24 hours
Purger Pull down
(PDT): 45 min
Time
Power on
Purger Pull down
(PDT): 45 min
On
Off
On
Off
Compressor
Purge valve
Time
On
Off
On
Off
Compressor
Purge valve
Evaporator Temp.
Upper Threshold
Lower Threshold
Non condensables has been purged
- new cycle starts *
User Guide | Intelligent Purger System (IPS) for Ammonia - Technical data, installation, and use
6 | BC297731816824en-000101 | 148R9643
Air traps
dP cond
Liquid level
2
1
a
b
3
4
y
x
2
1
a
b
3
4
dP cond
Liquid level
y
x
Fig. 4 Liquid level. Bottom connected receiver Fig. 5 Liquid level. Top connected receiver
For systems with low pressure liquid level control,
the proper installation of the condenser/ receiver
is as shown in fig. 4 and 5.
The discharge gas from the compressor (1) is
led to the condenser (2) where it is condensed.
The receiver (3) holds the liquid until there is a
demand for liquid from the LP side, e.g., until the
expansion valve (4) opens. If the expansion valve
is closed, the liquid condensed in the condenser
will need to be stored in the receiver and the
level will increase. To secure a free flow to the
receiver, the gas must be allowed to leave the
receiver; this process is accomplished through
the pressure equalizing line (a). The pressure
equalizing line makes the pressure in the receiver
the same as in the compressor discharge line.
The pressure in the condenser outlet is lower
due to the pressure loss in the condenser. Since
the pressure is lower than in the receiver, it is
necessary to mount the condenser higher than
the receiver and allow for a higher liquid level
in the piping between the condenser and the
receiver (b).
This liquid column in the line (b) compensates for
the pressure difference.
Fig. 4 shows the connection to the bottom of the
receiver.
If the liquid from the condenser is connected to
the top of the receiver (fig. 5), a slightly different
arrangement must be made.
The liquid line (b) from the condenser to the
receiver will need to have a goose neck/liquid
trap to secure the additional liquid column to be
established.
While air is heavier than ammonia gas, the air will
collect in two locations in this type of installation:
On top of the liquid in the receiver (x) or on top
of the liquid in the drop leg from the condenser
(y).
© Danfoss | DCS (hhr) | 2019.02
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