Danfoss DGS-SC, DGS-IR Installation And Operation Manual
Danfoss Gas Sensor
Type DGS-SC and DGS-IR
with MODBUS
Installation and Operation Guide
ADAP-KOOL® Refrigeration Control System
Installation and Operation Guide | DGS Modbus
© Danfoss | ADAP-KOOL® | 2016.12
2 | RS8HJ102 |
Contents
1. Overview ..................................................................................3
1.1 General Information .................................................................. 3
1.2 Technical Specifications ........................................................... 3
2. General Placement Guidelines ...............................................4
2.1 Machinery Rooms ...................................................................... 4
2.2 Refrigerated Spaces................................................................... 4
2.3 Chillers............................................................................................ 4
2.4 Air Conditioning (Direct Systems VRF/VRV) ..................... 5
3. Dimensions and mounting .....................................................6
4. Installation and Wiring ............................................................7
4.1 Electrical connection and diagram ...................................... 7
4.2 Jumper Configurations ..........................................................10
4.3 Adjusting the Alarm Setpoint .............................................. 11
4.4 System integration ..................................................................12
5. Operation and Stabilisation .................................................13
6. Functional Tests and Calibration ..........................................14
6.1 Introduction ............................................................................... 14
6.2 Bump Testing .............................................................................15
6.3 Calibration Overview .............................................................. 16
6.4 Calculating Calibration Voltage ..........................................16
6.5 Calibrating Semiconductor (SC) Sensors ......................... 16
6.6 Calibrating Infrared (IR) Sensors .........................................16
6.7 Calibration of alarm setpoint ...............................................16
6.8 Calibration of 4-20mA output .............................................16
6.9 Issue Test certificate ................................................................16
7. Installation .............................................................................17
8. Accessories .............................................................................21
9. Troubleshooting ....................................................................22
Appendix A.................................................................................23
Appendix B .................................................................................24
Appendix C .................................................................................25
Installation and Operation Guide | DGS Modbus
RS8HJ102 | 3
© Danfoss | ADAP-KOOL® | 2016.12
1. Overview
The DGS Modbus is a state-of-the-art fixed gas detector which can
detect a wide range of gases. It can also activate external systems
such as fans or shut down and activate sirens, warning lights,
activate dial out systems, or connect to BMS systems including
Danfoss AK-SM 720/ AK-SM 350 and the AK-SM 800 series.
The DGS Modbus can be used:
• in new buildings/areas that require continuous monitoring.
• to add gas detection solutions to an existing system.
1.1 General Information
1.2 Technical Specifications
Power Supply 12/24V AC/DC ±20%, 50/60 Hz, 2 W max.
Power Consumption
SC:153mA / IR: 136mA
Power Monitoring Green LED indication
Visual Alarm RED LED indication
Audible Alarm Buzzer, enabled/disabled
Fault Monitoring Red LED ON ~ Green LED OFF
Fault State 0 - 0.5V (1-5V), 0 - 1V(2-10V), 0 - 2mA (4-20mA)
Analogue Outputs 0-5V, 1-5V, 0-10V, 2-10V, 4-20mA
Digital Outputs 1-Relay, SPDT, Failsafe configured by Modbus or
by product selection
1-Amp / 24V A.C./D.C. / 120V A.C.
Configurable delay by Modbus or by jumper
configuration: 0, 1min., 5min., 10min.
IP Enclosure rating IP 41 or IP 66
Temperature Ratings
IP 41: -20°C to +50°C ( -4°F to 122°F )
IP 66: -40°C to +50°C (-40°F to +122°F )
Dimensions/
Weights per Enclosure Type
IP41 86 x 142 x 53 mm
3.35” x 5.59” x 2.09”
180 g
6.3 oz
IP66 175 x 165 x 82 mm
6.89” x 6.5” x 3.29”
629 g
1 lb 6 oz
IP66 w/
Remote
Sensor
175 x 155 x 82 mm
6.89” x 6.1” x 3.29”
790 g
1 lb 11 oz
IP66 Airflow/
Duct *
175 x 125 x 82 mm
6.89” x 4.9” x 3.29”
578 g
1 lb 4 oz
RS-485 Communications
Baud rate : 9,600, 19,200 or 38,400 (default)
Start bits: 1 Data bits: 8
Parity: even Stop bits: 1
Retry time: 500ms (min time between retries)
End of message: silent 3.5 characters
Approvals
IEC61010-1 RoHS WEEE
* See appendix A for supported air flows and duct sizes
Installation and Operation Guide | DGS Modbus
© Danfoss | ADAP-KOOL® | 2016.12
4 | RS8HJ102 |
NOTE: The DGS Modbus should be installed plumb and level and
securely fastened to a rigid mounting surface.
Sensors must be located within the appropriate wire lengths from
the central control unit (if used).
In all cases the sensor supplied is designed for maximum sensitivity to a particular gas. However, in certain circumstances false
alarms may be caused by the occasional presence of sufficiently
high concentrations of other gaseous impurities. Examples of situations where such abnormalities may arise include the following:
• Plant room maintenance activity involving solvent or paint fumes
or refrigerant leaks.
• Accidental gas migration in fruit ripening/storage facilities (bananas - ethylene, apples - carbon dioxide).
• Heavy localised exhaust fumes (carbon monoxide, dioxide,
propane) from engine-driven forklifts in confined spaces or close
to sensors.
It is recommended setting the alarm delay to minimise false
alarms.
2.1 Machinery Rooms
There is no absolute rule in determining the number of sensors
and their locations. However, a number of simple guidelines will
help to make a decision. Sensors monitor a point as opposed to
an area. If the gas leak does not reach the sensor then no alarm
will be triggered. Therefore, it is extremely important to carefully select the sensor location. Also consider ease of access for
maintenance.
The size and nature of the site will help to decide which method is
the most appropriate to use. Locations requiring the most protection in a machinery or plant room would be around compressors,
pressurised storage vessels, refrigerant cylinders or storage rooms
or pipelines. The most common leak sources are valves, gauges,
flanges, joints (brazed or mechanical), filling or draining connections, etc.
• When mechanical or natural ventilation is present, mount a sensor in the airflow.
• In machinery rooms where there is no discernible or strong
airflow then options are:
Point Detection, where sensors are located as near as possible to
the most likely sources of leakage, such as the compressor, expansion valves, mechanical joints or cable duct trenches.
Perimeter Detection, where sensors completely surround the area
or equipment.
• For heavier-than-air gases such as halocarbon and hydrocarbon
refrigerants such as R404A, propane, and butane sensors should
be located near ground level.
• For lighter-than-air gas (e.g., ammonia), the sensor needs to be
located above the equipment to be monitored on a bracket or
high on a wall within 300 mm (12 in) of (or on) the ceiling – provided there is no possibility of a thermal layer trapped under the
ceiling preventing gas from reaching the sensor.
NOTE: At very low temperatures (e.g., refrigerated cold store), ammonia gas becomes heavier than air.
• With similar density or miscible gases (e.g., CO2), sensors should
be mounted about head high (about 1.5 m [5 ft]).
However, with CO2 in a machinery room it is recommended to
mount it 0.3 m (1 ft) above the floor as the air flow is low and
CO2 slightly heavier than air.
• Sensors should be positioned just far enough back from any
high-pressure parts to allow gas clouds to form and be detected.
Otherwise, a gas leak might pass by in a high-speed jet and not
be detected by the sensor.
• Make sure that pits, stairwells and trenches are monitored since
they may fill with stagnant pockets of gas.
• For racks or chillers pre-fitted with refrigerant sensors, these
should be mounted so as to monitor the compressors. If extract
ducts are fitted the airflow in the duct may be monitored.
2.2 Refrigerated Spaces
In refrigerated spaces, sensors should be located in the return
airflow to the evaporators on a sidewall (below head-high is
preferred), or on the ceiling, not directly in front of an evaporator. In large rooms with multiple evaporators, sensors should be
mounted on the central line between 2 adjacent evaporators, as
turbulence will result in airflows mixing.
2.3 Chillers
In the case of small water- or air-cooled enclosed chiller units
mount the sensor so as to monitor airflow to the extract fans. With
larger models also place a sensor inside the enclosure under or
adjacent to the compressors.
In the case of outdoor units:
• For enclosed air-cooled chillers or the outdoor unit for variable refrigerant volume and variable refrigerant flow (VRV/VRF)
systems, mount the sensor so as to monitor airflow to the extract
fan. With large units also place a sensor inside the enclosure
under or adjacent to the compressors.
In the case of non-enclosed outdoor units:
• If there is an enclosed machinery section locate a sensor there.
• In the case of units with enclosed compressors, mount sensors in
the enclosures.
• Where you have protective or acoustic panels mount the sensor
low down under the compressors where it is protected by the
panels.
• With air-cooled chillers or air-cooled condensers with nonenclosed condenser sections it is difficult to effectively monitor
leaks in the coil sections. With some designs it will be possible
using an airflow sensor to monitor airflow to the start–up fans in
the front or rear sections.
• If there is a possibility of refrigerant leaks into a duct or air-handling unit install a sensor to monitor the airflow.
Weatherproof sensors should be used for unprotected outdoor
applications.
2. General Placement Guidelines
Installation and Operation Guide | DGS Modbus
RS8HJ102 | 5
© Danfoss | ADAP-KOOL® | 2016.12
2.4 Air Conditioning (Direct Systems VRF/VRV)
For compliance with EN378, at least one detector shall be installed
in each occupied space being considered and the location of detectors shall be chosen in relation to the refrigerant and they shall
be located where the refrigerant from the leak will collect. In this
case refrigerants are heavier than air and detectors should have
their sensors mounted low, e.g., at less than bed height in the case
of an hotel or other similar Category Class A spaces. Ceilings or
other voids if not sealed are part of the occupied space.
CAUTION: Monitoring ceiling voids in a hotel room would not
strictly comply with EN378.
Best practice installation includes installing the gas detector at a
height below the room occupants. E.g. in a hotel room this is less
than bed height (between 200 and 500 mm [8 and 20 inches] off
the floor).
Ensure the sensor is mounted away from drafts and heat sources
like radiators etc. and avoid sources of steam.
Avoid mounting it under mirrors, at vanity units and in or near
bed bathrooms.
Installation and Operation Guide | DGS Modbus
© Danfoss | ADAP-KOOL® | 2016.12
6 | RS8HJ102 |
3. Dimensions and mounting
DGS Modbus Standard Housing
50 mm
75 mm
IP66 (with Splashguard)
Splashguard
IP66 Airflow Duct Mount Housing
mounting slots =
9mm long x 6mm
wide use 5mm 6mm screws
mounting
measurements
2
3
4
IP66 Housing with Remote Sensor Head
M42 thread
5
mounting slots =
9mm long x 6mm
wide use 5mm 6mm screws
Installation and Operation Guide | DGS Modbus
RS8HJ102 | 7
© Danfoss | ADAP-KOOL® | 2016.12
4. Installation and Wiring
WARNING
Explosion hazard! Do not mount the DGS Modbus in
an area that may contain flammable liquids, vapors,
or aerosols. Operation of any electrical equipment
in such an environment constitutes a safety hazard.
CAUTION
The DGS contains sensitive electronic components
that can be easily damaged. Do not touch nor disturb any of these components.
NOTE The mounting location of the monitor should allow
it to be easily accessible for visual monitoring and
servicing.
NOTE The monitor must be connected by a marked, suit-
ably located and easily reached switch or circuitbreaker as means of disconnection
NOTE Connect monitor power and signaling terminals us-
ing wiring that complies with local electrical codes
or regulations for the intended application.
NOTE This instrument can be equipped with a semicon-
ductor sensor for the detection of refrigerant, combustible or VOC gases. Semiconductor sensors are
not gas specific and respond to a variety of other
gases including propane exhaust, cleaners, and solvents. Changes in temperature and humidity may
also affect the sensor’s performance.
4.1 Electrical connection and diagram
NOTE: The wiring is the same for the semi-conductor and infrared
models. The controller wiring is the same for all controllers.
There is a 5-minute power-up delay to allow the sensor to stabilise. Also see section 5.
Refer to Figure 1 for internal components and wiring.
Installation and Operation Guide | DGS Modbus
© Danfoss | ADAP-KOOL® | 2016.12
8 | RS8HJ102 |
Figure 1a. Sensor Components (IR sensor)
Figure 1b. Sensor Components (SC Sensor)
Danfoss
80Z731.10
Alarm
P1
J4
Reset
TP1
(Alarm)
Delay
J5
J6
INFRARED
(IR) SENSOR
PC BOARD
GREEN
LED
RED
LED
P4
4-20mA
TP2
(Vs)
P3
Span
TP3
0V
J7 J8 J9 J10
CN4
0012
510510
G+
_
MODBUS
VOLTS
Audible
Alarm
J3
Addressing
AC Select
J1
CN1
CN2 CN3
DC
Select
0V V+
0V V I
Power
Supply
Output Signal
Relay
Out
N / O
COM
N / C
J2
Zero
P2
TX
+V
-V
RX
SIGNAL
SW1SW2
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
Danfoss
80Z730.10
Alarm
P1
J4
Reset
TP1
(Alarm)
Delay
J5
J6
SEMICONDUCTOR
(SC) SENSOR
PC BOARD
GREEN
LED
RED
LED
P4
P2
Zero
4-20mATP2
(Vs)
P3
Span
TP3
0V
J7 J8 J9 J10
CN4
0012
510510
G+
_
MODBUS
VOLTS
Audible
Alarm
J3
Addressing
AC Select
J1
CN1
CN2 CN3
DC
Select
0V V+
0V V I
Power
Supply
Output Signal
Relay
Out
N / O
COM
N / C
J2
SW1SW2
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
Sensor Voltage
Test Point
Sensor Voltage
Test Point
Board Ground
Plane Test Point
Board Ground
Plane Test Point
Audible Alarm and
Relay Set Point
Volage Test Point
Audible Alarm and
Relay Set Point
Volage Test Point
Loading...