Watts UR20S Series Instruction Manual

WattsIndustries.com
UR20S Series
Gas detectors
Technical Data Sheet

Gas detector in metal housing (Group II protection mode, category 3G, Ex nA IIC T6) with
operating status indicator light, for indicating gas alarms by means of a 4-20 mA analogue
output or a trip threshold (pre-alarm, level 1 and 2 alarm, fault) that can be freely set with DIP
switches. Power supply: 11-28 VDC. Signal output: 4-20 mA. An explosion-proof version is
available to order, marked with the ATEX hexagon symbol and designation II 2G, Ex d IIC T6.
Compliant with Directives EMC 2014/30/EU and ATEX 2014/34/EU.
II 3G, Ex nA IIC T6.
UR20S
Type Part No. DN Protection Weight (Kg)
UR20S 0940571 NATURAL GAS IP55 0.65
UR20S 0940572 LPG IP55 0.65
UR20S 0940573 CO IP55 0.65
UR20S Series gas detectors are used for detecting inflammable or toxic gases in classified areas in industrial environments
and boiler rooms. All models can be used with CIVIC1 Series control units (one sensor) and CIVIC4 Series control units (up
to 4 sensors) or with other control units set up to receive a 4-20 mA signal (generally combined fire/intrusion detection systems).
Description
Technical features Natural gas and LPG Carbon monoxide
Sensor type Standard catalytic, pellistor
or semiconductor
Electrochemical cell
or semiconductor
Power supply 11-28VDC 11-28VDC
Maximum power consumption 3.2 W 1.5 W
Measuring range 0-100% LEL 0-500 ppm
Precision (excluding semiconductor) + 5% of full scale, + 10% of reading
Precision (semiconductor) + 10% full scale (at setpoint)
Measurement resolution 1% LEL 5 ppm
Microprocessor resolution 1024 pixels (10 bit) 1024 pixels (10 bit)
Safety circuit Internal watchdog
Warm-up time < 2 mins. < 2 mins.
Stabilisation time < 2 mins. < 2 mins.
Maximum response time < 20s (T50), < 60s (T90)
Average service life of sensor in air 255 weeks 255 weeks
4-20 mA output signal:
Proportional output signal 4mA = 0% LEL 4mA = 0 ppm
(default) 20mA = 100% LEL 20mA = 500 ppm
Threshold-based output signal 0mA = no alarm 0mA = no alarm
(applications with 1 or 2 thresholds)
10mA = 1st threshold = 20% LEL 10mA = 1st threshold = 100 ppm
20mA = 2nd threshold = 40% LEL 20mA = 2nd threshold = 200 ppm
4-20mA output reference selection jumpers with ref. to power supply negative or positive
Fault sensor 22 mA 22 mA
4-20mA output load resistor < 200Ω at 12VDC power supply < 200Ω at 12VDC power supply
200Ω-700Ω at 24VDC power supply 200Ω-700Ω at 24VDC power supply
Ambient temperature (°C):
Operation -20÷50°C -20÷50°C
Storage -20÷70°C -20÷70°C
Ambient relative humidity:
Operation 15%-90% non-condensing 15%-90% non-condensing
Storage 45%-75% non-condensing 45%-75% non-condensing
Operating pressure 80-110 kPa 80-110 kPa
Ambient air speed < 6 m/s < 6 m/s
2
Watts Water Technologies, Inc.

When installing the gas detector, adhere to the following rules:
- fit approximately 20/40cm from the floor for gases heavier than air (LPG);
- fit approximately 20/40cm from the ceiling for gases lighter than air (natural gas);
- fit approximately 150/200cm from the floor for gases with similar density to air (CO). Since CO is a toxic gas, the gas detector
must always be fitted at the breathing height of the room's occupants.
20-40 cm dal sotto
1,5-2 m dal
pavimento
20-40 cm dal
pavimento
Light gases (e.g. natural gas)
Gases with similar density to air
(e.g. carbon monoxide)
Heavy gases
(LPG, petrol vapour)
The UR20S Series gas detector consists of an electronic board, which processes the signal from the sensor and generates
an output signal to send to the gas detector control units on the basis of the concentrations detected. The board is mounted
in a hermetic aluminium housing, which also contains the sensor, fixed at the bottom of it. Change the position of DIP switch 5
to select the detector's operating logic.
12345678
ON
12345678
ON
12345678
ON
12345678
ON
Proportional output signal (default) Threshold-based output signal
Housing
Electrical
connector
Cable gland
Electronic
board
Operating logic DIP
switch Sensor
UR20S Series gas detectors are equipped with an internal sensor that is sensitive to the different gases to be monitored.
After a warm-up and stabilisation period, in which the sensing element comes up to optimum operating temperature, the gas
detectors continuously measure the concentration of gas (CH4, LPG, CO depending on model) and generate a proportional
or threshold-based output signal.
Proportional output signal: the electrical output signal is proportional to the gas concentration, expressed as a percentage
of LEL (Lower Explosion Limit) for flammable gases, and in parts per million for toxic gases.
Threshold-based output signal: when the concentration of gas in the room reaches certain threshold values, the detector
generates electrical output signals. The gas concentration thresholds are expressed as a percentage of LEL (Lower Explosion
Limit) for flammable gases, and in parts per million for toxic gases.
The signal generated must then be managed by the CIVIC Series (or similar compatible) gas detector control units, which
indicate the alarm state by means of a visual or audible alarm.
Operation
Installation
In addition to general considerations, also take account
of the following when selecting the installation position of
the gas detector: proximity of possible gas escape points;
distance of at least 1.5 m from heat sources and ventilation
apertures; never fit in poorly ventilated areas where gas
pockets may occur; keep away from objects that might
obstruct the natural movement of the gas; do not fit in the
immediate vicinity of machines that routinely emit gas in the
course of operation; the installation environment must have
a temperature of between -20°C and 50°C and relative
humidity of less than 90% non-condensing. The device must
be powered off before fitting or removal. The number of gas
detectors to install in an environment is proportional to its
height and surface area.
Electrical connections
The sensor must be installed in accordance with EN 60079-14. Use cables with the following minimum sections in relation to
their length:
In environments exposed to electromagnetic interference, use shielded cable. The sensor must be earthed using the system
provided.
Cable length Minimum section of cable
< 100 m 0.75 mm2
< 200 m 1 mm2
< 500 m 1.5 mm2
3
Watts Water Technologies, Inc.

4-20 mA signal reference
to NEGATIVE (-)
default
to POSITIVE (+)
Earth
terminal
Set of three jumpers JP2
Electrical connector
In its default setting, the sensor uses
the power signal negative as the
4-20mA signal reference; to change
this setting, change the position of the
three jumpers marked JP2.
Output
signal Power supply
4-20 mA 12/24 VDC
+ - +-
UR20S Series gas detectors require regular testing as laid down in the installation manual.
Average service life of sensors: 5 years.
Post-installation checks
UR20S Series gas detectors are factory-set. No on-site setting is required. After
installation, run the following functional test: power up the detector; wait for at least
2 minutes for the sensing element to warm up; check correct operation of the sensor
using a mixture with a concentration of 50% of the LEL of the gas to be detected (CH4
and LPG), or of 500 ppm for CO; check the operation of the sensor status LED; check
that the output signal is as follows:
Proportional output signal: 10.5-13.5 mA
Threshold-based output: 18.5-21 mA
CO detector: 18.5-21 mA LED
Posizione LED di stato sensore
UR20S gas detector status LED status
Warm-up 2 flashes/sec.
Fully operational 1 flash every 10 sec.
Pre-alarm 2 flashes every 5 sec.
1st threshold alarm 3 flashes every 5 sec.
2nd threshold alarm 4 flashes every 5 sec.
Fault Steadily lit
UR20S Series
Gas detector sensor UR20S Series – WATTS brand – in
metal housing (Group II protection mode, category 3G, Ex
nA IIC T6) with operating status indicator LED, for indicating
gas alarms by means of a 4-20mA analogue output or a
trip threshold (pre-alarm, level 1 and 2 alarm, fault) that can
be freely set with DIP switches. Available in three versions,
for detecting natural gas, LPG and carbon monoxide (CO).
Compliant with Directives EMC 2014/30/EU and ATEX
2014/34/EU. II 3G, Ex nA IIC T6.
Specification textOverall dimensions (mm)
UR20S
100
100
155
55
60
Ø 43
CH 22
26
Watts Industries Italia S.r.l.
Via Brenno, 21 • 20853 Biassono (MB) • Italy
Tel. [phone] • Fax [phone]
[e-mail] • www.wattsindustries.com
© 2017 Watts
The descriptions and photographs contained in this product specification sheet are supplied by way of information only and are not binding.
Watts Industries reserves the right to carry out any technical and design improvements to its products without prior notice. Warranty: All sales and contracts for sale are expressly
conditioned on the buyer’s assent to Watts terms and conditions found on its website at www.wattsindustries.com. Watts hereby objects to any term, different from or additional to Watts
terms, contained in any buyer communication in any form, unless agreed to in a writing signed by an officer of Watts.
UR20S-TS-IT-W-UK-01-18-Rev.2