Oxygen Detectors - Prosense PQ Series Installation And User Manual

The relay module set to NO (Normally Open – De-Energised) position at factory. The Fault
relay is set to NO (Normally Open – Energised). It will be de-energized in case of power
failure. This helps user to easily identify any power outage on detector side.
The alarm levels are also adjustable via using SW1 and SW2 alarm level pins. Alarm levels are
defined as percentage in LEL for flammable gases. The alarm levels can be adjusted using
jumpers to switch SW1 and SW2. Possible options are given in table-9:
SW1
Open
Open
Closed
Closed
Alarm levels can be adjusted via user menu in PQD models. These settings will overwrite to
SW1 and SW2 settings.
The alarm levels for toxic gases are defined with the same percantage level of the
measurement range as given in the table. For example an Ammonia detector with 0-100
ppm range will provide alert at 10ppm while SW1 and SW2 is open. If the measurement

Oxygen detectors:

range is 0-300 ppm for the ammonia detector the first alarm will be released at 30ppm.
For oxygen detectors the output values and meanings are different as oxygen is naturally
available in atmosphere:
Alarm levels are also different as given in below table:
In PQD model detectors, alarm levels and relay outputs can be set to the desired value except for
lower or upper level definitions given for oxygen. Both alarm levels can be used for decreasing or
increasing values.
PRS-UM-PQ-EN-Rev.05-18.06.2020
SW2 Al1 Level (LEL or PPM)
Open
Closed
Closed
Open
Table 9: Alarm level pin positions (for % LEL or % PPM)
Port Usage
Fault Fault Relay output
AL1 Alarm 1 Relay output - Lower level for Oxygen
AL2
Alarm 2 Relay output - Higher level for Oxygen
Table 10: Relay module output meanings for Oxygen detectors
SW1 SW2
Open Open
Open Closed
Closed Closed
Closed Open
Table 11: Alarm level (% Vol) pin positions for Oxygen detectors
Al2 Level (LEL or PPM)
10 %
10 %
20 %
20 %
Al1 Level Al2 Level
19 %vol 23 %vol
19 %vol 22 %vol
18 %vol 22 %vol
18 %vol 23 %vol
15 %
20 %
25 %
40 %
22