Dräger Polytron 8900 UGLD Notice D'utilisation page 11

Sensor orientation and coverage
The instrument detects ultrasound within a 360° coverage.
However, coverage is not spherical since the sensor is more
sensitive to the front than off to the side or back. Therefore,
coverage range is affected by the sensor's orientation towards
possible leaks.
Detection range for different leaks sizes of CH
alarm thresholds.
5 m above ground
100,0 g/s, alarm ≥ 70 dB or 50,0 g/s, alarm ≥ 64 dB
1
2 50,0 g/s, alarm ≥ 70 dB or 50,0 g/s, alarm ≥ 70 dB
3 25,0 g/s, alarm ≥ 70 dB or 50,0 g/s, alarm ≥ 76 dB
4 12,5 g/s, alarm ≥ 70 dB or 50,0 g/s, alarm ≥ 82 dB
Limits to sensor orientation
The sensor surface should be facing potential gas leak
sources. In most cases, the orientation of the sensor will be
best facing downwards. In any case, objects (e. g. raindrops)
falling onto the sensor surface generating a signal due to
physical impact should be prevented.
3.4.5 Mapping survey
Mapping surveys should be conducted before an instrument
is installed. A mapping survey is conducted by using a field
survey device to record background ultrasound noise. The
field survey device uses the same microphone as the
instrument. Background noise readings serve as the basis for
defining alarm set points. A background noise level must be
determined for each installation location so that an
appropriate alarm threshold can be defined for that location.
A mapping survey can be requested through the Dräger
Service organization.
The following environmental conditions need to be considered
because they can affect the measurement radius of the
sensor.
– Typical temperature and humidity range
Ultrasonic range is higher with cold, dry air and lower with
warm, humid air
– Typical and maximum background noise
A field survey device may be used to log background
noise.
Instructions for use |
Dräger Polytron
at different
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Distance [m]:
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8900 UGLD
There are two initial situations for a mapping survey.
– Green field
The site to be mapped does not yet exist. During the
planning stage, possible installation locations are
determined based on estimated background levels.
– Brown field
The site to be secured does already exist and is in
operation. Measurements of typical and maximum
background levels may be performed on site.
3.5 Interfaces
● 4 to 20 mA analog (per NAMUR recommendation NE43)
®
● Digital HART output signal
● Relays with alarm delay functionality
3.6 Approvals
3.6.1 ATEX
See approval label. There is also a printout of the approval
label inside the shipping box of the instrument.
3.6.2 Marking
The marking is reproduced on a separate piece of paper
shipped with the instrument.
Serial Number key: The third letter of the serial number
specifies the manufacturing year: M = 2019, N = 2020, P =
2021, R = 2022, S = 2023, T = 2024, U = 2025, W = 2026, X =
2027, Y = 2028, Z = 2029, etc. (Letters G, I, O, Q are omitted)
Example: Serial Number ARMB-0001: the third letter is M,
which means that the unit was manufactured in 2019.
4 Installation
Obey the safety statements mentioned in 1 Safety-related
information!
4.1 Mechanical installation
The instrument can be mounted for measuring ultrasound in
ambient air.
1. Use M6 (1/4'') bolts with hex socket caps to mount the
enclosure to one of the following options.
Option
Mounting on a flat surface
Mounting on a pole
1) Alarm delay functionality will be available in a future firmware release.
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Installation
1)
Drilling template 4544299
Pole mount kit (part number
4544198)
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