Kipp&Zonen Brewer MkIII - Manual (Page 14)

MKIII OPERATOR’S MANUAL 11
2.1.1 Mechanical Construction
Refer to Figure 2.1 and Figure 2.2.
The Brewer Spectrophotometer is housed in a weatherproof container constructed from two pieces
- a base, to which all optical and electronic assemblies are anchored, and a removable cover.
When the cover is fastened in place, a weatherproof seal is formed between the top edge of the
base and the bottom of the cover. The dimensions of the assembled container are 70 x 46 x 34 cm.
The Brewer instrument control panel can be viewed through a perspex window in the top of the
cover. Viewing ports for both the iris and the spectrometer entrance slit are visible through this
window.
In one corner of the cover is a 14cm deep, 35° inclined surface. A 6.35 cm by 14 cm hole has been
cut from this surface to provide an opening which is properly positioned to pass direct sunlight or
zenith skylight to the spectrophotometer. This opening is covered by a quartz window [QW 1],
which is secured by a weatherproof seal. ( Items enclosed by square brackets, [ ], are references to
the Selected Parts List, Table 2-2, and Figure 2-5).
Three circular weatherproof connectors are mounted on the side of the Brewer base below the
weatherproof seal. A six-pin male connector marked AC POWER connects to the 120V (or 240 V)
AC power supply. A ten-pin female connector marked COMPUTER carries the RS-422 data
communication signals. A ten pin male connector marked AZIMUTH carries motor control and
monitor signals for the azimuth tracker.
All exposed surfaces of the spectrophotometer container and mechanical linkages are painted with
an enamel for durability and to minimize radiative heating. All machined aluminum parts in the
spectrophotometer system are black-anodized to minimize scattered light and provide a protective
finish.
Mounted inside the Spectrophotometer is a cannister of desiccant which is designed to remove
moisture from the air as the Brewer ‘breathes’ with changes in temperature from night to day. The
desiccant is a ‘self indicating’ type, and can be conveniently removed, without tools, through the
base of the instrument.
This cannister will NOT remove moisture from within the spectrophotometer, and bags or trays of
loose desiccant are usually used for this purpose.
Moisture Sensor
As standard feature, the spectrometer is fitted with a Moisture Sensor. The sensor outputs the
moisture content of the spectrophotometer housing in gm/m
3 and RH%, and can be used as an
indication of moisture leakage problems, or when internal desiccant requires changing. Two
humidity indicators are printed at the top of the Brewer screen: the absolute humidity in grams/m
3
and a temperature weighted moisture index. The moisture index is a relative number that indicates
whether the desicant requires changing. Consistent moisture index values of greater then 10
means that the desicant should be changed.
Heater / Fan Assembly
A heater / circulating fan assembly is included as for in cases where it is desired to maintain
constant temperature or good air mixing within the instrument. The air mixing feature is especially
useful in moist climates, and it enables the internal desiccant to be exposed to the total air volume.
In addition, the mixed air will give a more representitive value of moisture content if the Brewer is
fitted with the moisture sensor option.
The heater will attempt to hold the Brewer’s internal temperature at or above a set minimum
temperature. The minimun temperature can be set at 10°C or 20°C. The minimum temperature is
selected by moving the jumper (J1) on the porportional heater controller (bolted to the Brewer
foreoptics supports near the zenith prism):
2. SYSTEM DESCRIPTION