Campbell Scientific TGA100 Trace Gas Analyzer Manual - Manual (Page 96)

9 TGA100 ACCESSORIES
9.1 TGA100 Insulated Enclosure Cover
The TGA100 insulated enclosure cover is recommended when the TGA100 is operated in the field without additional
shelter. The cover has a rain-proof, white exterior to reflect the sun’s heat, and additional insulation to dampen diurnal
temperature fluctuations. It fits over the TGA100, attaching with integral hook-and-loop fasteners. It has a flap over the
access hole in the top of the TGA100 enclosure to allow easy refilling of the liquid nitrogen-cooled laser dewar.
To install the TGA cover, place the bottom (uninsulated) piece under the TGA100 analyzer. The bottom has the fuzzy
part (loops) of the hook-and-loop fastener strip around the periphery. Orient the bottom piece so the periphery folds up,
with the strips on the outside. Place the top (insulated) piece over the analyzer, oriented with the flap over the deck plate
to allow the laser dewar to be filled. Connect the side flaps to the end flaps with the hook-and-loop fastener strips, and
then attach the top to the bottom.
9.2 Dewar Evacuation System
The TGA100 dewar evacuation system includes a two-stage, oil-sealed, rotary vacuum pump (Edwards model
E2M1.5). It has a capacity of 2.0 m
3 hr -1 and ultimate vacuum rating of 1.1 mtorr. It includes an activated alumina trap
to prevent back-migration of pump oil, a thermocouple vacuum gauge, and a vacuum shut-off valve. It is used to
periodically evacuate the LN2DEWAR or CRYODEWAR to maintain their insulating vacuum.
Connecting a LN2DEWAR to the dewar evacuation system requires a ½" insert valve operator (CSI VALVOP
TGA100 Evacuation Valve Operator), and a flexible vacuum line with fittings (CSI PN 15896, TGA100 Dewar
Evacuation Kit).
Connecting a CRYODEWAR to the dewar evacuation system requires only the flexible vacuum line with fittings (CSI
PN 15896). No valve operator is required for the CRYODEWAR.
9.3 Sample Vacuum Pump
Campbell Scientific offers two vacuum pumps to pull sample air through the TGA100. The RB0021 and the RA0040
are air-cooled, direct-drive, oil-sealed, rotary-vane pumps. They are supplied with oil, a suction hose (user-specified
length), and all of the fittings needed to connect to the TGA100. Specifications are given for 115 Vac, 60 Hz, single
phase power, but other power options are available. The RB0021's capacity is adequate for most TGA100 applications;
the RA0040 is available for applications requiring a larger capacity.
RB0021-L Specifications RB0040-L Specifications
Length: 44.2 cm (17.4 in) 70.1 cm (27.6 in)
Width: 29.2 cm (11.5 in) 35.6 cm (14.0 in)
Height: 26.9 cm (10.6 in) 26.7 cm (10.5 in)
Weight: 19 kg (42 lbs) 59 kg (129 lbs)
Capacity: 6 actual liters/sec @ 50 mbar 11 actual liters/sec @ 50 mbar
Power: 950 W 1.6 kW
For detailed installation and operating instructions, refer to the user manual supplied with the pump. The following
suggestions may be helpful. The pump must be level to make sure the pump oil reaches the proper places inside the
pump. The pump must be filled with oil of appropriate type, and the oil must be changed regularly. The pump must be
sheltered from weather, but it must be very well ventilated, or it will overheat. The pump requires significant power,
especially at startup. The AC mains wiring must be adequate to supply this power. If an extension cord is used, it must
have conductors large enough to avoid excessive voltage drops for the length of the cord.
The pump pressure depends on the motor speed (which depends on the AC line frequency) and the total flow rate, as
shown in
. The pressure at the TGA sample cell will be slightly higher due to pressure drop in the suction
hose connecting the TGA to the pump.
Figure 9-1
96