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BAS Research - Launching a weather balloon
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Thelaboratoryitselfisconstructedfrom3x20ftshippingcontainers, andmountedonasteel, leggedplatform. Theplatformisraisedapproximatelyeverytwoyearstomaintainitsheightabovethesnowsurface. ThisisnecessarybecauseoftheamountofsnowaccumulationatHalley.
The trace gas inlet stack comprises a 100 mm internal diameter (i.d.) electropolished stainless steel tube ventilated by a fan at the far end (see diagram below). The air flow through this central stack is ∼314 m³/hour, giving a residence time within the stack of less than 1 second. Samplers drawing from the stack remove only a small percentage of the total air flow. Access to the air flow is achieved via individual 1/4″ stainless steel tubing ports that penetrate to the centre of the air flow.
The aerosol inlet stack comprises a 200 mm i.d. stainless steel chimney with a cowl at the air intake to prevent snow ingress (see diagram below). Ventilation is achieved using a fan with a variable flow rate. The flow rate can be altered according to the volume of air being drawn from the stack by samplers, thus enabling isokinetic sampling.
Each sampler accesses the stack via stainless steel cones installed at the base of the chimney (see Figs A and B below). The area of each cone is specific to a particular sampler’s flow rate, thus maintaining isokinetic flow up to the point of sampling (see Fig A below). Samplers connect to the cones via swagelock connectors.
There are various locations in the walls and ceiling of the laboratory where gland plates allow penetration to the outside world. For equipment that cannot sample from the inlet stacks, dedicated inlets can be passed through the laboratory structure to equipment inside.
Electricity in the CASLab runs at 240V, but a second circuit is available at 110V.
There are two gas stores on the CASLab, one for flammable and one for non-flammable gases. A comprehensive gas distribution system exists for delivering gases to instruments in the laboratory.
There is space in the laboratory for instruments to be either rack-mounted or bench mounted.
There is no running water at the CASLab, but any associated wet chemistry can be carried out at the wet chemistry laboratory on the main station platform. A supply of MilliQ water is available in the wet chemistry lab. Any solutions required for instrumentation can be brought to the CASLab on a sledge.
A cross section through the CASLab showing the main trace gas sampling stack. Trace gas analysers access ambient air through individual access ports along the length of the stack. (Drawing not to scale)
Details of the air intake and sampling set up for the aerosol stack within the CASLab. Note that the drawings are not to scale.
Floor plan of the CASLab: footprint is 20ft by 24ft. (Drawing not to scale)
Photo A cross section through the CASLab showing the main trace gas sampling stack. Trace gas analysers access ambient air through individual access ports along the length of the stack. (Drawing not to scale)
Photo Details of the air intake and sampling set up for the aerosol stack within the CASLab. Note that the drawings are not to scale.
Photo Floor plan of the CASLab: footprint is 20ft by 24ft. (Drawing not to scale)
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