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Technical information

The laboratory

The laboratory itself is constructed from 3 x 20 ft shipping containers, and mounted on a steel, legged platform. The platform is raised approximately every two years to maintain its height above the snow surface. This is necessary because of the amount of snow accumulation at Halley.

Inlets

The CASLab has dedicated inlet stacks for trace gas and for aerosol sampling which are at roughly 8 m height above the snow surface.

Trace gas inlet stack

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.

Aerosol inlet stack

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.

Gland plates

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.

Power supply

Electricity in the CASLab runs at 240V, but a second circuit is available at 110V.

Compressed gas cylinders

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.

Aerosol sampling

The CASLab is equipped with both high-volume and low-volume aerosol sampling equipment as well as a cascade impactor. Filter changes are done in a clean are of the lab under a laminar flow hood.

Instrument storage

There is space in the laboratory for instruments to be either rack-mounted or bench mounted.

Wet chemistry

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.

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)