Vacuum cryostat 459

Dewar typeliquid nitrogen

Description
The Cryostat 459 is a very low-temperature calibration system operating from -80°C to -180°C using liquid nitrogen.

• Very low-temperature calibration
• High stability
• Controlled operating costs

Low-temperature calibration operations can be costly, hazardous and inconsistent when relying on expensive cooling blocks and hazardous fluids. The Cryostat 459 uses a single controlled fluid to bring a metallic assembly to temperature, providing a straightforward and safe solution. When immersed in liquid nitrogen the system will be cooled to -195°C. Using a controller and a heating block, the Cryostat can be brought to temperatures above that of liquid nitrogen.
The Cryostat includes an insulated copper equalization block inserted into a tube 80 mm in diameter and 480 mm long, held by a flange on the lid designed to accommodate three thermometers, a vacuum connector and a Lemo connector for the temperature sensor and heating block. A cable links the assembly to the controller, which controls the system temperature. An RS-422 connector allows automation of the calibration process via software.
The Cryostat is primarily used between -80°C and -180°C. Oxygen tends to condense from -186°C, which could create safety and health risks if it were to boil.
Operating method
The Cryostat is connected to a vacuum pump for 5 minutes and then sealed. It is connected to the controller to verify connections. Next, it is immersed in the liquid nitrogen container, positioned 25 to 75 mm below the flange. Three thermometer tubes exit the Cryostat and are equipped with nylon compression rings. The platinum resistance thermometer and the thermometers to be checked are inserted into the tubes and the rings are tightened by hand until the nylon grips the thermometer without damaging it. The controller is set to the required temperature and the Cryostat stabilizes. The readings of each thermometer can then be read and compared.
Models and accessories

• Instrument: 459 — Cryostat 459, from -80°C to -180°C
• Liquid nitrogen is not supplied with the system and must be sourced locally
• 459-01-01: Hand pump
• 459-01-02: Electric pump
• 459-01-03: 35-litre container
• 459-01-04: 25-litre upper container
• 459-02-13: Filling tube

Characteristics / technical specifications

• Model: 459
• Temperature range: -80°C to -180°C
• Absolute stability (over 30 min): ±0.005°C at -80°C; ±0.0015°C at -150°C; measurement performed using a 670 thermometer placed at the bottom of one of the wells
• Well-to-well homogeneity: ±0.005°C
• Vertical profile (over 50 mm from the bottom): ±0.005°C at -80°C; ±0.01°C at -150°C
• Immersion depth: 560 mm
• Opening diameter: 120 mm
• Compatibility: liquid nitrogen containers
• Capacity: 35 litres of nitrogen