MI 9400 Standard Resistor Oil Bath

The MI 9400 Standard Resistor Oil Bath has been developed based on years of practical experience and feedback from leading laboratories. The result is an extremely stable, quiet and electrically clean oil bath that is ideal for conditioning standard resistors, shunts and other precision components. Thanks to its low electrical noise and excellent temperature uniformity, the 9400 is particularly suitable for use in combination with CCC (Cryogenic Current Comparator) systems and QHR (Quantum Hall Resistance) setups.

Designed for stability and low noise

The 9400 uses Peltier cooling instead of a conventional compressor. This makes the system virtually silent, with minimal vibration and a very low electrical noise floor — essential for measurements at the highest level. Temperature stability is < 0.002 °C, while the maximum temperature gradient in the bath is only 0.1 °C. This performance is achieved through a combination of efficient heat exchange and a carefully designed flow pattern that prevents ‘temperature shadows’. The heat emitted by one heating element therefore does not affect other components in the bath.

Improved flow and quiet operation

The bath is equipped with brushless DC agitators that ensure uniform liquid circulation without electrical interference. The agitation speed is adjustable, allowing the flow pattern to be optimised for different configurations or load conditions. The stainless steel tank is fully grounded and electrically isolated from the anodised resistor shelf, contributing to low noise and safe operation.

Practical design for everyday use

The 9400 is designed as a freestanding system at workbench height, making it easily accessible. The large 25 × 8 inch access door makes it easy to handle larger resistors and shunts. The bath has two drain/fill ports, which facilitates maintenance and fluid replacement. In addition, there are two 2-inch vertical cable glands that minimise wicking and allow the tank lid to be kept closed for maximum temperature stability.

Intuitive operation and advanced control

The 9400 features a modern touchscreen control panel that clearly displays temperature, PID settings, alarm limits and stirring speed. Users can easily adjust setpoints, configure alarms and optimise PID parameters for specific applications. The system has two-stage temperature protection, with both the main controller and a redundant sensor monitoring the temperature. This increases safety and protects both the bath and the connected heating elements.

Integration with MI software

The 9400 comes standard with IEEE-488 (GPIB) and RS232, allowing the bath to be easily integrated into automated measurement systems. It is fully compatible with Measurements International’s Resistance Bridge Operating Software, allowing temperature control and data logging to be seamlessly combined with resistance measurements.

Capacity and fluid

The bath can be filled with 70 to 80 litres of oil or water, depending on the application. The tank dimensions of 686 × 368 × 356 mm provide sufficient space for multiple standard resistors or shunts. The usable tank space is 686 × 279 × 330 mm, offering flexibility for a variety of configurations.

Construction and dimensions

The MI 9400 is built for intensive professional use. Its overall dimensions are 876 × 572 × 1384 mm, with a weight of 113 kg. The solid construction contributes to thermal stability and vibration-free operation. The system operates at 120–240 V, 50/60 Hz, with a maximum consumption of 2400 VA. The Measurements International 9400 Standard Resistor Oil Bath offers an exceptional combination of stability, low electrical noise, ease of use and robustness. Thanks to its quiet Peltier cooling, advanced flow control and modern operation, the bath is ideal for laboratories working with standard resistors, shunts and CCC or QHR systems. The 9400 is a reliable and future-proof solution for precision temperature conditioning at the highest level.