The 915 is, no question, the finest stirred liquid parallel tube bath produced.
Using best practice ratio methods of comparison calibration uncertainties of less than 1mK can be obtained. The bath can also be used to realise ITS-90 Fixed Point Cells (Mercury to Tin Points) with absolute uncertainties to less than 1mK.
The Isotech Parallel Tube Liquid Bath is a development of the previous 815 model and has many features which enhance its performance and enable ease of operation. It is suitable for the calibration of Liquid in Glass Thermometers, Industrial Platinum Resistance thermometers, Standard Platinum Resistance Thermometers, Thermocouples and Industrial Temperature sensors. It can also be used with fixed point cells.
The temperature range of the standard 915 liquid calibration bath (915H) is 40°C to 300°C. When the 915 is used in conjunction with our external chiller the low temperature limit can be extended to -65°C.
The 915 has a wide temperature range using silicon oils and other suitable liquids. All components in contact with the liquid are of stainless steel and are insulated with materials which are completely safe in use. The 915 used in conjunction with a chiller, utilizes the latest ozone friendly gases.
Liquids are circulated by a propeller which mixes and forces the liquid through a specially designed orifice in the rear of the two parallel tubes. A variable speed motor optimizes the flow as the viscosity of the liquid changes. Below the orifice plate liquid is circulated over a mineral insulated heater and temperature sensors which control the temperature of the bath.
The liquid flows up the calibration tube and weirs over the tube into a collection tray where it returns to the rear tube for recirculation. An angled side entry tube enables a refrigeration cooling probe to be inserted in the rear of the two parallel tubes. The standard temperature controller has resolution from 0.01°C to 0.1°C which auto scales to suit the four digit display (all digits can be read with the Cal NotePad Software).
The standard controller can be replaced with a model offering a display resolution of 0.01°C over the whole range. This High Stability controller (Option 915/E) also offers better short term temperature stability, see table.
With the high cost of some silicon oils the 915’s seven litre capacity makes it relatively inexpensive to fill compared to many other baths.
The changing of liquid is easily enabled by using the fitted drain. The design also allows for the expansion of liquids when being raised to a particular calibration temperature.