Pond Engineering's Primary Fixed Point Cells (Indium, Tin, Zinc, Aluminum and Silver on the ITS-90) combine outstanding precision, repeatability and accuracy with superb durability and ease of use to produce a uniquely convenient, reliable cell. Following the cell geometry described in NIST Technical Note 1265, these cells contain approximately 1.2kg of high purity metal (0.4kg for Aluminum and 1.6kg for Silver) in a machined graphite crucible with a graphite thermowell liner sealed within a quartz glass envelope.
Unique to Pond Engineering's cells is a set of graphite "springs" directly above the crucible. These springs allow the thermowell to float and the crucible to expand more than 1/8" without stressing the envelope. Two glass spacers above the crucible and thermowell liner maintain proper relative positioning of the thermowell liner. Without this precaution, mechanical forces or hydrostatic pressures developed during heating can easily rupture the crucible, thermowell liner, or glass envelope; destroying both cell and thermometer.
The outer envelope extends approximately four inches above the sealed portion of the cell and is fitted with several layers of ceramic fiber insulation to minimize axial heat loss and keep the cell top cool. A machined aluminum cell top bonded to the envelope enhances durability, suspends the cell in the furnace and accommodates a removable handle. These features ensure safe, easy cell insertion, removal and inspection - particularly helpful when the cell must be removed from the furnace to initiate a freeze (as with the Tin cell).
Since the defined Freeze Point conditions can only exist at the liquid-to-gas interfaces under one standard atmosphere pressure, our cells are sealed with high purity Argon at one standard atmosphere with the cell at operating temperature. Hydrostatic head corrections applied to the theoretical freezing point temperature compensate for the pressure of the liquid metal at the effective sensing point of the thermometer used in the cell. A user manual included with each cell includes tables and charts characterizing a typical freeze plateau profile and the cell's hydrostatic head correction. The bound report also includes a certificate of metal sample purity.
- SPECIFICATIONS
- KEY FEATURES
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- K23
- K23MR
- K23XR
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System Setpoint Range 90°C to 455°C Control Stability Better than ±0.02°C Core Gradients Less than ±0.15°C in inner core Setpoint Accuracy Better than ±0.3°C in inner core Preheat Wells 3x Series 600 Inconel
≈0.33" (8.0 mm) I.D.
≈16.0" (40 cm) deepPower Requirements 120 / 240 Volts
8.0 Amps max.
A.C. 47 - 63 Hz.Cabinet Physical Dimensions 18" (46 cm) wide
20" (51 cm) deep
36" (92 cm) high -
System Setpoint Range 90°C to 680°C Control Stability Better than ±0.02°C Core Gradients Less than ±0.15°C in inner core Setpoint Accuracy Better than ±0.3°C in inner core Preheat Wells 3x Series 600 Inconel
≈0.33" (8.0 mm) I.D.
≈16.0" (40 cm) deepPower Requirements 120 / 240 Volts
8.0 Amps max.
A.C. 47 - 63 Hz.Cabinet Physical Dimensions 18" (46 cm) wide
20" (51 cm) deep
36" (92 cm) high -
System Setpoint Range 220°C to 1000°C
(Optional to 1100°C)Control Stability Better than ±0.03°C
(Optional ±0.005°C)Core Gradients Less than ±0.15°C in inner core Setpoint Accuracy Better than ±0.5°C in inner core Main Well Series 600 Inconel
≈2.05" (52 mm) I.D.
≈17.8" (40 cm) deepPower Requirements 120 / 240 Volts
8.0 Amps max.
A.C. 47 - 63 Hz.Cabinet Physical Dimensions 18" (46 cm) wide
20" (51 cm) deep
36" (92 cm) high
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- K23
- K23MR
- K23XR
-
1. Thermally-floating inner core provides tremendous axial and circumferential gradient suppression, protecting against cell damage 2. Linear D.C. heater drive electronics in conjunction with bifilar heater construction minimize electrical interference with thermometer resistance measurements 3. High-temperature PRTs with 20-bit ratiometric signal conditioning used for all temperature sensing means you have no thermocouple drift to compensate for 4. Three-zone furnace geometry and integrated control system provide unsurpassed temperature stability, particularly important when performing comparison calibrations 5. Three preheat wells allow thermometers to be heated prior to insertion into cell, prolonging plateau life 6. Optional comparison blocks allow use of the furnace for comparison calibrations. Ultra-high stability (better than±0.001°C over 15 minutes) available 7. Unique bezel suspends the cell in the isothermal zone and allows for easy insertion, removal and inspection 8. Overtemperature protection (both primary and secondary) is ensured by multiple sensors and an integrated microprocessor-based controller with watchdog safety shutoff -
1. Thermally-floating inner core provides tremendous axial and circumferential gradient suppression, protecting against cell damage 2. Linear D.C. heater drive electronics in conjunction with bifilar heater construction minimize electrical interference with thermometer resistance measurements 3. High-temperature PRTs with 20-bit ratiometric signal conditioning used for all temperature sensing means you have no thermocouple drift to compensate for 4. Three-zone furnace geometry and integrated control system provide unsurpassed temperature stability, particularly important when performing comparison calibrations 5. Three preheat wells allow thermometers to be heated prior to insertion into cell, prolonging plateau life 6. Optional comparison blocks allow use of the furnace for comparison calibrations. Ultra-high stability (better than±0.001°C over 15 minutes) available 7. Unique bezel suspends the cell in the isothermal zone and allows for easy insertion, removal and inspection 8. Overtemperature protection (both primary and secondary) is ensured by multiple sensors and an integrated microprocessor-based controller with watchdog safety shutoff -
1. Machined graphite core, with approximately 10x the thermal conductivity of Nickel-Iron alloys, provides tremendous axial and circumferential gradient suppression, protecting cell from damage 2. Linear D.C. heater drive electronics in conjunction with bifilar heater construction minimize electrical interference with precision thermometer resistance measurements 3. High-temperature 10 ohm PRTs with 20-bit ratiometric signal conditioning are used for all temperature sensing, eliminating thermocouple drift 4. Two zone furnace geometry and integrated control system provides unsurpassed temperature stability, particularly important when performing comparison calibrations. Optional comparison blocks allow furnace to be used for comparison calibrations. With the ultra high stability control option, temperature stability within the comparison block is typically better than ±0.005°C over 15 minutes for unsurpassed high temperature comparisons 5. Unique cell top and furnace design suspends the cell in the isothermal zone, providing for easy insertion, removal and inspection 6. Over temperature protection (both primary and secondary) is ensured by an integrated microprocessor based controller with watchdog safety shutoff