Made of gold-sheathed tungsten, tungsten, rhenium-tungsten, nickel and nickel alloy. Each provides specific performance characteristics such as corrosion resistance, oxidation resistance, catalytic reactions and sensitivity for use under different application conditions.
- GOW-MAC thermistor detector elements utilize the same mounts as hotwires.
- A thermistor is a thermally sensitive resistor having a high negative co-efficient of resistance.
- Thermistors have relatively low operating temperatures, and should not be used in hydrogen atmospheres.
- They have high sensitivity at low temperatures and can be used at sub-ambient temperatures.
Chemical Resistance Behavior of Various GOW-MAC Filaments
Maximum Operating Currents for Various Cell Temperatures Chart
It is important to remember that the detector bridge should be operated at the lowest temperature (sic current) consistent with the sensitivity required for analysis. The lower the temperature the longer the life. Lower temperatures also reduce noise and increase stability.
The filament chart indicates maximum bridge currents. Recommended values at any temperature are 60 to 70% of those shown.
The thermistor chart indicates recommended values for maximum sensitivity. The sensitivity of thermistor cells tends to have a peak value. Exceeding this value can result in lowered sensitivity. Since the cold resistance varies between pairs, it is recommended that the exact value be determined by experimentation, using the chart as a guide.
Order Information for GOW-MAC Filaments and Thermistors
The basic filaments and thermistors manufactured by GOW-MAC have special lead lengths and spade lugs for easy installation in GOW-MAC GCs. For details of part numbers for GOW-MAC GCs, please contact us or send for our Repair/Replacement List. GOW-MAC also manufacturers replacement detectors and filaments for most GCs made. Refer to the section "Replacement TCDs and Filaments for GCs" for a listing of those GCs.
All shipments are made FOB Bethlehem, PA USA. Terms of sale are Net 30 Days. It is our policy to maintain all filaments and thermistors offered, in stock, for immediate shipment.
All GOW-MAC filaments are tested before shipment. Most filaments are tested and matched in helium but can be matched in other gases on special request.
Pairs vs. Quads
GOW-MAC filaments are sold in matched pairs of quads. A matched pair consists of two elements matched in gas under varying current conditions. While the filaments in a pair are matched, one pair is not matched to another pair. When ordering, we suggest purchasing 3 or 4 pairs to make a well balanced bridge. A quad consists of four elements matched as in a cell. All four filaments exhibit characteristics which tend to compensate for changes in current, temperature and flow. Quads are supplied with 18" electrical leads (longer or shorter leads are available on request) and new tube nuts and are ready for installation in the detector block.
GOW-MAC also offers special filaments for other manufacturers instruments, e.g., Beckman, Perkin Elmer, Agilent (Hewlett Packard), Finnigan, Varian and many more. Contact us for a listing of those manufacturers.
GOW-MAC offers complete cell repair service at our Bethlehem, PA USA facility. We clean, repair and refilament to original equipment specifications. Pricing information is available. Contact us at firstname.lastname@example.org