Now In: Frequently Asked Questions
  FREQUENTLY ASKED QUESTIONS   ANSWER
Is a bimetal thermometer tip sensitive? Yes. For the most accurate temperature reading the stem must be immersed into the medium at least 2-3". Unique to all Tel-Tru bimetal thermometers is a groove on the stem that equals the minimum immersion depth so you won't have to measure.
How do I recalibrate a bimetal thermometer? To recalibrate Tel-Tru Bimetal Thermometers see our Pocket/Laboratory/Testing/Spot Checking or Industrial Bimetal Thermometers product manuals.
How can I tell if my thermometer is reading accurately? The Tel-Tru Check-Temp Calibrator allow you to verify the accuracy of dial thermometers and digital probes of all sizes. Our multi hole units fit probes up to .250", .125", .187" and .375" diameter. The Tel-Tru Check-Temp Calibrator allows accurate verification of thermometer accuracy at the temperature point critical to the users actual application. For more information visit Tel-Tru Check-Temp Calibrators.
Do you manufacture thermometers for barbecue cookers and smokers? Yes. Visit Barbecue Thermometers.
What is Oxygen cleaning? The service is technically “cleaned for oxygen service”. The purpose is to have an instrument free of oil, grease or other impurities. The instrument that is used to measure oxygen must be cleaned to avoid possible explosions. Oxygen and oil do not mix well. Liquid filled gauges are not recommended for this application. The cleaning process involves cleaning the socket and the internal part of the bourdon tube with a chemical solution.
What is the accuracy of Tel-Tru bimetal thermometers? +/- 1% full span per ASME B40.3 Grade A.
How do you sell your products? We sell our products primarily through distributors and catalog houses that serve industrial, HVAC, food service and other specialized industries. End-users who can not find a Tel-Tru distributor within their area can buy Tel-Tru products online, visit our Shop page.

Some products are sold direct to original equipment manufacturers (OEMs). Please contact Tel-Tru to select the most appropriate channel of distribution to meet your needs or visit our Distributors page. Call us at 800-232-5335/585-232-1440.
Are Tel-Tru bimetal thermometers hermetically sealed? Yes, Tel-Tru bimetal thermometers are hermetically sealed per ASME B40.3 test.
How do I select the correct thermowell for my application? See How to Select Thermowells by viewing our Thermowell brochure.
What is the shortest stem length available on Tel-Tru bimetal thermometers? Stem length depends on the model, temperature range and the application. Please contact us at 800-232-5335/585-232-1440 or contact us via the web.
Can I shorten the stem length of a bimetal thermometer by cutting it? No, you will destroy the thermometer. The bimetal coil assembly in the lower 2" of the stem is the operating mechanism.
Can Tel-Tru crossover other companies' product part numbers. Yes, on most items. Contact the factory for more information. Please contact us at 800-232-5335/585-232-1440 or contact us via the web.
How do you measure stem lengths? Stem lengths for thermometers with threaded connections are measured from the top of the thread to the tip of the stem. Non threaded thermometers are measured from the back of the case to the tip of the stem. See our Bimetal Thermometer catalog.
What is the procedure for the return or repair of damaged goods? The original buyer must contact Tel-Tru to receive return materials authorization (RMA) number. The item must be returned pre-paid in its original box with the RMA number written on the box. It will be evaluated upon receipt. If an item is repairable and under warranty, Tel-Tru will repair and return it no charge. If the item is not repairable and is still under warranty, Tel-Tru will replace it at no charge. If the thermometer shows signs of abuse, it should not be returned to the factory.
Can you make special dials? Custom dial configurations are available. Contact our factory with your requirements. Please contact us at 800-232-5335/585-232-1440 or contact us via the web.
What temperature ranges are available on Tel-Tru bimetal thermometers? See our Bimetal Thermometer catalog.
What material is used to make Tel-Tru thermometers? 304SS is the standard material for the case, bezel and wetted parts. 316 stainless steel parts are available on some models as an option.
Why do some Tel-Tru thermometers have a pointed stem? The pointed stem is the result of a high quality manufacturing process for sealing the stem tip.
What is the maximum stem pressure a bimetal thermometer can withstand? Bimetal thermometers are not certified for pressure applications. It is standard industry recommendation that anytime pressure is an issue a thermowell should be used for safety reasons.
What is the anti-parallax dial? The dial is not flat. There is an outer ring that is raised to the same height as the pointer which allows the pointer position to be read more accurately from various angles.
Can a Surface Thermometer be calibrated in the field? No. The surface thermometer is calibrated when it is originally manufactured to an accuracy of +/- 2%.
What are the operating temperature limits for Tel-Tru bimetal thermometers with silicone fill? The maximum operating temperature is 500F(260C). The minimum operating temperature is -50F (-45C).
Are calibration certificates and certificate of origin and compliance available? Yes, contact factory for charges (if required) 800-232-5335/585-232-1440.. These certificates must be requested on your purchase order with the thermometers or pressure gauges.
How quickly can you manufacture bimetal thermometers? 1 to 2 day turnaround is available. Standard lead time is 5 to 7 business days. Please contact us at 800-232-5335/585-232-1440 or contact us via the web.
Do Tel-Tru bimetal thermometers carry the "N Stamp" so that they can be used on the "hot" system (nuclear side) of a nuclear power plant? Tel-Tru products do not carry the "N Stamp", but our products are used in the non-nuclear system or side of nuclear power plants. To our knowledge, there are no manufacturers of bimetal thermometers who have "N Stamp" approval.
Does Tel-Tru have a lens material for thermometers which is UV stabilized? Both the polycarbonate plastic and the acrylic plastic materials are UV stabalized materials, which means the yellowing is delayed but will still happen over a long period of time.
Can you offer a silicone filled bimetal thermometer with shatterproof glass? Yes, polycarbonate plastic is standard on silicone thermometers. Shatterproof glass is available upon request.
Can bimetal thermometers be filled with glycerine instead of silicone? No. Glycerine is not an option for filling bimetal thermometers because it is too viscous and it will not tolerate high temperatures.
What is the active length of a bulb on Tel-Tru Gas Actuated thermometers? The standard active length of a bulb is 3" x 3/8" diameter for all temperature ranges and capillary lengths up to 120 feet. (36m). A 6" x 1/4" is available on request for certain temperature ranges.
Can you manufacture bimetal thermometers with non-standard stem lengths? Yes. Tel-Tru can manufacture custom stem lengths up to 120" for bimetal thermometers.