Stow Laboratories Inc.

• About STOLAB
• Address, Phone, Fax, e-mail   NOTE :   STOLAB has a new area code
• The STOLAB PL SYSTEM for accurate temperature measurement
• PL SYSTEM Applications
• Ordering Information
• Application Help

• Replacing mercury-in-glass thermometers with the STOLAB PL SYSTEM
• Calibration of STOLAB PL SYSTEM components by independent calibration labs

Founded in 1966, STOLAB designs and manufactures industrial instruments, primarily the highly accurate PL SYSTEM for temperature measurement and control. Our products have earned a reputation for reliability, ease of use, and dependable performance. We are a small company, our phones are answered by people, not machines. If you need to measure temperature accurately, would like some application help, further product information, pricing, and ordering information, please contact us :
 
 

• Mail        Stow Laboratories Inc.

               7 Kane Industrial Dr
               Hudson  MA  01749-2976
               USA

As of 1 September 1997, STOLAB has a new phone and fax area code (our location is unchanged). The new area code is "978" and should work from everywhere by  1 December 1997, but if it does not work from your area, try the old (508) area code. The phone companies will get it sorted out eventually.

• Phone     978-562-9347

 
• Fax         978-568-9172

 
• e-mail     stomail@stolab.com

The STOLAB PL SYSTEM was designed for accurate, trouble-free, versatile, and reliable temperature measurement in industrial environments. It is also widely used in laboratories, hospitals, metrology, power generation, pipelines, and many other fields. Because it was designed and is manufactured as a complete system, it eliminates many common temperature measurement errors. PL SYSTEM users can add, replace, and interchange all system elements : sensors, electronics, switch boxes, sensor cable extensions, etc., at any time, without loss of accuracy, and without any need to recalibrate anything. This key feature prevents inadvertent - and often unrecognized - measurement errors inherent in the use of instruments and sensors which must be calibrated and used only as "matched sets".

Brief  PL SYSTEM specifications :

• measurement range is -85C to +200C (-121F to +392F)
• the system accuracy is  +/- 0.10C  +/-0.15% of reading
•  the system is guaranteed to perform within the published specifications for two years without recalibration.

Type PL Sensors include a very stable, platinum resistance temperature detector (RTD) and selected compensating resistors, sealed in a stainless steel housing. A cable and a connector complete the assembly.  Standard Type PL Sensors are available in three types of stainless-steel housings (304, 316, and Teflon-coated 316), housing lengths from 3 inches to 24 inches, a choice of two cable types, and cable lengths from 3 feet to 10 feet. Many other configurations are available on special order.

Type PL sensors are :

• individually factory compensated, which makes them ten times more accurate than standard RTD's, and fully interchangeable in the field at any time. This key feature of the PL SYSTEM means that any number of sensors can be used at a site, production line, or lab, without having to keep track of "matched" instrument/sensor sets. Multiple sensors can be used with an instrument/readout; sensors can be added, interchanged, and replaced without any loss of measurement accuracy.
• rated for continuous use at temperatures from -85C to +200C (or -121F to +392F), including the sensor cable.
• sealed, fully immersible in all gases and fluids compatible with the housing and cable materials (stainless steel, Teflon, and silicone rubber).
• complete with cable and plug, ready to use.
• rugged and reliable, with proven long-term stability and reliability.

PL SYSTEM electronics are designed for long-term stability and reliability. Their unique, patented circuit converts the sensor reading to a linearized voltage signal, calibrated to 10 millivolts per degree (C or F). This signal is available for control, recording, and monitoring, data acquisition, and data logging. It is also used as the input for digital display if applicable. The circuit eliminates the effects on the output of series resistances interposed between the sensor and the electronics, such as the use of sensor cable extensions or connector contact resistances, even if these resistances are unbalanced and variable. Connectors and interconnecting sensor cables need not be made from any special materials, as is the case with thermocouple systems. This key feature eliminates all errors due to sensor installation and wiring, and allows the use of very long sensor cable extensions. Computer-matched and tested components are used in the production of PL SYSTEM electronics to minimize signal noise and ambient temperature effects.

Standard electronics models include :

• Benchtop (and rack-mountable), line-powered digital thermometers, the 921 A PL-F/C (for 115 VAC) and the 922 A PL-F/C (for 220 VAC). These units have a large digital display highly legible in all ambient light conditions from up to 35 feet, a F/C temperature scale selector switch, a calibrated analog voltage signal output (10 millivolts per degree, F or C), a digital BCD output equivalent to the displayed digital information, all housed in an all-metal, rugged case.
• Bench top (and rack mountable), line powered electronic thermometers, the 911 PL-F/C (for 115 VAC) and the 912 PL-F/C (for 220 VAC). Similar to the digital thermometers, these models omit the digital display - the output is the calibrated, linear analog voltage of 10 millivolts per degree F or C.
• Printed-circuit card versions for OEM, test stands, and other built-in uses, the 954 PL-C and 954 PL-F are powered by +/- 15 VDC and provide a calibrated, linear analog voltage signal of 10 millivolts per degree C or F, respectively.

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• Process control, manufacturing, QC and QA : monitoring and calibration of production line thermal baths for thermostats, temperature controls, bi-metal elements, and thermal switches. Temperature coefficients of crystal oscillators, transducers, microwave components, etc. Gas and liquid temperatures in flow stands. Sterilization and fermentation temperature control in the chemical and pharmaceutical industries. Photo processing. Viscosity measurements in the production of lubricants.
• Pipelines, power generation : Compressor and gas turbine efficiency measurements, gas and air density monitoring
• Metrology : Calibration of thermocouples and thermistors, secondary temperature standard for field and production use
• Hospitals : Servicing and calibration of temperature-sensitive equipment such as incubators, blood storage units, centrifuges
• R & D : product development, automotive, rubber products, microwave components, crystal oscillators, differential temperature measurement of heat exchangers, battery temperatures, carburation test stands, environmental testing, temperature and humidity chamber monitoring and control, time/temperature recording, boiling and freezing point determinations,

• mercury-in-glass thermometers; it eliminates mercury contamination risks, and breakage. It allows remote, safe, convenient, and accurate readings, and has a much higher range and resolution.
• thermocouple systems : it is much more stable and accurate
• thermistor systems : much wider temperature range, generally more accurate
• other RTD systems : compensated Type PL sensors are more accurate and are interchangeable

All STOLAB products are sold and shipped directly from our factory in Hudson, MA, USA. Most standard PL SYSTEM items are in stock for immediate delivery - contact us for current prices and availability.
 
 

We have over twenty five years of experience helping our customers to apply the STOLAB PL SYSTEM to many different temperature measuring needs. Contact us to discuss your requirements, and we will help you determine the best choice of equipment. Listed below are some of the parameters which may affect the choice :

• What is to be measured (liquid, gas, solid), physical constraints/size limitations if any. Can the sensor be immersed in, or surrounded by, the material whose temperature is to be measured?
• Maximum and minimum temperature to be measured (i.e., sensor temperature range)
• Desired accuracy of the temperature measurement, either as a percentage of the reading or as an absolute value (+/- degrees); desired time period between recalibration/verification of the equipment performance
• Response time, i.e. how rapidly does the temperature to be measured change and how accurately should the sensor track it while it is changing
• Number of locations where temperature is to be measured. If more than one, are these measurements to be taken simultaneously, or can they be made sequentially ?
• Distance(s) from the point of temperature measurement to the location of the electronic display unit or sensor switch box.
• Environment for the sensors and the electronics (indoor, outdoor, etc)
• Intrinsic safety requirements, if any