CHOOSING YOUR COMARK PROBES PROBE IDENTIFICATION SENSOR TYPE Choose a sensor best suited to your needs for CODES measurement range, accuracy and response time. Comark has a simple order code for each probe which Some accuracy levels are set by legislation, such as the identifies the key characteristics. United Kingdom Food Safety Act, or by local Quality These are set out in the diagram below. Assurance standards. The sensor must also match the instrument. Probe Category Connector Type Comark standard probes use three basic sensor types:- P: Penetration M: Sub-miniature S: Surface L: Lumberg 1. Thermocouples - two wires of dissimilar metals joined A: Air D: Din together at the measurement tip (the hot junction) and D: Damped C: Cable Tailed joined at the other end to the input terminals of the I: Immersion B: Bipole instrument (the cold junction). E: Lemo/MCX Comark thermocouple material is monitored to exceed the international standards (BS4937:1983, Sensor Type BS EN60584-2:1993 and other related standards). K: Type K thermocouple Two main thermocouple types are used:- T: Type T thermocouple X: Thermistor (PST) Type K Thermocouple - Ni-Cr/Ni-AL- a general purpose P: PT100 thermocouple with a wide measurement range and a fast response to temperature changes. Type T thermocouple - Cu/Cu-Ni - particularly suited to low and sub-zero temperatures such as those found in autoclaves and health applications. PK 24 M Also has a fast response to temperature changes and Example Sequential code number high accuracy, useful for food applications. 2. Thermistor (PST) - used for precision measurements using a semi-conductor sensor. PROBE CATEGORY Provides high accuracy over a narrow temperature range and good performance over long lead runs. Suitable for Choose a probe suitable for the material to be measured food and cold store applications. e.g. a low mass flexible air probe would be a better choice for fast, accurate air temperature measurement than a 3. Platinum Resistance Thermometers - the electrical penetration probe which would take too long to stabilise. resistance of these sensors changes with temperature and this is measured to give the most accurate Also the application should be considered:- temperature measurements. Solid and semi-solid materials - use surface probes for Comark uses PT100 sensors with a resistance of 100 surface measurement. Surface probes include angled ohms at 0C which meet the tolerances set out in head models for restricted areas, patch probes for BS EN60751 (1996), Class A. permanent measurement points and velcro or clamp probes for pipes. Use penetration or immersion probes for internal temperatures. Where holes have to be drilled into solids, use a thermocouple or thermistor probe inserted to a PROBE CONNECTOR TYPES depth 6 times the probe diameter or a PT100 probe Choose a probe to match the connector type of the inserted to a depth 10 times its diameter. instrument. A range of adaptors is available for use where a Use a thermal transfer compound for improved accuracy non matching probe has to be specified. and response time (the speed at which the probe adjusts Connector details for all Comark and Kane-May instruments from its current temperature to that of the measured and adaptors are given in the compatibility charts. materials). Liquids - use immersion or some penetration probes, but M: Sub-Miniature C: Bare Cable Tails check the possible corrosive effects of the liquid on the sensor first. Agitate the liquid for faster response. Air and other Gases - check the possible corrosive effects of the gas on the sensor first. Response times are affected by heat transfer from or into L: Lumberg B: Bipole the sensor and the smaller the sensor area of the probe, the faster the response time. Response is also affected by air/gas movement. Food simulant and damped sensor probes have a large D: Din E: Lemo/MCX mass surrounding the sensor to slow down response times, essential in food applications where fridge or freezer doors being opened or defrost cycles can trigger temperature alarms. 3OTHER ESSENTIALS PROBE TIPS FOR PROBE SELECTION Check that the probe measurement range matches your 1: Damped Sensor instrument specification and your application. Check that the probe tip design is suitable for your application e.g. do not use an air probe with an exposed 2: Air probe tip with thermistor sensor to measure internal temperatures of solids. The main tip designs are shown opposite and the numbers are listed in the probe selection charts:- 3: Air probe tip Check the probe lead material. Comark temperature probe leads are matched to the intended applications for the probe. Materials used are:- 4: Heavy duty surface spring tip PVC - PVC coiled leads provide ease of use in ambient temperatures of up to 70C and are specified for standard 5: Ribbon surface tip and heavy duty industrial probes. FEP and PTFE - These leads are especially suited to food probes and can be used in sub-zero temperatures. 6: Rounded immersion tip Steel braided PTFE leads give greater strength. Fibre Glass (FG) - Fibre glass insulated leads are used for special application probes where the lead could be 7: Pointed penetration tip subjected to very high ambient temperatures of up to 600C. 8: Tarmac probe tip Check Intrinsic Safety requirements - some applications and industries are covered by the Intrinsic Safety Regulations including fuel refining, chemical production and mining. 9: Plastic sheathed food surface Most Comark probes can be used with Intrinsically Safe probe tip instruments, but those not suitable are marked * in the probe selection charts. 10: Pallet probe tip Always check for Intrinsic Safety requirements before selecting probes. PROBE ACCESSORIES Description Sensor type Code Sub miniature thermocouple socket (in pack of 5) Type K B25 Sub miniature thermocouple plug (in pack of 5) Type K B26 Standard thermocouple plug Type K CSPK Standard thermocouple socket Type K CSSK Standard socket for panel mounting Type K CSSK/P Type B thermocouple sub-miniature plug for micro-volt input on M8600/K module Type B CMPC Lumberg plug - 4187 3-way screwblock connector for M8600/X module - 16720 50m reel of PVC probe extension lead Type K B27 2m extension lead with sub-miniature connectors Type K EK21M 10m extension lead with sub-miniature connectors Type K EK22M 20m extension lead with sub-miniature connectors Thermistor (PST) EX21M 40m extension lead with sub-miniature connectors Thermistor (PST) EX22M 60m extension lead with sub-miniature connectors Thermistor (PST) EX23M 80m extension lead with sub-miniature connectors Thermistor (PST) EX24M 10 way switch box with 350mm lead to enable up to 10 probes to be measured by a single thermometer, see page 8 Type K LK22M 1m coiled connecting lead for PT29L corkscrew probe, see page 5 Type T ADP34 1m coiled connecting lead for PT29M corkscrew probe, see page 5 Type T ADP35 1.5mm stainless steel olive gland adaptor* - B22 3mm stainless steel olive gland adaptor* - B23 6mm stainless steel olive gland adaptor* - B24 Thermal transfer compound - CSG12 Pack of 10 Tempatch indicators. Available in ranges: 37 to 65C - CTMP/A 71 to 110C - CTMP/B 116 to 154C - CTMP/C 160 to 199C - CTMP/D 204 to 260C - CTMP/E Cable ties in pack of 50 - T50 SPECIAL ORDER PROBE EXTENSION LEADS Most Comark thermocouple probes can be manufactured to special order with leads in non-standard lengths. Full details can be provided by Comark Customer Support or your local distributor. *Olive gland adaptors are used as compression sealing joints for probes used in measuring internal temperatures in pipes. 4