IEEE Std 442-2017 pdf free download – IEEE Guide for Thermal Resistivity Measurements of Soils and Backfill Materials.
4. Test equipment Figure
A.I and Figure B.1 show diagrams of the system required to measure thermal resistivity in the laboratory or in the field. The equipment for testing dffese primarily in the size of the probe and the prtability requirements of the devics used in the field as shown in Amnex A and Annex B.
4.1 Equipment required for field measurements
4.1.1 Field thermal probe The field thermal probe is fabricated fom a stainless steel tubing that can be made of various diameters and lengths. The tubing contains a beater element ocupying the length of the seamless stainless steel tubing. A mumber of temperature sensors, electrically insulated fom the heater element, and the probe body are shown in Annex A. Thermal probes of long lengths (more than 1 m) may contain multiple termperature sensors, positiomed al imtervals of 300 mm to 450 mm from the probe tip, with suitble means at the top ofthe probe for making electrical conections. In order to eliminate moisture infltration in the probe and to reduce the itial thermal transient, the probe may be flled with an epoxy resin.
4.1.2 Power supply/power monitor An adjustable, regulated leltec power supply should be used in the constant curent mode, The umit should be capable ofproviding a stabl and constant power ranging from 1 W up to 250 W to alow fexibility to test with small lab probes and or lange field probes. The field probes require higher power to heat the soil to the required temperatures and thus llow the determnination of the soil’s thermal resistivity.
If such a power souIce is not available in the field, a portable generntor or power inverter may be used to energize the heater in the probe. In such an application, accurate contol can be exercised by using an ammeter and variable resistors to adjust the bheater current. This configunation shall be able to adjust the curents between 0.1 Ato SA and thus the heater power. Alternatively, power meter (digital or analog) may also be used to accurately measure the input power being applied to the heater in the probe.
4.1.3 Temperature monitor A mulipoint poriable digital instument designed 10 measure temperatumes with 3 resolution of betler than 0.1 C is pefered for feld we. Manual balance potentioeters with reference junctios have also been wed scsstully
4.2 Equipment required for laboratory measurements
4.2.1 Laboratory thermal probe Laboratory measurements use a small sainless stel prbe with a length to diameter mtio of 50 I, The intemal parts. ofthe probe include a henter cemrm and a temprauee 8e1801 thalt are both ecrially insulmted fom each cther and fromm the sainlsss steel pruobe bory. Detaled diagrams ae depisted in Figure B.I and Figure B.2 of 4.22 Power supplyipower monitor Am adjusable regulated dc power supply is required with tbe apbiltofrovidig atleast 20W.Alermatively, power meter (digital or amnalog) of up 1020 W can be used in place of power supply for the power input to the thermal probe.
4.2.3 Temperature monitor Amultipoint poruble digial instument designed measure empenatures wih arsol ution of beterhan0.I C 8 pefeired frlubl us. Manual belamce poctioteres withreference junctioros have alsobe used setull
5. Test methods
5.1 Methods for field measurements
5.1.1 Insllalion of field probe The thermal probe with multiple temperature sensoes should be carfully inseted in the carth. IEEE Std 442 pdf download.