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50S & 50D Thermometer

Calibration Information

6

Required Test Equipment

Table 2 lists the required test equipment needed to perform the performance test and calibration procedures
for the 50S and 50D thermometers. If the required equipment is not available, instruments with equivalent
specifications may be used.

Table 2. Required Test Equipment

Test Equipment

Required Characteristics

Recommended Model

DMM

DC Voltage Accuracy: 0.5%

Fluke 87 Series IV Digital
Multimeter

Temperature Probe

Accuracy: Certified to 

±

 0.2 

o

C ambient

Fluke Model 80T-150U

DC Voltage Calibrator

Output Voltage 0 to 10 V
Accuracy: 0.025%
Resolution: 10 

µ

V

Fluke 5520A

Elastomeric Switch Pad

Fluke Part Number 680686

Thermocouple Connector

For K-type thermocouple

Fluke 80CK-M
Fluke Part Number 779942

Thermocouple Connector

For J-type thermocouple

80CJ-M
Fluke Part Number 833046

Thermocouple Wire
(K or J Type)

Standard

Omega

Dewar Flask/Cap

1-pint capacity

Thermos

Mercury Thermometer
(either 

o

C or 

o

F)

0.02 

o

C resolution

0.05 

o

F resolution

Princo Model ASTM56C
Princo Model ASTM56F

Performance Tests

Performance tests are recommended for incoming inspection, periodic maintenance, and for verifying the
thermometer’s specifications. If the thermometer fails any part of the performance tests, calibration and/or
repair is indicated.

Use the following procedure to prepare the thermometer before beginning the performance tests or
calibration procedures.

1.

 

Allow the thermometer to stabilize to room temperature, 23 

o

±

 5 

o

C (73 

o

±

 9 

o

F).

2.

 

Check the battery and replace it if necessary.

Display Test

Turn the thermometer on while pressing the HOLD button. All display segments are shown until the HOLD
button is released. Check that all the display segments are showing as in Figure 3.

Note

Because pressing the HOLD button during power-up activates one of the thermometers other
functions, take care to return the instrument to its normal function (if necessary).

Summary of Contents for 50D

Page 1: ...446 5500 Or visit Fluke s Web site at www fluke com Warranty This Fluke product will be free from defects in material and workmanship for one year from the date of purchase This warranty does not cover fuses disposable batteries or damage from accident neglect misuse or abnormal conditions of operation or handling Resellers are not authorized to extend any other warranty on Fluke s behalf To obtai...

Page 2: ...r if it appears damaged Look for cracks or missing plastic Pay particular attention to the insulation around the connectors Disconnect the thermocouple s from the thermometer before opening the case Replace the battery as soon as the low battery indicator N appears The possibility of false readings can lead to personal injury Do not use the thermometer if it operates abnormally Protection may be i...

Page 3: ...0 8 o C 0 1 of reading 1 4 o F Temperature Coefficient 0 01 of reading 0 03 o C 0 03 o F for ambient temperatures from 18 o C to 28 o C 64 o F to 82 o F Maximum Differential Common Mode Voltage 1 V Maximum voltage difference between T1 and T2 Temperature Scale IPTS 68 Certification P Applicable Standards NBS 125 IEC 584 Accuracy is specified for ambient temperatures between 18 o C 64 o F and 28 o ...

Page 4: ... Thermometer disassembly is necessary to replace the battery and some interior parts see Replaceable Parts later in this document Refer to Figure 1 when disassembling and reassembling the thermometer To disassemble the thermometer 1 Turn the thermometer OFF if necessary 2 Loosen the four bottom case screws and remove the top case To reasemble the thermometer 1 Replace the top case 2 Tighten the fo...

Page 5: ...to personal injury To avoid electrical shock disconnect the thermocouple s before opening the case Caution Do not attempt to recharge the battery To prevent explosion do not dispose of the battery in fire Follow local laws or regulations when disposing of batteries To replace the battery refer to Figure 2 and the assembly procedures located previously in this document zf02f eps Figure 2 Replacing ...

Page 6: ...Wire K or J Type Standard Omega Dewar Flask Cap 1 pint capacity Thermos Mercury Thermometer either o C or o F 0 02 o C resolution 0 05 o F resolution Princo Model ASTM56C Princo Model ASTM56F Performance Tests Performance tests are recommended for incoming inspection periodic maintenance and for verifying the thermometer s specifications If the thermometer fails any part of the performance tests c...

Page 7: ...st construct an ice bath using the following steps 1 Prepare a Dewar Flask by drilling two holes in its cap to accept the thermometer and thermocouple wires or use a standard laboratory cork 2 Fill the Dewar Flask with shaved or crushed ice made from distilled water 3 Fill the Dewar Flask with enough distilled water so that the ice turns to slush but do not add enough water to float the ice Note A...

Page 8: ...copper wires at the 5520A Calibrator 4 Verify the thermometer reads 0 0 o C 0 4 o C 5 If this test fails reposition the thermocouple wires and Mercury Thermometer in the ice bath and repeat steps 2 4 If the test continues to fail perform the calibration procedure located later in this document 6 Remove the short applied in step 3 7 Using Table 3 for the corresponding thermocouple type obtain an ou...

Page 9: ...s the thermometer into the Thermocouple Calibration mode 3 Allow the thermometer to stabilize at room temperature 23 o C 5 o C 73 o F 9 o F 4 Select o C mode Select T1 if the thermometer is a Fluke 50D 5 Adjust the 5520A for 0 00000V Connect the 5520A output to the TP1 input 6 Allow the thermometer reading to stabilize Refer to Figure 6 and adjust the T1 offset adjustment R7 for a display reading ...

Page 10: ...150U and the Fluke 87 Series IV Digital Multimeter DMM measure the reference junction transistor temperature by placing the 80T 150U probe tip against Q1 located in the middle hole of the isothermal block Wait for the temperature reading to stabilize 14 Adjust R16 for a temperature reading that is the same as displayed on the DMM 15 Turn the thermometer OFF by shorting the ON OFF switch grid and r...

Page 11: ...d allow the instrument reading to stabilize 5 Slowly and in small increments adjust R7 T1 offset until the thermometer reading matches the Mercury Thermometer reading Allow the thermometer reading to stabilize and repeat the adjustment as necessary until a stable and correct reading can be attained 6 Repeat steps 4 and 5 for R13 T2 offset Fluke 50D only Thermocouple Input Calibration Optional Note...

Page 12: ...qual to the reading of the lag bath reference thermometer 6 Calibration of the thermometers is complete Disconnect all test equipment from the instrument Lag bath room temperature water Mercury thermometer 0 02 C resolution Immersed to approximately same depth Thermocouple wire 50S or 50D Thermometer _ zf06f eps Figure 7 Room Temperature Lag Bath ...

Page 13: ... AM THD FORM STL 4 14 375 All 6 1 1280490 1280483 CASE TOP CASE TOP 50S 50D 7 1 1280766 1280753 CASE BOTTOM CASE BOTTOM 50S 50D 8 1 646653 BRACKET LCD All 9 1 1280151 1280160 MASK BRACKET FLUKE 50S MASK BRACKET FLUKE 50D 50S 50D 10 1 745794 ISOTHERMAL BLOCK All 11 2 649632 CONNECTOR ELASTOMERIC LCD TO PWB 1 900 L All 12 1 761924 BOTTOM SHIELD MYLAR All 13 4 640565 FOOT NON SKID All 14 1 844340 LAB...

Page 14: ...50S 50D Thermometer Calibration Information 14 15 6 10 1 12 7 13 3 11 8 16 9 2X 4X 4X 4X 2 4 5 zf08f eps Figure 8 Exploded View Diagram Model 50D is Shown ...

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