Thermocouple info

pplication:

The multi-point thermocouple is suitable for the production site where the temperature gradient is not significant, multiple locations or multiple locations should be measured at the same time. Multi-point thermocouple is widely used in large chemical fertilizer synthesis tower, storage tank and other devices.

Principle:

Multipoint thermocouple thermoelectric emf will grows with the temperature measuring end, only the size of the thermoelectric emfs associated with thermocouple conductor material and temperature difference on both ends, with hot electrode length and diameter of prefabricated thermocouple is mainly composed of junction box, protection tube, thermal insulation casing, terminal blocks, electrode structure, and with various mounting device.

Technical parameters:

1. Electrical outlet: M27X2, NPT3/4;

2. Thermal response time: ≤ 8S;

3, I wire diameter: Φ 3;

4. Protection level: IP65.

Industrial thermocouple and thermoelectric barrier detonation technical conditions

Industrial thermocouple and thermoelectric barrier detonation technical conditions

1, scope,

This standard specifies the flameproof technical requirements, test methods, inspection rules, packaging, storage and transportation of industrial thermocouples and thermal resistors (hereinafter referred to as thermocouples and thermal resistors).

This standard is applicable to industrial flameproof thermocouples and thermal resistors used in factory explosive mixing sites where the ambient temperature is -20~+60℃ relative humidity is no more than 85% and atmospheric pressure is 86kPa~106kPa.

2. Normative reference documents

The terms in the following documents become the terms of this part by reference to this part of GB/T1. All subsequent amendments (excluding corrigendum) or revisions to dated citations do not apply to this part. However, the parties to this part of the agreement are encouraged to study the availability of the latest version of these documents, which applies to any undated reference documents.

Term for explosion-proof electrical equipment used in explosive environments

Explosion-proof electrics for use in environments with explosive gases - Part 1: General requirements

Gb3836.2-2000 Explosion-proof electricity for environments with explosive gases - Part 2: Flameproof type: 'D'

Shell Protection Grade (IP code)

Environmental tests for electrical and electronic products -- Part 2: Test methods -- Test Db Alternating humidity and heat (12h+12h cycle)

GB228 Tensile test method for metals

GB6987.16 For chemical analysis of aluminum and aluminum alloys -- DETERMINATION of magnesium content by CDTA -- titration method

GB6987.17 -- Methods for chemical analysis of aluminum and aluminum alloys -- Determination of magnesium content by atomic absorption spectrophotometry

GB 2829 cycle check count sampling procedure and sampling table

Technical conditions for detonation barrier between industrial thermocouples and thermoelectricity

General technical conditions for instrumentation packaging

3. Technical requirements

Thermocouple and thermoelectric detonation barrier shall meet the requirements of this standard, and shall be manufactured and inspected in accordance with the drawings and technical documents approved by the prescribed procedures.

3.1 Appearance and assembly quality

3.1.1 The junction box housing surface of thermocouple and thermal resistance shall be marked as follows

A. The connection box shall be provided with grounding bolts no less than M4 outside, and the grounding symbol '' shall be marked.

B. Permanent convex mark 'Ex' and explosion-proof mark shall be clearly set in the obvious place of junction box;

C. The junction box shall have a clear and permanent embossed warning 'Open cap after power supply is cut off'.

3.1.2 The assembly quality of thermocouple and thermal resistance shall meet the following requirements:

A. The box cover locking device is reliable and effective;

B. The contents of the nameplate are correct and reliable. The nameplate shall be made of copper plate or stainless steel plate with a thickness of no less than 0.5mm;

3.2 Enclosure protection

The shell protection of thermocouple and thermal resistance shall comply with the provisions of GB4208 IP65 protection class.

3.3 Humidity and heat test

There should be no corrosion on the flameproof surface of thermocouple and thermal resistance after alternating wet and hot test.

3.4 Structural parameters of thread flameproof

3.4.1 track for Ⅱ B shell, screw thread joint surface button minimum mesh number is 5, when the volume is more than 100 cubic centimeter, axial length minimum mesh

Degree of 8 mm; When the volume is no more than 100cm3, the minimum tooth meshing axial length is 5mm.

3.4.2 for Ⅱ C shell. Threaded joint surfaces shall comply with table 2

3.4.3 The threaded structure shall be provided with measures to prevent self-release.

3.4.4 Surface roughness of the flameproof bonding surface

A. when Ⅱ is explosion-proof grade B, Ra should be no greater than 6.3 (including m;

B. when Ⅱ is explosion-proof grade C, Ra should be no greater than 3.2 (including m.

3.4.5 Protective measures for flameproof joint surface

Anti-rust measures shall be taken on the flameproof joint surface, such as anodic oxidation, electroplating, coating with 204-1 anti-rust oil, etc., but no painting shall be applied.

3.5 Gasket and type 0 ring

3.5.1 Liners of compressible material (e.g. IP protection grade to prevent moisture, dust from entering or to prevent liquid infiltration) shall be used as an auxiliary part of the flap-proof joint surface and shall not be included in the flap-proof joint surface.

3.5.2 If the gasket is metal or metal-clad compressible and non-combustible material in accordance with IS01210, the gasket may be installed on the joint surface of the insulating sleeve and the joint surface of the transparent component. This type of liner has an explosion-proof effect, which is an exception to the requirement of 3.5.1.

3.6 Fasteners and fastening

3.6.1 When fastening any part of the flameproof housing with removable screws or bolts, the screws or bolt holes shall not penetrate the housing wall. The metal thickness around the hole shall not be less than one third of the aperture and shall be at least 3mm.

3.6.2 When the screw or bolt is completely screwed into the hole without a washer, a thread allowance shall be left between the end of the screw or bolt and the bottom of the screw hole.

3.6.3 Fastening screws shall have anti-release devices.

3.6.4 The connection shall be strong and shall not become loose due to vibration, heating, thermal expansion and cold contraction of conductor and insulation parts, etc. Different measures shall be taken according to the following circumstances;

A. When a single conductor is pressed with a screw or nut, there shall be an elastic washer or a double nut under the screw head or nut;

B. A bow washer or a bowl washer shall be used to tighten a single conductor with screws or nuts, and special wiring plates may also be used to connect the conductor. It is not allowed to tighten the conductor with screws or nuts only;

C. Measures shall be taken to prevent rotation of the terminal to prevent twisting of the wires at the base of the terminal.

3.7 Cable lead-in device

3.7.1 Introduction

The cable introduction device of thermocouple and thermal resistance adopts the compression nut type device.

3.7.1.1 When cable wiring is used in the installation site, the inlet of the cable on the compression nut shall be made into flared mouth with smooth inner edge.

3.7.1.2 When steel pipe wiring is used in the installation site, the connection between the compression nut of the introduced device and the wiring nut or the explosion-proof flexible connecting hose shall be made into thread connection mode (see Figure 9), and the number of connecting threads shall not be less than 6, and the threaded part shall have anti-rust measures.

3.7.2 sealing ring

3.7.2.1 The rubber material of sealing ring shall undergo aging test. During the test, the hardness after aging shall be determined at room temperature, and the change of its hardness shall not exceed 20% before treatment.

3.7.2.2 If any sealing ring with the same outside diameter but different inside diameter is used in the cable introduction device, the uncompressed axial length of the sealing ring shall conform to:

A) The diameter of circular cable shall not be greater than 20mm, and the circumference of non-circular cable section shall not be greater than 60mm, with a minimum of 20mm;

B) When the diameter of circular cable is greater than 20mm and the circumference of non-circular cable section grows beyond 60mm, the minimum is 25mm;

D = Nominal outside diameter ±1mm; B≥0.3d (no less than 4mm)

3.7.2.3 The diameter difference (DO-D) between the aperture Do of the sealing ring placed on the junction box and the outer diameter D of the sealing ring shall not be greater than 1.0mm.

3.7.2.4 For the introduction device of the compression nut, a metal washer shall be installed between the nut and the sealing ring (see FIG. 8 and 9).

3.7.3 sealing

After tightening the compression nut, the introduction device lasted for 2min under the action of internal water pressure of 3Mpa, without any leakage water drop mark.

3.7.4 Mechanical strength

Apply 2 times the torque required in the sealing test to the compression nut, but the torque applied (in n m) shall be at least 3 times the maximum allowable cable diameter of the circular cable (in mm) or the maximum allowable cable circumference of the non-circular cable (in mm).

3.8 Junction box and cover

3.8.1 material

The junction box and cover shall be made of aluminum alloy with tensile strength not less than 120Mpa.

3.8.2 Strength of junction box and cover

On the plane or surface of any part of the junction box and the cover shell, no deformation or damage affecting the flak proof performance shall occur after impact test with 7J impact energy.

3.8.3 Junction box cavity and main cavity

3.8.3.1 The junction box is divided into two parts: the cavity and the main cavity. The plane, cylinder or stop-mouth flameproof structure is used between them, and the sealing structure can also be used. Sealing structure shall comply with 4.5.2 and 4.5.3.

3.8.3.2 Screw thread flameproof structure is used between the junction box cavity and the main cavity and the external environment.

3.8.3.3 The electric gap and creepage distance in the junction box cavity shall be no less than 3mm.

3.8.4 Hydrostatic test

+ 2

0

The junction box and cover shall be able to withstand the internal water test at 1.5 times of the reference pressure measured in Article 5.10, with no leakage for 10 S.

3.9 protection tube

3.9.1 The protective tube shall be made of cold-drawn stainless acid-resistant seamless steel tube or other heat-resistant metal materials.

3.9.2 The maximum temperature and pressure for long-term use that the protective tube can withstand, as well as the applicable medium. The manufacturer shall state this in the operating instructions.

3.9.3 The protective tube shall be able to withstand external hydrostatic test at room temperature at 1.5 times of the maximum operating pressure specified by the manufacturer. During the test, no damage or leakage shall occur to the protective tube.

3.10 socket

3.10.1 The thermocouple and thermal resistance wiring block shall be made of flame-retardant insulating materials with heat resistance grade above H according to regulations.

3.10.2 The electrical clearance and creepage distance between two terminals with different potentials of the connection block and between the terminals and the flap-proof enclosure shall be no less than 3mm.

3.11 Flameproof strength

The thermocouple and thermal resistance shall meet the following requirements after the shell withstand test as specified:

A. No damage;

B. There is no permanent deformation affecting the explosion-proof performance;

C. Gaps at any point shall not be greater than those specified in Table 1 respectively.

3.12 Flameproof performance

When the thermocouple and the thermal resistance carry out the internal ignition non-detonation test according to the regulations, the detonation transmission should not occur.

4. Test methods

4.1 Appearance and assembly quality

4.1.1 Visual inspection of thermocouple and thermal resistance shall be carried out by visual inspection.

4.1.2 The assembly quality inspection of thermocouple and thermal resistance shall be checked with the drawing.

4.2 Shell protection

4.2.1 General requirements

The test sample must be new and unused, and all parts must be assembled according to the drawings specified by the manufacturer.

4.2.2 Dustproof test

When the first characteristic number of GB4208 is 6, the second shell test method is used.

After the test, the amount and location of talc deposition were observed.

4.2.3 Waterproofing test

The test was carried out according to the test method when the second characteristic number of GB4208 was 5.

Immediately after the test, check the tested samples for mechanical damage, open or short circuit, no visible water marks in the junction box, and measure the insulation resistance value at room temperature.

4.3 Humidity and heat test

The alternating humidity and heat test of thermocouple and thermal resistance was carried out in accordance with GB2423.4. The test temperature was 55℃ and the cycle was 2 days. Immediately after the test, check the flameproof joint surface.

4.4 Structural parameters of flameproof joint surface

4.4.1 The surface quality and surface roughness of the flameproof joint surface shall be inspected by visual inspection or standard template comparison method.

4.4.2 The structural parameters of the flameproof joint surface shall be measured according to the accuracy requirements, such as vernier caliper, micrometer, thread ring gauge, thread plug gauge, etc.

4.5 Cable introduction device

4.5.1 Introduction method

The structure of the compensation conductor or cable lead-in device shall be checked against the drawing.

4.5.2 of sealing ring

4.5.2.1 The aging test of rubber sealing ring materials shall be conducted according to each batch sampling, with no less than 3 specimens. The test shall be conducted according to the aging test provisions of GB3836.1.

4.5.2.2 The sealing ring and its mounting dimensions shall be inspected with vernier calipers or special measuring tools.

4.5.3 Seal ring performance test

The sealing performance test shall be carried out in accordance with GB3836.2.

4.5.4 Mechanical strength test

The mechanical strength test shall be carried out in accordance with GB3836.2.

4.6 Fastener and fastening

4.6.1 The structure and dimensions of fasteners shall be inspected by eye inspection and thread ring gauges and thread plug gauges of corresponding grades.

4.6.2 Fasteners shall be subjected to torsion test. Connectors for torsion test shall be tightened with torque wrench according to the torque specified in Table 3. Connectors and insulated pipes shall not be turned and damaged.

4.7 Junction box and cover

4.7.1 material

4.7.1.1 The tensile strength of the junction box and the cover material shall be sampled for each batch, with no less than 2 specimens.

4.7.1.2 Tensile strength test shall be conducted in accordance with GB228.

4.7.1.3 Determination of magnesium content shall be conducted in accordance with GB6987.16 or GB6987.17.

4.7.1.4 This test may not be performed on materials with a quality guarantee when the magnesium content in their tensile strength is confirmed to conform to rule 4.7.1.

4.7.2 Strength of junction box and cover

4.7.2.1 General requirements of impact test are as follows:

A. The sample shall be tested in a state of complete assembly;

B. The test shall be carried out at ambient temperature of 25±10℃.

C. The number of samples for each test shall be 2, and each test shall be conducted twice.

4.7.2.2 Test equipment and its basic principle As shown in Appendix G of GB3836.1-2000, the hammer head is a hardened steel hemisphere with a diameter of 25mm and a weight of 1kg. The surface state of the end of the hammer head should be checked before each test, and the surface damage to the injured should be replaced. During the test, the hammer falls freely from a height of 0.7m and strikes any part of the junction box and cover along the normal direction.

After the sample withstands the impact test:

A. There shall be no variable form or damage affecting the isolation performance;

B. The sample is allowed to have local damage that does not affect the isolation performance, such as paint peeling, etc.

4.7.3 Junction box cavity and main cavity

The flast-proof structure of the junction box cavity and main cavity, and the electrical gap and creepage distance of the junction box cavity were examined by visual inspection and vernier caliper.

4.7.4 Hydrostatic test

Junction box and cover

Hydrostatic test of junction box and cover shall be carried out according to the method in Appendix A of GB3836.2.

4.8 protection tube

The compressive strength of the protective tube should be tested with water at room temperature. The hydrostatic test should be carried out on a special water pump. The test pressure should be 1.5 times of the maximum operating pressure and the test time should be 1min.

4.9 socket

The electrical clearance and creepage distance between two terminals with different potentials on the connection block and between the terminals and the flap-proof enclosure shall be checked by vernier caliper against the assembly drawing.

4.10 Flameproof strength

The housing pressure test of thermocouple and thermal resistance, including the reference pressure measurement and dynamic strength test, shall be carried out in accordance with GB3836.2.

Flameproof performance

The test of internal ignition without detonation of thermocouple and thermal resistance shall be conducted in accordance with GB3836.2.

5. Inspection rules

5.1 Review and issue of explosion-proof certificate

5.1.1 The thermocouple and thermal resistance produced by each unit in accordance with this standard shall be sent to the National Instrument and Meter Explosion-proof Safety Supervision and Inspection Station for inspection in accordance with the standards.

5.1.2 The inspection procedure shall be in accordance with gb3836.1-2000.

5.1.3 The following test reports shall be provided when the samples are sent for inspection;

A. Enclosure material test report (or material quality guarantee);

B. Technical performance test report of the product according to other relevant standards of thermocouple and thermal resistance;

C. Hydrostatic test report;

D. Detection record of flameproof structure parameters;

E. The inspection unit shall submit the required test report.

5.2 Delivery Inspection

Each thermocouple and thermal resistance must pass the exit inspection. After passing the inspection, the product certificate will be attached before leaving the factory.

If one of the factory inspection results does not conform to this standard, the product shall be considered unqualified.

5.3 Type Test

5.3.1 The thermocouple and thermal resistance of various structural types shall be type tested in one of the following situations.

A. When new products are trial-produced or old products are transferred to factories for production;

B. Normal production shall be conducted every three years;

C. When there are major changes in product structure, material and process that may affect product performance;

D. When there is a big difference between the outgoing inspection result and the previous type inspection;

E. When the national quality supervision institution puts forward the requirement of conducting type inspection.

5.3.2 Type test shall be sampled according to the one-sampling scheme of GB2829, and the following provisions shall be made:

A. discrimination horizontal Ⅱ level;

B. Non-conforming quality level RQL=40;

C. Number of decision groups: Ac=0 Re=1

5.4 Inspection Items

6, mark

6.1 mark

The product adopts the nameplate mark, and the basic content of the nameplate shall include the content stipulated in Article 27 of GB3836.1 in addition to the relevant standards of thermocouple and thermal resistance.

6.2 Operating Instructions

The manufacturer shall provide the user with the operation manual, the basic contents of which shall be added in addition to the relevant provisions on thermocouple and thermal resistance:

A. Explosion-proof marks;

B. Installation site;

C. Special technical conditions;

D. Explosion-proof qualification certificate Number;

E. Matters needing attention for maintenance.

7. Packaging, storage and transportation

7.1 the packing

The packaging of thermocouples and thermoresistors shall comply with the provisions of GB/T15464-1995

7.2 stored

The thermocouple and thermal resistance shall be stored in a ventilated room with an ambient temperature of 5℃ to 40℃ and a relative humidity of not more than 85%, and shall not contain harmful impurities that corrode the thermometer.

Appendix A

Explosion-proof marks

A1 explosion-proof mark