Hx-wz explosion-proof thermal resistance

An overview,

Flameproof thermal resistance is according to Q/ZZ HHX003-2012 "HX - WZ flameproof thermal resistance and GB3836.1-2010" explosive environment, part 1: general requirements for equipment and GB3836.2-2010 "explosive environment part 2: the flame-proof shell" d "protection equipment" provisions, the explosion-proof marks for the Ex d Ⅱ C T6 Gb.

This product is can be used in explosive gas, steam, the mist in factory environment, a measuring sensor, and usually display instrument and meter, transmitter adjustment, to directly measure the production of gases, the temperature of the liquid medium in the engineering.

The product is inspected by the national quality inspection center of explosion-proof electrical products and has obtained the explosion-proof certificate. The explosion-proof certificate number is CNEx13.

Second, the principle of

1. Temperature measurement principle

The resistance value of the temperature probe wound on the skeleton changes with the temperature, and the two have some function relation Rt=f (t). Therefore, the temperature value of the moment can be determined only by measuring the resistance value at a certain time. Its resistance - temperature relationship is as follows:

In 0 ~ 450 ℃ temperature range:

Rt = Ro (1 + At + Bt2)

In 200 ~ 0 ℃ temperature range:

Rt = Ro (1 + At + Bt2 + C2 (t - 100) t3]

Type:

Ro to 0 ℃ when the resistance value

Rt for t ℃ resistance value

T is the temperature of the measured medium (ipts-68 international temperature scale)

A = 3.90802 x 10-3 ℃ - 1

B = 5.80195 x 10-7 ℃ - 2

C = 4.27350 x 10 to 12 ℃ - 4

2. Explosion-proof principle

Explosion-proof enclosure is based on the maximum test security clearance, through the flame-proof joint surface quenching and cooling effect, make the explosive gas mixture inside the flame-proof shell exploded don't damage the explosion-proof enclosure, and does not cause external explosive gas mixture ignites the principle of design and manufacturing.

This product is suitable for factory exist or there may be A and B Ⅱ Ⅱ, Ⅱ C class, T1 ~ T6 group of combustible gas, steam and air mixture formation of explosion danger place 1 zone and 2 zone.

3. Basic technical parameters

The specifications and meanings of the thermal resistance are as follows:

1. Measuring range: - 200 ~ + 200 ℃

2. Explosion-proof marks: Ex d Ⅱ C T6 Gb

3. Scale: 1. P stands for Pt100 2, C stands for Cu50

4. Tolerance delta: thermal resistance measurement tolerance level is class B, and the tolerance value of different temperatures is calculated according to the calculation formula of different temperatures:

Delta = + (0.30 + 0.005 t) ℃

Type t is the absolute value of temperature in ℃

5. Rated voltage: 24VDC

6. Rated current: 20mA

7. Heat response time: (tau 0.5)

Tau 0.5 or less (liquid water test)

8. Insulation resistance:

(1) under normal temperature insulation resistance: when the ambient air temperature is 15 ~ 35 ℃ and relative humidity is less than 80%, the platinum thermal resistance sensor element and the insulation resistance between the protecting tube not less than 100 m Ω.

(2) high temperature insulation resistance: platinum thermal resistance in 300 ~ 450 ℃, the temperature sensing element and the insulation resistance between the protection pipe not less than 2 M Ω.

9. Environmental conditions

A atmospheric pressure of 80 ~ 110kPa;

Ambient temperature: b - 20 ~ 40 ℃;

C air maximum relative humidity is not more than 80% (+ 25 ℃);

D A and B Ⅱ Ⅱ, Ⅱ class C, T1 ~ T6 group of combustible gas, steam and air mixture formation of explosion danger zone 1 or 2 area place;

E in a gas or vapor environment without damaging insulation;

F where there is no significant shaking and impact vibration.

Iv. Structure and model specifications

The heat-proof thermal resistance consists of four parts, such as the temperature component, the junction box, the protection pipe and the installation of the fixed device. The basic structure of the system is seen in the general assembly drawing of wz.001.001-4.

1. Sensor components

The components of the thermal components of this product are the second-line normal temperature components, consisting of platinum resistance, silver wire, ceramic insulating tubes, and wiring bases.

2. The junction box

Box and lifted the lid with magnesium and titanium content is not more than 7.5% (by mass percent), tensile strength is greater than 120 n/was made of aluminum alloy, with screw joint connection between them, and is equipped with the loose screw. After the installation of the external lead, not only should tighten the box cover, also should tighten the loosening screw. After putting into use, without breaking the platinum resistance power supply power supply, must not unscrew the anti-loosening screw. The junction box is connected to the protective pipe by a thread separation joint. The junction box adopts the pressure-tight nut to introduce the device. The cable shall be fitted in the proper size, so that the sealing ring of the introduced device can be clamped into the cable, and no space shall be left.

3. The protection tube

All made of stainless steel, good temperature resistance, corrosion resistance and sufficient mechanical strength.

The design insert depth of the protection tube of this model is 150mm. Besides, the user can provide specific dimensions according to the requirements.

4. Install fixtures

Install the fixed device for the nut type fixed or flange fixed, as shown in figure WZ. 008.1-2.

V. installation and use

1. The selection of thermal resistance of explosive type

The proper selection of explosion-proof instrument is one of the important conditions for the safety of the factory, and it is also related to whether the instrument is economical and practical.

(1) selection principle:

The use of the thermal resistance of the insulation must be adapted to the division of the explosive mixture at the temperature measuring site, the group and the danger zone.

(2) explosion-proof marks

The symbol for the Ex explosion-proof product d Ⅱ C T6 Gb.

2. Installation requirements:

The site installation of this product shall conform to the relevant provisions of gb3836.15-2000 "electrical equipment for explosive gas environment" part 15: electrical installation (except coal mines) in dangerous places.

The installation site of thermal resistance should be avoided near the furnace door to the heating object. The heat resistance junction box shall not meet the container wall of the measured medium, and shall be installed in the place where the junction box is well ventilated. The wiring holes of the thermal resistance junction box should be down to the hole with water proof, dust and dirt.

3. wiring

The product from the temperature element to the terminal of the two wire system, the user may adopt two, three or four wire system to connect with the secondary instrument or transmitter.

The junction box has an internal and external grounding screw. In order to ensure safety, the grounding symbol should be reliably grounded during installation.

Introducing the cable insulation should be adopted (preferably shielding) copper wire, cable diameter should be compatible with sealing ring, specific see table size, copper wire cross-sectional area depending on the distance between thermal resistance and secondary instrument, but shall not be less than 1.5 was, conductor resistance value should be specified by the technical conditions the secondary instrument of the standard data (generally for 5 Ω).

4. The use of thermal resistance of the isolation type

The thermoelectric resistance is applied to measure the temperature and the thermal resistor is installed in the measured place. After a period of time, the actual temperature can be measured. Under the conditions of work pressure permits, the convection heat transfer between the thermal resistor and the measured medium should be increased and the insertion depth of the thermal resistance should be increased. When used, the thermal resistance should be matched with the second instrument of the corresponding dividing number to properly display and control the temperature, and a thermal resistor should not be used at the same time with two secondary instrument connections.

5. Precautions:

(1) check whether the product shell has explosion-proof mark and explosion-proof certificate number.

(2) check whether there are mechanical damage to the products in the transportation, installation and other links, especially the surface of the explosion joint and the anti-loosening device. If there is damage, loose can affect the explosion - proof performance.

(3) check the explosion-proof category, temperature group, and the use of the site and the requirements of the site of the explosive gas mixture.

(4) whether it has internal and external grounding screws and signs.

(5) it is strictly forbidden to change the parts that are related to the explosion-proof.

(6) it is strictly forbidden to charge the lid. You must turn off the power supply of the thermal resistor to open the cover. After the installation has been checked, the lid should be tightened and the protective screw of the top of the box can be used.

(7) removed or replaced thermal resistance, must stay the insertion part of the temperature dropped below 80 ℃ temperature or allow the use conditions, can be removed or replaced.