JB/T 5266-1991 Indirect resistance furnace RY series electric heating bath furnace
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T 5266 -1991
Indirect Resistance Furnace
RY Series Electric Heating Bath Furnace
Published on 1991-06-28
Implementation by the Ministry of Machinery and Electronics Industry of the People's Republic of China on 1992-07-01
Mechanical Industry Standard of the People's Republic of China
Indirect Resistance Furnace
RY Series Electric Heating Bath Furnace
1 Subject Content and Scope of Application
JB/T5266-1991
This standard specifies the requirements for RY series electric heating bath products (hereinafter referred to as bath furnaces), including variety specifications, technical performance, and ordering and supply conditions.
This standard applies to electric heating bath furnaces designed according to the requirements of Articles 4.1, 5.1 and 5.2, mainly used for heat treatment and heating of metal parts in salt baths, alkali baths or oil baths.
This standard is also applicable to similar electric heating bath furnaces, such as metal bath furnaces. Different parts may be specified separately with reference to this standard. 2 Reference standards
GB10067.1
GB10037.4
GB10066.1
GB10066.4
ZBK60001
JB2379
3 Terminology
Basic technical conditions for electric heating equipment
General part
Basic technical conditions for electric heating equipment
Indirect resistance furnace||tt ||Test methods for electric heating equipment General part
Test methods for electric heating equipment Safety of indirect resistance furnace electric heating equipment Part 1
General requirements
Safety of electric heating equipment Part 4
Method for compiling product models of electric heating equipment
Technical conditions for tubular electric heating elements
General requirements for resistance furnaces
Except for the following supplementary provisions, the rest shall be in accordance with the provisions of Chapter 3 of GB10066.4. 3.1 Bath size
The internal dimensions of the bath specified in the design and marked on the nameplate. For a circular bath, it refers to the nominal inner diameter of the bath and the height between the top plane of the bath and the bottom. For a rectangular bath, it refers to the width and length of the bath cross section, as well as the height between the top plane of the bath and the bottom of the bath. The operator faces the bath, and the "width" of the bath is parallel to the left-right line connecting the operator's body. 3.2 Working area size
The size of the internal space of the bath that allows the placement of the charge as specified in the bath furnace design (see Section 5.2.11). The working area size includes the cross-sectional size (diameter, or width and length) and the effective height. The cross-sectional size of the working area is equal to the cross-sectional size of the bath. The exception is that for RYN and RYD type bath furnaces where the electrode passes through the cross-sectional area of the bath, the cross-sectional size of the working area is equal to the cross-sectional size of the bath minus the corresponding size of the area occupied by the tubular heating element or electrode.
3.3 Power-to-capacity ratio
The ratio of the rated power (kW) of the electrode salt bath furnace to the bath volume (L). When the bath depth does not exceed 1m, the bath volume is calculated based on the salt liquid surface being 100mm away from the top surface of the bath. When the bath depth exceeds 1m, it is calculated based on 150mm from the top surface of the bath. Approved by the Ministry of Machinery and Electronics Industry on June 28, 1991 and implemented on July 1, 1992
4 Product classification
4.1 Varieties and specifications
JB/T5266-1991
4.1.1 Bath furnaces are divided into multiple varieties according to the structural type and the maximum working temperature, as shown in Table 1. Table
Variety code
Rectangular bath, internal tubular heating element heating Rectangular bath, external electric heating
Circular bath, external electric heating
Rectangular or circular bath, internal electrode heating
Maximum working temperature
Other maximum working temperature values are allowed in the enterprise product standards. In this case, the number in the variety code (maximum working temperature divided by 100, without decimals) should be changed accordingly.
4.1.2 Each variety of bath furnaces is divided into multiple specifications according to the bath size. Unless otherwise specified or required (see Article 9.2), the bath dimensions shall comply with the provisions of Table 2. Table 2
Minimum specifications
Width × length × height
200 × 200 × 400
Diameter × height
200 × 300
Width and length increase by 50, and increase by 100 after reaching 600; height increases by 100, and increases by 200 after reaching 800.
Diameter increases by 50, and increases by 100 after reaching 500; height increases by 100, and increases by 200 after reaching 800.
4.1.3 Each bath furnace manufacturer may choose from the varieties and specifications specified in Articles 4.1.1 and 4.1.2, and formulate their own enterprise product standards accordingly.
4.2 Model
The model of the bath furnace should be compiled according to ZBK60001, but the "main parameters" in the model should be "maximum operating temperature" and "bath size". The technical level code in the model shall be determined in accordance with Article 7.4 of this standard. 4.3 Main parameters
The following items should be listed separately for each model of bath furnace in the enterprise product standard: a.
Power supply voltage, V,
Power supply frequency, Hz
Number of power supply phases:
Rated power, kW;
JB/T 5266-1991
Rated capacity of transformer (or voltage regulator), kV·A (applicable to RYD type bath furnace) rated (secondary) voltage, V (applicable to RYD type bath furnace), working voltage, V (applicable to RYD type bath furnace); maximum working temperature,;
Bath tank size, mm;
Empty furnace heating time, h,
Furnace temperature uniformity,;
Empty furnace loss, kW,
Surface temperature rise, ℃;
Furnace body weight, t,
Furnace body dimensions, mm.
5 Technical requirements
General requirements
The bath furnace shall comply with the relevant provisions of Chapter 5 of GB10067.1 and GB5959.1 and GB5959.4. 5.2 Supplementary requirements for design and manufacture
5.2.1 Overall design
The bath furnace consists of the furnace body, control cabinet (or controller), etc.; RYD type bath furnaces shall be equipped with step-down transformers or similar voltage regulating devices with graded voltage regulation.
The furnace body consists of bath, furnace lining, furnace shell, heating elements or electrodes, etc. 5.2.1.1RYN type
RYN type bath furnaces use metal baths and are heated by tubular heating elements installed inside the bath. This type of bath furnace generally uses oil, alkali or low melting point salt as a bathing agent.
5.2.1.2RYW
RYW bath furnaces use a metal bath, heated by a heating element located outside the bath, and use salt as a bathing agent. Among them, RYW5 bath furnaces can use nitrate as a bathing agent.
5.2.1.3RYD
This type of bath furnace is a suspended electrode salt bath furnace, heated by electrodes in direct contact with the salt. The electrodes can be embedded, inserted or other types, but embedded is recommended. 5.2.2 Power supply
5.2.2.1 Power supply
The power supply of the bath furnace shall comply with the provisions of Article 5.2.2 of GB10067.4. 5.2,2.2 Rated power
5.2.2.2.1 The rated power of RYN and RYW bath furnaces is designed to meet the requirements of Article 5.3.4 empty furnace heating time. 5.2.222 For RYD bath furnaces with a bath volume not exceeding 150L and a depth not exceeding 0.7m, the rated power shall be designed with reference to the power-to-capacity ratio in Table 3, and the larger value shall be used for small-volume furnaces.
For RYD bath furnaces beyond the above range, the power-to-capacity ratio may be appropriately reduced. 5.2.2.8 Transformer
The secondary voltage of the transformer used for RYD bath furnaces shall generally be below 36V and shall not exceed 50V at most. The secondary voltage shall be adjustable in at least 7 gears. When it is 7 gears, the 5th gear is the rated gear of the transformer. The transformer shall be able to work for a long time at the rated gear, and its temperature rise shall not exceed the design allowable value.
It is recommended to use T-type wiring for three-phase transformers.
JB/T 5266 -1991
The rated capacity of the transformer (at the rated gear) shall not be less than 1.3 times the rated power of the furnace. When otherwise specified or required (see Article 9.2), a magnetic voltage regulator or other voltage regulating device may be used instead of a transformer. Table 3
Maximum operating temperature
≤700
850~950
1250~1350
5.2.2.4 Electrical connection
Monwby
The copper bar (or aluminum bar) connecting the RYD type bath furnace transformer to the furnace body should have a sufficient cross-section to ensure that its surface temperature rise does not exceed the requirements of Article 5.3.7. The joint part where the copper bar (or aluminum bar) is connected to the electrode shall be water-cooled if necessary. 5.2.8 Furnace Shell
The furnace shell of the bath furnace shall be welded with steel plates and reinforced with steel sections. Unless otherwise required (see Article 9.2), the bottom of the bath furnace shall be equipped with a steel frame so that the bottom of the furnace shell is at least 75mm away from the ground to facilitate bottom ventilation.
The design of the top of the furnace shell shall take into account the influence of thermal expansion to minimize the deformation of the top. 5.2.4 Exhaust port and liquid drain port
RYW8 and RYD bath furnaces shall be equipped with exhaust ports for installing ventilation and smoke exhaust devices. The lower part of the RYW bath furnace shall be equipped with a liquid drain port to discharge the leaked liquid bath agent when the bath leaks. The refractory layer at the bottom of the furnace shall have a flow channel inclined toward the liquid drain port. The liquid drain port is generally not designed with a cover, but it should be stated in the product manual that this port should be sealed with thick paper when the bath furnace is in normal use.
5.2.5 Furnace cover
When specified or required (see 9.2), the bath furnace shall be equipped with a furnace cover. For bath furnaces with round baths, a manual, split, upward swing-opening furnace cover is recommended. For bath furnaces with rectangular baths, a manual, integrally sliding or split-sliding furnace cover is used. It is recommended that the furnace cover be insulated with refractory fiber felt.
5.2.6 Bath
The dimensional deviation of the bath shall be within the range of 0 to 3% of the specified value of each dimension, but the maximum shall not exceed 15 mm. 5.2.6.1RYN, RYW5 and RYD6 types
The baths of these types of bath furnaces shall be made of ordinary or aluminized low-carbon steel plates welded inside and outside. The thickness of the bath wall shall not be less than 8 mm except for RYN type bath furnaces.
5.2.6.2RYW8
The bath of this type of furnace shall be cast from heat-resistant steel in the form of a hemispherical bottom cylinder, or welded from heat-resistant steel plates in the form of a butterfly bottom cylinder. The top of the bath shall have a flange to support the bath on the top plate of the bath and to facilitate the sealing between the bath and the top plate. The wall thickness of the bath shall not be less than 10mm. The service life of the bath shall be not less than 1000h and 2000h for Class A and Class B baths respectively. 5.26.8RYD8, RYD9 and RYD13
The bath of these types of furnaces shall be built with refractory bricks, cast with refractory concrete, or fired as a whole with refractory materials. When rebuilt with refractory bricks, the mortar joints shall not be greater than 1.5mm and shall be staggered. The service life of the bath shall comply with the provisions of Table 4. Maximum operating temperature
850~950
1250~1350
JB/T5266-1991
Service life of bath
5.2.7 Furnace lining
There should be a furnace lining outside the bath. The design and manufacture of the furnace lining should meet the requirements of Article 5.3.7 for surface temperature rise. C-level
The lining of RYN, RYW and RYD6 bath furnaces should be designed and manufactured in accordance with the requirements of Article 5.2.5 of GB10067.4. The lining of the RYD bath furnace with a refractory bath should have a steel plate groove with a wall thickness of not less than 6mm. The outer wall of the steel plate groove is built with insulating bricks between the furnace shell, and the inner wall and the bath are filled with a refractory clay entrapment layer or similar interlayer with a thickness of not less than 30mm to prevent seepage, expansion and insulation.
5.2.8 Heating elements and electrodes
5.2.8.1RYN type
The tubular heating elements used for this type of bath furnace should be inserted from the top of the bath liquid. The sleeve material should be able to withstand the erosion of the bath agent. The heating element should be kept at a certain distance from the bottom of the bath tank to prevent the heating element from being buried by slag during use, causing overheating of the element. The tubular heating elements used should meet the requirements of relevant standards such as JB2379. 5.2,8.2RYW type
The heating elements of this type of bath furnace are made of electric heating alloy wire or strip. The layout of the heating elements should take into account the use conditions of the bath furnace to ensure uniform furnace temperature and avoid local overheating of the bath tank. The heating elements should generally be arranged only below the liquid level around the bath tank and should not be arranged at the bottom. For RYW type bath furnaces using nitrate salts, when it is necessary to arrange heating elements at the bottom, the power density (kW/m*) of the heating elements at the bottom should be at least 20% smaller than that of the surrounding areas. The heating element circuit should be able to switch the bottom heating element on and off independently, and the bottom heating element can only be switched on when the surrounding heating elements have been switched on first and the solid salt in the bath has been partially melted. The service life of the heating element is limited to the input power of the bath furnace at the rated power supply voltage being 15% less than the rated power, and should comply with the provisions of Table 5.
Maximum operating temperature
600~950
5.2.8.3RYD type
Service life of heating elements》
The electrodes used in this type of bath furnace are generally made of low carbon steel. If necessary, the electrode parts that are corroded by salt should be made of stainless steel, or manufactured as required (see Article 9.2).
The service life of the electrodes of the RYD type bath furnace should be equivalent to the service life of its bath. The arrangement of the electrodes should avoid overburning of the charge due to the current between the electrodes flowing through the heated charge during operation. The distance between electrodes should be reasonably designed so that the bath furnace can operate within the working voltage range through the voltage regulation of the transformer or voltage regulator, and the rated power of the bath furnace can meet the requirements of Article 5.3.3 at the rated voltage level. If the electrode enters the bath tank from the side of the furnace shell, the electrode and the bath tank, as well as the electrode and the furnace lining should be sealed to ensure that the salt solution will not leak when the bath furnace is in use.
5.2.9 Starting melting of RYD type bath furnace.
JB/T5266-1991
Unless otherwise required (see Article 9.2), rapid melting measures should be taken according to the time requirements of Article 5.3.4. 5.2.10 Measurement, control and record
The measurement, control and record of the bath furnace shall comply with Article 5.2.7 of GB10067.4 and the following supplementary provisions. In case of any difference, this standard shall prevail.
5.2.10.1 Thermocouple or auxiliary radiation type sensor 5.2.10.1.1 Each RYN, RYD6, RYD8, and RYD9 bath furnace shall be equipped with a thermocouple. The thermocouple extends into the bath and is connected to the temperature controller.
5.2.10.1.2 A RYD13 bath furnace shall be equipped with a radiation type sensor or thermocouple and connected to the temperature controller. If there are special requirements, they can be proposed in accordance with Article 9.2.
5.2.10.1.3 Two thermocouples shall be equipped for RYW bath furnaces. One extends between the furnace lining and the bath and is connected to the over-temperature controller, and the other extends into the bath and is connected to the temperature controller.
5.2.10.2 Temperature instrument and temperature control system 5.2.10.2.1 Each RYN and RYD class A and B bath furnace shall be equipped with a non-recording temperature indicating controller. A temperature indicator, recorder and controller shall be provided for RYD Class C bath furnaces. 5.2.10.2.2 A temperature indicator, recorder, controller and an over-temperature controller shall be provided for RYW Class bath furnaces. 5.2.10.2.3 The control type of the bath furnace temperature controller shall generally be a time proportion type that controls the contactor through an intermediate relay system, or other technically more advanced types. Position control is allowed to be retained for Class A furnaces. When it is required to equip the bath furnace with a microprocessor digital display temperature control instrument, it can be proposed in accordance with Article 9.2. The temperature setting accuracy of the temperature control instrument shall not be less than 0.5%, and the resolution shall not be less than 1°C. The digital height shall not be less than 15mm. The instrument shall be equipped with an external socket for connecting a recorder or printer. The effective width or diameter of the recording paper of the furnace temperature recorder shall not be less than 150mm. When a printer is required to replace the recorder, it can also be proposed in accordance with Article 9.2.
5.2.10.2.4When it is required to equip RYN and RYD bath furnaces with recording temperature controllers, over-temperature controllers or high and low temperature controllers, it may be proposed in accordance with Article 9.2. The over-temperature controller or high and low temperature controller shall be equipped with corresponding temperature sensors and control circuits. The high and low temperature controller shall be able to select high temperature control points and low temperature control points. When the bath furnace temperature reaches the high temperature control point, the high and low temperature controller shall be able to switch the heating power supply and issue an audible alarm. When the temperature drops to the low temperature control point, the furnace temperature shall be able to maintain at the low temperature point and issue an audible alarm. 5.2.10.3 Electrical Instruments
RYD bath furnaces shall be equipped with electric energy meters, primary and secondary electric meters, and primary ammeters. For three-phase bath furnaces, a voltmeter can be provided for each primary and secondary, and each phase is switched by a conversion switch. A primary ammeter shall be provided for each phase. 5.2.11 Product manual
In addition to the contents required by Article 5.1.9 of GB100067.1, the product manual of the bath furnace should also include the location and size of the working area on the bath grid drawing. For RYD bath furnaces, it should also include component drawings and parts drawings of the bath, electrodes, and melting devices, as well as materials and manufacturing requirements for masonry or casting of refractory baths, and melting procedures, so that users can make replacement baths and electrodes by themselves.
5.2.12 Other requirements
Other design and manufacturing requirements that should be met should be supplemented in the enterprise product standards of bath furnaces when necessary. 5.3 Performance requirements
The bath furnace should be able to work reliably under the specified design parameters and use conditions and meet the following requirements. 5.3.1 Insulation resistance
Except for the furnace body of the RYD type bath furnace, the insulation resistance of the bath furnace shall comply with the provisions of Article 5.3.1 of GB10067.4. 5.8.2 Working temperature
The maximum working temperature of the bath furnace shall be in accordance with Article 4.1.1. 6
JB/T5266-1991
The minimum working temperature of the bath furnace depends on the type of bath agent used. It is not specified in this standard and can be found in the relevant technical manual. 5.8.8 Rated power deviation
The rated power deviation of the RYN type bath furnace should be within the range of ±10%. The rated power deviation of the RYW type bath furnace should be within the range of 0-10%. The rated power deviation of the RYD type bath furnace should be within the range of 0-20%. 5.3.4 Empty furnace heating time
The empty furnace heating time of RYN and RYW bath furnaces shall generally not exceed 2.5h. The specific value shall be specified in the enterprise product standards or agreed upon by the supply and demand parties.
Unless otherwise required (see Article 9.2), the empty furnace heating time of RYD bath furnaces with a bath volume not exceeding 150L and a bath depth not exceeding 0.7m shall comply with the following provisions.
Grade A furnace
Grade B furnace
Grade C furnace
When the bath volume and depth exceed the above range, the empty furnace heating time shall be specified in the enterprise product standards or agreed upon by the supply and demand parties. 5.3.5 Furnace temperature uniformity
5.3.5.1 The furnace temperature uniformity of RYN and RYD bath furnaces shall not exceed the range specified in Table 6, based on the temperature measured by the furnace temperature control thermocouple.
Maximum working temperature
≤550
850~1350
5.3.5.2The temperature uniformity of RYW type bath furnace shall meet the following requirements: Class A furnace
Class B furnace
(ab)≤15℃bzxz.net
(ab)≤10
Among them, a-the highest value of the temperature measured at each temperature measuring point in the bath, ℃; b. The lowest value of the temperature measured at each temperature measuring point in the bath, C. 5,3.6 Empty furnace loss
The empty furnace loss of the bath furnace shall meet the requirements of the enterprise product standards. Guard
5.3.7 Surface temperature rise
When the bath furnace is in the thermally stable state at the highest working temperature, the surface temperature rise of the side wall of the furnace shell shall meet the requirements of Table 7. The surface temperature rise of the handle, etc. shall not exceed 30℃. The surface temperature rise of the copper bar (or aluminum bar) and its joints of the RYD type bath furnace shall not exceed 60℃. 5.8.8 Three-phase current imbalance
The three-phase current imbalance of the RYD type three-phase bath furnace shall not exceed 10%. 5.3.9 Others
The other performances of the bath furnace shall comply with Article 5.2 of this standard, as well as the corresponding provisions in the enterprise product standards and supply contracts. 5.4 Requirements for complete sets
5.4.1 The complete set supply scope of the bath furnace specified by the supplier shall be listed in the enterprise product standards, which shall mainly include the following items: a. Bath furnace body,
Transformer (applicable to RYD bath furnaces):
Control cabinet (or controller),
Temperature instrument;
JB/T5266-1991
Temperature sensor (thermocouple or radiation sensor, etc.); e.
Compensation wire (applicable to bath furnaces equipped with thermocouples); f.
Equipment for starting melting (when these equipment are required by the design); g.
h. Spare parts,
i. "Product Manual", including necessary drawings. The above items may be added or deleted in the enterprise product standards, and the specific content of each item shall be listed, including model, specification and quantity.
If the demander has different requirements for the items specified by the supplier, it can be proposed according to Article 9.2. Table
Maximum working temperature
500~950
1250~1350
Surface temperature rise《
When the following materials, accessories or devices are required to be provided, they can be proposed according to Article 9.2. Necessary technical requirements shall be agreed upon by the supply and demand parties a. Other measuring instruments, exhaust hoods or other exhaust facilities not specified in this standard;
Bath (oil or salt, etc.)
Quenching materials and fixtures;
Special tools, such as barrels, scoops, electrode scrapers, etc. e.
Fire troughs and cleaning machines,
Hand-held air compressors for removing molten salts.
6 Experimental methods
The test of the bath furnace shall be carried out in accordance with the corresponding provisions of GB10066.1 and GB10066.4 and the following supplementary provisions. In case of differences in the provisions of the three standards, this standard shall prevail.
When conducting the empty furnace power-on heating test of the bath furnace, a certain amount of bath agent shall be contained in the bath. Unless otherwise specified or required (see Article 9.2), the bath agent and dosage for the test of various types of bath furnaces shall comply with the provisions of Table 8. 6.1 Measurement of empty furnace heating time
The empty furnace heating time of RYN and RYW bath furnaces shall be measured in accordance with Article 6.6.1 of GB100664. The heating procedure shall be specified in the enterprise product standard when necessary.
The empty furnace heating time of RYD bath furnace shall be measured in accordance with Article 6.6.2 of GB10066.4. The melting procedure of the bath furnace shall be consistent with the melting procedure specified in the product manual during normal operation. Melt and heat the solid salt that has been melted and completely cooled to the ambient temperature. The time from the start of power-on to the time when the bath furnace reaches the maximum operating temperature is the empty furnace heating time. No salt is added during the measurement. 6.2 Measurement of rated power
The rated power of the bath furnace shall be measured in accordance with Article 6.7 of GB10066.4. The rated power of the RYD bath furnace shall be measured on the primary side of the transformer after the start of melting is completed, the auxiliary heat source for melting has been cut off, the transformer is adjusted to the rated gear, and the furnace temperature reaches the maximum operating temperature. The rated power of the bath furnace is equal to the measured power minus the loss power of the transformer. 8
Bath furnace name
Oil bath furnace
Nitrate salt furnace
Low-temperature salt
Medium-temperature salt
High-temperature salt
Variety code
RYW8, RYD8
JB/T 5266 -1991
HG-65H synthetic cylinder oil
50%KNOs+50%NaNOs
50%BaC12+30%KC1+
20%NaCl
50%BaCl+50%NaCI
100%BaC12
According to the bath furnace design regulations, it should be specified in the enterprise product standards or product instructions
When the bath tank depth does not exceed 1m, the wave surface is 100mm away from the top surface of the bath grid.
When the bath tank depth exceeds 1m, it is 150mm.
6.3 Measurement of furnace temperature uniformity
The measurement work is carried out after the bath furnace reaches a thermally stable state. Unless otherwise specified, when the bath furnace is kept warm at the test temperature, it can be considered that the bath furnace has actually reached a thermally stable state that meets the requirements of this test. The test temperature of RYD13 bath furnace is 1200℃. The test temperatures of other types of bath furnaces are their maximum working temperatures. The measuring area is the part of the working area limited by the bottom plane of the effective height of the working area and the top plane 50mm below the surface of the bath liquid during the test.
Unless otherwise required (see Article 9.2), for a bath furnace with a rectangular temperature measuring area, there are five temperature measuring points, which are arranged according to the requirements of Article 6.13.3.2 of GB10066.4. For a bath furnace with a cylindrical temperature measuring area. There are three temperature measuring points: one is located in the center of the temperature measuring area and the other two are located at the edges of the top and bottom planes of the temperature measuring area, and are symmetrical with the center point. When the thermocouples for measurement are actually arranged, the ends of the thermocouples can be 10 to 20mm away from the wall of the bath. 6.4 Measurement of surface temperature rise
The surface temperature rise of the bath furnace is measured in the thermally stable state at the highest working temperature of the bath furnace. Select a temperature measuring point on the furnace shell corresponding to the center of the bath at a distance of more than 100mm from the edge of the heating element or the electrode lead-out hole. Measure its surface temperature every 0.5h. When the difference between the surface temperatures measured twice before and after is no more than 2C in four consecutive measurements, it is considered that the bath furnace has reached an actual thermal stability state. Then measure the surface temperature rise.
The temperature measuring point can be any point on the outer surface of the furnace shell, except within 75mm from the edge of the metal heating element and the thermocouple lead-out hole, and within 100mm from the edge of the electrode lead-out hole. Unless otherwise specified, the outer surface of the furnace cover and the furnace top plate shall not be measured for surface temperature rise. Measurement of empty furnace loss
The empty furnace loss of the bath furnace is measured with an electric energy meter after the test in Article 6.4. The measurement time should not be less than 1h. The empty furnace loss is calculated according to formula (1):
Where: Ps-empty furnace loss, kW,
E-electric energy input to the bath furnace during the measurement period, kWb,t——Measurement time, h.
（1）
It is allowed to measure on the primary side of the bath furnace transformer. At this time, the empty furnace loss of the bath furnace is equal to the power on the side minus the loss power of the transformer.
JB/T5266-1991
During the measurement, the bath furnace is not covered with a furnace cover, and temporary measures such as covering the furnace opening are not allowed. 6.6 Measurement of three-phase current balance
This test is only carried out on RYD three-phase bath furnaces. When the bath furnace is in a thermally stable state at the highest operating temperature, at the rated voltage, use the ammeter equipped with the bath furnace itself to measure the current of each phase on the primary side of the transformer.
The three-phase current unbalance degree is calculated according to formula (2): K=
Wherein, K..three-phase current unbalance degree,
I...—the ammeter reading of the phase with the largest current, A, I...—the ammeter reading of the phase with the smallest current, AI.——the arithmetic mean of the three ammeter readings, A. 7 Inspection rules and classification
.100%.
The inspection and classification of bath furnaces shall be carried out in accordance with Chapter 7 of GB10067.1 and the following provisions. The factory inspection items of the bath furnace shall include the following: 7.1
General inspection;
Safety inspection;
Durability test of the label writing,
Inspection of power-to-capacity ratio and transformer capacity (according to Articles 5.2.2.2.2 and 5.2.2.3, applicable to RYD bath furnaces); inspection of bath tank size and working area size, inspection of furnace lining and bath tank manufacturing quality;
Inspection of electrode manufacturing quality (applicable to RYD bath furnaces); inspection of heating element manufacturing quality (applicable to RYW bath furnaces); metal heating Measurement of cold DC resistance of components (applicable to RYW type bath furnaces); inspection of short circuit of heating elements or electrodes to furnace shell; measurement of insulation resistance (not applicable to furnace body of RYD type bath furnaces); calibration of temperature instruments; cold inspection of operation or action of motion mechanism (when such mechanism is available); inspection of interlock alarm system; inspection of water, gas and hydraulic systems (when such systems are available); inspection of accessories, including inspection of model, specification and factory certificates; scope of supply, including inspection of completeness of factory technical documents and packaging inspection.
Type inspection items of bath furnaces shall include the following items; a.
All factory inspection items (under type test conditions) measurement of empty furnace heating time,
measurement of rated power,
measurement of maximum operating temperature;
measurement of empty furnace loss
measurement of furnace temperature uniformity,
measurement of surface temperature rise;
(2)
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