MT/T765-1997 Approved by the Ministry of Coal Industry of the People’s Republic of China on December 30th, 1997 Implemented on June 1st, 1998
This standard specifies the requirements, test methods, inspection rules, marking, packaging, transportation and storage of automatic spray control valves for hydraulic supports.
This standard is applicable to various automatic spray control valves used for underground hydraulic supports in coal mines.
2 Referenced standards
The provisions contained in the following standards, through reference in this standard, constitute the provisions of this standard. At the time of publication of this standard, all versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest version of the standard.
GBl91-90 Packaging, Storage and Transportation Pictorial Symbols
GB/T6388-86 Transport Packaging Shipping and Receiving Marks
GB/T13264-91 Sampling Procedures and Tables for Small Batch Count Inspection of Nonconforming Product Rates
GB/T14437-93 Single supervision sampling inspection procedure for product quality counting (applicable to situations with large overall quantities)
GB/T15482-1995 Product Quality Supervision – Single Sampling Inspection Procedure and Sampling Table for Small Population Count
Emulsified oil for MT76-83 hydraulic support
This standard adopts the following definitions. 3.1 Control valve of automatic spray hydraulic supports
It is a device installed on the underground hydraulic support of the coal mine and connected with its corresponding hydraulic pipeline. When operating the corresponding handle of the support to make the support move, it uses the working fluid to automatically open or close the spray water path (hereinafter referred to as the control valve). 3.2 Operating fluid
Emulsion that opens or closes the control valve and has a certain pressure. 3.3 Opening pressure
The minimum pressure required to open the control valve, in MPa.
The control valve should comply with the provisions of this standard and be manufactured in accordance with the approved drawings and technical documents according to the prescribed procedures.
4.1 Operating Environment Temperature
It can be used normally at an ambient temperature of 4~40 ℃.
The outer surface should be flat and smooth, and there should be an anti-corrosion protective layer. The protective layer should be uniform, without peeling or scratches; The shell shall be free from deformation, cracking, corrosion, and mechanical damage; Clearly mark the inlet and outlet holes, as well as the working fluid inlet holes; The nameplate is firmly installed and the handwriting is clear. 4.3 Interface
The inlet and outlet holes, as well as the interface of the working fluid inlet hole, should adopt the form of a quick connector. The interface size and surface roughness should meet the requirements of Appendix A (standard appendix) of this standard. Each interface has been tested without water or liquid leakage. 4.4 Strength
The rated pressure of the control valve fluid is 32MPa, and the test is conducted by applying 1.5 times the rated working pressure to the inlet of the control valve. There is no leakage, and the shell and parts do not undergo any deformation or damage. 4.5 Resistance loss
When water passes through the control valve at a flow rate of 20L/min, the pressure difference between the inlet and outlet should not exceed 0.1MPa. 4.6 Opening pressure
When the water supply pressure is within the range of 1.0~7.0MPa, the opening pressure should not exceed 2MPa. 4.7 Using water pressure
The control valve should be able to open and close normally during the test with a water pressure range of 1.0~7.0MPa, and there should be no automatic opening or closing of the control valve during the test process. 4.8 Service life
After 4000 cycles of testing, the sealing should comply with the provisions of 4.9. 4.9 Sealing
When conducting the test according to the sealing test method in Table 1, each test pressure should have no pressure drop.
Within the rated pressure and water pressure range of the working fluid, after a 2-hour pressure stabilization test, the working fluid should not have a pressure drop.
5 Test methods
5.1 Test System
The experimental system is shown in Figure 1. 5.2 Test instruments and equipment 5.2.1 Pressure gauge: The range is 0~1.6MPa and 0~40MPa, with an accuracy of 1.5 levels. 5.2.2 Water meter: rated pressure ≥ 7.0MPa, rated flow rate ≥ 30L/min. 5.2.3 Stop watch: ordinary mechanical or electronic stop watch. 5.2.4 spray pump: rated pressure ≥ 7.0MPa, rated flow ≥ 30L ／ min. 5.2.5 Working fluid pump: rated pressure ≥ 32MPa. 5.2.6 Directional valve: Directional valve for hydraulic support. 5.2.7 Counter: Blood cell counter. 5.2.8 Pressurizing device: rated pressure ≥ 48MPa. 5.3 Test conditions 5.3.1 Water temperature for test spray is 4 ℃~40 ℃. 5.3.2 The working fluid used for the test shall be an emulsion or anti rust low pour point 5 # hydraulic oil prepared by mixing emulsified oil and neutral soft water as specified in MT76-83 at a weight ratio of 5:95. 5.3.3 Control the working fluid temperature between 10 ℃ and 50 ℃. 5.3.4 spray water and working fluid shall be filtered by a filter with a filtration precision of 0.125mm. 5.3.5 The outlet end of the control valve should be connected with a certain number of nozzles to meet the flow requirements for resistance measurement. 5.4 Test items and methods
6 Inspection Rules
6.1 Product inspection is divided into two types: factory inspection and type inspection. 6.2 Factory inspection: 6.2.1 Control valves should be inspected by the quality inspection department of the manufacturer, and can only be shipped after passing the inspection and issuing a certificate of conformity. 6.2.2 Batch rules:
Control valves should be accepted in batches. An inspection batch can be composed of a production batch, and when a production batch batch N<100, it can be composed of several batches that meet the following conditions:
——Production batches are all manufactured under basically the same conditions of materials, processes, and equipment;
——The time for several production batches to form an inspection batch shall not exceed 30 days. 6.2.3 Sampling method and judgment rules:
It should comply with the provisions of GB/T13264.
——The risk quality of the production party is 5%, and the risk quality of the user party is 35%;
——Adopting a one-time sampling plan;,
——Classification of non-conforming products: not classified; 6.3 Type inspection: 6.3.1 In case of any of the following situations, type inspection should be carried out.
——When trial producing new control valves or transferring to another factory for production;
——Regularly inspect the product for 4 years of production;
——When production is resumed after more than 3 years of suspension;
——After formal production, there are significant changes in structure, process, and zirconia material that may affect the performance of the control valve;
——When there is a significant difference between the factory inspection and the previous type inspection results;
——When the national quality supervision agency requests type inspection. 6.3.2 The type inspection shall be carried out by a nationally authorized unit. 6.3.3 Sampling method and judgment rules:
When the total supervision volume N>250, it should comply with the provisions of GB/T14437; When the total supervision volume N ≤ 250, it should comply with the provisions of GB/T15482.
Several elements of execution are specified as follows:
——Classification of non-conforming products: not classified;
——The quality level of product supervision is 5%;
——When using GB/T14437, the inspection level is selected as II; When using GB/T15482, the supervision and inspection level is selected as the first level. 7. Marking, Packaging, Transportation, and Storage 7.1 Marking 7.1.1 Each control valve should have a nameplate in a prominent position. The nameplate should clearly indicate the product name, model, main performance parameters, manufacturing date, and factory name; The inlet and outlet of the control valve working fluid should be marked accordingly and indicated in the product manual. 7.1.2 The transportation packaging, storage, and shipping marks should comply with the provisions of GB191 and GB/T6388. 7.2 Packaging 7.2.1 After passing the inspection of the control valve, the working fluid inside the valve should be drained. The inlet and outlet of the working fluid should be tightly plugged with plastic plugs, and the plastic plug gauge should comply with the requirements of Appendix B (informative appendix) of this standard. 7.2.2 The packaging box should be equipped with a certain number of vulnerable parts, accessories, and special tools. 7.2.3 The packaging box should be accompanied by the following documents:
——Product qualification certificate;
——Product user manual. 7.3 Transportation 7.3.1 Product packaging should comply with the relevant requirements of the transportation department. 7.3.2 The product should be protected from rain during transportation. 7.4 Storage
The product should be stored in a well ventilated and corrosion-free warehouse.
Link to this article：General technology of automatic spray control valve applied to hydraulic support
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