Want to choose the high quality starting valve, first of all we have to know what is pneumatic valve.
Pneumatic valve: by means of air operated valve. Pneumatic valve purchase only when clear specification, class, work pressure will meet purchasing requirements of the practice, the current market economy, the environment is not perfect because pneumatic valve system
Made of manufacturer for product competition, each are pneumatic valve unified design concept, carries on the different innovation, formed respective enterprise standard and product personality. So in pneumatic valve when purchasing a detailed mention
The technical requirements, and manufacturers agreed coordination, as pneumatic valve procurement contract annex is very necessary.
The quality of pneumatic valve should have? What are the conditions. The several aspects to introduce.
Pneumatic valve purchase only when clear specification, class, work pressure will meet purchasing requirements of the practice, the current market economy, the environment is not perfect. Because pneumatic valve manufacturers in order to the product competition, each all in
Pneumatic valve unified design concept, carries on the different innovation, formed respective enterprise standard and product personality. So in pneumatic valve when purchasing a detailed out technology requirements, and manufacturers agreed coordination
As pneumatic valve procurement contract annex is very necessary.
1. The general requirements for
1.1 pneumatic valve specifications and categories, shall conform to the requirements of the pipeline design documents.
1.2 pneumatic valve model should specify the basis of the national standard Numbers requirements. If the enterprise standard, should indicate the type of relevant specification.
1.3 pneumatic valve working pressure, the requirement of pipe was working pressure, in does not affect the price of the premise, the valve can bear work pressure should be greater than pipe actual working pressure; Air valve closed condition of any side
Should be able to withstand 1.1 times the valve working pressure value without leakage, The valve opens conditions, the body should be able to withstand double valve working pressure requirements.
1.4 pneumatic valve manufacturing standards, and shall explain based on gb Numbers, if the enterprise standard, purchasing contract shall attach enterprise file.
2. Pneumatic valve standard quality
2.1 body material, should with spheroidal graphite cast iron is given priority to, and indicate the brand and cast iron actual physical and chemical testing data.
2.2 valve rod material, and strive to stainless steel stem (2 cr13), large diameter valves should also is stainless steel panel bag stem.
2.3 nut material, using casting aluminium brass or cast aluminum bronze, and the hardness and strength are greater than the valve stem.
2.4 stem bushing material, its hardness and strength which shall be no greater than the valve stem, and in water soak conditions and stem, the body do not form electrochemical corrosion.
2.5 sealing surface material
(1) pneumatic valve category is differ, seal way and material requirements differ;
(2) the common wedge gate valve, copper ring material, fixed mode, grinding mode shall explain;
(3) soft-sealing gate valve, valve plate rubber lining material of physical chemistry and health testing data;
(4) the butterfly valve should be marked on the body sealing surface material and butterfly plate on the sealing surface material; Their physical and chemical inspection data, especially rubber health requirements, ageing resistance, wear resistance, Usually adopt butyl
Fine rubber, epdm, etc., it is strictly prohibited to mixed with reclaimed rubber.
2.6 valve shaft packing
(1) due to the network of the pneumatic valve, usually open/close not frequent, request packing in a number of years don't activities, packing nor aging, maintained for a long time seal effect;
(2) the valve shaft packing should also be under frequent alignment, seal effect good sex;
(3) in view of the above requirements, valve shaft packing strive to lifelong don't change or more than ten years not to change;
(4) packing if need to change, pneumatic valve design should consider to have hydraulic pressure change under the condition of the measures.
3. Variable speed drive box
3.1 housing material and internal &external anti-corrosion requirements and body principles.
The 3.2 should seal measures, housing after assembly can withstand the 3 meters water column status of soak.
The 3.3 the open-close limit device, its adjustment nut should be in the cabinet or in box outside, but need special tools to work.
3.4 drive structural design is reasonable, the opening and closing can only drive valve shaft rotation, don't make its fluctuation channeling move, transmission parts bite measurable, do not produce loading when opening and closing separation skid.
3.5 variable speed drive housing and valve shaft seal not linked to no leakage of the whole, or should have reliable anti string leakage measures.
3.6 the cabinet without sundry, gear bite site should have grease protection.
4. Pneumatic valve operating mechanism
4.1 pneumatic valve opening and closing operation of the direction, all should be clockwise closed.
4.2 because of the pipe pneumatic valve, often is artificial opening and closing, open the revolution is unfavorable and overmuch, is the large diameter valves should also be in 200-600 in turn.
4.3 in order to facilitate a person's opening and closing operation, in the plumber pressure condition, the biggest open-close torque appropriate for 240 n - m.
4.4 pneumatic valve opening and closing operation end shall be the party tenon, and size standardization, and to the ground, so that people from the ground can direct operation. With roulette valve does not apply to the underground pipe network.
4.5 pneumatic valve opening and closing degree of display panel
(1) pneumatic valve opening and closing degree of scale line, should casting in gearbox cover or conversion direction after the display panel shell, are facing the ground, scale line brush on fluorescent powder, in order to show marked;
(2) the indicator panel needle material in the management of the good use of stainless steel plate, or to brush paint of steel, do not use the aluminum skin production;
(3) indicator panel needle striking, fixation, once the on-off control accurate, should with rivet lock.
4.6 if pneumatic valve buried deep, operating mechanism and display panel from the ground or distance of 1.5 m, should have extension rod facilities, and fixed firm prison, so that people from the face of the earth observation and operation. That is to say, tube
Net of valve opening and closing operation, unfavorable the well operation.
5. Pneumatic valve performance testing
5.1 valve a specification batch manufacturing, should entrust authority institution for the following properties testing:
(1) the valve in the working pressure condition of opening and closing moment;
(2) in the working pressure conditions, can guarantee that the valve closed tight continuous on-off times;
(3) the valve in the pipeline under condition of flow resistance coefficient detection.
5.2 the valve in the factory should be done before the following detection:
(1) the valve in open situation, the body should inherit the valve working pressure value two times of the internal pressure detection;
(2) the valve shutoff conditions, respectively 1.1 times on both sides under the valve working pressure value, no leakage, But the metal sealing butterfly valve, leakage value also is not more than requirements.
6. Pneumatic valve internal and external anticorrosion
6.1 the body (including variable speed drive housing) inside and outside, first of all should be blast cleaning rust removal, and strive to electrostatic spraying powder non-toxic epoxy resin, thickness of 0.3 mm above. Large valve electrostatic spraying non-toxic epoxy
Fat is in difficulty, should also be brush, spraying similar non-toxic epoxy paint.
6.2 body internal and valve plate parts requirements comprehensive anticorrosive, on the one hand, soak in water will not rust, in between two metal do not produce electrochemical corrosion; Two aspects of smooth surface that reduce water resistance
.
6.3 the body anti-corrosive epoxy resin or paint health requirements, should have corresponding authorities inspection report. Chemistry physics performance also should comply with the relevant requirements.
7. Pneumatic valve packing and shipping
7.1 on both sides of the valve should be set light blocking board solid seal.
In 7.2, the valve should be small in straw rope strapping, and modes of transport in container it is advisable.
7.3 large diameter valves also have simple strip framework solid packing, in order to avoid the transport process touch damage.
8. Pneumatic valve factory specifications
Pneumatic valve is equipment, in the factory the specification shall indicate the following data:
Valve specifications; Model; Work pressure, Manufacturing standards; Body material; Valve lever material; Sealing material; Valve shaft packing material; Valve rod shaft sleeve material; Internal &external anti-corrosion material; Operation start direction; Revolution; Working pressure condition open-close torque; Factory name; Release date; The factory Numbers; Weight; Connecting flange of the pore diameter and hole number, center hole spacing, To graphic way marked overall length, width and height control size; Valve flow resistance coefficient; Effective number of opening and closing, Valve factory testing related data and installation, maintenance precautions, etc.
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