Ductile Iron Fittings selection should pay attention to matters

(1) Valve use requirements:

① ordinary gate valve, ball valve, cut-off valve according to its structural characteristics is to stop the use of conditioning. But in the technical planning, throughout the use of mediation. Due to the use of conditioning, the valve seal for a long time in the throttling state, the oil impurities in the erosion of the seal, damage the sealing surface, constitute a closed lax or because the operator in order to damage the sealing surface has reached the seal, constitute the valve clearance Open appearance.
② the location of the valve equipment is unreasonable, when the use of media rich in impurities, there is no filter in front of the device or filter, so that impurities into the valve inside the composition of the sealing surface damage, and perhaps impurities in the bottom of the valve accumulation, resulting in strict valve closure, And the release of leakage.
(2) from the perspective of technical needs
① for corrosive media, if the temperature and pressure is not high,
Should try to use non-metallic valves, if the temperature and pressure higher, available fabric valve to save precious metals. In the selection
Non-metallic valves, should still think about economic rationality; for large viscosity medium, the demand for a smaller flow resistance, should use DC-type cut-off valve, gate valve, ball valve, plug valve and other flow resistance of small valves. Flow resistance of small valves, less energy consumption; when the medium is oxygen or ammonia and other special media, should use the corresponding oxygen valve or ammonia valve.
② double flow of the pipeline should not use directional valve,
Should use non-directional valve.
For example, refinery heavy oil pipeline after the suspension operation, the use of steam reverse purge pipeline to prevent heavy oil coagulation blocking pipeline, here should not use cut-off valve, due to reverse inflow, the simple erosion valve sealing surface, also Affect the effectiveness of the valve, but should choose the valve is better.
③ for some of the crystallization or precipitation-rich media, should not use cut-off valve and gate valve, because of their sealing surface is simply crystal precipitation or sediment wear. Therefore, it should be selected ball valve or plug valve is more appropriate; also available flat gate valve, but the best choice of jacket valve.
④ in the selection of the gate valve, the stem and the dark rod double gate more common use of corrosive media;
Single gate for large viscosity medium; wedge double gate on the high temperature and the deformation of the sealing surface habit is better than the wedge single gate,
There will not be due to changes in the temperature of the onset of jamming appearance, in particular, is more than a rigid single gate.
⑤ general water, steam pipes on the valve, optional cast iron valves, but in the outdoor steam pipe if the stop, will constitute a condensate icing, and then freeze the valve. So in the cold area, the valve selection of cast steel, low temperature steel raw materials or to be useful insulation measures is appropriate.
⑥ on the risk of highly toxic media or other harmful media, should use the bellows structure of the valve, to avoid the media from the catch in the leak.
⑦ gate valve, globe valve and ball valve is the valve in the use of the largest valve, should be considered when selected. Gate valve flow can be strong, less energy consumption of transport media, but the equipment space is large, the valve structure is simple, easy to repair, but the flow resistance is large, the ball valve has a low flow resistance, rapid opening and closing characteristics, but the use of temperature restrictions , Oil products and other large viscosity of the medium, thinking to the gate valve can be strong, most of the selection of gate valve; and in the water and steam pipe, the use of cut-off valve, the pressure drop is not large, so the valve in the water, steam and other media In the use of more, the ball valve in the use of conditions agreed under the conditions of both can be.
(3) think from the operation convenience point of view
① For large diameter valves and long distance, high altitude, high temperature, high pressure occasions, should use electric and pneumatic valves, flammable and explosive occasions, to use explosion-proof equipment, in order to safe and reliable, the use of hydraulic and pneumatic equipment.
② on the demand for quick opening, fast clearance of the valve, should be selected according to demand butterfly valve, ball valve, plug valve or quick opening valve and other valves, should not use the general gate valve, globe valve. In the operation space is limited to the occasion, should not use the pole gate valve, should be used dark bar gate valve is appropriate, but the best choice butterfly valve.
(4) from the conditioning flow of the accuracy of thinking
Require accurate conditioning flow, you should use the conditioning valve, when the demand for conditioning the accuracy of small flow, should use needle valve or throttle valve. Demand to reduce the pressure after the valve should be used pressure reducing valve, to adhere to the stability of the valve after the pressure should be used regulator valve.
(5) from the temperature and pressure to think
High temperature and high pressure medium often use castings of chrome molybdenum steel and chrome molybdenum vanadium steel, for ultra-high temperature and high pressure medium should consider the use of its corresponding castings, forgings induction function is better than castings, temperature and pressure can also be better than casting.
(6) from the cleanliness of thinking
Food and bio-engineering production and transportation, the technical needs of the pipeline on the pipeline needs to think about the cleanliness of the media, the general gate valve and cut-off valve can not be guaranteed. From the cleanliness of thinking, there is no one kind of valve can be compared with the valve.
① valve structure is simple, valve body and a variety of information, can be widely used in food and biological engineering areas, but also for some difficult to transport and risk of the media.
A. Only the valve body and the gap with the logistics touch, and some other all blocked, the steam can be completely sterilized valve.
B. With their own net talent.
C. Can be repaired online. Thus the valve has become the most widely used valve for food and bioengineering.
② bottom valve.
In the case of severe sterilization requirements, the bottom of the tank discharge valve is simply no choice of the point. The bottom valve in the equipment produced directly welded to the bottom of the tank head, and the general selection of the bottom of the tank to do a mouth, and then in the nozzle on the practice of the valve is very different, the valve closed, the spool And the bottom of the tank flat, so it is useful to get along with the dead ends of the tank,
So that all the liquid in the tank can be fully mixed in the fermentation process, coupled with the unique steam seal system, greatly reduced the quality of the goods may be infected.