+0086-574-89017168
Call Us 
fuchun@fu-chun.com
Send me an inquiry
9:00-18:00
Monday - Friday
What’s Valve?
You are here: Home » News » HYDRAULIC SYSTEM » What’s Valve?

What’s Valve?

Views: 28     Author: Site Editor     Publish Time: 2019-05-09      Origin: www.fuchun-casting.com


What’s Valve?


As we know that valve is a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries ) by opening, closing, or partially obstructing various passageways. Technically,Valves are fittings, but are usually discussed as a separate category because of the wide range of applications and quite diverse of types. When the valve stays open, fluid flows in a direction from higher pressure to the lower.

 

How does the valve work?

The simplest, and very ancient, valve is a freely hinged flap. which drops to obstruct fluid (gas or liquid) flow in one direction, but is pushed open by flow in the opposite direction. This is called a check valve, as it prevents or "checks" the flow in one direction. Modern control valves may regulate pressure or flow downstream and operate on sophisticated automation systems.

 

Where can the valve be used?

Valves are used in a wide range of applications. Like controlling water for irrigation, processes in industrial uses, residential uses such as on/off and pressure control to dish and clothes washers and taps in civil use. Valves are also used in the military and transport sectors.Valves are instead called dampers in HVAC duct work and other near-atmospheric air flows. However, valves are used with the most common type being ball valves, in compressed air systems.

 

Components

The main parts of the most usual type of valve are the body and the bonnet. These two parts form the casing that holds the fluid going through the valve.

 

Material

According to he material, stainless steel, carbon steel, ductile cast iron, aluminum, High temperature copper as the main material of the valve. In many petroleum related applications where steel valves are normally used, ductile iron valves perform equally well. Above is mainly for the valve body material. Of course, different parts of the valve are made of different material.


 



Products

FAQS

  • What is 'multiple certification'?

    This is where a batch of steel meets more than one specification or grade. It is a way of allowing melting shops to produce stainless steel more efficiently by restricting the number of different types of steel. The chemical composition and mechanical properties of the steel can meet more than one grade within the same standard or across a number of standards. This also allows stockholders to minimise stock levels.

    For example, it is common for 1.4401 and 1.4404 (316 and 316L) to be dual certified - that is the carbon content is less than 0.030%. Steel certified to both European and US standards is also common.

  • What surface finishes are available on stainless steels?

    There are many different types of surface finish on stainless steel. Some of these originate from the mill but many are applied later during processing, for example polished, brushed, blasted, etched and coloured finishes.

    The importance of surface finish in determining the corrosion resistance of the stainless steel surface cannot be overemphasised. A rough surface finish can effectively lower the corrosion resistance to that of a lower grade of stainless steel.

  • Can I use stainless steel at high temperatures?

    Various types of stainless steel are used across the whole temperature range from ambient to 1100 deg C. The choice of grade depends on several factors:

    1. Maximum temperature of operation
    2. Time at temperature, cyclic nature of process
    3. Type of atmosphere, oxidising , reducing, sulphidising, carburising.
    4. Strength requirement

    In the European standards, a distinction is made between stainless steels and heat-resisting steels. However, this distinction is often blurred and it is useful to consider them as one range of steels.

    Increasing amounts of Chromium and silicon impart greater oxidation resistance. Increasing amounts of Nickel impart greater carburisation resistance.

  • Can I use stainless steel at low temperatures?

    Austenitic stainless steels are extensively used for service down to as low as liquid helium temperature (-269 deg C). This is largely due to the lack of a clearly defined transition from ductile to brittle fracture in impact toughness testing.

    Toughness is measured by impacting a small sample with a swinging hammer. The distance which the hammer swings after impact is a measure of the toughness. The shorter the distance, the tougher the steel as the energy of the hammer is absorbed by the sample. Toughness is measured in Joules (J). Minimum values of toughness are specified for different applications. A value of 40 J is regarded as reasonable for most service conditions.

    Steels with ferritic or martensitic structures show a sudden change from ductile (safe) to brittle (unsafe) fracture over a small temperature difference. Even the best of these steels show this behaviour at temperatures higher than -100 deg C and in many cases only just below zero.

    In contrast austenitic steels only show a gradual fall in the impact toughness value and are still well above 100 J at -196 deg C.

    Another factor in affecting the choice of steel at low temperature is the ability to resist transformation from austenite to martensite. 

  • Is stainless steel non-magnetic?

    It is commonly stated that “stainless steel is non-magnetic”. This is not strictly true and the real situation is rather more complicated. The degree of magnetic response or magnetic permeability is derived from the microstructure of the steel. A totally non-magnetic material has a relative magnetic permeability of 1. Austenitic structures are totally non-magnetic and so a 100% austenitic stainless steel would have a permeability of 1. In practice this is not achieved. There is always a small amount of ferrite and/or martensite in the steel and so permeability values are always above 1. Typical values for standard austenitic stainless steels can be in the order of 1.05 – 1.1. 

    It is possible for the magnetic permeability of austenitic steels to be changed during processing. For example, cold work and welding are liable to increase the amount of martensite and ferrite respectively in the steel. A familiar example is in a stainless steel sink where the flat drainer has little magnetic response whereas the pressed bowl has a higher response due to the formation of martensite particularly in the corners.

    In practical terms, austenitic stainless steels are used for “non-magnetic” applications, for example magnetic resonance imaging (MRI). In these cases, it is often necessary to agree a maximum magnetic permeability between customer and supplier. It can be as low as 1.004.

    Martensitic, ferritic, duplex and precipitation hardening steels are magnetic.

CONTACT US
Tel: +0086-574-89017168-8007
Room2503,Tower A, Trade Centre of Ningbo,Tiantong South Road No.588,Yinzhou District,Ningbo
COPYRIGHT © Ningbo Yinzhou FUCHUN Precision casting CO.,LTD