Diaphragm valve
Encyclopedia
Diaphragm valves consists of a valve
body with two or more ports, a diaphragm, and a "saddle" or seat upon which the diaphragm closes the valve. The valve is constructed from either plastic
or steel
.
Originally, the diaphragm valve was developed for use in non-hygienic applications. Later on the design was adapted for use in the bio-pharmaceutical industry by using compliant materials that can withstand sanitizing and sterilizing methods.
There are two main categories of diaphragm valves: one type seals over a "weir
" (saddle) and the other (sometimes called a "straight-way" valve) seals over a seat. The main difference is that a saddle-type valve has its two ports in line with each other on the opposite sides of the valve, whereas the seat-type has the in/out ports located at a 90 degree angle
from one another. The saddle type is the most common in process applications and the seat-type is more commonly used as a tank bottom valve but exists also as a process valve. While diaphragm valves usually come in two-port forms (2/2-way diaphragm valve), they can also come with three ports (3/2-way diaphragm valves also called t-valves) and more (so called block-valves). When more than three ports are included, they generally require more than one diaphragm seat; however, special dual actuators can handle more ports with one membrane
.
Diaphragm valves can be manual or automated. Their application is generally as shut-off valves in process systems within the food and beverage, pharmaceutical and biotech industries. The older generation of these valves is not suited for regulating and controlling process flows, however newer developments in this area have successfully tackled this problem.
In addition to the well known, two way shut off diaphragm valve, other types include: three way zero deadleg valve, sterile
access port, block and bleed, valbow and tank bottom valve just to name a few.
s; in this type of valve, air pressure is applied through a Schrader valve
which raises the diaphragm and opens the valve. This type of valve is extremely quick and as such is one of the more common valves used in operations where valve speed is a necessity.
Hydraulic diaphragm valves also exist for higher pressure and lower speed operations. Some diaphragm valves are also controlled manually.
Valve
A valve is a device that regulates, directs or controls the flow of a fluid by opening, closing, or partially obstructing various passageways. Valves are technically pipe fittings, but are usually discussed as a separate category...
body with two or more ports, a diaphragm, and a "saddle" or seat upon which the diaphragm closes the valve. The valve is constructed from either plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
or steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
.
Originally, the diaphragm valve was developed for use in non-hygienic applications. Later on the design was adapted for use in the bio-pharmaceutical industry by using compliant materials that can withstand sanitizing and sterilizing methods.
There are two main categories of diaphragm valves: one type seals over a "weir
Weir
A weir is a small overflow dam used to alter the flow characteristics of a river or stream. In most cases weirs take the form of a barrier across the river that causes water to pool behind the structure , but allows water to flow over the top...
" (saddle) and the other (sometimes called a "straight-way" valve) seals over a seat. The main difference is that a saddle-type valve has its two ports in line with each other on the opposite sides of the valve, whereas the seat-type has the in/out ports located at a 90 degree angle
Right angle
In geometry and trigonometry, a right angle is an angle that bisects the angle formed by two halves of a straight line. More precisely, if a ray is placed so that its endpoint is on a line and the adjacent angles are equal, then they are right angles...
from one another. The saddle type is the most common in process applications and the seat-type is more commonly used as a tank bottom valve but exists also as a process valve. While diaphragm valves usually come in two-port forms (2/2-way diaphragm valve), they can also come with three ports (3/2-way diaphragm valves also called t-valves) and more (so called block-valves). When more than three ports are included, they generally require more than one diaphragm seat; however, special dual actuators can handle more ports with one membrane
Biological membrane
A biological membrane or biomembrane is an enclosing or separatingmembrane that acts as a selective barrier, within or around a cell. It consists of a lipid bilayer with embedded proteins that may constitute close to 50% of membrane content...
.
Diaphragm valves can be manual or automated. Their application is generally as shut-off valves in process systems within the food and beverage, pharmaceutical and biotech industries. The older generation of these valves is not suited for regulating and controlling process flows, however newer developments in this area have successfully tackled this problem.
In addition to the well known, two way shut off diaphragm valve, other types include: three way zero deadleg valve, sterile
Sterilization (microbiology)
Sterilization is a term referring to any process that eliminates or kills all forms of microbial life, including transmissible agents present on a surface, contained in a fluid, in medication, or in a compound such as biological culture media...
access port, block and bleed, valbow and tank bottom valve just to name a few.
Actuators
Diaphragm valves can be controlled by various types of actuators e.g. manual, pneumatic, hydraulic, electric etc. The most common diaphragm valves use pneumatic actuatorPneumatic actuator
A pneumatic actuator converts energy into motion. The motion can be rotary or linear, depending on the type of actuator.Some types of pneumatic actuators include:*Tie rod cylinders*Rotary actuators*Grippers...
s; in this type of valve, air pressure is applied through a Schrader valve
Schrader valve
The Schrader valve is a brand of pneumatic tire valve used on virtually every motor vehicle in the world today. The Schrader company, for which it was named, was founded in 1844 by August Schrader...
which raises the diaphragm and opens the valve. This type of valve is extremely quick and as such is one of the more common valves used in operations where valve speed is a necessity.
Hydraulic diaphragm valves also exist for higher pressure and lower speed operations. Some diaphragm valves are also controlled manually.
Body materials
- Brass
- Steel type:
- Cast Iron
- Ductile Iron
- Carbon Steel
- Stainless Steel
- Plastic type:
- ABS (Acrylonitrile butadiene styreneAcrylonitrile butadiene styreneAcrylonitrile butadiene styrene is a common thermoplastic. Its melting point is approximately 105 °C ....
) - PVC-U (Polyvinyl chloridePolyvinyl chloridePolyvinyl chloride, commonly abbreviated PVC, is a thermoplastic polymer. It is a vinyl polymer constructed of repeating vinyl groups having one hydrogen replaced by chloride. Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene. PVC is widely used in...
, unplasticized) also known as PVCu or uPVC - PVC-C (Polyvinyl chloride, post chlorinated) also known as PVCc or cPVC
- PP (PolypropylenePolypropylenePolypropylene , also known as polypropene, is a thermoplastic polymer used in a wide variety of applications including packaging, textiles , stationery, plastic parts and reusable containers of various types, laboratory equipment, loudspeakers, automotive components, and polymer banknotes...
) - PE (PolyethylenePolyethylenePolyethylene or polythene is the most widely used plastic, with an annual production of approximately 80 million metric tons...
) also known as LDPE, MDPE and HDPE (see note) - PVDF (Polyvinylidene fluoridePolyvinylidene fluoridePolyvinylidene fluoride, or PVDF is a highly non-reactive and pure thermoplastic fluoropolymer.PVDF is a specialty plastic material in the fluoropolymer family; it is used generally in applications requiring the highest purity, strength, and resistance to solvents, acids, bases and heat and low...
)
- ABS (Acrylonitrile butadiene styrene
Body lining materials
Depending on temperature, pressure and chemical resistance, one of the following is used:- Unlined type
- Rubber lined type:
- NR/Hard Rubber/Ebonite,
- BR/Soft rubber
- EPDM
- Fluorine plastic lined type
- FEP/F46
- PFA
- PO
Diaphragm materials
- Unlined or Rubber Lined Type:
- NR/Natural Rubber
- NBR/Nitrile/Buna-N
- EPDM
-
- FKM/Viton
- SI/Silicone rubber
- Fluorine Plastic Type:
- FEP/F46,with EPDM back
- PTFE/F4,with EPDM back
- PFA,with EPDM back
Diaphragm valve manufacturers
- Bürkert
- Georg Fischer (Swiss company)Georg Fischer (Swiss company)Georg Fischer is a Swiss manufacturer of piping systems for water treatment and corrosion fluids, as well as oil and gas markets. +GF+ is a multinational corporation with 120 facilities around the world, 12,500 employees and US$ 4 billion in sales per year...
- Gemü
- FestoFestoFesto is a German industrial control and automation company based in Esslingen am Neckar, Germany. Festo is an engineering-driven company that sells pneumatic and electric transducers primarily to the automation industry.-History:...
- ITT CorporationITT CorporationITT Corporation is a global diversified manufacturing company based in the United States. ITT participates in global markets including water and fluids management, defense and security, and motion and flow control...
- Novaseptic
- SaundersSaundersSaunders is a surname of English and Scottish patronymic origin derived from Sander, a mediæval form of Alexander.People with the surname Saunders include:* Al Saunders, American football coach* Allen Saunders, American cartoonist...
- Galassi & Ortolani SpA
- Kim Diaphragm Valves Australia