The document discusses hygienic design considerations for selecting valves for use in food processing according to EHEDG guidelines. It describes various types of valves that have historically been used for food applications and their hygienic limitations. Circular seal valves that conform to EHEDG guidelines are recommended as they allow flexible multi-seat designs and self-drainage in various orientations. When assessing valves, factors like durability, ease of maintenance, life cycle costs, and materials compatibility must be considered in addition to hygienic performance levels required.
Optimizing Seal Design for Improved Medical Ventilator Life & PerformanceBSEmarketing
The seal you choose for your medical ventilator design or retrofit can have a big impact on its performance. And a custom-engineered seal, one that's designed to meet your exact requirements, can significantly improve service life, accuracy, and consistency.
This short but informative presentation examines the relationship between seal choice and ventilator performance, and it addresses important design criteria, such as hardware surface finish and seal geometry. It also suggests some ways to avoid common sealing mistakes that can cost you time, money, and market share.
For more information about how a Bal Seal® can help you elevate your new or existing ventilator design, visit us at www.balseal.com, or email solutions@balseal.com.
Filter housing catalog - Jon from Snowate
As a senior sourcing expert on water treatment facilities and accessories, our procurement covers a comprehensive range of water treatment facilities and components, mainly including FRP water tanks, membrane housings, membrane elements, cartridges, security filters, metering pumps, etc. These products are widely used in drinking water, commercial water, municipal, medical, food and other fields.
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
If you are looking for water treatment facilities and accessories. Please contact
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
Cartridge filter catalog - Jon from Snowatejon sun
Cartridge filter catalog - Jon from Snowate
As a senior sourcing expert on water treatment facilities and accessories, our procurement covers a comprehensive range of water treatment facilities and components, mainly including FRP water tanks, membrane housings, membrane elements, cartridges, security filters, metering pumps, etc. These products are widely used in drinking water, commercial water, municipal, medical, food and other fields.
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
If you are looking for water treatment facilities and accessories. Please contact
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
frp ro pressure vessel catalog - Jon from Snowatejon sun
FRP RO membrane housings can stand more than 100,000 times of cyclic test & burst test with 6 times of its design pressure.
Applied to complex media environment and have been used in large & medium-sized projects at home and abroad since 2008.
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
As a senior sourcing expert on water treatment facilities and accessories, our procurement covers a comprehensive range of water treatment facilities and components, mainly including FRP water tanks, membrane housings, membrane elements, cartridges, security filters, metering pumps, etc. These products are widely used in drinking water, commercial water, municipal, medical, food and other fields.
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
Double and Triple Offset Butterfly Valve are made from high quality raw materials such as carbon steel, iron, aluminum and stainless steel with standard features and benefits using latest technology.
Sanitary diaphragm valves that are widely used on water and wastewater pipes, for example, valve covers and pipes, should only be used where they have sufficient quality. They will be damaged if a valve cap is left on. But since they are most commonly used for domestic water and wastewater systems, it’s more common to see these in water supplies than in wastewater systems.
Optimizing Seal Design for Improved Medical Ventilator Life & PerformanceBSEmarketing
The seal you choose for your medical ventilator design or retrofit can have a big impact on its performance. And a custom-engineered seal, one that's designed to meet your exact requirements, can significantly improve service life, accuracy, and consistency.
This short but informative presentation examines the relationship between seal choice and ventilator performance, and it addresses important design criteria, such as hardware surface finish and seal geometry. It also suggests some ways to avoid common sealing mistakes that can cost you time, money, and market share.
For more information about how a Bal Seal® can help you elevate your new or existing ventilator design, visit us at www.balseal.com, or email solutions@balseal.com.
Filter housing catalog - Jon from Snowate
As a senior sourcing expert on water treatment facilities and accessories, our procurement covers a comprehensive range of water treatment facilities and components, mainly including FRP water tanks, membrane housings, membrane elements, cartridges, security filters, metering pumps, etc. These products are widely used in drinking water, commercial water, municipal, medical, food and other fields.
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
If you are looking for water treatment facilities and accessories. Please contact
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
Cartridge filter catalog - Jon from Snowatejon sun
Cartridge filter catalog - Jon from Snowate
As a senior sourcing expert on water treatment facilities and accessories, our procurement covers a comprehensive range of water treatment facilities and components, mainly including FRP water tanks, membrane housings, membrane elements, cartridges, security filters, metering pumps, etc. These products are widely used in drinking water, commercial water, municipal, medical, food and other fields.
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
If you are looking for water treatment facilities and accessories. Please contact
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
frp ro pressure vessel catalog - Jon from Snowatejon sun
FRP RO membrane housings can stand more than 100,000 times of cyclic test & burst test with 6 times of its design pressure.
Applied to complex media environment and have been used in large & medium-sized projects at home and abroad since 2008.
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
As a senior sourcing expert on water treatment facilities and accessories, our procurement covers a comprehensive range of water treatment facilities and components, mainly including FRP water tanks, membrane housings, membrane elements, cartridges, security filters, metering pumps, etc. These products are widely used in drinking water, commercial water, municipal, medical, food and other fields.
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
Double and Triple Offset Butterfly Valve are made from high quality raw materials such as carbon steel, iron, aluminum and stainless steel with standard features and benefits using latest technology.
Sanitary diaphragm valves that are widely used on water and wastewater pipes, for example, valve covers and pipes, should only be used where they have sufficient quality. They will be damaged if a valve cap is left on. But since they are most commonly used for domestic water and wastewater systems, it’s more common to see these in water supplies than in wastewater systems.
Household RO membrane & industrial Ro membrane for water treatment
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
If you are looking for water treatment facilities and accessories. Please contact
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
In a nutshell, Flexible Isolators are soft walled containment systems often used as alternatives to rigid isolators. They come in a couple options: flexible and semi-flexible. Flexible Isolators are commonly used in industries such as biotech, pharmaceutical, healthcare and universities to protect workers and/ or their process from the external environment.
Why is using a volumetric pipette considered more accurate in a Science- lab ...Science Equip
All the glasswares play a crucial role of serving as the correct measuring equipment in a chemistry laboratory. However, certain parameters differentiate them when it comes to accuracy. While there are many measuring glasswares available such as graduated cylinders, beakers, and flasks; out of all, the volumetric pipet
How to-choose-air-rotor-the-ultimate-guide-convertedUnicorn Denmart
Still not sure of the ideal #Air_Rotor for your #Dental_Practice?
Don't worry we are sharing the factors you should consider for trouble-free operation using the right Handpiece.
Water distributor pressure gauge solenoid valve catalogjon sun
Water distributor pressure gauge solenoid valve catalog
As a senior sourcing expert on water treatment facilities and accessories, our procurement covers a comprehensive range of water treatment facilities and components, mainly including FRP water tanks, membrane housings, membrane elements, cartridges, security filters, metering pumps, etc. These products are widely used in drinking water, commercial water, municipal, medical, food and other fields.
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
If you are looking for water treatment facilities and accessories. Please contact
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
Gate valves are known for its durability, rugged construction, performance and accuracy. These devices are in great demand due to its cost effectiveness and easy installation. For more details visit:
http://catalogs.indiamart.com/products/gate-valves.html
Dosing pump for water treatment
As a senior sourcing expert on water treatment facilities and accessories, our procurement covers a comprehensive range of water treatment facilities and components, mainly including FRP water tanks, membrane housings, membrane elements, cartridges, security filters, metering pumps, etc. These products are widely used in drinking water, commercial water, municipal, medical, food and other fields.
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
If you are looking for water treatment facilities and accessories. Please contact
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
Household RO membrane & industrial Ro membrane for water treatment
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
If you are looking for water treatment facilities and accessories. Please contact
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
In a nutshell, Flexible Isolators are soft walled containment systems often used as alternatives to rigid isolators. They come in a couple options: flexible and semi-flexible. Flexible Isolators are commonly used in industries such as biotech, pharmaceutical, healthcare and universities to protect workers and/ or their process from the external environment.
Why is using a volumetric pipette considered more accurate in a Science- lab ...Science Equip
All the glasswares play a crucial role of serving as the correct measuring equipment in a chemistry laboratory. However, certain parameters differentiate them when it comes to accuracy. While there are many measuring glasswares available such as graduated cylinders, beakers, and flasks; out of all, the volumetric pipet
How to-choose-air-rotor-the-ultimate-guide-convertedUnicorn Denmart
Still not sure of the ideal #Air_Rotor for your #Dental_Practice?
Don't worry we are sharing the factors you should consider for trouble-free operation using the right Handpiece.
Water distributor pressure gauge solenoid valve catalogjon sun
Water distributor pressure gauge solenoid valve catalog
As a senior sourcing expert on water treatment facilities and accessories, our procurement covers a comprehensive range of water treatment facilities and components, mainly including FRP water tanks, membrane housings, membrane elements, cartridges, security filters, metering pumps, etc. These products are widely used in drinking water, commercial water, municipal, medical, food and other fields.
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
If you are looking for water treatment facilities and accessories. Please contact
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
Gate valves are known for its durability, rugged construction, performance and accuracy. These devices are in great demand due to its cost effectiveness and easy installation. For more details visit:
http://catalogs.indiamart.com/products/gate-valves.html
Dosing pump for water treatment
As a senior sourcing expert on water treatment facilities and accessories, our procurement covers a comprehensive range of water treatment facilities and components, mainly including FRP water tanks, membrane housings, membrane elements, cartridges, security filters, metering pumps, etc. These products are widely used in drinking water, commercial water, municipal, medical, food and other fields.
We integrate upstream supply chain products of the water treatment industry. In addition, we work with renowned suppliers and manufacturers. As a result, we can continuously supply high-quality water treatment components and systems for customers across the world to meet the needs of a wide range of applications, thereby optimizing water resources and promoting the sustainable development of the global environment.
If you are looking for water treatment facilities and accessories. Please contact
E-mail: jon@membranehousing.org
Mobile: +86-15633187985 (WhatsApp, WeChat)
PVC (Polyvinyl Chloride) ball valves are a popular type of valve used in plumbing and industrial applications. These valves are known for their versatility, durability, and affordability. In this Doc, we will discuss the Benefits of PVC Ball Valves and why they are the preferred choice for many applications.
Industrial Valves – Extending their Service Liferameshbabu91988
The proper maintenance can extend the durability of valves, although they need to be done regularly. Industrial valves can be operated manually or electrically but since the industrial valves used to regulate the flow of slurries, chemicals, gases, and other fluids.
Valves are one of the important mechanical device that helps in controlling the fluid flow through pipes or tubes. Selecting the right kind of economic valve for a specified fluid service requires many considerations. Fevisa, known as European Valve Manufacturers and Spanish Valve Manufacturers and we are the leading valve stockist in Dubai, advises help our clients conduct necessary inquiry and procurement of suitable valves
Basics of Self-Supported Rotary Joint Installation on Steam-Heated Paper DryersKadant Inc.
Long service life of rotary joints and adjacent flexible hoses can be achieved by following basic installation guidelines. This is particularly important with self-supported rotary pressure joints that are used for paper dryers. General installation guidelines are provided.
Unveiling the Top 5 Advantages of Gate & Check Valves in Industrial Applicati...SchulteSupply
Gate and check valves are essential components in industrial applications, particularly in controlling the flow of fluids and gasses. These valves are designed to regulate the flow of materials, ensuring that they move in the right direction and at the right pressure. Let’s explore the top five advantages of using gate and check valves in industrial applications.
Top 5 Advantages of Using Gate & Check Valves in Industrial Applications.pdfSchulteSupply
Explore the top 5 advantages of incorporating gate and check valves in industrial settings. From enhanced flow control to improved reliability and safety, these valves play a crucial role in various applications such as oil and gas, water treatment, and manufacturing processes. Discover how gate and check valves contribute to operational efficiency, cost savings, and system integrity, making them essential components in the industrial sector.
Flex-Valve, is a brand under General Rubber Corp. representing a state of the art line of pinch valves, pressure isolation rings and duck bill check valves. Flex-Valve has become a worldwide recognized brand and leading manufacturer in the industry
Valves in Industrial Plumbing – A Versatile Guiderameshbabu91988
Valves can be used in both household and industrial plumbing systems. Valves are a vital element of any plumbing system since they are used to regulate flow, modify the flow of water, or shut off the water in the occurrence of an emergency.
Listed below, are India's top 10 valve manufacturing businesses each of which provides high-quality valves at reasonable costs. Several manufacturers of valves in India manufacture various types of valves with several applications.
Other parts of the butterfly valve include a butterfly disc, external case, stem, a tough situating plate, pressing, and an actuator. A bar is gone via the disc joined to an actuator outside the valve.
Hierarchical Digital Twin of a Naval Power SystemKerry Sado
A hierarchical digital twin of a Naval DC power system has been developed and experimentally verified. Similar to other state-of-the-art digital twins, this technology creates a digital replica of the physical system executed in real-time or faster, which can modify hardware controls. However, its advantage stems from distributing computational efforts by utilizing a hierarchical structure composed of lower-level digital twin blocks and a higher-level system digital twin. Each digital twin block is associated with a physical subsystem of the hardware and communicates with a singular system digital twin, which creates a system-level response. By extracting information from each level of the hierarchy, power system controls of the hardware were reconfigured autonomously. This hierarchical digital twin development offers several advantages over other digital twins, particularly in the field of naval power systems. The hierarchical structure allows for greater computational efficiency and scalability while the ability to autonomously reconfigure hardware controls offers increased flexibility and responsiveness. The hierarchical decomposition and models utilized were well aligned with the physical twin, as indicated by the maximum deviations between the developed digital twin hierarchy and the hardware.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
In this month's edition, along with this month's industry news to celebrate the 13 years since the group was created we have articles including
A case study of the used of Advanced Process Control at the Wastewater Treatment works at Lleida in Spain
A look back on an article on smart wastewater networks in order to see how the industry has measured up in the interim around the adoption of Digital Transformation in the Water Industry.
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Cosmetic shop management system project report.pdf
evalves.pdf
1. T
he guidelines are written with European
conditions, standards and laws in mind.
Therefore valves for hygienic or aseptic use
should conform to EHEDG guidelines as follows:
● Doc. 8: Hygienic Equipment Design Criteria
● Doc. 9: Welding Stainless Steel to meet
Hygienic Requirements
● Doc.10: Hygienic Design of closed Equipment
for the Processing of Liquid Food
● Doc.13: Hygienic Design of Equipment for
Open Processing
● Doc.14: Hygienic Design of Valves for Food
Processing
● Doc.16: Hygienic Pipe Couplings
● Doc. 20: Hygienic Design and Safe Use of
Double-Seat Mix proof Valves
This will ensure, amongst other things, adequate
surface finish, cleanability and absence of crevices
and sharp corners and absence of metal-to-metal
contact surfaces. Where the valves are powered,
they must also conform to the Machinery Directive
and be CE-marked.
Origins of valve-types used in
food manufacture
Historically, there has been widespread adoption
and adaptation of existing types of equipment
components, including valves, for food applications.
In some cases, usually where the product is resistant
to spoilage, this has been relatively successful even
though the design may be relatively weak in
hygienic terms. However, given that such valves
were originally designed neither for hygienic
applications nor with the benefit of modern
hygienic design knowledge, variable levels
of hygienic success and failure have resulted.
Sliding seal valves
Ball, gate, plug and other sliding-seal valves
have been used, but these rely on seat shut-off
and, in some cases, body sealing on comparatively
large sliding seals that may easily become scored
and/or fouled. The sliding seals commonly
contain a thin, stagnant film of product and there
may also be stagnant product in spaces behind the
sliding seals. They usually need to be dismantled
each time for cleaning, except perhaps when used
with very clean products such as water or ethanol.
Some manufacturers have adapted them by
providing drainage to these cavities, but it is
up to the users to satisfy themselves as to whether
this really works successfully with their own
products and conditions. Generally there are
better options.
In a special case, sliding seal configurations have
often been chosen for integral aseptic block and
bleed sampling designs, primarily in order to permit
single-step manual operation of the block-and-
bleed, together with the product seat opening.
However, the sliding seals are not bacteria-tight,
even though this is usually a requirement for aseptic
performance. Generally, butt sealing is preferable
for shut off applications.
Metal-to-metal seated valves
Although some suppliers have offered these
types for hygienic duties, a clear category that is
normally unsafe for hygienic or aseptic duties
is that based on metal-to-metal seat seals.
Such seals are not bacteria-tight and therefore
should be used only where bacteria-tightness is
not required.
Butterfly valves
Butterfly types can be hygienic and cleanable in
place if designed according to EHEDG guidelines.
They are useful where a low-cost single or double
seat solution is required and have the advantage of
occupying a very short length of pipe-run.
However, as they are not hermetically sealed, they
are not suitable for aseptic duties.
new food
8
F O O D P R O C E S S I N G V A L V E S
Hygienic design and
assessment
❖ Dr. Roland Cocker, Member, EHEDG Valves subgroup
When assessing valves for use in safe food
production there are a number of considerations to
be made. This article discusses the implication of
EHEDG guidelines.
2. new food
10
Weir-type valves
Weir-type diaphragm valves were originally
designed as an alternative where hermetic sealing
was required. They have been widely adopted for
aseptic duties because the diaphragm seal provides
a permanent hermetic body seal as well as a seat
seal. However, as they were not designed specifically
for hygienic and aseptic application, care needs to
be exercised with respect to a number of points:
There is usually no fixed compression-stop on
the bonnet fastening screws, so these are commonly
over-tightened. This may lead to shrinkage and
hardening (compression-set) of the membrane, with
consequent crevice and/or leak formation. The
common fix of re-tightening the fittings to combat
leaks leaves the risk of unseen crevices and
aggravates the compression-set. In the worst cases, a
circular disc is cut out of the rectangular
membrane.
This configuration of valve is often supplied
with an adjustable compression-stop on the seal
travel to allow for interchangeable fitting of
membranes of different thickness. This provides
significant opportunity for error that is often
realised in practice. In the worst case, the
membrane may be punctured by the valve-stem. It
can be safer to opt for valve tops with fixed stops if
available, even though this would mean a change of
top if the membrane were changed to a different
thickness.
In vertical piping, this type of valve is normally
free draining, but when the pipe axis is
approximately horizontal, there is a critical
tolerance on orientation for drainage past the weir.
Typically the valve-stem has to be inclined from the
vertical within a narrow arc of tolerance. The exact
angle is in the range 60-70 degrees from the
horizontal. Unfortunately, this angle can differ
according to the valve-size, giving further
opportunity for error where multiple valve-sizes are
used in the same installation.
Blocks of steel can be machined-out to provide
multi-axis, multi-seat valve blocks, but care needs to
be taken to ensure that all of these seats are free
draining.
Weir-type diaphragm valves are, more than any
other, often supplied and installed with couplings
on both sides. Apart from increasing the number of
vulnerable seals, this carries a very high risk that the
valve will be re-installed in the wrong orientation,
because the couplings allow rotation outside the
safe angle of inclination.
Pinch valves
Pinch-type valves, where a reinforced flexible
elastomeric tube is externally compressed to close it
off, are intrinsically hermetic and therefore
potentially hygienic and aseptic. This type is
compact, can give full-bore flow and has the widest
range of orientations for self-draining. It is
currently available in a hygienic implementation
only in small sizes. It is not found in multi-seat
versions.
Circular seal valves
The introduction of flush circular seals has allowed
valves to be purpose-designed for hygienic and
aseptic applications. The entry of a number of
competitors, principally based in Europe, has led to
a family of improvements and advantages for this
type and they are now used widely where
demanding hygienic performance is required, such
as in food, (bio) pharmaceutical and even paint
processing. Figure One gives an example of a
double-seat variant (the most important variant) of
this configuration of valve:
Characteristics include:
● They are self-draining in a wide range of
orientations
● This is the most flexible design for multiple seat
versions, with unique integration capabilities
that permit highly efficient and hygienically safe
plants
● Because of their flush-fitting seals, multiple seat
versions permit the elimination of stagnant
zones in a way not possible with single-seat
valves
● It is possible to integrate several valve functions
into a single, factory-made multiple-seat valve
module, eliminating the vagaries of site-
assembled equivalents. An example would be an
aseptic block-and-bleed module such as
an aseptic barrier
Figure One: Schematic of a Double-Seat Circular Seal Valve
3. ● Hermetically sealed aseptic versions
incorporating flexible polymeric diaphragms or
stainless steel/polymeric bellows are now
commonplace
Balanced pressure versions are available that
prevent the valve being forced open by hydraulic
shocks. The combination of powerful return springs
with fixed compression-stops provides fail-safe
operation without over compression of the
elastomeric seals. The use of sensors on the valve-
top permits positional feedback, critically
confirming when the seat is properly closed.
With double-seat mix-proof types, there must be
atmospheric leakage detection. However, this means
that a small amount of product can be lost at each
changeover unless the design incorporates axial
seals. These are circular seals that maintain a sliding
seal during movement, followed by a butt seal at
closure (See EHEDG Doc. 20 Hygienic Design and
Safe Use of Double-Seat Mix proof Valves).
Note however the emphasis has been on larger-
size piping (>DN50) and that most of the
pneumatic actuators currently available are not
compact, relative to the smaller sized versions. This
may be problematical in confined spaces or where
small valves are required. Some more compact non-
pneumatic actuators are available which may allow
them to be employed.
Assessment and selection
Inadequate selection practice
In real life, the choice of valves for hygienic
applications may often be made on the basis of
custom and practice, tradition or even dogma
rather than on a systematic technical and hygienic
appraisal. This can result in designs that are
relatively expensive to run and maintain and have
failure-rates well below best practice.
To counter this and to make assessment and
selection more objective and scientific, the EHEDG
Figure Two: Aseptic Mix proof Valve
4. new food
12
has pioneered the provision of guidance on hygienic
design and the establishment of standardised
challenge tests and corresponding certification
facilities.
Concurrent design
Hygienic considerations need to be made
concurrently with all other legal, design and
performance requirements when assessing valves for
hygienic use, so that the valves fulfil the global user
specification as comprehensively as possible.
Valves for dry materials
Valves for use with dry materials may follow a
much more relaxed set of design rules. For example
they often have extensive sliding contact surfaces.
They will not be considered here, but note that if
any valve is expected to be wetted at any time, for
example cleaning between successive batches to
remove a strong flavour or to Kosherize, then all
the considerations of this article apply.
Defining the required hygienic performance level
An early consideration determining the
performance specification is whether aseptic or
hygienic performance is needed. (It may be that a
valve for use in food production etc. does not even
need to conform to a ‘full’ hygienic specification, for
example if the product is edible oil, vinegar or rice
grains). The documented risk assessment phase as
described in EN 1672-2 and ISO 14159 or the
Hazard Analysis and Critical Control Points
(HACCP) study of the process/product design can
be an opportunity to justify a relaxation of some
prescriptive requirements of these standards. For
example many potable water valves are not made of
stainless steel, but instead brass, copper and
chrome-plated brass.
Durability and reproducibility of hygienic
performance
A major factor is the durability and reliability of
hygienic performance for the application in
question. This is covered to a large extent by the
guidance in the above EHEDG guidelines.
However, issues such as materials compatibility are
often poorly considered, especially at design
changes such as the introduction of new
products/formulations or expansions of heat- and
temperature -exposure limits.
In this context, the availability of a good
selection of seal elastomers can be very important
in allowing such variation to be accommodated. A
restricted range can mean that a branded valve
range is unable to perform to its full potential with
certain products and/or conditions. Elastomers do
age and are relatively perishable, therefore their
handling, composition, packaging, labelling and
surface finish are critical for reproducible
performance. It has also been known for critical
attributes of original seal parts to be varied by the
moulding company without the knowledge of the
valve manufacturer. Therefore it is important that
the valve supplier can provide documented evidence
and control of composition, traceability, storage
and handling. Seals should also be supplied
individually labelled and have an expiry date.
Colour-coding via elastomer pigmentation can be a
helpful fail-safe, but only if it does not impair
performance of the elastomer compound. Non-
original supplies of non-proprietary seal shapes
such as ‘o’-rings can cause serious problems unless
they comply exactly with the valve manufacturer's
specifications and all the above quality assurance
provisions are implemented.
Seals made of fluoroplastics have been
introduced for use in general applications where
much higher chemical and heat resistance is
required. In some cases, these are also offered for
hygienic applications. Bacteria-tight seals for liquids
require that at least one part of the seal is elastic
and can flow into the microscopic imperfections of
the seal face and maintain this seal during
expansion, contraction and vibration of the
equipment. It is questionable whether a plastic seal-
face contacting a metal seat can do this, even when
backed by an elastomer for resilience. A more
recent adaptation has been to use a fluoroplastic-
on-elastomer seat, which is likely to be more
successful. However, careful designers and users will
satisfy themselves by challenge testing that any seals
required to be bacteria-tight still give a bacteria-
tight seal after a simulated normal lifetime of use.
Maintenance
Ease, speed and reliability of maintenance are
important issues for users. It is important in an
installation with many valves that each valve can be
overhauled reliably and quickly to avoid expensive
downtime. Useful enhancements here are the
provision of single-armature multi-seat valve
modules (you can replace several seat seals at once),
single-fastener body clamps and fail-safe aids such
as fixed compression-stops on all seals. For a
realistic appraisal of such features it is wise to
involve the maintenance technicians and even for
them to conduct replacement tests to estimate the
replacement time per seal and the frequency of
correct body and seal compression.
Life cycle costs
As with all equipment purchases, the buying
5. strategy can vary between an emphasis on low
initial cost to one on low life-cycle costs. Life-cycle
costs can be strongly dependent on maintenance
frequency, because a major component of valve
change-out costs stems from the loss of production
time and output. It is important therefore to take
this into account when considering maintenance
costs. Comparison of replacement costs will also
show that for the larger pipe-size, a comparable
membrane for a weir-type valve is considerably
more expensive than the seal kit for a circular seal
valve. In my experience, the seals of circular seal
valves also last far longer under the same
conditions than those in weir-type valves. This can
probably be attributed to the minimisation of the
tension forces on the elastomeric seals, assisted by
the use of non-adjustable metal compression stops.
(In the past, the single-diaphragm circular seal
valve was modified so that the body seal was
separate from the seat seal. This eliminated the
cycle of simultaneous stretching and compression
of the elastomer, and was found to increase the seal
lifetime. Such a modification is not at present
available for the weir-type, to my knowledge).
It is therefore important to ensure that the
cost/benefit assessment is based on a comprehensive
identification of all costs rather than just the cost of
the valve and its service parts.
Body stiffness
Valve-body stiffness may be a key defence against
torsion, compression and pipe-stress, for example
from thermal expansion and contraction or from
poor installation practices. Instances are known
where the valves distorted and there was an
intermittent failure to close fully. Although the use
of pipe-stress software calculations can minimise
this risk, variations from plan do occur during
installation and a strong, stiff valve-body
construction is therefore less likely to run into
trouble.
Materials compatibility under non-routine
conditions
Assuring materials compatibility is a requirement of
EHEDG guidelines, but in practice this is not
always as simple as it may seem. It is important to
consider all operations such as fail-safe modes,
shutdown, cleaning and maintenance. For example,
where high temperatures and/or halides are present,
drying-out can lead to very corrosive conditions,
even though normal operational conditions are
much less severe. Intelligent changes to operational
procedures and the integrated design can mitigate
these kinds of stresses but in other cases the cost of
using higher-grade materials may have to be
6. new food
14
balanced against the cost of failure during
production.
Design principles
Apart from the requirements for conformance to
the more generic EHEDG guidelines 8 and 10,
valves have some specific hygienic design
requirements. Whilst it is not intended to duplicate
the EHEDG guidelines Doc.14: Hygienic design of
valves for food processing and Doc. 20: Hygienic
Design and Safe Use of Double-Seat Mix proof
Valves, some examples of specific requirements are:
Leak detection
Continuous leak detection for the seat seal is
normally required for assurance of safe operation
and should be an integral part of the design. As a
minimum, this takes the form of an atmospheric
leakage port, though some automatic detection and
feedback systems are in evidence, especially for
aseptic barrier modules, where the barrier zone has
to be pressurised. Note that in the case of plastic-
faced elastomeric membranes, an unacceptable
crack in the plastic face will usually not be
detectable because it will still be sealed from the
leak-detection port by the elastomeric component.
Note that if such a penetration is accompanied by
delamination, then a hazardous crevice will form
between the plastic and elastomeric layers.
Seat-lift actuation
The ability to clean the face of each seal seat has to
be facilitated in multiple seat and mixproof valves
by the provision of seat-lift actuation during CIP
operations, independently of concurrent product
operation.
Safe closure
Valve seats are usually sprung closed and opened by
powered actuators, so that in the event of power
failure, the valve fails in the closed position.
Validation
Challenge-testing – where and when
It is not unknown for organisations to test or even
implement new valve designs, brands or
components in their production equipment under
working conditions after only a cursory inspection
of the design. This can be a hazardous and
potentially expensive strategy. In the majority of
cases it is safer to challenge-test the equipment off-
line (following simulation of a required cycle and
conditions of use) before testing a sample in the
production environment. A useful aid to this can be
where the manufacturer has had the valve type-
tested and certified by an EHEDG-accredited
laboratory, to the EHEDG guidelines. See
‘EHEDG certification’ below.
Appropriate specification and selection
Suppliers are regularly confronted with complaints
about their valves from users who have made
inappropriate selections from their range of models
and components. For example use of Ethylene
Propylene Diene Terpolymer Rubber (EPDM) with
oily or fatty material such as antifoam or use of low
temperature EPDM with steam sterilisation. It is
important prior to design changes or validation of
any equipment to define and document the exact
requirements and conditions of use (temperatures,
chemical exposure, maintenance availability,
available space, temperatures, pressures, etc). It is
also necessary to make the optimal selection from
the supplier's available body and seal materials for
these requirements.
Legal compliance
Any power-actuated valve is subject to the EU
Machinery Directive and CE-marking. EN 1672-2
was produced in support of the food safety aspect
of the Machinery Directive and provides guidance
on prescriptive equipment design, augmented and
potentially modifiable by a documented hygienic
risk assessment. (ISO 14159 is effectively a more
recent update of EN 1672-2 and could be used
instead if desired). Users should ask for a copy of a
manufacturer's risk assessment to support their
initial appraisal and validation of the design. A key
feature of such documentary evidence could be the
provision of a documented EHEDG or comparable
challenge-test or EHEDG certificate.
EHEDG certification
A considerable aid to validation and selection of
valves is testing and certification by EHEDG-
approved laboratories to EHEDG guidelines. The
EHEDG tests are reference tests that challenge the
equipment for cleanability, sterilisability and
bacteria-tightness under defined test conditions.
The certification qualifies compliance to EHEDG
guideline number 8, supplemented by the
cleanability test. Note that certification does not
cover bacteria-tightness of the body or
sterilisability, although there is no reason why a
manufacturer cannot request this EHEDG test and
provide a test-report. There is not yet an EHEDG
test for bacteria-tightness of the valve seat, nor is
there a period of simulated use prior to testing a
specified requirement. The test and/or certification
are for reference only and users should request both
test reports and certifications to confirm exactly
what was done. User's conditions may in some
7. respects be more challenging than the test
conditions and this should be taken into account.
As described above, it is suggested that a period of
simulated use is performed prior to challenge-
testing and users with critical applications may be
wise to have this done prior to testing in processes
whose results or products are costly.
Integration characteristics
The manufacturer’s instructions
It is essential that everyone involved in design and
installation understands the manufacturer's
installation instructions. For example, a frequent
cause of hygienic failure of valves is the incorrect
orientation of the valve, such that the valve body
does not drain freely. (It is of no use to have
selected and validated equipment, for example to a
surface finish of 0.8 micron Ra on every
component of a plant, only to have comparatively
enormous sumps or weirs as a result of incorrect
valve orientation. This is especially true where
steam sterilisation is needed, as the collection of
condensate will result in cold spots and an
increased risk of microbial survival). Consequently
it can be safer where feasible to select valves with
weld-stubs rather than couplings and to prefer
designs that have a greater range of orientations in
which free draining is assured. Similarly, it is
essential that valves can be and are operated within
the manufacturers' recommended operating
conditions. Excessive temperatures, pressures, and
hydraulic shocks are common causes of hygienic
failure and it can be frustrating for suppliers to
receive complaints about their designs, sometimes
via third parties, only to find that a sub-optimal
selection or easily-avoided abuse was the root cause.
Integration flexibility
The flexibility and suitability of a valve design for
integration into relatively compact precision
fabricated modules/manifolds can be very
important. Such modular constructions can
eliminate dead-legs and eliminate vessel wait-times.
This capability is most evident with circular seal
type valves, particularly double-seat mix-proof
valves, in which fluids that may not safely be
allowed to contact each other can be isolated within
a single valve-body.
Conclusion
This article has focused on some practical
implications of implementing EHEDG guidelines
with respect to the assessment of valves for hygienic
and aseptic applications. For more specific and
detailed information, readers should refer to the
relevant EHEDG guidelines. ■