How to choose the best process valve solution for your food and beverage facility
Designing the processing system for a food and beverage facility is a lot like doing a jigsaw puzzle. You can probably force many of the pieces to fit into various spaces. However, if you do not find the perfect fit, you will ultimately wind up with holes and weaknesses in your finished puzzle — or in this case, elevated food safety and quality risks that may cost your business valuable time and money.
To make an educated decision about valve selection, owners and their construction partners should consider the different types of valves available in the market and how they will interact with other components in the individual facility’s production lines.
Types of valves in food processing
Valves are a vital feature in the implementation of process controls and automation. They are used to stop or start flow, direct fluid between one or multiple paths, or control the flow rate, pressure or temperature of a process.
Generally, valves for food and beverage applications can be divided into two main groups: hygienic valves and utility valves.
Hygienic valves
Hygienic valves, also called “process valves,” come into direct contact with food and beverage products and require high levels of cleanability to maintain food safety.
The most common types of valves in the food and beverage industry are seat valves, which can be used to turn on/off or divert or control flow. Seat valves are used because all wetted parts are cleanable, easy to maintain and come in a variety of configurations that permit them to work in almost any piping system.
In cases where multiple products share piping and cross-contamination is a concern, seat valves can be replaced with mixproof valves. Mixproof valves provide double block and bleed protection, allowing dissimilar products to be produced simultaneously or cleaning to occur on one section of a system without contaminating another area.
Butterfly valves can be used as a low-cost alternative to seat valves in some hygienic applications. Their compact design creates space savings in complex process lines while providing direct access for maintenance.
There are some limitations to using butterfly valves in food processing. Butterfly valves are not recommended on high-pressure lines because they have a lower holding pressure than other sanitary process valves. Their design makes these valves less effective at closing against the flow of a fluid and can increase the risk of hydraulic shock, which can damage the piping system. Additionally, these valves are not used in dairy facilities because they do not meet the Food and Drug Administration’s (FDA) Pasteurized Milk Ordinance requirements.
Utility valves
Utility valves do not require cleanability and are, therefore, not limited in design. For this reason, food manufacturers will find that utility valves can be found in all shapes and sizes, including ball, butterfly, gate, plug, globe, angle seat and single seat. Each type of valve can have different variants for use in specific applications.
Ball valves and butterfly valves are used as shutoff valves in many of the same applications. Ball valves are used on smaller lines as they provide a better shutoff than butterfly valves, but butterfly valves are used on larger lines since they weigh less and are more cost-effective to manufacture.
Gate valves are used commonly on steam systems. They can be opened and closed slowly, reducing the interaction of steam and condensation on system startups and limiting flashing. Angle seat valves are used in systems where the valve needs to close against a pressurized fluid. Their design allows for a reduction in hydraulic shock during actuation.
3 factors that influence valve selection
There is no cookie-cutter approach to selecting from the many different types of available process valves.
Facility owners and their process engineering partners should carefully consider the cleanability, compatibility and maintenance of individual valves within their overall system in order to select the best one for the job.
1. Cleanability
The first step in ensuring food safety and sanitation is determining whether a valve will come into contact with a food or beverage product. This will tell you whether you need a hygienic or utility valve.
A valve that is part of a product line will need to be fully cleanable and compatible with cleaning agents.
If the valve is not part of the processing system but is installed in an area where sanitation is performed, then the valve should be water-resistant and compatible with surface cleaning agents to prevent corrosion.
2. Material compatibility
Valve material
Every material is compatible with many things, but there are certain materials that are highly incompatible with each other. The consequences can be immense when incompatible materials are installed together in a food production line. At best, it will threaten product quality. At worst, corroded foreign materials could end up in a food product consumed by a customer.
The most common material of construction used in the food industry for valves is 316 stainless steel. Other materials — like AL-6XN or Hastelloy — are used with harsh or corrosive products where traditional stainless steel is insufficient.
Trim material
Valves contain trim materials that come into contact with process fluids. Unlike valve bodies, stems and other elements of process valves, trims are not constructed from stainless steel.
Selecting the proper elastomer for the trim materials and seals is a key consideration that should not be overlooked. Consider the properties of both the products and cleaning agents coming into contact with the valves, the temperature of the system and the operating pressure.
For example, if you are making orange juice, which contains oils that are incompatible with EPDM rubber sealants, then your EPDM elastomers will likely swell over time. Once you take that valve apart, you will never be able to put it back together.
The inverse is also possible. If you use an incompatible cleaning agent on an elastomer and it begins to degrade, then the valves will leak, and parts of the seal could contaminate the product. You may end up with a bottle of sparkling water that has bits of plastic in it, which is dangerous for consumers and a major liability.
Lastly, if you fail to select an elastomer rated for high temperature or high pressure, your elastomer could also be damaged over time.
3. Maintenance
Certain process valves are easier to repair and maintain than others. When planning a large investment in process valves, it is important to discuss the maintenance needs of the valve, the cost of spare parts and how readily available they are in the event of an emergency to minimize production shutdowns.
Additionally, owners and plant operators should understand the manufacturer’s requirements for the valves installed in their facility. For example, do the valves on a brewery’s bottle-filling line require special tools for maintenance and repairs? If the valves leak and it takes several days to access the needed tools, how will the production loss impact revenue?
Is automation a worthwhile investment?
Upfront costs can give owners sticker shock, but investing in automated process valves pays off. At its baseline, automation maximizes output and reduces operational costs in food manufacturing settings. More importantly, it reduces manual error and limits operator involvement, which can result in elevated personnel and food safety risks.
Thomas Burley is a process engineer at Stellar. Stellar is a fully integrated firm focused on planning, design, pre-construction, construction, refrigeration, mechanical & utility, building envelope, and total operations & maintenance services worldwide. Visit the company's blog at www.stellarfoodforthought.netor learn about its projects at stellar.net.
