The right liquid system can make food processing and production easy and efficient, while the wrong one can cause downtime, expensive maintenance and frustration. The optimal design of a liquid system is highly dependent on the characteristics of the liquid. Liquid systems that are designed with ingredient characteristics in mind perform better and last longer. If you are upgrading, altering or installing a new liquid system, understanding all of the characteristics of the liquid can help to prevent problems.
Engineering Liquid Systems: 6 Liquid Ingredients Characteristics You Should Know
The best source of information for these liquid characteristics is your liquid ingredient supplier. Your supplier may not have all of this information, and some of it may not be relevant, depending on the ingredients you are working with. Obviously, working with common ingredients such as a brine solution will require less consideration than uncommon ingredients, like a liquid adhesive. Still, even many common ingredients can cause problems with liquid systems over time if their characteristics are not well understood. Talk with your liquid systems manufacturer about the following during the design phase.
1. PH: Acidic vs Basic
The pH scale measures how basic or acidic an ingredient is. Liquids with a pH near 7 are neutral, and this won’t be an important consideration for liquids with a neutral pH. However, liquids that are highly acidic, with a pH close to 0, or highly basic, with a pH close to 14, can present problems. Strong acids or bases should be stored in containers that will not corrode or react with the liquids. These can also be very hazardous to workers, and safety precautions should be clearly displayed around storage containers or liquid systems carrying these substances.
2. Process Temperature
Temperature can change liquids in seemingly subtle ways. When working with large volumes over long periods of time, these subtle changes can have big effects. Colder temperatures can make liquids thicker and more difficult for pumps and flow meters to work with. Warmer temperatures can have the opposite effect, making the liquids move faster and potentially metering too much. This is particularly important for liquids with a high oil or fat content, such as those containing palm oil or fish oil. Fats and oils can change density by as much as a percent for every 25 degrees F change in temperature.
3. Solution vs Suspension
A solution is a homogenous mixture with no visible particles, while a suspension is not fully dissolved and has small particles present. Suspended abrasive solids can wear away pipes over time, even if they are made from stainless steel. Wear-resistant coatings can help to reduce maintenance in these cases. If the suspension in the liquid system is used in food, it is also important to consider good manufacturing practices, so the small solids do not become lodged in tight spaces and become havens for bacteria.
4. Chemical Interactions
Chemical interactions can create dangerous reactions or simply ruin the substance. The most common chemical interactions to be aware of are those involved with water or air. Cyanoacrylate, for example, will become solid almost immediately if it touches water. It is also important to consider humidity in these reactions, as high humidity conditions can trigger reactions with water. Another chemical reaction to consider are those with common cleaning chemicals, such as bleach or ammonia. If liquid systems are cleaned with these chemicals, it is important to know how the ingredients may react with them. Finally, copper alloys causes fats to oxidize, so ingredients with high fat content should not be used with systems containing copper.
Viscosity can be considered a measure of a liquid’s “thickness” or how easily it flows. This metric is particularly important for the pump and flow meters on the liquid system. Some pumps will clog and wear down easily when working with thick liquids. A sine pump is ideal for thick liquids with suspended solids, particularly for foods such as pie fillings, jams and salad dressing. These types of pumps are gentle and predictable, allowing thick liquids and suspensions to flow without damage to the recipe or the pump itself.
6. Food Grade Applications
Liquid systems used in food processing must be held to a higher standard than others. As previously mentioned, food-grade liquid systems must be completely sealed to prevent particles from accumulating in small spaces. This includes welded joints and screws as well as hermetically sealed weighing devices. Liquid systems involved in food processing must also be easy to clean, either through clean-in-place processes or through disassembly.
There are many considerations when it comes to designing liquid systems. In our next blog posts, we’ll discuss liquid system pumps and meters in more detail, and how to choose these mechanisms based on liquid characteristics.