When selecting valves for a steam line in a food factory, the first step is to distinguish whether the steam comes into direct contact with the product or not. From there, keeping three points in mind—the hygienic suitability of the body and seal materials, pressure reduction matched to the operating pressure, and the actual flow conditions—makes it easier to achieve both hygiene management and energy savings. In food factories, where applications are diverse—heating, sterilization, humidification, and cleaning—selecting based on catalog bore size alone tends to cause oversizing, undersizing, condensation, or liquid pooling. Here, we organize the criteria to check during selection in the order they arise in practice.
Key points of this article
- Whether the steam is a “direct application” that contacts the product or a food-contact surface, or an “indirect application” such as jacket heating, changes the required hygiene level and materials.
- Energy savings are an accumulation of “pressure reduction to the appropriate pressure,” “suppression of leakage and heat radiation,” and “a bore size matched to the flow conditions”—not a single magic valve.
- Considering not only the maximum flow rate but also the minimum flow rate and fluctuations in inlet pressure improves selection accuracy.
Distinguishing hygiene level by direct or indirect application
Even on the same steam line, the required hygiene of a valve differs between a direct application, where steam is sprayed onto food or a food-contact surface, and an indirect application, where heat is transferred via a heat exchanger or jacket. Direct applications may involve handling steam of high cleanliness (so-called clean steam), making the selection of wetted-part materials and seal materials more important.
As a general guideline, use stainless steel (such as SUS304 or SUS316) for wetted and steam-contact parts, and select materials for seals and diaphragms that take heat resistance and suitability for food applications into account. First confirming which application your own line falls under—from both the drawings and the operational side—is the starting point for a selection with neither excess nor shortfall.
Look at materials, seal materials, and “ease of cleaning”
In hygiene management, in addition to the materials themselves, the ease of disassembly and cleaning and the resistance to liquid pooling and dead legs also become factors for judgment. Shapes with complex structures where cleaning water or condensate tends to stagnate can, under certain conditions, become breeding grounds for contamination or microorganisms. It is safer to confirm—incorporating the perspective of the maintenance staff—whether the valve fits the operation of periodic disassembly inspections and CIP (Clean-In-Place).
Energy savings are an accumulation of “appropriate pressure, leak suppression, and appropriate bore size”
The energy-saving effect is not determined by a single valve; it is an accumulation of multiple factors. First, rather than sending steam at high pressure as generated, adjusting it to the required pressure of each device with a pressure reducing valve makes it easier to suppress wasted heat and excessive steam consumption. Next, reducing leakage from connections and glands and heat radiation from insufficient insulation is another modest but effective measure.
Select a bore size matched to the flow conditions
Optimizing the bore size is important for both energy savings and stable control. Selecting a valve simply to match the piping size can result in a size that is too large for the actual flow rate, which may make control unstable or cause weak response in the minimum flow range. Conversely, an undersized valve increases pressure loss. The guideline is to select based on the actual flow rate—identifying not only the maximum flow rate but also the minimum flow rate, which differs between startup and steady operation, and the range of inlet pressure fluctuation—while allowing an appropriate margin.
Frequently asked questions
Q1. Because it is a food factory, should all valves be stainless steel?
A1. Stainless steel is the basic guideline for wetted and steam-contact parts and locations that may come into contact with food. It is not necessarily required to apply it uniformly even to areas of indirect application with low hygiene requirements; judge according to each application.
Q2. How much energy can be saved by installing a pressure reducing valve?
A2. Because the effect varies greatly with pressure conditions, flow rate, and operation, a uniform figure cannot be given. Please understand it in terms of the idea that lowering excess pressure to the required pressure tends to lead to reductions in steam consumption and heat radiation.
Q3. Isn’t it fine to match the bore size to the piping size?
A3. Basing selection on piping size tends to lead to oversizing. Selecting based on the actual flow rate (especially the minimum flow rate) and inlet pressure is often more advantageous in both controllability and energy savings.
Q4. Does selection differ between clean steam and ordinary steam?
A4. When cleanliness is required in a direct application, the requirements for wetted-part materials, seal materials, and surface finish may change. It is safer to make the selection after clarifying the application and the required level.
Q5. What should be noted when updating an existing valve?
A5. Rather than searching for an equivalent by model number alone, confirm whether the flow rate, pressure, and operation have changed between the original installation and the present. If the operation has changed, reviewing the conditions at the time of the update improves selection accuracy.
Q6. What should I do if I don’t know the minimum flow rate?
A6. Confirm the low-load conditions, such as startup and insulation operation, with the operations side. If the information needed for judgment is not available, the reliable approach is to organize the conditions and then make use of a technical consultation.
Summary
Selecting steam valves for a food factory is a task that starts from distinguishing direct versus indirect applications, then layers together the hygienic suitability and cleanability of the body and seal materials, and energy savings through appropriate pressure, leak suppression, and appropriate bore size. In every case, starting from the “guidelines” and then translating them into your own actual flow rate, pressure, and operation is what determines accuracy.
If you have concerns such as “I know the piping size but can’t judge whether the bore is appropriate,” “I know the maximum flow rate but the minimum flow rate is unclear,” or “I want to select an equivalent for an existing valve but the operation has changed,” please organize the conditions and make use of Yoshitake’s technical and selection consultation. Based on the application and hygiene requirements as well as the flow rate and pressure conditions, we will work with you to consider a suitable valve selection.