6 Common Questions About Sanitary Valves

As one of the indispensable equipment in the food or pharmaceutical industry, sanitary valves may encounter many problems from selection to use and maintenance. The following are some common types of problems.

 

1. What are the three main factors to consider when selecting an actuator?
The output force of the actuator should be greater than the valve load and reasonably matched;

When inspecting the standard combination, it is necessary to consider whether the allowable pressure difference specified by the valve meets the process requirements;

The response speed of the actuator should be considered to meet the requirements of process operation, especially the electric actuator.

2. Which valves need flow direction selection?
The flow direction should use a single-seal regulating valve without a balancing hole, such as a single-seat valve, a high-pressure valve, a single-seal sleeve valve, etc.

The flow-opening valve works stably, but the self-cleaning performance and sealing performance are poor, and the service life is short; the flow-closing valve has a long service life, good self-cleaning performance, and good sealing performance, but when the valve stem diameter is smaller than the valve core diameter, the stability is poor.

3. Why is selection more important than calculation?
Compared with calculation, selection is much more important and complicated. Calculation is just a simple formula calculation, which does not depend on the accuracy of the formula itself, but on whether the given process parameters are accurate.

There are many contents involved in the selection. If you are not careful, it will lead to improper selection, which will not only cause waste of manpower, material resources and financial resources, but also unsatisfactory use effect, bringing problems such as reliability, service life and operation quality.

Seat valve

4. Why can't the double seal valve be used as a stop valve?

The advantage of the double seat valve core is the force balance structure, which allows a large pressure difference, but its outstanding disadvantage is that the two sealing surfaces cannot be in good contact at the same time, resulting in large leakage.

If it is artificially and forcibly used for cutting operations, it obviously cannot play a good role, although many improvements have been made to it (such as double seal sleeve valve).

5. Why is the blocking performance of the straight stroke control valve worse than that of the angle stroke control valve?

The valve core of the straight stroke valve is vertical throttling, while the medium flows in and out horizontally, and the flow of the valve cavity must turn, which makes the valve flow direction quite complicated (in an inverted "S" shape). In this way, there are many dead zones, which provide space for the medium to settle, and will cause blockage in the long run.

The throttling direction of the angle-turn valve is horizontal, and the medium flows in horizontally and then flows out horizontally, which is convenient for taking away the dirty medium. In addition, the flow channel of the angle-turn valve is simple, and there is little space for the medium to settle, so the blocking performance of the angle-turn valve is good.

6. Why should the stop valve use hard seals as much as possible?
The stop valve requires the leakage to be as small as possible. The soft-sealed valve has the lowest leakage, and its cut-off effect is of course good, but it is not wear-resistant and has poor reliability. From the dual standards of small leakage and reliable sealing, the soft-sealed cut-off is not as good as the hard-sealed cut-off. For example, the full-function ultra-light regulating valve, the seal stack is protected by wear-resistant alloy, the reliability is high, and the leakage rate can reach 10~7, which can meet the requirements of the stop valve.