Electric bypass valve

When they talk about electric bypass valves, many people immediately imagine a simple electromechanical unit - they say, it opens/closes and that’s it. But in practice, even in basic configurations of intelligent agricultural systems, this element turns out to be critical for balancing pressure. At Shandong Linyao Intelligent Agriculture Technology LLC, we had cases when customers tried to save on bypass valves by installing Chinese analogues without calibration for local conditions - as a result, they either received water hammer in the main line or underfilled in distant sectors of the field.

Design features that are not always obvious

Modernelectric bypass valve— it’s not just a solenoid + spring. In our projects, for example, for drip irrigation in greenhouse complexes, a modification with a stepper motor and pressure feedback is used. The valve does not just open 100%, but can operate in the range of 15-85% of capacity, which allows fine control of the flow between zones.

The case material is a different story. For Uzbekistan, where the water has a high salt content, we offer AISI 316L stainless steel through the website https://www.lyzhihuinongye.ru, although it is 30% more expensive. But clients often first take cheap brass analogues - and after six months they end up with jammed rods due to sulfate deposits.

An interesting point: in systems with frequency converters, sometimes a resonant frequency occurs at which the valve begins to 'sing'. You have to add damping washers or change the PID controller settings. This is exactly the case when theory diverges from practice - you won’t find such nuances in the device’s data sheet.

Integration with control systems

When we design automated areas,electric bypass valveWe always connect with pressure sensors at three points: before the valve, after it and at the end of the line. Without this, the meaning of 'intelligence' is lost - the valve must not just relieve excess pressure, but maintain stability in the entire branch.

At one of the facilities in Kazakhstan, they tried to use valves with analog control 0-10V instead of the MODBUS bus. It turned out that with long lines (more than 200 meters) significant positioning errors appear. I had to re-arrange the cables and install signal repeaters - a lesson costing half a million tenge.

Now, for most projects, Shandong Linyao Intelligent Agriculture Technology LLC uses valves with its own PLC, which can autonomously handle the simplest scenarios. For example, when the pressure in the line drops, the valve automatically limits the flow so that priority areas (for example, seedlings in cassettes) continue to be watered.

Installation and operation problems

The most common mistake installers make is installing a valve without taking into account the direction of flow. It would seem elementary, but last season three facilities had to be redone. It is especially difficult with compact models, where the arrow on the body is almost invisible.

Winter preservation is a separate issue. If drainage holes are not provided below the valve level, residual water will burst the housing when it freezes. Now we always additionally install manual resetters at the lowest points, although this is not always provided for in the design.

Another point: when using fertilizers through a drip irrigation system, small particles sometimes clog the calibration jets in the valve. We have to recommend that customers install an additional fine disc filter directly in front of the valve, although according to hydraulic calculations it is not always necessary.

Cases from practice

Last year we made a project for an intelligent greenhouse for strawberries in the Moscow region. They used a cascade of fourelectric bypass valvewith different bandwidths. It was interesting to observe how the system automatically redistributed pressure between zones while simultaneously turning on drip lines and aerosol cooling.

But in a cotton field in the Fergana Valley they were faced with the problem of electromagnetic interference from powerful pumping stations. The valves would sometimes open spontaneously. Shielding the cables and installing ferrite filters helped - and this solution was found not in the instructions, but by trial and error.

We are currently testing a new model with a flow sensor in one housing. It shows good results, but there are questions about accuracy at low flows - the firmware will probably have to be modified.

Prospects for technology development

Judging by the trends, in the coming yearselectric bypass valvewill become not just an actuator, but a diagnostic unit. We are already seeing prototypes that can independently detect seal wear based on changes in current characteristics and proactively signal the need for maintenance.

For large projects, such as smart agricultural parks, the concept of energy-autonomous valves is interesting - when the energy of the water flow is used for switching, and the electronics are powered by an integrated microturbine. True, such solutions are 2-3 times more expensive than usual ones.

Shandong Linyao Intelligent Agriculture Technology LLC is currently experimenting with valves that can operate in extreme temperatures (-40°C to +70°C) for projects in Siberia and Central Asia. The main problem is not the electronics, but the sealing materials, which lose elasticity under cyclic temperature changes.