Noisy solenoid valves can be more than just a nuisance. They can signal underlying issues that need to be addressed to ensure the longevity of your valves. While some valves are designed to make noise when operating correctly, it is vital to distinguish between normal valve noise and those caused by a solenoid valve, control circuitry, or plumbing issues. Here are some of the most common noises that can indicate a problem with your valves:
- Buzzing noise
- Water hammer
- Clicking noises
- Pneumatic valve exhaust
Buzzing Noise
AC Noise
Solenoid valves operating on alternating currents may produce a noise accompanied by vibrations. This is normal for some AC solenoid valves, producing a soft buzzing and slight vibrations. This is caused by the alternating current creating a varying magnetic field, which then acts on the armature of the valve. To help reduce this noise and vibration, most solenoid valves are equipped with a shading ring—usually made from copper—which helps buffer against magnetic energy produced by the solenoid current. In addition, the shading ring helps to smooth variations in magnetic field strength, storing the energy when the current is at its peak and releasing it when the AC is near zero.
Undervoltage
Undervoltage is a potentially dangerous issue affecting solenoids, resulting in excessive noise and vibrations. An improper control signal, faulty control system, bad wiring, or control relay malfunction cause it. When this happens, a solenoid may oscillate between open and closed states, producing abnormal vibrations and an audible hum. To diagnose this issue, the solenoid must be energized, and the voltage across it measured to ensure it is within the manufacturer-provided specifications. If the voltage falls below the expected level, Undervoltage is likely the cause and should be addressed promptly to avoid further damage.
Loose or Missing Parts
Another potential cause of chattering noises can be loose or missing parts within the assembly. To prevent this from occurring, it is essential to ensure that all components are installed correctly and properly tightened, as per the assembly manual. In addition, if incorrect maintenance is carried out on the valve, this problem may arise. In the event of missing components, you can find suitable replacements in your distributor’s catalog.
Excessive Pressure
If you’re experiencing humming noises from your solenoid valve, the pressure differential across the valve or the flow rate may be too high. To prevent this, ensure the solenoid valve you choose is appropriate for the pressure and flow requirements. Additionally, ensure that the inlet and exhaust tubing have a sufficient diameter for lower flow rates. In some cases, speed-control devices may also be necessary for proper operation.
Internal damage can cause excessive noise in the operations of a valve. Worn armature or damaged springs are usually the cause of such occurrences. If the issue is believed to be related to wear, the valve must be inspected and serviced by a qualified professional. Please address these issues to avoid costly repairs and potentially dangerous operations.
Too Low Differential Pressure
Valves that require a minimum pressure differential to open and remain in the open state are known as indirect-operated, pilot-operated, or servo-operated. If the minimum required pressure differential is unmet, the valve may not open fully or rapidly shift between the open and closed positions, producing noise. Consider the minimum operating pressure differential specification in the solenoid valve datasheet to avoid this issue. An alternative to these valve designs is a direct-operated solenoid or motor-driven ball valve, which does not have minimum pressure differential requirements.
Foreign matter
Foreign matter such as dirt, limescale, and calcium deposits can all lead to malfunctioning solenoid valves. Limescale is especially prevalent in systems that use hard water and can cause the armature to stick and possibly fail. It is essential to be aware of potential issues and seek out valves with designs that are more resistant to them. Noises are sometimes a tell-tale sign that a problem is developing, so keep an ear out for strange noises. Taking the time to properly maintain and inspect valves can prevent costly and time-consuming repairs.
Water Hammer
A water hammer is a phenomenon that occurs when a valve is abruptly shut off, causing a pressure surge in the pipes due to the momentum of the medium flowing through it. This pressure surge produces a sound similar to being struck by a hammer and is more pronounced in liquid media than in gaseous media because gasses are compressible and can absorb some of the kinetic energy the moment the valve is closed.
One of the most effective approaches to solving the water hammer problem is to reduce the flow rate by uprating the diameter of the tubing. This reduces the momentum of the medium and, in turn, decreases the maximum amplitude of the pressure surge. Additionally, reducing the flow rate decreases the wear and tear on the pipes and other components, reducing the need for maintenance and repair. Investing in the correct size tubing can help your system run more efficiently and cost-effectively.
Another solution to ensure a smooth and controlled valve closure is to use an electric or pneumatic actuated ball valve. These valves provide a slower switching response than solenoid valves, typically designed with fast-state switches. This ensures a gradual, rather than instantaneous, valve closure, which can help minimize the risk of system shock, overpressure, and other system damage.
A third solution to prevent the water hammer effect is a water hammer arrestor, sometimes called a shock arrestor. This device dissipates the energy the pressure surge carries in a controlled manner. It comprises an air pocket behind a sealed piston inside a cylinder, closed on one side. In high-flow applications, it is essential to guard against water hammers as they could be strong enough to cause ruptures or leaks in the weakest part of the system.
Clicking Noises
The clicking noise that may be heard when solenoid valves open and close is usually considered normal operating noise and can be challenging to prevent. This noise can come from the valve itself or from supporting circuitry, such as a relay that provides current to the valve. Sometimes, the clicking sound may be prevented by adjusting the valve’s settings or the supporting circuitry.
If your solenoid clicks rapidly every second or every few seconds, this usually indicates a problem. The most common cause is a faulty controller or bad wiring. To diagnose the issue, measure the voltage across the solenoid valve when energized and ensure it is within specifications and not fluctuating by more than a few volts. When the solenoid is first energized, a slight voltage fluctuation may be expected, but it should quickly settle to a specified value. Next, the solenoid can be connected directly to the controller using short leads to check if wiring is the issue. If this solves the problem, inspecting for a quick or bad connection somewhere in the wiring harness is a good idea.
Suppose the wiring is correct, and the controller is still not working. In that case, the problem could be coming from one of the controller inputs, a bad sensor, or incorrect input wiring, causing the solenoid valve to cycle rapidly. To prevent premature failure and increased wear, it’s essential to identify and correct the root cause of the problem.
Pneumatic Valve Exhaust
Pneumatic valve exhausts can be a source of loud, potentially harmful noise in industrial applications. Continuous or repeated exposure to sound pressure levels above 90 dB can lead to hearing loss, tinnitus, and overall stress for workers. To reduce or eliminate these risks, pneumatic mufflers or silencers can be installed in exhaust ports to reduce noise levels significantly. This measure can help protect workers from the potential dangers of long-term exposure to excessive noise.、
The noise generated by pneumatic valve exhaust ports is caused by turbulent air leaving the exhaust port. This turbulence is created by a sudden increase in the flow rate through the orifice, which releases energy and creates a sound pressure spike. Mufflers work by dissipating this energy, diffusing the air over a larger surface area, and reducing the total noise produced. In addition, dampers also serve to protect the exhaust port from water and dirt ingress.
There are a variety of pneumatic silencers on the market that come in different flow ratings, back pressures, noise reduction ratings, and fittings. In addition, many of these silencers are fitted with filters to prevent oil mist and other contaminants from being released into the atmosphere. Depending on the design, some pneumatic mufflers may require occasional maintenance to ensure the filter remains clear and compelling. Nevertheless, with their robust design and reliable performance, pneumatic silencers provide a cost-effective solution for reducing noise levels and protecting the environment.
