SMS-TORK has developed a proportional solenoid valve for use in ventilation machines that are critical in the health of patients in the Covid-19 outbreak.

Proportional valves are of great importance due to their direct effect on the valve flow rate given to the patient. It is produced 100% locally by our R&D unit and started to be distributed for use in ventilation machines.

What is Ventilation Machine?

A ventilation machine is a device that can mechanically send/receive the respiratory air to the lungs. Breathing equipment is used in cases where the patient has difficulty breathing on his own or during special treatment processes on respiratory organs.

Depending on the physical properties of the patient and the treatment process, the air needs to be transferred to the patient in different pressure, flow, and oxygen ratios. At this point, precise flow control is extremely important in these devices. In this context, our company produces sensitive solenoid valves to these devices with its experience of fluid control over 35 years.

What is Proportional Solenoid Valve?

Solenoid valves are widely used in the industry as they are fast opening and closing, compact, cost-effective, and long life. In general, solenoid valves are used in the industry for On / Off applications. However, it is also possible to achieve flow control proportionally, in other words, flow rate control by changing the control signal, in solenoid valves.

TORK SP series proportional solenoid valves are designed as a result of special calculations that provide flow control with voltage change. For example, when you gradually increase the supply voltage starting from zero to a proportional solenoid valve operating with a 24VDC coil, the valve will be opened gradually and the flow rate will increase. Similarly, when you gradually decrease the 24VDC voltage, the valve will be gradually closed and the flow rate will decrease.

Proportional solenoid valves of the TORK SP series can provide very precise (3% precision) flow control.

Hysteresis and Repeatability

One of the important concepts in proportional flow control is the hysteresis concept. While the voltage of a proportional solenoid valve, ie the control signal increases, it takes certain flow values and reaches fully open maximum flow. When we do the opposite of this process while decreasing the voltage, the flow takes certain values and the valve becomes fully closed. These two increases and decreases may not always be on the same curve. In other words, if the voltage x corresponds to the y flow rate during the voltage increase, the voltage at the x value corresponds to the y flow value. This situation is defined as Hysteresis in proportional flow control. A hysteresis is an undesirable event, as it often complicates precise control.

Thanks to the special designs and tests carried out on proportional solenoid valves of the TORK SP series, the products show an average of 4% hysteresis. In this way, the flow control process can be done more easily and with high precision.

Another issue that is important in proportional flow control equipment is Repeatability. When you turn a product on and off several times, the same change in flow rate shown against the voltage change means that the product shows good repeatability. It is very important for a product to be repeatable in terms of control sensitivity and ease.

The coils of the solenoid valves increase their temperature when they are energized for a long time due to their nature. The increase in temperature means the magnetic field force decreases in the coils. For this reason, it is not an easy process to keep the force balance constant in proportional solenoid valves and to ensure the repeatability of the product. However, TORK SP series shows a very good repeatability behavior (3% deviation) compared to its competitor’s thanks to its special magnetic field analysis and sensitive electro-mechanical design made in solenoid valves.

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SMS TORK started to serve in its sector with trademark TORK since 1985. We are the first producer of solenoid valve, pneumatic actuator, pneumatic actuated angle seat valve, pulse valve and electric actuator in Turkey. Today, TORK is preferred by 87 countries. With 17 000 square meters factory at IMES OSB and R&D department, we produce 100% domestic …