Instrumentation design engineers will always use all kinds of solenoid valves on the instrument, these precision solenoid valves for medical, environmental protection and analytical instrumentation have a great impact on the realization of the function. Especially data analysis equipment, so most engineers need to weigh all kinds of application factors to consider the use of the most appropriate solenoid valve. Instrumentation pursuit of solenoid valve miniaturization makes it necessary for designers to use lighter, smaller, more durable miniature solenoid valves, improper screening may lead to instrument failure, data analysis errors, or not work properly at all. Design engineers need to consider both the reliability and durability of miniature solenoid valves as well as performance details such as their light weight, switching response time, effective flow rate, and low power consumption.
Ensure reliability and repeatability
When instrument design engineers in the selection of miniature solenoid valves, often hope that the solenoid valve can be very reliable repeated operation, in particular, to ensure that the stability of the long time that repeat performance, it is best to hope for a long time without any operation fluctuations and exceptions, this often become the first element of the screening of precision solenoid valves.
For example, the selection of isolation solenoid valves for blood cell sampling and counting channels usually affects the repeatability of the whole machine, high-performance liquid chromatography in the quadratic gradient isolation valves need to respond to the more uniform, the more rapid in order to achieve the test requirements more easily, if the lack of uniformity is not rapid, then, in the detection of the sensitivity of the reproducibility of the results of the difference in the intuitive.
Even an early carelessness in the selection of original parts can lead to serious unforeseen consequences. The later such design flaws are discovered, the more costly the modifications become. This is because when it comes time to replace the solenoid valve, a series of tests will need to be done all over again. So in this case engineers will generally use a high reliability solenoid valve, but also will pay special attention to the solenoid valve production process, quality inspection and test control and so on.
Solenoid valve and media contact material
Special solenoid valve design will have a direct impact on the reliability of the device itself, so in the design and use of solenoid valve sealing material (and media contact material), we must do more mathematical analysis of all the application of the material is not simply corrosion resistance to acid and alkali.
For example, in analytical test instruments, solenoid valves are in direct contact with sample reagents, but most miniature isolation valves have internal rubber materials that may dissolve when in contact with sample reagents. If you do not consider any design pre-compensation, then after a long time of use the rubber material will therefore change the parameters and performance of the valve, or even affect the components to not work properly, resulting in the entire instrument can not work. Experienced solenoid valve designers will take into account the scope of application of the valve, especially the compatibility of chemical substances and other practical applications on the valve.
Solenoid valve switching response time
Solenoid valve switching response time, which directly affects the authenticity of the results of the mathematical analysis of each group of your experiments. Often this data is many engineers in the industry is most likely to ignore one of the key indicators of parameters, but also high-quality solenoid valve to distinguish between the low level of solenoid valve is one of the important indicators, because the solenoid valve switching response time solenoid valve coils, springs, the internal structure of the components to determine if there is no extensive application of the research experiment as a basis for the design, it is impossible to come up with an accurate value.
For example, in the analytical instruments, the use of pinch valves, then, from the medium of the special application, is indeed to achieve the compatibility of the medium and the contact material, but the solenoid valve itself to control the time of the problem, from the solenoid valve plunger contact with the rubber tube to cut off the flow of the process of this process time is far more than ms ms unit value of a customer in North China with a pinch valve cut-off time is 1.63s (seconds) - the solenoid valve switch reaction time is currently the international do a good job is about 30ms, plus the plunger suppression of the rubber tube buffer time, it has been a long time, so and the isolation valve switch reaction time of 30ms, this value is actually much larger than the theoretical value, the difference in time leads to more media flow to lose the authenticity of the data, so the analysis of the The result of analyzing the data naturally deviates greatly.
Ensuring longer service life
Continuous service life is the first parameter that should be considered for solenoid valves in most applications, especially in those where a longer continuous service life is required. For example, in medical equipment and high-running instruments, where continuous operation is required, the number of solenoid valve failures should be minimized or even zero, even after a long period of use. Frequent maintenance and replacement of solenoids is best avoided. Continuous high service life at the same time also indicates that the components in the complex and changing applications have better reliability.
In fact, the high reliability of the service life guarantee is very difficult to do, in the solenoid valve design experienced experts once mentioned, high service life of the most troublesome is the coil, springs, seals, that is, the design of the coil. Whenever the solenoid valve work, the electromagnetic excitation will pull up the plunger, repeated millions of times, will lead to the coil in a short period of time to renew the current and coil heating situation occurs, if the coil does not have the function of renewing and stabilizing the current will lead to the coil burned, of course, if the coil temperature rise is too high, the same will be burned coil, the more important thing is that the coil's temperature will be thermal conductivity to the media, resulting in the entire experimental data distortion; plunger seals and at the same time and the channel end face for millions of reciprocal flow. The seal of the plunger and at the same time with the channel end face for millions of reciprocating motion, will be worn, leakage, most of the valves will have this situation, some manufacturers through the replacement of the spring or sealing material design to solve the problem, but the actual effect will not be too good.
Experienced application engineers in the consideration of the long service life, will consider taking the solenoid valve coil current stabilization design, the addition of electronic components in the coil inside, so as to ensure that the short-term current impact leads to burn the coil, while reducing the temperature rise. At the same time on the spring wire diameter to do the most stringent requirements, sealing materials are generally used in the international Dupont as a supplier, so as to ensure that there is a more polished contact surface and less impact, especially compared to the metal body of the valve, the plastic valve body and the plastic actuator have better durability.
Should also be included in the life of the factors affecting the application of the liquid, the valve needs to be continuously energized time, some extreme use cases, such as: rocket propellant filler with solenoid valves, it must be ensured that the solenoid valve 12 hours of continuous operation after the temperature rise can not be reached 5K, some manufacturers will test the service life of 500,000 times, but some international brand manufacturers have already done several tens of millions of times. The service life of some international brand manufacturers has already achieved tens of millions of times.
Ensure that the design is lighter and smaller
Almost every improved instrument needs to be lighter, smaller and more energy-efficient than the original instrument, so every instrument design engineer needs to take into account the dimensions of each component when designing. In some precision, convenient equipment, online monitoring equipment, especially the need to reduce the size of the solenoid valve, solenoid valve volume can be reduced to better accommodate the circuit board, container bottles and other non-valve components. A compact valve body can also reduce the inconvenience of carrying and transportation.
As long as the size of the solenoid valve becomes smaller, design engineers can reserve more space for the rest of the structural design, which allows the device to reserve space for expansion of more functions. For online monitoring instruments, the size also has certain provisions, such as alcohol tester need to be able to handheld portable. Online total phosphorus and nitrogen instruments contain a lot of micro-solenoid valves and power source devices, the size of the solenoid valve becomes the main factor in the design of the choice, to make room for the installation of other components.
Domestic traditional valves are generally larger than international valves specializing in miniature solenoid valves, and design engineers will find that even if the size and weight of each valve is a little smaller, it can be more advantageous to install the entire machine in a limited space.
Many traditional valves are still made of stainless steel body, the new plastic valve body can significantly reduce the weight.
If there is a need for more flow or less power, there is a need to increase the weight of the valve body, and valve designers need to get the same performance at the weight and size that the conditions allow.
Ensuring flow rates that meet the application
As long as the trend toward miniaturization of instruments continues, every design engineer will need components with the same performance but smaller size. Increasing flow rate is a critical parameter for miniature solenoid valves. However, changing the flow rate affects a number of parameters such as energy consumption, pressure and flow rate which are all related to each other. the Cv (coefficient of flow) value is related to the internal channel design of the valve itself. The flow coefficient can reflect the valve itself in one aspect of the flow design level, each valve Cv may be the same, but the volume is different; and the volume size of the valve seems to be similar, but the Cv may be very different.
When higher flow rates are required, the overall energy consumption and pressure design must be kept within the user's requirements.
Experienced instrument design engineers know that even small increases in flow rate can affect a variety of applications. For example, in order to speed up a single test program, waste or cleaning drains need to be removed as quickly as possible in a matter of seconds to save time occupying the entire instrument's common pressure source, which is often chosen to be larger than the diameter of the test line.
Orifice issues often make valve selection more difficult. For example, some modular valves due to the asymmetrical distribution of internal outlets, the two ports will have different restrictions on the flow rate and pressure, in the design of the base plate flow path should be adjusted to the direction of the valve mounting holes.
Often designers weigh the need for the largest possible orifice for high flow rates, but larger orifices usually require greater energy consumption and a larger valve body. So you need to choose to ensure reliability, in the weight and small size advantage, choose the appropriate flow rate corresponding to the application conditions of the valve body is appropriate, the choice of too large a flow rate of the valve body will only increase the energy consumption and space, too small may not be suitable for the use of the conditions, the use of the appropriate aperture in the application to meet the flow rate of the reasonable application is the best choice.
PeterPaul solenoid valve flow path design is not simply direct drilling 90 °, we are through the precision machining machine tool on the valve body inside the flow path of the rounded-type design and processing, in order to reduce the flow path resistance, we and the application of aerodynamic testing software, equipment for wind resistance coefficient of the test, to ensure that the flow rate of the maximum optimization value.
Ensuring more energy-efficient devices
Energy efficiency is a very important factor for devices that use solenoid valves in a compact or portable manner. A good miniature solenoid valve needs to optimize electrical energy use, while also reducing the weight of the valve body and making the most of each amp of power generated by the battery or power supply.
But in reality many products on the market are still very power hungry. Solenoid valve control in many cases can be added to the PWM circuit to save energy, switching power supplies generally use pulse width modulation (PWM) technology, which is characterized by high frequency, high efficiency, high power density and high reliability. This type of circuit makes the overall electrical energy down but also can use the holding voltage to work, but relatively also cost becomes higher. Valve design engineers are often concerned about finding lower energy consumption, more efficient coils, for the valve also requires energy saving, can increase the space of other devices on the instrument and the overall performance of the instrument.
Ensuring component fit
Each instrument design engineer has a different knowledge and understanding of components, and it is not possible to comprehensively and professionally know the essentials of different suppliers' product choices in the selection of a large number of parameters. Only through the assistance of a professional fluid fitting application engineer can a component be selected in a large number of models to suit the application. For example, metric fittings are mostly 1mm, 2mm and other integer values, while British or American fittings are mostly 1.6mm (1/16″), 3.2mm (1/8″) and other non-integer values. The like-for-like design of the product reduces the risk of selection and maximizes the match with the individual components of the application.
In order to better minimize the selection of parameters for various miniature solenoid valves and the difficulty of matching each component, fluid accessory product engineers will always come up with some novel ideas.
Summary
The selection of miniature solenoid valves needs to be weighed against the actual conditions of the application and the instrument itself, taking into account factors such as reliability at certain pressures, durability, shape, leakage, explosion-proof safety, switching response time, weight and effective flow rate, low power consumption, and specialized matching components. In all types of mid-range and high-end instruments, solenoid valves need to be used tend to be more high-quality electronic components.
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