Venturi nozzle: principle of operation, description, application

Pipelines for various purposes inevitably must have technological units in which measurements are made of the medium served. This applies to traditional water pipelines and gas infrastructure, as well as to specialized industrial complexes working with special chemical liquids. In all cases, technologists provide for equipping the circuits with special flow meters. One of the most attractive from the point of view of operational characteristics of the elements of such equipment is a Venturi nozzle, which is built in at a certain measuring point. This component has many advantages, but when choosing a specific model, the nuances of use should be taken into account.

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Nozzle Overview

The main function of this nozzle is to measure the environment that the target water supply serves. At the same time, the feature of the device is not so much the ability to contact with liquids of different properties, as structural advantages. The fact is that the nozzle, or venturi, is able to maintain an optimal pressure indicator at the time of passage of the medium. That is, the narrowing of the channel, of course, affects this parameter, but not as much as in the case of other types of flow meters.

There is another important feature. The fact is that the quality of the measurement of the volumes of the passing fluid is often affected by the diameter of the channel, which is a source of medium relative to the measuring device. During operation, the Venturi nozzle practically does not change the measurement accuracy depending on the parameters of this channel.

Device

This is a small device in the form of a pipe, the device of which provides for the availability of technological sections, designed to perform measuring operations. As a rule, the middle, that is, the central part of the nozzle, is pulled by a clamp, from which a special chamber for measuring, and also a hole for pressure collection, go to one side. On the other hand, the shape of the tube goes into a cone and forms a neck. There are several holes for pressure selection, as well as a diffuser. Typically, the jet pump is connected on this side either directly or using a specialplumbing fixtures.

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Among the structural advantages of this product, experts note the efficiency in the cramped conditions pipeline. However, there is a significant plus for inexperienced masters. It consists in a simplified model of nozzle installation.

How does a venturi nozzle work?

The device was named after the Italian scientist precisely for the reason that he discovered the effect of reducing pressure when the working medium passes through a narrowed area. It is on this principle, supplemented by Bernoulli Law, such tubes function. In practice, this means that the liquid passes the narrowed area, during which pressure is sampled in special annular chambers that supply the Venturi nozzle. The principle of operation also involves the interaction of the exhaust channels with direct measuring instruments. For accurate measurement, in particular, a pressure gauge is used, which can be presented both in the form of an analog device and a digital apparatus.

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Characteristics

The main criterion for choosing such pipes is a characteristic of the diameter. The most common formats range from 6 to 12 mm. There are also large sizes that should be selected for specific pipelines. At the same time, it is possible to use adapters of a suitable size, so strict fitting to a specific pipe is not so important. In addition to the diameter, the material of which the Venturi tube or the measuring system of valves as a whole is of great importance. Typically, stainless or carbon steel is used as the base. However, operational and protective properties are largely determined by the type of coating. To ensure durability, experts recommend contacting models treated with enamel or primer, which, among other things, protects against chemical influences. If we are talking about installation in industrial channels, then the best solution in terms of reliability would be galvanized galvanized coatings.

Varieties

The main differences are structural in the sense that the individual technological parts have a special design. For example, nozzles are used in which a cast conical part is provided without treatment. Such models are produced by injection molding using special sand matrices, and only the part and the neck are curved. A more complicated modification is the model, which also provides for the preliminary treatment of the inlet sections, with which the jet pump interacts in different versions. In this case, the central base can be performed without special processing.

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Fundamental differences from the above types has a device manufactured not by injection, but by welding. In this case, the conical part can be implemented in both straight and rounded shapes.

Areas of Application

Design features are due to non-standard ways of using the nozzle. In particular, valves of this type have found application in injection units that work in conjunction with the aforementioned jet pumps. Such mechanisms serve to compress gas mixtures, liquid vapors, as well as for their subsequent shipment to places with high pressure. Not without such a nozzle and gas cleaning system in some variations. For example, a high-speed gas scrubber is equipped with a nozzle, which filters the serviced mixtures from submicron and micron particles. Devices of this type are also used in some thermal and steam boilers, but mainly from the industrial sphere.

Pros and Cons of Venturi Nozzle

The undoubted advantages of valves operating on the Venturi effect include the possibility of installation in nodes with changing parameters of the supply channels. True, for the full use of this advantage, you should initially prepare the appropriate adapters. For example, if a Venturi nozzle is selected for pumping station, operating at different times of the year, then depending on the hydraulic requirements, the volumes of fluid supply may change - accordingly, the settings of the supply source are also adjusted.

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As for the disadvantages, they boil down to the fragility of the use of pipes that do not have a high-quality protective coating. On the other hand, models with modern surface treatments are much more expensive.

Conclusion

Modern pipelines coupled with pumping stations are actively being transferred to automated monitoring and control tools with the introduction of electronic remotes. In some functional parameters, the operators of such installations also monitor the indicators of measuring equipment.

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Perhaps the Venturi nozzle is one of the few devices in its class in which operational efficiency is based precisely on the physical principle of control. The technique of integrating such products into the structure of pipelines determines the accuracy of measurements and the minimum negative impact on the functioning of the main channel. Another thing is that in order to maintain optimal performance, regular maintenance of the measuring units is required.