Homemade pressure gauge. U-shaped pressure gauge: in detail in simple language Tools and materials

Proper functioning of the vehicle's fuel system is a guarantee of the safety of the driver and passengers. Determining the volume of air in it allows you to control uninterrupted operation and troubleshoot in time. The pressure is checked by pressure gauges. These devices are quite simple in design and operation, so making them yourself is not difficult.

Purpose and technical parameters

A pressure gauge is a device designed to measure fuel pressure. If this indicator is unstable, then it will not be possible to correctly establish the operation of the engine. Interruptions in the functionality of the engine increase fuel consumption, and also affect the duration of the operation of the equipment as a whole. The technical condition in the car is monitored due to the built-in ECU (electronic control unit), covering also the check of the pressure in the fuel rail.

It controls the power of the engine, the volume of fuel consumption, and in case of malfunctions of one of the systems, it issues errors to the on-board computer in the form of an encrypted code, which is not very convenient.

The operation of the ECU is not always stable, and with several deviations in the functionality of the car, it can be difficult to immediately determine the breakdown. At the same time, the pressure gauge will make it possible to control the operation of the fuel supply system and eliminate or eliminate such a defect as soon as possible.

Meter specifications:

  • control of excess pressure of non-crystallizing liquid, gas, steam;
  • accuracy class - 1–2.5;
  • measurement range - 5–8 A.

How does it work

The base of the device is a hollow hose with an oval or ellipsoidal section, elastic structure. The fuel presses with its mass on it and deforms it. Its first end is connected to the mechanism of the fuel system, and the second to the meter, which gives the result of deformation on the scoreboard.

There is a spring inside the transmission that prevents backlash.

The hollow hose has cross-sectional planes of different diameters inside and outside, therefore, being under pressure, it tries to align itself all the time. The end connected to the renderer moves the arrow up the scale. At a maximum pressure of 25 bar and below, the accuracy of the device will be 2.5, more than 25 bar - 1.5.

The advantage of the device is the possibility of parallel connection to the system without interrupting its operation. This allows you to take a measurement while the motor is running.

Varieties

There are 2 types of fuel pressure gauges:

  • analog;
  • electronic.

By the type of action, the devices differ in the device of the sensing element:

  • liquid;
  • membrane;
  • spring;
  • bellows;
  • piston;
  • piezoelectronic;
  • radioactive;
  • wire.

What to look for when buying

When choosing which pressure gauge to use, you should pay attention to the following factors:

  • device device;
  • technical specifications.

Both analog and electronic devices are used to control air exchange in the fuel system.

Analog devices are distinguished by their simplicity of design and low cost. The data is displayed on a scale equipped with a pointer mechanism. The disadvantage is the high pressure error.

Electronic devices are more accurate and more expensive. The data is displayed on the LCD screen. The user is given the opportunity to independently select the unit of measurement.

Did you know? The pressure in the fuel rail can be monitored using devices for monitoring the volume of oxygen in the tire. They work on the same principle. For accurate control of the fuel system, pressure fluctuations must be within 5– 7 atmospheres. To control oxygen pressure, fluctuations vary in the range8 –16 atmospheres.

The scale of the meter must be legible, with the limit values ​​5–6 kgf / cm 2. Check the connections for leaks before purchasing, evaluate the quality of the materials.

How to do it yourself

A pressure gauge for diagnosing the fuel system can be assembled with your own hands, at a minimum cost. You don't have to be an auto mechanic to do this. The main thing is to choose the right components. We propose to consider an option upgraded with a fuel drain cock.

Tools and materials

When constructing the meter, the following materials are required:

  • a hose for filling air conditioners with a fitting;
  • 1/4 threaded tee;
  • 2 fittings with a landing diameter of 6 mm;
  • faucet with 1/4 thread;
  • 6 bar pressure gauge with user-friendly scale.

The size of the hose for filling the air conditioner must be selected in accordance with the size of the cap, which is attached to the nozzle rail. The cap is easily removable, so you can take it with you when you go shopping.

Important! The pressure gauge must be checked for an error before starting work in order to be able to replace it in time.

Of the tools you will need:

  • fumlent for sealing joints;
  • hose clamp;
  • compressor to check the manometer error.

Homemade fuel gauge: video

Manufacturing process

Step-by-step instructions for making a pressure gauge for measuring fuel pressure:

  1. Screw the tee to the pressure gauge.
  2. Attach a faucet to the tee.
  3. Attach the fittings to the faucet.
  4. Seal each joint with fumulent.
  5. Cut the hose. Attach the cut end to the lower fitting on the faucet, reinforce the structure with a clamp.

A car pressure gauge is required to measure air movement in the fuel rail. Such a device is easy to assemble on your own, and this will make it possible to constantly monitor the performance of the fuel system.

Schemes no programs no pressure gauge available

Having smoked a little these topics: Digital pressure gauge

I realized that many of the motorists are not programmers or radio amateurs, and not everyone will be able to assemble this digital pressure gauge. I suggest a simpler digital pressure gauge that almost every car enthusiast can repeat.

Since all of the above listed devices are based on voltage measurement. I decided to make friends with a 24 V voltmeter I have implemented on the MEGA48PA microcontroller and an MM370 0-10kg / cm2 pressure sensor with a resistance of 195 Ohms. Since we have the upper limit of the sensor 10kg / cm2, then I applied a voltage of 10V to the voltmeter and measured the voltage at the input of the MEGA48PA 28 leg, it was 0.5V, therefore the measurement limit of 0-10kg / cm2 will correspond to the input of the ADC (28 leg) 0-0, 5B.

Since the resistance of the sensor decreases from 195 Ohm to 0 Ohm with increasing pressure, it must be slightly redone so that the resistance increases from 0 Ohm to 195 Ohm with increasing pressure.

Alteration of the MM370 sensor for a digital pressure gauge.

Before reworking the sensor, the circuit can be drawn like this (decrease in resistance with increasing pressure)

we need to redo it so that the circuit looks like this (increase in resistance with increasing pressure)

To do this, it is necessary to flare the sensor, I used side cutters.

Before that, it is necessary to put marks on the cover and the sensor body (later it will be useful during assembly). After disassembling, we see what is inside, namely the measuring element itself and the moving contact. Using a screwdriver, unscrew and remove the measuring element,

it must be turned 180 degrees, before that, having cut the contact a little (so that it does not reach the body, I got it)

Test measurements were made, and a graph was drawn up of the dependence of the resistance of the MM370 on the readings of the pressure gauge.

and a graph is built (almost linear)

Also, my MM370 (BU) had a damaged wire,

connecting the movable contact with the body, I replaced it with a wire from a telephone headset.

We assemble and carefully roll (without using a hammer), you can fix it a little by welding (semiautomatic)

ADJUSTMENT OF THE VOLTMETER

To do this, you need to replace the 28 volt divider (in my case) in the input circuits of the voltmeter

Since we need a voltage limit from 0 to 0.5V, we use a 5V reference voltage source, which is located in the voltmeter itself (power supply of the MEGA48PA microcontroller 4 legs) By simple calculations, we need a divider by 10, since the resistance of the MM370 pressure sensor is 195 Ohm, then the resistance for the divider 1.95 kOhm is needed, it is better to put two, one of which is variable, I put two on 1 Kom

Now we have three wires plus + minus power supply and pressure measurement on the voltmeter.

We connect the pressure gauge to the compressor, do the calibration with a variable resistor (for more accurate readings, the calibration must be carried out at the pressure we expect to use)

They withstood the blow of the elements at the Sayano-Shushenskaya hydroelectric power station. They work on submarines and in mines. They are not taken by tropical humidity and arctic cold. They are real Tomsk manometers.

The former Tomsk manometer plant, and now the Manotom company, managed to provide almost half of the world with its instruments. 70 years of experience, combined with a modernized material base and a team retained at the enterprise, makes it possible to practically work wonders.

The plant produces 500 thousand devices per year. Along with all modifications, the production range includes 10 thousand items. All this is supplied to almost 10 thousand consumers from various fields - from shipbuilding to nuclear power plants.

What is the manufacture of pressure gauges today?

The first step is development

It all starts when the company receives an order. The first to enter the business are the employees of the design department. They determine how the device should be. If necessary, additional design equipment is ordered, which is produced here, in the tool shop. As soon as the designers create an image of the future device, the production workshops are involved. It is not so rare to develop new modifications of devices - consumers are constantly asking for something new.

Parallel production: from body to spring

From the designers, the development goes into the main production cycle, where 700 people work, and the equipment park is 527 units. The technologies used here, by the way, were developed within the factory walls.

As soon as development enters the mainstream, the case makers come into play. Each type of pressure gauge and pressure sensor needs its own housing. If the device will be used in not too harsh conditions, then the case can be made of plastic or aluminum. If the pressure gauge is made for the military, or will be used in a "harsh" environment, then the case will be steel. In different cases, the body of the device goes to the workshop for mechanical or galvanic processing. There is also a cold stamping workshop.

In parallel with this, the assembly of the "insides" of the device is going on in other workshops.

The next step is painting the body. Here, too, it was not without know-how. “We have introduced the most advanced powder coating technology to date,” says Andrey Metalnikov, Deputy General Director for Production. - The bottom line is that the usual painting from a spray gun with paint by spraying is too expensive. Too much of it simply dissolves in the air without getting on the product. When powder painting, the paint is used 100%, because what did not get on the product returns to the drum again and is not lost. In addition, the coating is stronger and more durable. "

A separate place in the list of subdivisions of the plant is the section of flexible springs. This is where the heart of any pressure gauge is made. The quality of the flexible spring determines the reliability and accuracy of the manometer, its specifications... For "Manotomi" the Ural metal experts have developed a special alloy, from which the springs are made.

The soldering section is the next step. Depending on the need, either soft or hard soldering of the device is performed, and if necessary, then welding, including argon-arc welding.

A separate area is the shop of plastic products. Thanks to modern thermoplastic equipment, parts of polypropylene, polystyrene and any other plastics can be produced here.

Naturally, "Manotom" cannot make the production cycle completely autonomous. For example, the factory receives glass parts and rolled metal from trusted suppliers. But, as far as possible, the plant tries to produce everything necessary in its own workshops. By the way, they work here only with Russian materials, imported parts are not used.

Those of the pressure gauges that require strengthening of the case, being almost ready, are sent to the galvanic workshop. Its presence is a feature of the Tomsk plant, because few enterprises can afford to maintain a galvanic shop. This is a very costly production - both in terms of the necessary equipment and by its very nature. After all, electroplating is a variety of chemicals and acids that must be disposed of after technological processes. And here they not only maintain such a workshop, but also constantly improve the technological process in it.

The most important element of the pressure gauge production is the workshop in which the transmission mechanism is created. The transmission mechanism is the central element of the pressure gauge, just as important as the spring. The more accurate and thinner the transmission mechanism works, the more accurate the readings of the device. Therefore, the most experienced workers work in the production of transmission mechanisms, and the technological equipment of the workshop meets the most stringent modern requirements.

“We installed the newest equipment in mid-2010. This gave several tangible advantages at once. Firstly, the accuracy of machining parts of the transmission mechanism has increased. It was possible to eliminate roughness, to improve the accuracy of the readings of our products. Secondly, thanks to this, we were able to raise the warranty period of our pressure gauges from one and a half years to three - twice, ”explained Andrey Metalnikov. Other suppliers Russian market pressure gauges are still guaranteed for a year and a half.

The final stage of production is the assembly line. There are four main conveyors. Each serves its own direction: technical devices, thermometers, special devices and electrical contact devices. Here the devices are assembled and undergo final quality control.

Before handing over the products, each department without fail checks it for compliance with the requirements. The technical control department of the plant puts a stamp on the products and this completes the process of creating a pressure gauge.

In recent years, "Manotom" has been developing the direction service their products. So, customers from the nearest regions can send a broken product to the factory, where specialists will take care of it. In more remote areas and outside Russia, the plant concludes contracts for the maintenance of its pressure gauges with contractors.

Another new direction in work is the production of so-called "smart" electronic pressure gauges. They not only provide data, but also participate in the process of managing production facilities, replacing the human operator. So far, their share is not so large - only 15-20%. But the volume of production of such pressure gauges is growing all the time.

“Today, our devices float not only on all civilian ships, but also on all warships, fly in rockets, and service artillery. The supplies go to the countries of the CIS, Europe, Asia and Africa, ”notes Andrey Metalnikov.

By tradition, a short video about how pressure gauges are made:

... I decided to write a strange post. Somehow, a post about the manufacture of a pressure gauge caught my eye. Or rather, not the device itself, but its miniature copy. For what? For all kinds of crafts where you do not need to use these devices (and hardly - you can hardly find them in this size).

MANOMETER (from the Greek manos - loose and metron - measure, metreo - I measure), a device for measuring the pressure of liquid and gas. Depending on the design of the sensitivity of the element, there are liquid, piston, deformation and spring pressure gauges (tubular, diaphragm, bellows);

some dependencies are also used physical quantities(e.g., electric current) from pressure. There are absolute manometers - they measure absolute pressure (from zero), gauge pressure gauges - measure the difference between the pressure in any system and atmospheric pressure, barometers, differential pressure gauges, vacuum gauges.


A "cork" is cut out of the rubber band with the help of a tube. Later, we will need it as a substrate for the pressure gauge scale.

We cut off the tubes of the required diameter. One tube a little more - this will be our body. The second tube is smaller. It will serve as a stopper for the back wall on one side and glass on the other.


We make the elastic band as thick as we want to place the scale of the device.

Cut out the image of the desired scale, suitable in size. I made the scales in advance. I collected pictures over the network, removed everything unnecessary, made several images of the same scale of different sizes and printed them at the nearest photo kiosk.


For glass, we take any transparent plastic. I used a CD case. Cut out a circle along the inner diameter of a wide tube with side cutters. We adjust with a file. The glass should fit very tightly, then glue will not be needed.

We make from a brass plate back wall... It should be the same diameter as the glass.

Let's start assembling the product. First, we glue the back wall to the end of the smaller tube. Then we glue the tubes so that one is in the other, while the bottom should be flush with the end of the larger tube. We drill a hole in the body.

We insert a wire into the drilled hole, on both sides of which we place the halves of our substrate, Glue it.

We make a decorative ring out of thinner wire that will hide the edges of the paper scale.

Shorten the second hand from wrist watch to suitable sizes and glue to the scale.

This is how the reverse side of our device looks like. On the wire coming out of it, you can put on a shorter thin tube. The part of the wire that is not closed by the tube will later be inserted into the tank (or into that part of your craft on which the installation of this dummy is planned).

It remains to grind the case and insert the glass.

You can simplify the task by using these nuts as a body.

Result.

Hello! Many people know firsthand about this measuring instrument like a pressure gauge. But many find it difficult to imagine the device and the principle of its operation.

The pressure gauge is designed to measure the pressure of a liquid or gas. Moreover, the pressure gauge for measuring the pressure of gas and liquid does not differ structurally from each other. So if you have a manometer somewhere lying around to measure the pressure of a liquid, then you can safely use it to measure the pressure of a gas and vice versa.

To better understand how the pressure gauge works and works, look at the figure below.

The pressure gauge consists of a body with a measuring scale, a copper flat tube 1 rolled in the shape of a circle, a fitting 2, a transfer mechanism 3 from the tube to an arrow 4. Using the fitting, the pressure gauge is wrapped in a vessel where the pressure of the medium (gas or liquid) is to be measured.

How does a pressure gauge work

When gas and liquid are supplied under pressure through the nozzle 2, the rolled tube 1 will tend to straighten, while the movement of the tube will be transmitted through the transmission mechanism to the arrow 4. It, in turn, will indicate the pressure value that can be read using a scale. When the pressure decreases, the tube will coagulate again and the arrow will indicate a decrease in pressure.

Electrical contact pressure gauge device

How the electrocontact pressure gauge works, I think you guessed it yourself. It does not differ in design from an ordinary pressure gauge, except that it has built-in contacts. There are usually two of them and their position on the manometer scale can be changed.

And if you do not have an electrical contact pressure gauge, but you really need it? What to do then? Then you need to make a homemade electrical contact pressure gauge.

I will tell you how to make a homemade electrical contact pressure gauge. To do this, you will need a simple pressure gauge, two small strips of tin from a tin can, double-sided tape, and two thin wires.

Use a sharp awl to tuck in and remove the large retaining ring. Then remove the glass and then the rubber washer. Drill two holes in the pressure gauge body to route two wires through them.

Cut two strips out of the tin and bend them in the shape of the letter G. Solder a thin insulated wire to the base. From double-sided tape, cut two strips equal in size to the strips and stick it on the strips. Next, glue the obtained contacts to the pressure gauge scale within the specified pressure limits.


Pass the wires through the holes and take them out.

Reinstall the rubber gasket and then the glass. Secure everything with the retaining ring. That's it, the homemade electrical contact pressure gauge is ready. For example, I used this in a homemade automatic system water supply of a private house.

Electrical contact pressure gauge connection diagram

In order for this pressure gauge to act on any actuator, a special circuit is needed. You can see an example of this circuit in the figure below.

At minimum pressure medium (gas or liquid) in the electrocontact pressure gauge contacts 1 and 2 will be closed. This will activate the electromagnetic relay K1. It, in turn, with its contacts K1.1 will supply power to the winding of the K3 magnetic starter. With contacts K3.1, it will bypass contacts K1.1, while opening the contacts in the pressure gauge 1 and 2, relay K1 will release its contacts K1.1. But at the same time, the winding K3 of the starter will continue to flow around with current. With its contacts K3.2, the magnetic starter will supply power to the M motor of the pump or compressor.

With a further increase in pressure in the manometer, contacts 1 and 3 close. At the same time, the electromagnetic relay K2 will work and its contacts will open the power circuit of the coil K3 of the magnetic starter. In this case, contacts K3.2 will open and the power supply to the motor M will disappear. With a further decrease in pressure and the closure of the contacts of the manometer 1 and 2, the cycle will repeat.

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