How to measure the pressure at the outlet of the reducer:
Those who have tried to purchase a pressure gauge for measuring low pressure know that it is not so easy to do this, and the price for them is not small, 2000-3000 rubles.
How to measure the gas pressure at the outlet of the reducer?
In this article we will tell you about several, fairly budgetary, ways.
Method number 1:
Pressure measurement with a U-shaped manometer
U A -shaped manometer is a liquid manometer consisting of communicating vessels in which the measured pressure is determined from one or more liquid levels.
IN U-shaped glass pressure gauges, the free end of the tube communicates with the atmosphere, and the measured pressure is applied to the other end. The simplest circuit pressure measurement with a liquid glass manometer is shown in the figure:
Atmosphere pressure P atm acts on one end U-shaped tube partially filled with working fluid. The other end of the tube is connected to the area of the measured pressure using various types of supply devices. P abs. At R abs > R atm, the liquid in the part of the measured pressure supplied will be displaced into the part connected to the atmosphere. As a result, between the levels of liquids in different parts U-shaped tube, a liquid column is formed, height h- measured overpressure.
The figure shows U-shaped liquid glass manovacuummeter. U-shaped glass tube 1 is fixed with brackets 2 on a metal or wooden base 3. On it, between the two tubes, there is a scale plate 4 with applied linear markings. The tube is filled with working fluid to the zero mark relative to the scale plate. The bulges at the ends of the glass tube are designed for tighter connection of rubber hoses.
When measuring overpressure to one end U-shaped tube is supplied with the measured pressure medium. The second exit remains free and communicates with the atmosphere. A similar situation occurs when measuring vacuum pressure. The symmetry of the linear markings on the scale plate ensures the applicability of the device for measuring excess and (or) vacuum pressure.
U-shaped liquid manometers with water as a working liquid can be used as pressure gauges, thrust gauges and draft gauges for measuring the pressure of air, non-aggressive gases in the range of ±10 kPa (100 mbar).
You can buy a ready-made manometer with a glass tube. Also, this manometer can be made on their own using transparent PVC tube and ruler.
Naturally, the readings of this pressure gauge will be in mm. water column. To convert them to another value, use the converter at the end of this page.
Method number 2:
Measuring pressure with a household blood pressure monitor
Blood pressure can be measured with a household blood pressure monitor.
1. Take a blood pressure monitor (not a full machine, but one in which the cuff is inflated with a rubber bulb).
2. Disconnect the pear and pick up a piece of hose that will act as an adapter between the reducer and the tonometer hose.
3. Connect the outlet of the reducer to the hose of the tonometer (the valve on the cylinder must be closed)
4. Clamp the hose leading to the cuff (you can use a clamp, a small vise, or, folding the hose several times, pull it with a thread).
5. Press the "Start" button on the tonometer. The tonometer will calibrate and in a few seconds it will be ready for measurement, the display will show “0”
6. Open the valve on the cylinder, the tonometer will show outlet pressure gearbox in mm. mercury column. Pay attention to the cuff, it should not inflate.
7. CLOSE VALVE ON CYLINDER.
To convert the resulting value to millibars, use the converter located at the end of the page.
If you have an adjustable reducer and you need to set a certain pressure, follow these steps:
- in the converter of values, enter the required value in millibars
- determine the corresponding value in mm. mercury column
- press the start button on the tonometer, the tonometer will calibrate and in a few seconds it will be ready for measurement, the display will show “0”
- open the valve on the cylinder, the tonometer will show the outlet pressure of the reducer in mm. mercury column
- by adjusting the reducer, set the value you need.
- close the valve on the cylinder
ATTENTION!
Do not use the tonometer for continuous (continuous) measurement of gas pressure.
The materials of which the tonometer is made are not intended for long-term contact with LPG.
Gas Converter:
Soon we will tell about another simple and inexpensive way low pressure measurements
Pressure gauges- devices for measuring the pressure of liquids or gases - there are different designs. A simple measurement of air pressure, for example, in a car or bicycle chamber, can be done by hand. Depending on the power of the spring and the strength of the housing, they can also measure the oil pressure. It is suitable for school experiments in physics lessons. Plus, you can make it with your kids.
You will need
- - Disposable syringe
- - Metal spring, the diameter of which is equal to the diameter of the syringe balloon
- - Needle
- - Alcohol or gas burner
- - Glue "Moment"
- - Pliers
- - Wire cutters
Instruction
Take a disposable syringe and pull the piston out of it to the limit. Cut the piston rod so that a piece about 1 cm long remains. Heat the remaining piece of the piston rod with gas burner and melt one end of the coil spring into it.
Insert the plunger back into the syringe barrel so that a small piece of spring remains outside, and most of would be inside the balloon.
Warm up the needle and pierce the syringe balloon with it from the side opposite the tip, near the edge. Using pliers, attach the end of the spring to the needle. Bite off the rest of the spring. Got a spring pressure gauge.
If you put a rubber tube instead of a needle on the side of the syringe tip and connect it to the container or pipeline in which the pressure is measured, the piston in the cylinder will move relative to the graduation scale on the syringe body, thus indicating the pressure in the line or container under test.
It is recommended to first calibrate the scale to a known pressure source. Link the scale to pressure units according to the reference source. To do this, pick up the handset from transparent material and fill it with water to a certain height. On the other hand, connect the rubber tube to the pressure gauge. Mark the scale according to the height of the water column according to Torricelli's law. In the place where the piston has moved, make a mark of the resulting pressure. After changing the amount of water in the tube, make the following marks.
Hello! Many people know firsthand about such a measuring device as 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 manometer for measuring the pressure of gas and liquid does not structurally differ from each other. So if you have a pressure gauge lying around somewhere to measure liquid pressure, then you can safely use it to measure gas pressure and vice versa.
To better understand how the pressure gauge works, look at the figure below.
The pressure gauge consists of a body with a measuring scale, a copper flat tube 1 rolled up in the shape of a circle, a fitting 2, a transmission mechanism 3 from the tube to the 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 a manometer works
When gas and liquid under pressure are supplied through the fitting 2, the rolled tube 1 will tend to straighten out, 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, which can be read using the scale. When the pressure decreases, the tube will again curl up and the arrow will indicate a decrease in pressure.
Electrocontact pressure gauge device
How the electrocontact pressure gauge works, I think you guessed it yourself. It does not differ in any way from a conventional pressure gauge, only with the exception that it has built-in contacts. There are usually two of them and their position on the pressure gauge scale can be changed.
And if you do not have an electrocontact pressure gauge, but you really need it? What to do then? Then you need to make a homemade electrocontact pressure gauge.
I will tell you how to make a homemade electrocontact pressure gauge. To do this, you will need a simple pressure gauge, two small strips of tin from a can, double-sided tape and two thin wires.
Use a sharp awl to pry and remove the large retaining ring. Then remove the glass and then the rubber washer. Drill two holes in the gauge body to allow two wires to pass through.
Cut two strips from the tin and bend them in the shape of the letter L. 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 resulting contacts to the pressure gauge scale within the specified pressure limits.
Pass the wires through the holes and bring them out.
Replace the rubber gasket and then the glass. Secure everything with a retaining ring. Everything, a home-made electrocontact pressure gauge is ready. For example, I used this one in a homemade automatic system water supply of a private house.
Wiring diagram for electrocontact pressure gauge
In order to act on any actuator with this pressure gauge, a special circuit is needed. You can see an example of this circuit in the figure below.
At the minimum pressure of the medium (gas or liquid) in the electrocontact pressure gauge, contacts 1 and 2 will be closed. In this case, the electromagnetic relay K1 will work. It, in turn, with its contacts K1.1 will supply power to the winding of the magnetic starter K3. With contacts K3.1, it will shunt contacts K1.1, while opening the contacts in the pressure gauge 1 and 2, relay K1 releases 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 motor M of the pump or compressor.
With a further increase in pressure in the pressure gauge, contacts 1 and 3 close. In this case, the electromagnetic relay K2 will operate and open the power supply circuit of the coil K3 of the magnetic starter with its contacts. Contacts K3.2 will then open and the power supply to the motor M will disappear. With a further decrease in pressure and the closure of the pressure gauge contacts 1 and 2, the cycle will repeat.
They withstood the impact of the elements at the Sayano-Shushenskaya HPP. 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 the world with its devices. 70 years of experience, combined with a modernized material base and a team retained at the enterprise, allows us to practically work miracles.
The plant produces 500 thousand devices per year. Together with all the modifications, the nomenclature of production 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 production of manometers today?
The first step is development
It all starts with the fact that the company receives an order. The employees of the design department are the first to enter the business. They determine what 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, they get involved production shops. It is not so rare to develop new modifications of devices - consumers are constantly requesting something new.
Parallel production: from housing to spring
From the designers, the development goes to the main production cycle, where 700 people work, and the equipment fleet is 527 units. The technologies used here, by the way, were developed within the factory walls.
As soon as the development enters the main production cycle, case manufacturers come into play. Each type of pressure gauge and pressure transmitter needs its own housing. If the device will be operated 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 occasions, the body of the device enters the workshops of mechanical or galvanic processing. There is also a cold stamping shop.
In parallel with this, other workshops are assembling the "insides" of the device.
The next step is painting the body. Here, too, there was no lack of know-how. “We have implemented the most advanced powder coating technology to date,” says Deputy CEO production Andrey Metalnikov. - The bottom line is that conventional spray painting with spray paint is too expensive. Too much of it simply dissolves in the air without getting on the product. When powder coating, 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 divisions 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 depends on the reliability and accuracy of the pressure gauge, its specifications. For "Manotomi" the Ural metallurgists have developed a special alloy, from which the springs are made.
The soldering area is the next step. Depending on the need, either soft or hard soldering of the device is performed, and, if necessary, welding, including argon-arc welding.
A separate direction is the shop of plastic products. Thanks to modern thermoplastic equipment, parts from polypropylene, polystyrene and any other plastics can be produced here.
Naturally, Manotom cannot make the production cycle completely autonomous. For example, the plant 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, only Russian materials are used here, no imported parts are used.
Those of the pressure gauges that need to strengthen the case, being almost ready, are sent to the galvanizing shop. Its presence is a feature of the Tomsk plant, because few enterprises can afford to maintain an electroplating shop. This is a very costly production necessary equipment, and by its very nature. After all, electroplating is a variety of chemicals and acids that need to be disposed of after technological processes. And here they not only maintain such a workshop, but also constantly improve technological process in him.
The most important element of manometer production is the workshop in which the transmission mechanism is created. The transmission mechanism is the central element of the pressure gauge, no less important than the spring. The more accurate and finer 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 latest equipment in mid-2010. This provided several tangible benefits. Firstly, the accuracy of processing parts of the transmission mechanism has increased. It was possible to eliminate roughness, improve the accuracy of the readings of our products. Secondly, thanks to this, we were able to double the warranty period of our pressure gauges from one and a half years to three years at once,” Andrey Metalnikov explained. Other providers Russian market gauges still give a one and a half year warranty.
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 electrocontact devices. Here the devices are assembled and pass the final quality control.
Before handing over the products, each workshop without fail checks them 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 last years"Manotom" develops the direction of service maintenance of its products. So, customers from nearby regions can send a broken product to the factory, where specialists will take care of it. In more remote areas and outside of Russia, the plant enters into contracts for the maintenance of its pressure gauges with contractors.
Another new line of work is the production of so-called "smart" electronic pressure gauges. They not only give out data, but also participate in the management process. 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, but also on all military ships, fly in rockets, serve artillery. Deliveries go to the countries of the CIS, Europe, Asia and Africa,” says Andrey Metalnikov.
By tradition, a short video on how pressure gauges are made:
Correct functioning fuel system car is a guarantee of the safety of the driver and passengers. Determining the volume of air in it allows you to control the smooth operation and timely troubleshoot. Pressure check is carried out by manometers. These devices are quite simple in design and operation, so making them yourself is not difficult.
Purpose and technical parameters
A manometer is a device designed to measure fuel pressure. If this indicator is unstable, then it will not be possible to properly adjust the operation of the engine. Interruptions in the functionality of the motor increase fuel consumption, and also affect the duration of operation of the equipment as a whole. The technical condition in the car is monitored by the built-in ECU (electronic control unit), including checking the pressure in the fuel rail.
It controls the power of the engine, the amount of fuel consumption, and if one of the systems malfunctions, it sends errors to the on-board computer in the form of an encrypted code, which is not very convenient.
The operation of the computer 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.
Specifications of the meter:
- 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 basis of the device is a hollow hose with an oval or ellipsoidal section, elastic structure. The fuel presses 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 displays the result of the deformation on the scoreboard.
Inside the transmission mechanism there is a spring that prevents the backlash. 
A hollow hose has a section plane of different diameters inside and outside, therefore, being under pressure, it tries to level out all the time. The end connected to the display advances the arrow on 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 parallel connection to the system without interrupting its operation. This allows you to take measurements while the engine is running.
Varieties
There are 2 types of pressure gauges for measuring fuel pressure:
- analog;
- electronic.
According to the type of action, the devices differ in the device of the sensitive 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 such factors:
- device device;
- technical specifications.
Both analog and electronic devices are used to control air exchange in the fuel system.
Analog devices are characterized by simple design and low cost. The data is displayed on a scale equipped with a pointer mechanism. The disadvantage is the high error when increasing the pressure.
Electronic devices are more accurate and cost more. 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 fuel rail pressure can be controlled using devices to monitor the amount 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 should be legible, with limit values of 5-6 kgf / cm 2. Before buying, check the connection for tightness, evaluate the quality of the materials. 
How to DIY
The pressure gauge for diagnosing the fuel system can be assembled with your own hands, spending a minimum of money. 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 a variant upgraded with a tap for draining fuel.
Tools and materials
When constructing the meter, the following materials will be required:
- hose for filling air conditioners with a fitting;
- tee with 1/4 thread;
- 2 fittings with a bore diameter of 6 mm;
- tap with 1/4 thread;
- manometer with a user-friendly scale for 6 atmospheres.
The size of the hose for filling the air conditioner must be selected in accordance with the size of the cap, which is fixed on the nozzle rail. The cap is easy to remove, so you can take it with you when you go shopping.
Important! Checking the pressure gauge for error must be carried out before starting work in order to be able to replace it in time.
From the tools you will need:
- fumlenta for sealing joints;
- hose clamp;
- compressor to check the accuracy of the pressure gauge.
Homemade fuel pressure gauge: video
Manufacturing process
Step-by-step instructions for making a pressure gauge for measuring fuel pressure:
- Screw the tee to the manometer.
- Attach a faucet to the tee.
- Attach fittings to the faucet.
- Seal each joint with tape.
- Cut the hose. Attach the cut end to the lower fitting on the faucet, strengthen the structure with a clamp.
A car pressure gauge is needed to measure the movement of air 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.
