What Is a Differential Manometer?

A differential pressure gauge is a pressure measuring instrument that measures the difference in pressure at two different points. In addition to measuring pressure difference, it is mostly used in conjunction with throttling devices (such as orifice plates, venturi tubes, etc.) to measure the flow of fluids. It can also be used to measure liquid levels (such as differential pressure level gauges) and pipelines and tower equipment Resistance (that is, the pressure drop at two points) and so on. There are many types of differential pressure gauges. In addition to simple liquid pressure gauges (U-shaped pipe differential pressure gauges, etc.), there are commonly used float differential pressure gauges, double bell-type differential pressure gauges, and ring-scale differential pressure gauges. At present commonly used double bellows differential pressure gauges, diaphragm type differential pressure gauges and differential pressure transmitters of unit combination meters.

Differential pressure gauge

The fluid filled in the pipeline, when it flows through the throttle in the pipeline, the flow velocity will form a local contraction at the throttle, so the flow velocity increases,

Where qm--mass flow, kg / s;

qv--volume flow, m / s;

C--outflow coefficient;

--expandability coefficient;

--diameter ratio, = d / D;

d-the aperture of the throttle under working conditions, m;

D--Inner diameter of upstream pipeline under working conditions, m;

P--differential pressure, Pa;

l--upstream fluid density, kg / m.

It can be seen from the above formula that the flow is a function of 6 parameters of C, , d, , P, and (D). These 6 parameters can be divided into real measurements [d, , P, (D)] And statistics (C, ).

1) The throttling type works according to the principle that fluid passes through the throttling part to convert part of the pressure energy into kinetic energy to generate differential pressure.

It is a throttling device and is the main type of DPF.

2) The dynamic pressure head type works according to the principle of dynamic pressure turning into static pressure, such as an average velocity tube flow meter.

3) The hydraulic resistance type works according to the pressure difference principle caused by the fluid resistance. The detection part is a capillary bundle, also known as a laminar flow meter.

Generally used for small flow measurement.

4) The centrifugal type works according to the pressure difference caused by the principle of centrifugal force generated by curved or circular tubes, such as elbow flow meters and circular tube flow.

Etc.

5) The dynamic pressure gain type works according to the principle of dynamic pressure amplification, such as the Pito-Venturi tube.

6) Jet type works according to the principle of fluid jet impact generation, such as jet differential pressure flowmeter.

1. Differential pressure gauge operators should be familiar with the working principle, performance characteristics, testing points and testing items of various instruments.

2. The operator of the differential pressure gauge prints production reports and monitoring reports regularly every day to reflect the production operation situation in the plant in time.

3. Regularly conduct on-site inspections of differential pressure gauges at various test points and make records. If abnormal conditions are found, they should be handled and reported in a timely manner.

4. In the rainy weather, inspect the differential pressure timing on site and the operator should pay attention to prevent electric shock.

5. The primary sensors of various types of differential pressure gauges should be cleaned and descaled as required.

6. The printing machinery parts of the microcomputer system should be regularly lubricated.

7. When the differential pressure gauge fails, the transmitter and converter must not be dismantled or dismounted at will.

8. When repairing the differential pressure gauge, protective measures should be taken. For various instruments that have not been used for a long time or have been soaked in water due to improper use, they should be dried before being used.

9. Non-factory computer software is not allowed to run on computers on the network. When running, it is strictly forbidden to quit the computer software or insert a floppy disk.

10. Regularly inspect various components of differential pressure gauges, probes, converters, calculators, conductive TVs, and secondary meters. Keep all parts intact, clean and rust-free, the dial scale is clear, the nameplate, markings and seals are intact; the central control room is clean; the microcomputer system works normally: the instrument well is clean and there is no water accumulation.

Ready to work

1. Add working fluid so that the level of the working fluid reaches about 0 on the scale on the inclined measuring tube, and then close the cap.

2. Blow the bubbles with your mouth and blow gently to raise the liquid level and observe whether there are bubbles.

3. Leveling Turn the zeroing screw to level the instrument.

4. Check the rubber tube for leaks and check whether the liquid level drops. If it does not drop, it means there is no air leakage.

1. The instrument is divided into two types: chrome steel mixed structure and all stainless steel structure; all stainless steel structure has strong corrosion resistance;
2. The control table is symmetrically designed with high static pressure resistance and strong overload resistance;
3. The use of special high-performance elastic components, small transmission error, high indication control accuracy;
4, has extremely high reliability and stability of work;
5.The pressure control range is continuously adjustable from zero to full scale;
6. It can take one upper and lower limit alarm switch output.

Ambient temperature: -5 60
Rated pressure: -0.7 1Kg / cm2
Overpressure: The drain port is automatically opened at about 1.75Kg / cm2. Connection: 1/8 "NPT internal thread, two pairs of high and low pressure interfaces, on the side and back respectively. Shell: ABS shell, main body and parts sprayed with salt mist for 168 hours. Test, accuracy of external dark gray coating: accuracy ± 2 [%] FS (3 [%]-suffix 0, 4 [%]-suffix 00, corresponding to mm and pa range units)
Standard accessories: two 1/8 "NPT threaded joints, used as high and low pressure joints, and can be connected to rubber pipes; two 1/8" NPT plugs, used to block excess ports; three threaded countersunk heads Mounting connector (mounting ring, snap ring retainer for three interfaces to replace accessories on MP and HP meters)
Weight: 0.5Kg

Widely used in air-conditioning system and clean room, filter resistance, exhaust pipe airflow detection, air speed, boiler furnace negative pressure, fan and blower pressure measurement, pressure drop on both sides of orifice plate, bubble system supporting for liquid level measurement, hydraulic pressure System pressure, gas, air flow measurement, automatic valves and blood flow monitoring and breathing detection in medical care equipment.