Why use 1.6 grades instead of 1.5 in the accuracy grades of general pressure gauges?

To understand the basic knowledge of the priority number of standardized technology. For digital systems, the power consumption of the national standard GB/T321 is 1/n of 10, which are respectively 1/5, 1/10, 1/20, 1/40, 1/80 power of 10, and the code names are R5, R10 , The accuracy level of the R20 pressure gauge is to use the R5 system.

Covariance of R5 numbers: 1/5 squared of 10=1.60. The number is 1.0, 1.6, 2.5, 4.0, 6.3, 10. In the past, 1.5 of the pressure gauge level was not part of the R5 water system, so it should be abolished and replaced with 1.6, which is the closest to 1.5. Therefore, the pressure gauge is set to 1.5, which is no longer allowed.

The ratio of two adjacent numbers is equal to the common ratio of R5 numbers to 1.6. For example, you can move 10/6.3=1.6, 6.3/4=1.6, 4/2.5=1.6, 2.5/1.6=1.6, 1.6/1=1.6, 1.3/1=1.6, and continue to move down. 1/0.63=1.6, 0.63/0.4=1.6, 0.4/0.25=1.6, 0.25/0.16=1.6, 6, 25/0.16=1.6, 6, 6, 6, 25=1.6, 6, 6, 6=1.6, 0.25=1.6, 0.25=1.6, 0.25=1.6, 0.25

Of course, the reverse calculation can also deduce the levels on both sides of a certain accuracy level. For example, Elevation 2.5, Elevation 2.5 (1.6=1.6, Elevation 2.51.6 = Elevation 4). For detailed knowledge of the water system, you can read the national standards.

In addition, the standard GB/T1226-2010GB/T1226-2010 conventional pressure gauge introduces the corresponding requirements for the accuracy level of the pressure gauge.

If you don't see such performance in related books, everything is subject to the latest national standards!

What is the difference between the pressure gauge detail level 1.6 and 1.5?

The accuracy level of the pressure gauge means that the total range of the pressure gauge is 100Mpa, the total pressure gauge range is 1.6, and the tolerance of 100MPa1.6%=1.6MPa. When the detail level is 1.5, the tolerance is 100mpa1.5%=1.5mpa.

Under normal conditions of use, the accuracy of the measurement results of the meter is called the accuracy of the meter. The smaller the reference error, the higher the accuracy of the instrument. The reference error is related to the range of the instrument. Therefore, when using the same precision instrument, in order to reduce the measurement error, the range is often compressed. In industrial measurement, the accuracy level is usually used to indicate the accuracy of the meter so as to indicate the quality of the meter. The accuracy level is the maximum reference error to eliminate positive and negative signs and percentage signs. The accuracy level is one of the important indicators to measure the quality of the instrument. In industrial measurement, in order to conveniently indicate the quality of the meter, the accuracy level is generally used to indicate the accuracy of the meter. The accuracy level is the maximum reference error to eliminate positive and negative signs and percentage signs. The accuracy level is one of the important indicators to measure the quality of the instrument.

Instrument accuracy = (maximum absolute error / instrument range) x 100%

Take the absolute value from the above equation and subtract %. This is the level of accuracy we see.

So, how to define a 1.5-level pressure gauge at present?

According to the current national standards for pressure gauges, the accuracy level is 1.6, the tolerance of the 1.5-level pressure gauge used is 1.6, and the accuracy level remains unchanged.

General pressure gauge accuracy grade:

The precision of the precision pressure gauge is 0.1, 0.25, 0.4.

The accuracy of general pressure gauge is 1.0, 1.6 (original 1.5), 2.5, 4.0 (default is none);

Pressure gauges above 60 are basically 1.0 and 1.6 grades.

The pressure gauge below 60 is basically 2.5 grade.

The bellows and diaphragm pressure gauges are usually 2.5 grades.

The difference between pressure gauge accuracy and index

The minimum division of the pressure gauge can use that resolution for general purpose, but it is not necessarily the accuracy of the gauge.

The pressure gauge is a test gauge, so what we see is the measured value, and there are some errors between the measured value and the actual value. The range of this error is actually the accuracy, so the smaller the value of the accuracy, the closer the instrument is to the actual value, the higher the reliability.

Pressure gauge accuracy level check

Pressure gauge accuracy grade is the abbreviation of pressure gauge accuracy grade or accuracy grade (referred to as metric accuracy grade in the national standard GB/T1226-2001 "General Pressure Gauge", in JJG52-1999 "Spring Tube Type General Pressure Gauge, Pressure Vacuum Gauge and Vacuum Gauge are referred to as the metric accuracy level).

Under the baseline operating conditions, the detailed level inspection of the pressure gauge must include the following four items:

1. Display error

Within the measurement range, the display error should not be greater than the tolerance specified in Table 2.

2. Return an error

Within the measurement range, the return error should not be greater than the absolute value of the tolerance specified in Table 2.

3. Knocking displacement

After tapping the dial lightly, the amount of change in the pointer display value should not be more than half of the absolute value of the tolerance specified in Table 2.

4. Stability of pointer deflection

Within the measurement range, the pointer deflection should be smooth, without jumping or paper jams.

The meaning of pressure gauge accuracy grade

The accuracy level of the pressure gauge is expressed as a percentage of the pressure gauge range, and is usually divided into 0.5, 1, 1.6, 2, 2.5, 3, 47 levels (the boiler does not use levels 3 and 4). The smaller the value, the more accurate high. For example, for a pressure gauge with a dial range of 0 to 2.5mpa and an accuracy of 2.5, the tolerance between the pressure value displayed on the pointer and the actual pressure value in the measured medium should not exceed 2.5mpa2.5%=0.0625mpa. If the pressure gauge shows that the pressure is 0.8MPa, the actual pressure is between 0.7375 and 0.8625MPa. It can be seen that the actual error size of the pressure gauge is not only related to the accuracy, but also related to the range of the pressure gauge. When the range is the same, the higher the accuracy (that is, the smaller the value), the smaller the tolerance of the pressure gauge. When the accuracy is the same, the greater the range, the greater the error of the pressure gauge.

Pressure gauge selection

The precision digital pressure gauge is a universal measuring instrument, which is widely used in various production fields. The selection of the pressure gauge is based on the use requirements to meet the process and technical requirements. It should be considered comprehensively based on the practical principle of saving, and the accuracy level, range, type and model should be selected reasonably.

1. Determination of the accuracy level of the pressure gauge

The accuracy grades of precision pressure gauges are 0.1, 0.16, 0.25 and 0.4 respectively. The accuracy grades of general pressure gauges are 1.0, 1.6, 2.5 and 4.0 grades respectively. The selection method of the accuracy level of the pressure gauge: the accuracy level must be determined according to the requirements of the production process, economic and practical, and test methods, and the tolerance required for the minimum pressure of the measurement.

2. Select the pressure gauge range

(1) When measuring stable pressure, the maximum working pressure shall not exceed two-thirds of the range.

(2) When measuring pulsating pressure, the maximum working pressure cannot exceed half of the range

(3) During high pressure measurement, the maximum working pressure shall not exceed 3/5 of the range

(4) To ensure measurement accuracy, the minimum working pressure must be less than one-third of the range.

After the maximum pressure value is calculated according to the above principles, the selected range is a value slightly larger than the value in the range of the pressure gauge.

3. Select the type of pressure gauge

To measure different media and use environments, different types of pressure gauges must be used.

(1) General media, such as air, water, steam, oil, etc., can be used as general pressure gauges.

(2) Special media such as ammonia pressure gauges require special pressure gauges. Oxygen pressure gauge; Hydrogen pressure gauge; Acetylene pressure gauge, etc.

(3) For general corrosive media and corrosive gas environments, stainless steel pressure gauges can be used.

(4) In terms of measuring viscosity, use a diaphragm pressure gauge to measure the medium pressure of liquid, gas or solid plankton that is easy to crystallize, corrode, and high in temperature.

(5) Pressure measurement of pulsed media and mechanical vibration. Choose a seismic pressure gauge.

(6) If there is a remote transmission requirement, you can choose a digital remote pressure gauge with current type, resistance type and voltage type.

(7) If there are requirements for control and protection, electrical contact pressure gauges can be selected.

(8) When explosion-proof requirements are required, explosion-proof electrical contact pressure gauges and other explosion-proof types should be used.

(9) When the pointer meter needs to be verified, the precision digital pressure gauge of grade 0.05 or grade 0.02 should be selected.

The accuracy level of the pressure gauge is divided into the percentage of the tolerance to the micrometer value. The higher the accuracy level, the tolerance is greater than the limit of the micrometer. The greater the range of the pressure gauge, the greater the absolute value tolerance of the pressure gauge with the same level of detail.

Used in industry: Commonly used high-precision pressure gauges with accuracy of 2.5, 1.6, 1.0 and 0.5 grades. At present, some digital pressures are expressed to 0.25 grade. The accuracy level of the pressure gauge is divided into the percentage of the tolerance to the micrometer value. The higher the accuracy level, the tolerance is greater than the limit of the micrometer. The greater the range of the pressure gauge, the greater the absolute value tolerance of the pressure gauge with the same level of detail.