Flat membrane pressure transmitter

Flat membrane pressure transmitterThe structure and various appearance methods can meet the needs of customers in various industries, especially suitable for industries such as food and pharmaceuticals, beverage processing, biological products, chemical adhesives, engineering machinery, and tunnel excavation.

1、 Product Features

No pressure inlet hole, no cavity planar structure

Designed with heat exchange fins, high temperature resistance, suitable for medium temperatures up to 300 ℃

Provide rich pressure range for low, medium, and high pressure

Sanitary and anti scaling type

Flat film design suitable for various viscous media

Multiple signal output forms, voltage, current, frequency signals, etc

2、 Performance parameters

Measurement medium: gas, liquid, oil and other media compatible with the material of the contact part.

Measurement range: -0.1... 0~0.01... 100MPa

Overload capacity: 1.5 times the range or 110MPa

Pressure type: gauge pressure, absolute pressure, or sealed reference pressure

Accuracy: Typical ± 0.1% F5, DA ± 0.5% F5 (including nonlinearity, hysteresis, and repeatability)

Long term stability: typical ± 0.1% FS/year, ± 0.2% FS/year

Working temperature: -30~80 ℃

Power supply: 15~30VDC

Output signal: 4~20mA (two wires) 0~10/20mA (three wires) 0/1~5/10V (three wires)

Media compatibility: Shell: 1Gr18Ni9Ti stainless steel, diaphragm: 316L stainless steel

Protection level: IP65

3、 Scope of application

QiFlat membrane pressure transmitterWidely used in fields such as food, medicine, hygiene, and brewing industry.

4、 Outline structure diagram (unit: mm)

5、 Understand the two-line system, three line system, and four line system at nine o'clock

Wire system "refers to the number of wires used for instrument power supply and standard signal transmission. The term 'several wire system' only emerged after the birth of two-wire transmitters. This is the result of the widespread application of electronic amplifiers in instruments. The essence of amplification is an energy conversion process, which cannot be separated from power supply. Therefore, four wire transmitters have long been used, where two wires are responsible for supplying power and the other two wires are responsible for outputting converted and amplified signals (such as voltage, current, etc.).

The instrument powered by 220VAC must be a four wire system.
A four wire signal instrument refers to a 4-20mA standard signal used for isolation, where the power supply circuit and signal circuit are independent and separated by an isolation circuit. So the signal must be isolated and usually not grounded. The power supply can be 24VDC or 220VAC.

When the power provided by the two-wire system is insufficient to power the instrument, a three wire system is used, with a signal of 4-20mA standard signal.

The three wires of the three wire system are: one is the power line (usually 24VDC+), one is the signal line, and one is the common line between the power and signal, used for voltage reference points and current circuits.

Non 4-20mA standard signals are not referred to as two-wire systems.

The two-wire system is a system where two wires supply power while transmitting 4-20mA standard signals. Non standard signals are not called two-wire systems. The two-wire system has a low power supply capacity of 4mA × 24V - receiving instrument power consumption - line loss.

So in actual on-site operations, what are the main power supply methods for four wire, three wire, and two wire systems?

The four wire power supply is mostly 220V AC, and there are also those that supply 24V DC.

Four wire transmitters are mostly powered by 220V AC, but there are also those powered by 24V DC. The output signal has 4-20mA. DC with a load resistance of 250 Ω, or 0-10mA. DC with a load resistance of 0-1.5K Ω; some also have mA and millivolt signals, but the value of the load resistance or input resistance varies depending on the output circuit form.

The three wire power supply is mostly 24V DC.

Three wire transmitter, the so-called three wire system means that one wire is used for the positive end of the power supply, one wire is used for the positive end of the signal output, and the negative end of the power supply and the negative end of the signal share the same wire. Most of its power supply is 24V DC, with output signals ranging from 4-20mA DC, load resistance of 250 Ω or 0-10mA DC, and load resistance of 0-1.5K Ω. Some also have mA and millivolt signals, but the value of load resistance or input resistance varies depending on the output circuit form.

The two-wire power supply is 24V DC.
A two-wire transmitter with a power supply of 24V DC, an output signal of 4-20mA DC, a load resistance of 250 Ω, and a negative line potential of 24V power supply It is the signal common line,

Due to the different working principles and structures of various transmitters, different products have emerged, which determines the wiring forms of transmitters in two-wire, three wire, and four wire systems. How to choose four wire, three wire, or two wire instruments?

When the power is greater than 10W and the accuracy requirement is high, a four wire instrument is generally selected.
The application of four wire instruments, with a power supply of 220V. AC and subsequent output signals of 0~10mA. DC, has been widely used in four wire transmitters. Due to the complexity of conversion circuits and high power consumption, many instruments still prefer the four wire system, such as the Huai'an Kehao liquid turbine flowmeter, which still uses the four wire system.

When the power is greater than 10W and the accuracy requirement is high, a four wire instrument is generally selected.
The application of four wire instruments, with a power supply of 220V. AC and subsequent output signals of 0~10mA. DC, has been widely used in four wire transmitters. Due to the complexity of conversion circuits and high power consumption, many instruments still prefer to use the four wire system.

Low power and cost-effective, usually using a two-wire system.
The application of two-wire instruments adopts 4-20mA. DC signals, and on-site instruments can achieve two-wire system. Nowadays, the application of two-wire transmitters is very widespread in China.