■ EDN.750, All st. steel housing Differential Pressure Transmitter

- All stainless steel housing & wetted parts

- Accuracy ±0.5%, ±0.25% & ±0.1% F.S

- LCD on white back light [option]

- 2 Switches, SW1 & SW2 [option] 

● Product Overview

The EDN.750 series pressure transmitter features a housing and wetted parts entirely constructed of stainless steel. It is suitable for most common corrosive environments and can be applied in food and beverage industries or pharmaceutical manufacturing environments requiring high hygiene and cleanliness standards.

The wetted parts utilize a piezoresistive silicon pressure sensor with a stainless steel diaphragm, offering exceptional precision and long-term stability. Incorporating the latest electronic components manufactured with cutting-edge technology ensures top-tier performance. The product is crafted to the highest standards by integrating the latest PCB chip design techniques.  

The electronic amplification circuitry, which receives and amplifies signals from the pressure sensor, incorporates top-tier noise, burst, insulation, and surge protection technologies under stringent standards. Through Daho's comprehensive quality control process, including full inspection, it delivers flawless analog and communication signals. The EDN.750 series is fundamentally designed to send RS485 digital communication and 2-channel relay signals, offering selective usage.

● Pressure Measurement Principle

The pressure sensor is a piezoresistive silicon pressure sensor. The minimum differential pressure sensing range is 10 mbar, and the maximum static pressure (line pressure) is 200 bar.

The EDN.750 differential pressure transmitter features a flush diaphragm contact surface fully constructed from stainless steel (316L) where it contacts the fluid, with all sections joined by laser welding. It incorporates two separate pressure-sensitive resistive sensors, each detecting pressure independently. The configuration of these two pressure sensing sections involves installing the silicon pressure sensors within separate stainless steel housings, each housing being a perfectly isolated space completely filled with silicone oil, ensuring no trace of air or gas remains. The pressure sensor, made of silicon material, is installed inside a stainless steel housing. It is completely isolated in a space filled with silicone oil, free from any air or gas. This sensor is solely influenced by the pressure received at the flush diaphragm section, which is the only part capable of receiving pressure.  

Pressure transmitted through the thin flush diaphragm to the sturdy stainless steel housing is conveyed to the silicon wafer die installed inside. The silicon oil and sensor die are connected to an amplifier, forming a circuit via electrical wiring and utilizing a semiconductor chip. The pressure signal is converted into an electrical signal using the pressure-resistance effect that modifies the differential. Subsequently, it establishes a good linear relationship with the very minute signal output from the Wheatstone bridge on the silicon wafer die. Through this process, the differential pressure transmitted and calculated from each pressure sensor is processed using Daeho's substantial accumulated technical know-how to eliminate burst, Surge noise is removed. The PCB control unit then calculates the differential pressure from the minute voltage electrical signals received by the pressure sensor diaphragms (flush diaphragm) of each of the two differential units. This value is amplified as an electrical analog signal and transmitted. The signal is sent after being amplified and converted into analog and digital formats, along with various protection functions.

● Materials of Wetted Parts

All wetted parts are stainless steel, 316L metal, preventing chemical corrosion except with special fluids. The pressure connection method can be supplied with a male adapter added to the female pressure connection to meet specific industrial environment requirements.

● Accuracy class

The EDN.750 series offers the following standard accuracy grades:

▶ ±0.5% F.S, ≥10 mbar & +20…+80 ℃

▶ ±0.25% F.S, ≥400 mbar & +0…+60 ℃

▶ ±0.1% F.S, ≥1000 mbar & +20…+60 ℃

DAHO supplies these three accuracy classes. Since differential pressure measurement often involves relatively low or near-zero pressures, it is influenced by the pressure range and the temperature of the measured medium.

● Communication & switches

The PCB electronics section, which receives and amplifies signals from the pressure sensor, was developed incorporating the highest standards of strict noise, burst, surge, and insulation protection technology. It is designed to send RS485 digital communication and 2 switch (SW1 & SW2) signals as additional optional specifications, allowing users to select them according to their purpose.

▶ RS485 communication

▶ 2 switches, SW1 & SW2 [2 Switch Signals]

● Applicable Industrial Environments

During development, it underwent over ten diverse and rigorous comparative performance tests against similar domestic and international products, meeting industrial environment requirements. Furthermore, industrial-standard EMC and EMI performance test results confirmed top-tier quality, demonstrating the instrument's ability to withstand harsh industrial environments where external factors could affect exposed measuring equipment. Specifically, it incorporates multiple safety and protection features enabling secure measurement management under aggressive, harsh environmental conditions such as high temperatures, various noises, and bursts that may occur in industrial sites. It was developed as an industrial pressure transmitter applicable in all possible industrial environments. Its application fields are as follows.

▶ Semiconductor and Electronics Industry

▶ Oil Refining and Chemical Industry

▶ Pharmaceutical and Medical Industry

▶ Food and Beverage Industry

▶ Power Energy and Nuclear Industry

▶ Wastewater and Water Treatment Industry

▶ Pneumatic and Hydraulic Industry

▶ Automotive Industry

▶ Heavy Industry, Shipbuilding Industry

● Explosion-Proof Rating

Currently certified by the Korea Occupational Safety and Health Agency (KOSHA) with the “General Explosion-Proof Rating Ex d IIC T6.” It has been developed to deliver stable and flawless analog and communication signals through Daho's comprehensive quality management system and a rigorous 100% inspection process of all shipped products.

● General Technical Specifications

Pressure range: 0…25 mbar to 0…35 bar

Accuracy: ± 0.5%, 0.25% & 0.15% F.S

Electrical connection: Frameproof cable gland , M12 plug

Signal output: 4...20 mA, 2 wire-system, 0…10V, 3 wire-system, 0…5V, 3 wire-system, 1…5 V, 3 wire-system, 0.5…4.5V, 3-wire system

Operating temperature: -20…+80 ℃ / standard, -40…+125℃ / option