When selecting digital transmitters for high-viscosity applications such as resin, slurry, adhesive, and heavy oil, both flat diaphragm and diaphragm digital transmitters avoid the traditional issue of pressure tap blockage. However, due to structural differences, their adaptability to medium viscosity, impurity content, and corrosion level varies. Combining the Longlv PTL535 diaphragm digital pressure transmitter we will sort out the selection logic for these two types of products.

1. Application Scenarios, Advantages, and Disadvantages of Flat-Diaphragm Digital Transmitters: Flat-diaphragm products adopt a flush diaphragm structure, with a flat pressure-measuring end face without grooves or pressure-guiding cavities. The medium directly adheres to the diaphragm to complete pressure transmission.

Suitable working conditions

Medium to low viscosity, with relatively few impurities: ordinary lubricating oil, syrup, conventional coatings, low viscosity slurry. The medium has decent fluidity and is not prone to adhering to the diaphragm in large areas.

No corrosion, normal temperature conditions: food slurry, conventional hydraulic heavy oil, the medium will not erode the stainless steel diaphragm.

Advantages and shortcomings: Advantages: compact structure, moderate cost, intuitive on-site digital display, fast response speed, simple daily cleaning, and mild material hanging and flushing can make it fall off. It is suitable for on-site pressure measurement of small and medium-sized equipment.

Shortcomings: Due to the small spacing between the diaphragm and the sensing core, it is not suitable for ultra-high viscosity, hard particles, or strong corrosive media; long-term adhesion of thick materials can lead to measurement drift, and exposure to acidic or alkaline corrosive media can directly damage the diaphragm, making it unable to operate stably for long periods.

II. Core Advantages of Diaphragm-type Digital Transmitter (Based on Longlv PTL535) The diaphragm structure relies on an isolation diaphragm and an internally sealed pressure transmission fluid to achieve pressure transmission. The viscous medium being measured only contacts the outer isolation diaphragm and cannot penetrate into the internal sensing components of the transmitter. The Longlv PTL535 diaphragm-type digital transmitter relies on this isolation structure to adapt to complex viscous working conditions.

Adapt to three severe viscous working conditions

Ultra-high viscosity and wall-clinging media: glue, asphalt, high viscosity resin, and thick paste-like materials, which have high viscosity and extremely poor fluidity, are prone to adhere to the end face of the instrument. The large area of the diaphragm outside the membrane is not prone to material accumulation and agglomeration.

Slurry containing solid particles: mud, ore pulp, coating with fillers, medium doped with small hard particles, diaphragm protective structure isolates particle impact, protects the internal precision sensing core, and prevents particle wear on components.

Corrosive viscous media: chemical viscous acid-base materials, salt-containing viscous liquids. Special material isolation membranes can be replaced as needed to prevent the intrusion of corrosive media, which is unachievable with ordinary flat membrane transmitters.

The practical value brought by the integrated digital display: The PTL535 comes with an integrated digital display screen, eliminating the need to rely on central control instruments. During inspection, pressure can be directly read on-site in the pipeline. In case of abnormal values, the on-site comparison between the screen and backend data allows for quick differentiation between medium blockage, pipeline failure, or instrument issues, significantly reducing the troubleshooting time for viscous medium equipment. The device comes with simple buttons for zero point calibration on-site, eliminating the need for disassembly and debugging after viscous medium material change or pipeline cleaning.

III. Pithy formula for rapid selection of viscous medium

Low viscosity, no particles, no corrosion → choose a flat diaphragm digital transmitter, which is cost-effective and compact in installation; High viscosity, multiple particles, with corrosion → prefer a diaphragm digital transmitter, and Longlu PTL535 is suitable for such complex working conditions.

IV. Supplementary reminder on landing model selection

Under the same viscous environment, flat diaphragms are more suitable for enclosed small pipelines, while diaphragms are suitable for large-opening pressure tapping points such as tank discharges, stirrer discharges, and large conveyor pipelines. For viscous conditions where flat diaphragms frequently cause meter blockages and require frequent disassembly and cleaning, replacing them with diaphragm-type digital transmitters directly results in lower long-term operation and maintenance costs.