Laminar differential pressure multivariable flow meters can display pressure, temperature, and flow rate.

2025-08-06

Word Size

When fluid (gas or liquid) flows in layers, the flow is described as laminar; when the fluid rotates and mixes across the pipe diameter, the flow is described as turbulent; flow between the two is described as transitional flow.

 

​image.png

 

 

Laminar and turbulent flows are two major flow states of fluid motion. The mechanism of turbulent flow is still not fully understood, but differential pressure flow meters based on turbulent flow have been widely used. In contrast, laminar flow has been thoroughly studied, with well-established mathematical models and descriptive equations. In a laminar flow state, the flow velocity and differential pressure are proportional. Because the differential pressure is linearly related to the flow rate, our laminar differential pressure flow meter has high measurement accuracy over a very wide measurement range.
 

image.png

Laminar differential pressure flow meters measure the mass flow rate of a fluid using the pressure drop generated inside a laminar element. The laminar element converts turbulent flow into laminar flow by separating it into a series of thin, parallel channels. Because the flow is laminar, not turbulent, the pressure drop can be related to the volumetric flow rate using the Poiseuille equation. At a given temperature and pressure, the volumetric flow rate can be converted to mass flow rate using density correction. For high-temperature, low-temperature, and high-pressure operating conditions, real-time measurement of multiple variables such as temperature/pressure/differential pressure can compensate for the physical properties of the medium and achieve accurate flow measurement.

 

 

Our laminar differential pressure flow meter uses differential pressure, absolute pressure, and temperature sensors to measure and compensate for the flow rate, pressure, and temperature of gases, measuring the volumetric flow rate of gases under standard conditions (e.g., 1 ATM @ 25℃).

It can measure 4 parameters: mass flow rate, volumetric flow rate, temperature, and absolute pressure. Cumulative flow rate is optional and can be displayed simultaneously on the dynamic display screen.


Related Products

ACU20FD Normally Open Valve Series


The ACU20FD digital mass flow meter comprises a mass flow sensor, a laminar‑flow element, a flow‑control regulating valve, and an amplification‑and‑control circuit. It employs digital signal input and output and features short warm‑up time, minimal zero drift, and high reliability.

ACU20PH Series


The ACU20PH series comes standard with a piezoelectric diaphragm‑type pressure sensor and a digital circuit board, delivering high‑accuracy, stable, and reliable pressure measurement and control. This basic digital PC board incorporates all the essential functions required for measurement and control. In addition to the standard RS485 output signal, the ACU20PH also offers analog I/O signals.

ACU10FA Series


The ACU10FA analog mass flow controller features fast response and high accuracy. It offers a wide control range, from 5 SCCM to 30 SLM, and can measure and regulate flow rates as low as 1 SCCM, making it suitable for controlling very small flow rates.

ACU10FD Series


The ACU10FD digital mass flow controller comprises a mass flow sensor, a laminar flow element, a flow‑control regulating valve, and an amplification control circuit. It features digital signal input and output, short warm‑up time, low zero drift, and high reliability.

ACU10FDR


The ACU10FDR low-pressure-drop gas mass flow controller is equipped with a proprietary high-flow electromagnetic valve, making it ideal for controlling mass flow even when system pressure is nearly unavailable. Its minimal pressure differential ensures the least possible impact on the system, enabling precise flow control under near-atmospheric conditions while significantly reducing system response time. We can customize the valve and PID control features based on your specific application parameters, guaranteeing fast, stable performance with minimized pressure loss.