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Alicat Scientific Flow Meters: Ultra-Low Pressure Drop Gas Flow Management Arrays

Quick Answer: Alicat Scientific flow meters are often specified for ultra-low pressure drop gas flow management arrays because they combine mass flow, volumetric flow, pressure and temperature in one device. Silver Automation Instruments supplies compatible thermal mass flow meters and pressure transmitters for these arrays. Send us your pressure (bar), temperature (°C), pipe size (DN), and flow range for a quote.

Why Gas Flow Arrays Need Ultra-Low Pressure Drop

In gas flow management arrays, pressure drop is a daily operating cost. A 50 mbar extra drop across a flow meter on a 12 mbar budget can stop a pilot plant. This is why engineers look for flow meters with a low internal restriction. Alicat Scientific flow meters use a laminar flow element. This design gives a linear signal and a low pressure drop. We have seen customer sites in Vietnam where the total pressure budget for an array was 15 mbar. Every mbar counted.

Here is the thing. A pressure drop number on a datasheet is only one part. The actual drop depends on gas type, flow rate, temperature and inlet pressure. Air at 20 °C and 1 bar behaves differently from methane at 40 °C and 0.8 bar. You need to state these values before you compare suppliers.

Alicat Scientific Flow Meters in Multi-Channel Arrays

Multi-channel arrays are common in gas blending, burner control, fuel cell testing and bioreactor feeds. A typical array has 4 to 12 channels. Each channel needs a mass flow meter or controller. Alicat Scientific flow meters are often built into these arrays with RS-232, RS-485, analog 0-5 V and 4-20 mA outputs. Some versions include totalizer functions and gas select menus. These features reduce wiring and PLC analog input cards.

We do not sell Alicat devices directly. But we do supply thermal mass flow meters with similar output options. Our meters support 4-20 mA HART, RS-485 Modbus and pulse output. For arrays with DN15 or DN25 process connections, this works well. Most engineers skip the proprietary software part and ask for a standard Modbus map. That is a practical request.

Technical Parameters That Matter for Ultra-Low Pressure Drop

When you specify a gas flow meter for a low pressure drop array, list these parameters. First, the gas type or gas mixture. Second, the minimum and maximum flow rate in kg/h or slpm. Third, the inlet pressure in bar or mbar. Fourth, the temperature in °C. Fifth, the allowed pressure drop in mbar. Sixth, the process connection size such as DN15 or DN25. Seventh, the output signal such as 4-20 mA HART or Modbus RTU. Eighth, the hazardous area rating such as ATEX Zone 1 or Zone 2.

We often see spec sheets with a missing pressure budget. Then the supplier cannot confirm the drop. A flow meter with a 5 mbar drop at 50 slpm may look good. But the pressure drop is not a single number. At 200 slpm the drop can rise to 25 mbar. This is not a linear relationship. It follows the square of the flow rate for turbulent elements. Laminar flow elements such as those in Alicat Scientific flow meters have a more linear relationship. That is why they are preferred for array service.

Installation Notes for Low Pressure Drop Arrays

Install the flow meter with straight inlet and outlet runs. For thermal mass flow meters, a 10 DN straight run before the meter and 5 DN after is enough in most cases. Do not install the meter directly after a control valve or an elbow. Flow disturbances create false readings without raising the pressure drop. In multi-channel arrays, place the pressure sensor downstream of the flow meter. This gives a stable pressure drop value for each channel. Here is the thing. A small leak in the compression fitting can cause a larger reading error than the pressure drop itself. Use a leak test with soap water or a handheld s