Background introduction – why use a flow stabilizer?

In the gas analysis and detection related industries, the gas sampling process has strict requirements on the sampling pump. The pump needs to output a relatively smooth and stable airflow to ensure the accuracy of the detection. At the same time, the pump needs to be compatible with complex medium and can work stably and reliably for a long time.

Common gas sampling pumps in the industry are micro diaphragm pumps and rotary vane pumps, both of which have their own advantages and disadvantages. If only considering characteristics such as medium compatibility, lifetime and reliability, diaphragm pumps have great advantages. Only in terms of air flow stability, the diaphragm pump is a reciprocating positive displacement pump, and the output air flow of the diaphragm pump will be more pulsating than that of the rotary vane pump.

The effects of airflow pulsation mainly include:

1. The pulsating air flow may affect the value of the gas sensor. Some sensors require the gas to pass through the sensor probe at a uniform and constant flow rate to obtain accurate values. When the pulsating air flow passes through the sensor probe at an uneven speed, it may cause numerical errors.

2. The pulsating air flow affects the flow control of the MFC. When the MFC performs flow control, it needs to measure the flow accurately, and the pulsation of the air flow will cause the flow rate to fluctuate within a certain range, affecting the control accuracy.

The test that affects the flow rate, especially the mass flow sensor needs to measure the speed of gas flowing through the sensor. When there is pulsation, the flow value obtained by the mass flow sensor is a fast-moving value, High sampling rate is required for sampling and average calculation in software, which increases the difficulty of flow measurement design.

Based on the above reasons, in the past, only rotary vane pumps could be used in the industry where stable flow was required, instead of positive displacement pumps such as diaphragm pumps, which inherently have gas pulsation, but correspondingly,the bottleneck of chemical compatibility, air tightness, lifetime of rotary vane pump will have adverse effects on the other hand

In order to make up for the problem of large air flow pulsation in reciprocating positive displacement pumps such as diaphragm pumps and piston pumps, flow stabilizers came into being.

Features of the flow stabilizer

Steady flow effect: Hilin FS0004A flow stabilizer adopts buffer and steady flow structure to stabilize air flow pulsation and achieve good steady flow effect.

Lifetime advantage: The product has a compact structure, no moving parts, no wear, and has obvious lifetime advantages

Chemical stability: The main body of the flow stabilizer is made of reinforced nylon, and the internal components are made of stainless steel. In order to ensure good sealing, the sealing ring made of nitrile material is used to ensure the sealing performance. The main material is resistant to alkali and most salt liquids, weak acids and some organic compounds, and has good flame retardancy and anti-aging performance; the internal material is resistant to oxidation and corrosion; the seal material is good in oil resistance, wear resistance and aging resistance .

 Modular connector: it can be matched with three different specifications of connectors, small straight hose connector (Default), large straight hose connector, and elbow connector, all of which are made of reinforced nylon

Operating conditions

1) Environment: The recommended ambient temperature 0°C ~50°C, and the relative humidity≤90%.

2) Medium: The temperature of the medium should be within the range of 0°C~ 50°C, and the gas is allowed to be rich in water vapor, but contains the size of solid particles must be less than 0.5mm, otherwise the flow stabilizer will be damaged; it is forbidden to suck oil mist gas.

3) Pressure resistance: The designed pressure resistance of the flow stabilizer shell is 200kPa, and limit the pressure of the air path not exceeding the designed pressure value.otherwise it may   lead to loss of air tightness and rupture risk.

The effect of the flow stabilizer

As shown in the figure below, the data curve measured by Hilin FS0004A flow stabilizer  combined with our C26S-24V miniature air pump.

As shown by the blue line, when the micro pump is not connected to the flow stabilizer, the output instantaneous flow rate presents obvious periodic pulsation. As shown by the orange line, after the micro pump is added with a flow stabilizer, the amplitude of the pulsation is greatly reduced, approaching the average flow after adding a flow stabilizer.

Connection method of Hilin flow stabilizer

When the flow stabilizer is connected with the vacuum pump, the flow stabilizer is located on the side of the air inlet pipeline of the air pump, and it is located in the negative pressure range during operation. Connect the air source side of the flow stabilizer to the air inlet of the air pump. As shown in the figure below:

When the air path is connected with a compressor, the flow stabilizer is located on the side of the exhaust pipe of the air pump, and it is at positive pressure range when working.connect the air source side of the flow stabilizer to the outlet of the air pump. As shown in the figure below: