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What effect does gaseous flow rate have on flame photometry?

Flame stability can be affected by a number of different factors when using a flame photometer. But today we ask about the effect gaseous flow has on flame photometry.


At BWB-Tech, our built-in air-compressor technology enables ambient air to be used in our flame photometers, instead of pressurised gas canisters like other manufacturers’ products.


However, the pressures of the fuel and air mixture, together with its throughput of the instrument, affects the stability of our all-important burner head flame.


In the instrument’s “rubber jungle” - which you could see if you opened it up - gas and air pass through the pipework and into the mixing chamber, where the sample is introduced.


Thinking logically, it would bring us to believe that fluctuations in the pressure would have a direct effect upon the stability of the flame.



How can you regulate the pressure of gasses in a flame photometer?


At BWB-Tech, we use an alternating valve in our gas intake valve.


This detects the pressure emitted from the gas canister and regulates the intake through changing the orifice size of the valve.


If the pressure is too low, the flame would be able to backburn through the system.


Too high, and the flame would become too large for the chimney section to handle, leading to safety concerns.


We also add a manually-adjustable dimmer valve to the right-hand side of the instrument so that you can manually adjust the flame size.



BWB Flame Photometer components

How is the air intake operated in a BWB-Tech flame photometer?


More importantly than the easily-regulated pressures from a canister of gas, is how the air intake is operated.


A pump is used to pressurise the air. This creates negative pressure within the system so that ambient air can be drawn into the intake valve.


However, the most important part of this is having very small yet high frequency pumps of air.


This is because if a large stroke volume in combination with a low frequency were to be used, the flame would fluctuate with the downstroke and upstroke of the pump as it works mechanically.


These large fluctuations in pressure would, therefore, cause the flame to physically shift in size as air is pushed through it.


A constant and controllable pressure of fuel and air is one of the most important factors in flame stability. It’s also crucial for accurate readings in practically all instrumentation that utilises a flame for detection.