passyourgas.blogspot.com/ Explains how the vapour expansion devices operate inside an oven. You will be asked to explain and test the working of these devices in your ACS Gas exams and Assessment.
What a useful and well explained video - explained with graphics and SLOVELY spoken, also without any distracting and unnecessary or confusing comments! Thank you very much for your time and effort sir! As a trainee (with the hope to qualify soon) found it very useful and informative!
Loving these videos, I actually understand how it works and how to test it. It would be great if you could do a video on testing the grill and hob. Also for me It would be really helpful if you did a dedicated video to combustion analysts and flue integrity. Please keep up this amazing content
Nice video only one thing am abit confused is that do both valves have a bypass but have one bypass in the cooker oven i thought the thermosat has bypass and not the fsd
Hi Ruman, thanks for the question. I can see why you’re confused. Think of it this way. An fsd must have a flame to make it open. But how do you get a flame when an fsd is always closed when an appliance is off? There are two ways we do this … 1 is how we do it with a fire or boiler.. we hold the fsd open by pressing down the control for 5 to 10 seconds to allow the gas through at the start, doing this allows a flame to light, heats up a thermocouple and the valve stays open when we release the control. On a cooker it would be a pain to have to do this every time you wanted to cook something, so we have to find an alternative. The only other way to allow gas to a flame with a closed fsd is to create a small bypass to allow enough gas through to light a flame big enough to heat the fsd and open it. You can see this in action when you first light the oven..it starts on a small flame..this is the gas going through the fsd bypass…then…when there’s enough heat and the fsd opens, he flame becomes much bigger. So it is a fact that an oven fsd never shuts off the gas fully it always allows a tiny amount through. This is ok though because the thermostat closes the gas off when it’s shut. I hope that helps
@@passyourgas i appreciate you replying to my question i understand that a fsd has a bypass to allow small amount of gas through to light on low then once heated it gets high flame. But am not understanding the bit on the themostat bypass whats that for, is this where when we turn on the oven it allows bypass rate through the thermostat as its always open goin to fsd bypass as its closed which then ignites on low and when the fsd heats up this then opens the fsd allowing full rate which will heat the oven allowing the thermostat bellows to close only allowing bypass rate to the fsd bypass please correct me if am wrong how it works i struggle with this gas controll in my acs class thank you your a star.
Ok, no problem. The thermostat controls the heat inside the oven. When the oven reaches the correct temperature that you’ve set (gas mark 4,5,6 or whatever) it will close, stopping the gas..then when the oven cools, it opens again allowing gas through, however, it’s like the fsd problem, if it closed the gas completely then the flame would go out and you would have to keep lighting the oven to keep it warm, so like with the fsd there is a bypass hole to allow gas through even when the valve is closed. This means the flame changes between high and low during cooking. Unlike the low flame at the start which is controlled by the fsd bypass, the low flame while cooking is controlled by the thermostat bypass (because the fsd is open while a flame is present) this low flame while cooking is called the bypass rate because the gas is being restricted by the thermostat not the fsd. Does that clear it up, if not let me know. 😁 Both controls have a bypass but the thermostat bypass only opens when you turn the control knob to a heat setting.
@@passyourgas lol yes i think i got it so as i mentioned earlier when you turn the thermostat control say any number gas flows through the thermostat bypass and this flow rate passes into fsd bypass allowing it to ignite on low. 😄 please say am right your a legend
Ruman, you’re ALMOST right. When you turn the thermostat to a number, the thermostat opens and gas goes straight through it, the bypass isn’t involved at this stage, in fact neither bypass is involved as the fsd is fully open as well (because the flame is on). The thermostat bypass only gets involved when the OVEN gets hot enough to close the thermostat. Think of it this way … if you are driving a car you use the accelerator to set your speed, once you’re going fast enough you lift your foot off the accelerator but the engine doesn’t stop because there’s still a bit of petrol allowed into the engine even when you’re not pressing down the accelerator. The thermostat is the accelerator of the oven. When it gets hot enough it “lifts its foot off the gas” but the thermostat bypass makes sure the flame doesn’t stop. The fsd bypass is only ever needed at start up of the oven, after that it does nothing at all and everything is controlled by the thermostat.
