Use of steam hoses at field service stations
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When using hot water, turn on the cold water first and then the steam; the order cannot be reversed, otherwise the hoses will move around. Here’s the question: why does the rubber hose swing? It doesn’t seem to be explainable by water impact; I hope experts can provide a detailed analysis
This post was last edited by ylb913 on 2016-5-21 at 12:25. 1. The amount of steam used is small (in terms of mass), while the amount of water used is large; water should be turned on first and then steam. The opening degree of the steam valve needs to be adjusted carefully. 2. In terms of flow velocity, with the same mass flow rate (or even a lower mass flow rate of steam), since steam is a gas, its flow velocity is high; even when only steam is used and no water is involved, the tape will still behave abnormally. Water, being a liquid with a low flow rate, is not easy to use for performing dragon dances. 3. The issue of whether a dragon should be used or not: What was mentioned earlier regarding flow rate actually refers to the reaction force caused by the jet at the outlet; the higher the flow rate and the stronger the jet, the greater the reaction force. Water is added first, followed by steam; hot water is produced rather than gas, so the flow rate cannot be very high.
When we blow air for heat tracing, someone has to step on it to open the valve!
First of all, I am very grateful to the forum moderator for their patient answers. I’m sorry my question did not clearly express my doubts. My main question is: the correct procedure is to turn on the cold water first and then the steam, and to turn off the steam first and then the water – why can’t it be done in reverse? Inspired by the forum moderator, my idea is to install a small mixer at the outlets for steam and water at the on-site service station. By opening the water valve first, water acts as the continuous phase; then, when steam is introduced, it mixes with the water, and the steam is immediately cooled, resulting in hot water coming out of the pipe. If steam is released first, it becomes the continuous phase while the gas is present in the pipes; when the valve is then opened, the steam is immediately cooled and turns into a liquid in the pipes. The medium in the pipes changes from gas to liquid, and since the flow velocity of gas is much higher than that of liquid, water hammer occurs, causing the connections to separate suddenly and potentially injuring people. Please give me some advice. Thank you