Selection of control valves
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Dear experts, for a hydrogen pipeline with a DN400 pipe, the CV value is determined based on the flow rate, while the valve seat has a DN150 size. I would like to ask which of these three types of valves is the best choice: balanced cage single-seat control valve, single-seat sleeve control valve, or sleeve-guided single-seat control valve? What’s the difference? Thank you
For these three types of valves, the first one is a single-seat valve with a cage; it can also be a sleeve valve. The latter two types are sleeve valves. For the hydrogen gas flowing through this valve, it is necessary to take into account the flow rate of the hydrogen gas; it’s best not to have too much reduction in diameter. If there are no impurities inside, a sleeve valve should be used. If the pressure is high, a pressure-reducing sleeve valve should be employed.
First of all, I should mention that I am still a student and have no experience in engineering. When setting up the test bench earlier, I chose a Kv400 control valve, which was suitable under the designed operating conditions; however, it couldn’t be adjusted under some non-designed operating conditions as it exceeded the adjustable range. It is recommended that you calculate all the non-designed operating conditions before determining a more appropriate Kv value
As for the advantages and disadvantages of these valves and how to choose among them, let’s wait together for the experts to provide answers{:9001:}
The first type of valve core is the balanced-type core; depending on the diameter of your valve seat, it is recommended to use a balanced valve core, as this ensures pressure balance on both the upper and lower sides of the valve core, allowing for the use of a smaller actuator. The other two types do not specify whether the valve core is of the balanced type, so they are not discussed. Also, for your pipe with a DN400 diameter and a valve seat of 150 mm, make sure to leave sufficient straight sections of pipe before and after the control valve.
I’ve always been curious about one thing: under the same operating conditions, which is more expensive, a shut-off valve or a control valve?
Your reduction in diameter is way too extreme; the pressure under hydrogen operation is quite low. For adjustable applications, butterfly valves are the better choice, mainly due to their excellent price advantage