Why are cam-deflected valves rarely used?
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Colleagues, many years ago I used a cam-deflection valve to reduce the pressure from 1.2 MPa to 0.6 MPa in the steam pipeline that led from the main steam line to the workshop; it was of German manufacture and worked extremely well, with no problems at all over a period of 3 years. It could be sealed tightly even when the workshop wasn’t using steam, which left a very strong impression on me. As a result, every time I purchased a control valve, I would think of this one. However, after visiting many other facilities, I found that cam-deflection valves (also known as eccentric rotary valves) were rarely used. I’m really puzzled by this – for reducing the pressure of superheated steam under high pressure differences, I believe these valves still perform very well. Why do people prefer sleeve valves and use cam-deflection valves so little? I truly can’t understand it.
My personal understanding may not be correct, but the phenomenon does exist. That means the “relationship unit” must be matched; you cannot buy from other units that are not part of that relationship network. This is to ensure that the benefits don’t go to outsiders. Everything must be analyzed from the source; the relevant entity for the design unit is the equipment manufacturing unit. It is difficult for suppliers to enter the market due to low profits. It is also difficult for companies to influence the equipment selection decisions of design firms, as they are the technical authorities. If things don’t go well, the design firm chosen by your company may also be determined through connections, and the situation can be quite complicated. If you are not one of the users, it’s best to just submit a report to explain the situation and make a request; it’s better not to get involved in anything else, as there are interests at stake. Often, the user has no control over the provider; the provider takes into account not only the user’s interests, and the user’s interests are merely related to ease of use.
What you’re talking about are all the realities and phenomena of this society; it’s clear that you’re very mature and have a lot of life experience. But now, when companies decide on technical upgrades and valve selections, they dare not use cam-deflected valves rashly, even though they may seem more suitable; due to the lack of sufficient precedents, they opt for conventional control valves instead. I’m facing this situation right now – I would rather choose sleeve valves than risk using cam-deflected valves. So I was wondering if my colleagues have used cam-deflected valves for steam pressure regulation, and what the results have been.
We use it here with heavy oil media that contain solid particles; it was specified in the design requirements at the time of installation, though the exact reason is unknown!
I think that if you have sufficient capability to ensure that such valves offer excellent competitiveness in terms of cost and reliability in actual use, then you should go with them. Just give it a try as long as it makes sense in principle. But one also has to consider what might happen to oneself if it is not successful. Back then, I built a fogger, but I ignored the impurity content in the waste heat steam; as a result, it got clogged very quickly and became unusable. Success is certainly satisfying, but the taste of failure is also quite unpleasant; P
Low pressure is handled by the C-type ball valve, while high pressure is handled by the sleeve. It is difficult to achieve low noise with this type of valve, and its precision is not as good as that of the previous type; some of them use spline connections, which makes maintenance inconvenient. The only thing I appreciate is its dirt resistance.
As a result, a sleeve valve was still chosen – it’s safer, as one cannot afford the consequences of poor regulation.
It makes sense; indeed that’s the case. It seems like sleeve valves are practically invincible. From a maintenance perspective, it is indeed inconvenient.
I didn’t choose this model; my predecessor, who had just graduated, picked it, and it works very well.
Last century, this valve was widely used, for example in steam applications