How to select a large pressure difference control valve?

The use of angle valves allows for a large pressure drop to be achieved.

A large pressure difference between the front and back sides allows the use of a regulating butterfly valve

Multi-stage pressure-reducing control valves can be used.

A straight-through valve or a needle valve should be chosen; butterfly valves are definitely not suitable. Butterfly valves are also rarely used in control valves.

Selection of large pressure difference control valves: First, it is necessary to determine the magnitude of the pressure difference. For high pressure differences of 10 MPa or more, high-pressure angle-type control valves can be used (with plungers or cage-type internals; the cage type offers better self-balancing capabilities and results in less wear on the valve element). If the pressure is around 2.5 MPa, either a double-seat valve or a cage valve can be used; the key factor here is the self-balancing capability. Ordinary single-seat valves cannot be closed properly under high pressure differences, and of course the properties of the medium also need to be taken into consideration. A corner valve around 4.0 MPa can be considered. The key is to know what occasion you will use it for.

I think each specific issue needs to be analyzed on its own. Generally, angle valves or single-seat valves are more suitable, as their design is well-suited to withstanding high pressures and they offer excellent control performance. Of course, it is still necessary to calculate the Cv value in order to select the appropriate valve size. However, for such valves operating under high pressure differences, the Cv value under normal operating conditions is usually very low. When choosing the valve size, it is important to consider whether there are any requirements regarding the flow rate of the fluid; in the case of valves used with high pressure differences, the flow rate is quite high, so selecting the right valve size is crucial for controlling this flow rate. Additionally, the material of the valve also needs to be taken into consideration. If the saturated vapor pressure of the fluid medium and other factors are also important considerations. There are also factors such as noise. In short, there are many things to consider.

Agree with what was said on floors 9 and 10. When selecting valves for high differential pressure environments, valves with strong pressure recovery capabilities (ball valves, butterfly valves) should definitely not be chosen; instead, single-seat valves or angle valves must be selected. Regarding the method chosen, as mentioned on floor 9, I’d like to add that for single-seat valves, when there is a high pressure difference, another option is the labyrinth valve; its flow channels are winding, which helps to gradually reduce the pressure and also effectively prevents cavitation.

Sleeve-type control valves can also be used in high differential pressure environments

I agree with the person above; using sleeves allows for large pressure differences before and after the valve, and multi-stage sleeves offer even greater functionality

I don’t know exactly how large the pressure difference is in what you call a large differential pressure, nor what type of gas it controls or whether leaks are allowed. Because this is a crucial issue in selecting a control valve. Only by clarifying the problem I mentioned can you select the appropriate control valve as stated on floor 9 and also in floor 10.

A straight-through valve or a needle valve should be chosen; butterfly valves are definitely not suitable. Butterfly valves are easier to operate compared to other control valves. They are used in pipelines with relatively large diameters; angle valves are chosen for applications involving pressure reduction. For example, in petroleum hydrocracking processes, pressure regulators for high and low pressure stages are used. For low-pressure applications, double-seat valves can be utilized, or globe valves can also be used – the choice depends on the specific circumstances

An eccentric rotary valve is something to consider, but it doesn’t seem cheap

When choosing a large pressure difference control valve, it is essential to first determine the pressures before and after the valve. When the control target is a gas, attention should be paid to cavitation phenomena, whether the medium is corrosive, toxic or harmful, flammable or explosive, as well as temperature, etc. Under normal circumstances, if the pressure difference is within 30 kPa, a control valve with a sleeve structure can be chosen ； If the pressure difference is high, multi-pole pressure reduction or orifice plate pressure reduction should be used. For details, you can consult our factory’s technical staff.

I have painful lessons to learn in this regard. Due to the inaccurate pressure difference specified in the process requirements (the values given for the pressure before and after the valve are too low; in practice, the actual pressure difference is much higher than the design value, which leads to excessive vibration of the valve body during automatic control and damage to the valve element), it is essential to determine exactly what the pressure difference before and after the valve will be when selecting a valve with a high pressure difference handling capacity. The pressure difference at which the valve closes should be one order of magnitude higher than the value specified in the process requirements. Then, depending on the properties of the medium, different types of control valves can be chosen, such as angle valves, cage control valves, sleeve valves, etc. If the pressure difference is very high, then pressure reduction methods such as using pressure reducers or orifice plates are necessary. What was said above is completely correct.