Questions about the oxygen pressure control valve

Regarding the performance of control valves, the valve flow rate should not be within the range of speed limitations.

Just use a orifice plate – it’s cheap and effective

In pressure-controlled PV systems, no matter how large the valve is, the flow area during actual operation remains the same; the flow velocity through the valve core is also the same. However, the velocity at the valve outlet varies, with larger valves having a lower velocity. Under these operating conditions, the flow downstream of 10 KG is choked flow; the flow rate through the valve has no relation to the pressure difference, but it is related to the actual flow area of the valve. The rated Cv of the valve must be at least 15, and this valve is quite noisy. The biggest issue is the flow velocity at the outlet of the control valve. According to IEC recommendations, the outlet flow velocity for O2 should not exceed 0.3 Mach. With a flow rate of 800 NM3 at 30 kPa at the valve outlet, a valve with a diameter of at least DN50 is required to meet these requirements – and even then it’s at the limit. This means that the process pipeline upstream of the valve needs to be enlarged to accommodate a control valve of DN50 or DN80, in order to satisfy the required outlet flow velocity. The valve body can be made of stainless steel, but the internal components of the valve (valve core, valve seat, valve stem) . . ) It should be Monel/INCONEL material, and the flow rate through the valve element is also safe. What is the diameter of the pipe downstream? Just one opinion. I suggest you find a few more reliable manufacturers with experience in O2 valves, and ask them how they determine the outlet flow rate for O2 The order specifies an oxygen valve, and documentation regarding oxygen cleaning is required (to avoid hassle at the site); the entire unit shall be sealed and packaged for delivery to the site. @jiaguoyun

I checked the oxygen regulator manual, and it states that the pipe diameter must be designed based on the minimum pressure in the piping system. The explanation of piping systems refers to a separate set of design conditions involving interconnected pipes. In other words, it is necessary to design the flow rate at 30 KPA based on a flow volume of 800 NM3/h. This way, the valve flow rate can be ensured, right? So the construction and valve costs will increase by hundreds of thousands again :'(

What follows is a setting similar to evacuation, where air is injected at the inlet of the fan under negative pressure. The valve opening functions as a negative pressure area. DN100

I checked the oxygen regulator manual, and it states that the pipe diameter must be designed based on the minimum pressure in the piping system. This is stipulated from a security perspective. The minimum pressure density is also low; for the same NM3 value, the actual flow velocity is the highest. Even a flow rate of 12 KG upstream is no problem; the density is high. Are the O2 pipes all made of stainless steel? The explanation of piping systems refers to a separate set of design conditions involving interconnected pipes. In other words, it is necessary to design the flow rate at 30 KPA based on a flow volume of 800 NM3/h. There are two flow velocity systems before and after the pressure relief valve; the flow velocity is determined based on the respective minimum pressures. Does the 30KPA pipeline have a pressure relief mechanism? This way, the valve flow rate can be ensured, right? That means additional costs of hundreds of thousands will be incurred for construction and valves. The flow rate at the valve outlet is related to the valve’s diameter; here we keep the O2 flow rate below 0.2 Mach, though different companies have varying regulations. If you don’t set any requirements, manufacturers can refer to this and choose those with O2-related performance records, as they are more reliable. For a DN100 valve, the flow velocity at negative pressure is around 30 meters per second; if it’s a DN50 control valve, then the flow velocity would be 120 m/s, which equals 0.3 Mach What about the DN40 control valve? There is some risk associated with O2 design (as everyone knows). Safety is more important than anything else, and it’s not excessive design anyway. @jiaguoyun

Do you deal in control valves? Could you recommend some manufacturers? Thank you

From 330 kPa to 0 Pa, the speed is quite fast as well

It’s not the manufacturer; we don’t do sales. There are rules regarding the forum; please send me a private message. O2 venting is also troublesome, whether it's the control valve or the safety valve.

Although there is a pressure of 12 KG upstream, if the valve fails or the transmitter malfunctions and causes the valve to open fully, then in a DN40 stainless steel pipe over 300 meters long, the pressure difference will drop from 15 KG (the pressure loss is relatively high for a 300-meter pipe of DN40) to 0 PaG. It is certain that at some point the pressure will be below 0.1 MPaG and the flow velocity will exceed 25 m/s. Therefore, my judgment is that for the piping system specified by the oxygen code (which is a separate set of interconnected design conditions), the pipes before and after the valve are also interconnected under these design conditions; thus, the designer must take into account the pressure before the valve when determining the pressure after it. So I think it is reasonable to design the pipe diameter based on the minimum pressure required for use. This is my first time dealing with oxygen pipeline design, so please forgive any mistakes or unclear points in my explanation!