I want to reduce the prssure of a liquid flow (ethanol) from 16.7 atm to 1.2 atm? Do I need more than one valve?
One control valve can reduce pressure, as long as there is always a significant flow through it. The main reason for using more than one valve is usually to reduce or prevent cavitation caused by a large pressure change through a given valve. Ethanol has a pretty high vapor pressure, so cavitation might be a problem. Control valve manufacturers usually provide design guides for their valve trim choices (often in software form) that lead you through the choices and requirements. Each valve design has different limits. But, my seat of the pants feel is that you can do this with one valve. I have included an example. I am not specifically recommending this company. -- Regards, John Popelish
