Mass Flow Meters with Low Pressure Drop
Now, this works if you have enough pressure in your subatmospheric system to lose a whole psi through the flow meter. If we look at the available pressure at ½ atm, the pressure drop across the oversized M-1SLPM-D meter restricts 1 psid, or around 14% of your available pressure. It gets even tighter working at ¼ atm, where the oversized M-2SLPM-D meter again induces 1 psid of pressure drop, which is now 27% of your available pressure. This is not optimal, especially when you are limited in your available pressure.
Whisper-series mass flow meter, shown with optional color display
Ah-ha! Alicat has a solution: Our “Whisper” series of low pressure drop mass flow meters are perfect for this type of scenario, since their pressure drops are very low compared to our standard M-series meters. An oversized MW-1SLPM-D Whisper meter has a pressure drop of only 0.07 psid at ½ atm and 500 sccm, which is now just 1% of your available pressure. Both the standard mass flow meter and the Whisper meter will perform with the same accuracy under these conditions, but using a low pressure drop Whisper will give you a lot more breathing room in terms of pressure loss as you design your subatmospheric system.
If you have questions about your subatmospheric or vacuum application, please contact us (firstname.lastname@example.org or 042-824-7001) so one of our applications engineers can help you find the right solution.