Q & A > Question Details
In our DHDT unit (Axens licensor) one PV is given after the feed filter package to maintain a back pressure of 5kg/cm2. What is its importance?
In the other DHDT unit (Haldor Topsoe) there is no PV given.

20/04/2021 A: Jake Gotham, InSite Technical Services, jake.gotham@insitetechnical.com
Without seeing your drawings it would be difficult to know for sure why the valve is there, but…
My first guess is that the Axens unit has backwashed filters that use filtered feed to flush the fouled filters. The backpressure is necessary to drive the backwash flow through the fouled filter and away to slop.
My next guess is that the Haldor Topsoe unit either has cartridge filters (no backwash required) or uses a different fluid for backwash (e.g. product rundown) or operates with the feed drum at high enough pressure to drive the backwash.