Check valve for inline fuel pump after surge tank

Hi all-

I have a 255 in tank feeds to a surge tank then a DW350 inline pump (no built in check valve) feeds to rail, is it necessary to run a check valve for DW350? Also I plan to do a parallel staged dual Bosch 044, is the check valve only needed on the 2nd pump that only comes on with a hobbs switch triggering a relay? Is there any significant difference to the position of the check valve (pump out vs close to rail)?

Thanks!

hello, i prefer to run a check valve on all twin pump setups and i fit them to both pumps after the surge tank on the outlet of the pumps. the reason for this is if either pump fails or is staged it stops the fuel recirculating to the tank and maintains constant fuel flow to the rail.