normally below 10 mic
reference :
Hot Oil System Design Guide - Daum
cfs10.blog.daum.net/upload_control/download.blog?fhandle...13...
Dowtherm for Low Temperature Transfer. Dowtherm A, G, HT, J, MX, ... 3: HTF filtration – How and Why ... Therminol 55, 59, 66, 72, 75, D12, FF, LT, VP-1, XP. 1.