Slotted strainers are mounted above positive displacement motor and used to prevent foreign objects and coarse slurry getting into motor. Main advantages of slotted strainers designed by NGT company in comparison with those of other manufacturers are listed below:

1. Filtering element is easy to extract to get cleaned in the field conditions.
2. Filter case works as “flex sub” reducing tension in stator thread of PDM when going through the smaller radius part of the well.

Specifications	Designations
	F-95 F-106	F-120	F-165	F-178	F-210	F-240
Outer diameter, mm	106	120	165	178	210	240
Total length, mm	889	870	1100	1100	1100	1 050
Case length, mm	800	768	986	973	973	923
Connecting thread, top (box)	З-86	З-102	З-133	З-152	З-152	З-171
Connecting thread, bottom (pin)	З-86	З-102	З-133	З-152	З-152	З-171
Filter degree, mm	4	4	4	4	4	4
Mud flow rate, l/s, not more than	18	21	31	45	45	70
Weight, kg	27	40	87	134	134	183

Sand content in the mud shouldn't be more than 1%.